Category: Week 16

2023 Week 16 (Released August 25, 2023)

Harvest is now well underway and the risk of insect damage to crops is declining as crops mature and are being harvested. This will be the last Weekly Update of 2023. The Prairie Pest Monitoring Network sincerely thanks everyone who has contributed to the 2023 Weekly Updates.

We wish everyone a safe and insect-free harvest season and fall insect scouting season – remember that the annual grasshopper survey is happening now across the prairies and that the wheat midge and wheat stem sawfly surveys will start after harvest is completed.

In 2023, development of many pest insects occurred earlier than normal, thanks to warmer than average weather during this growing season. In particular, we observed adult grasshoppers in mid-June for the first time in more than 30 years (if ever!). Adult grasshoppers will be busy reproducing now, and in looking to next year, insect surveyors are working to estimate grasshopper populations in ditches/roadsides and may be collecting samples of adult grasshoppers for species identification.

Diamondback moth, if present, are into the fifth non-migrant generation across the southern prairies now, with the fourth generation occurring in the more northern parts of the prairies. Diamondback moths could pose a threat to crucifer vegetables right now, as well as any canola that is late to mature.

This week, the Prairie Research post highlights studies being done at the University of Saskatchewan to learn more about the ability of ground beetles to contribute to weed seed management.

Use the links in the Provincial Insect Updates post to learn more about what is happening with populations of insect pests (and beneficial insects) in your province. In Manitoba, Dr. John Gavloski notes that grasshoppers remain a concern, that flea beetles are being found in high numbers on the pods in some canola fields and that some bertha armyworm larvae have been found in some canola fields. Dr. Gavloski also noted that there have been a lot of cabbage white and checkered white butterflies active in Manitoba late this summer. Dr. Vankosky observed high numbers of both butterflies in southeast Saskatchewan too. As in Manitoba, Dr. James Tansey reports that high grasshopper densities are a particular problem in central and southern Saskatchewan.

Remember:

1) There are many resources available to help with planning for late-season insecticide applications to ensure Pre-Harvest Interval requirements are met.

2) Insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification are available from the Prairie Pest Monitoring Network.

To receive Weekly Updates automatically, please subscribe to the website!

Questions or problems accessing the contents of this Weekly Update? Please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca) to get connected to our information. Past Weekly Updates, full of information and helpful links, can be accessed on our Weekly Update page.

Weather Synopsis

This past week (August 14-20, 2023) the southern prairies experienced warmer temperatures and minimal rain. In contrast, cooler, wetter conditions continued to persist across most of the Parkland region.

The seven day average daily temperature was 1.5 °C warmer than average in the last week. The coolest temperatures occurred across the central and western areas of the Parkland region (Fig 1).

Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of August 14-20, 2023. 

Growing season (April 1, 2023 to August 20, 2023) average temperatures were warmest across Alberta, southern Saskatchewan and southeastern Manitoba (Fig. 2).

Figure 2. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 20, 2023. 

In comparing the 2023 growing season temperature to the long-term average temperature for the same period (Fig. 3), growing season temperatures were 2°C warmer than average across Alberta in 2023. In Saskatchewan and Manitoba, the growing season average temperature was 1°C warmer than normal (Fig. 3).

Figure 3. Temperature (°C) anomaly (based on difference of average temperature between observed and climate normals) during the growing season (April 1 – August 20, 2023). 

Precipitation for the period of August 14-20, 2023 was greatest across the Parkland regions of Alberta and Saskatchewan (Fig. 4). Rainfall amounts were negligible for the Peace River region as well as south and central regions of the prairies. A more widespread rainfall event on the prairies occurred between August 21 and 24, bringing precipitation to many parts of the prairies.

Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 14-20, 2023. 

Growing season cumulative rainfall amounts were greatest in a region that extended from Red Deer to Grande Prairie (Fig. 5).

Figure 5. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 20, 2023. 

Rainfall amounts for central and southern regions of the prairies have been well below average (Fig. 6) in 2023. Areas around and including Lethbridge, Alberta, for example, received 40-70% of the precipitation expected in a ‘normal’ year, based on comparing 2023 to 30-year average weather datasets.

Figure 6. Percent of normal precipitation received during the 2023 growing season (April 1 – August 20, 2023), based on a comparison of cumulative rainfall in 2023 to the climate normal cumulative rainfall (mm).  

Predicted Grasshopper Development

As a result of warmer than normal temperatures, grasshopper development continues to be well ahead of normal in 2023. This year, adults have occurred much earlier than normal (middle of June in some locations!) and simulations also indicate that adult females have begun laying eggs much earlier than normal.

The oviposition index provides a relative comparison of grasshopper oviposition rates across the prairies. The oviposition index predicts that oviposition should be occurring across the prairies, and that egg production should be greatest across southern regions of Alberta (Fig. 1), as of August 20, 2023. Egg production should also be high in areas of southern Saskatchewan and southern Manitoba, assuming that grasshoppers are present.

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of Augst 20, 2023. Higher ovipositional index values indicate greater potential for oviposition (egg-laying). 

Compared to a ‘normal’ year (based on 30-year long-term average weather data), the potential for grasshopper oviposition in 2023 in August has been very high. In a ‘normal’ year, the grasshopper development model predicts that oviposition would be underway in early August, but only in the southern region of the prairies, and with a lower average oviposition index (Fig. 2) than predicted for 2023 (Fig. 1).

Figure 2. Long-term average predicted grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 20 (based on climate normals). Higher ovipositional index values indicate greater potential for oviposition. 

Geospatial maps are a tool to help time in-field scouting on a regional scale but grasshopper development and population densities can vary from place to place. Scouting is required to accurately assess the stage of grasshopper development and to estimate grasshopper densities.

Information about grasshoppers and grasshopper monitoring is available from the Prairie Pest Monitoring Network, in the Field Crop and Forage Pests guide, Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, and Manitoba Agriculture. 

Predicted Diamondback Moth Development

After arriving in western Canada in the spring, migrant diamondback moths begin to reproduce. In western Canada, there are usually up to four non-migrant generations of diamondback moth produced in ‘local populations’ during the growing season.

Due to warm weather in 2023, development of diamondback moth populations is well ahead of average development. Model simulations to August 20, 2023, indicate that the fourth and fifth generations of non-migrant adults (based on early May arrival dates) are currently occurring across the Canadian prairies (Fig. 1). Fourth generation diamondback moths, if present, are occurring farther north on the prairies compared to fifth generation diamondback moths.

Figure 1.  Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 20, 2023.  

In a ‘normal year’ based on climate normals data (e.g., 30-year averages), we would expect the third generation of non-migrant diamondback moth to be occurring across the northern prairie region at this time of year, with the fourth generation occurring across the southern regions of the prairies (Fig. 2).

Figure 2. The predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 20, based on climate normals data.

Considering advanced canola development, risk across the southern and central regions of the prairies associated with the development of a fifth generation of diamondback moth should be minimal. In regions where broccoli, rutabaga, and other brassica vegetables are grown and where crops are late to mature, these crops could still be at risk of damage from diamondback moth. Keep scouting for diamondback moth where crops are still green and could provide a desirable food source for developing diamondback moth larvae.

To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.

Provincial Insect Updates

Visit the Alberta Insect Pest Monitoring Network and Crop Insects pages for information about insects and monitoring in Alberta, including links for live maps from the 2023 monitoring season for diamondback moth, bertha armyworm, cutworms, and cabbage seedpod weevil.

Saskatchewan Crop Production News issues are now online! Issue 5 is available now and though it focuses mostly on plant pathogens and weed management, there is an updated Crop Report for the period of August 15-21. The crop report notes that grasshoppers and gophers are causing some late season damage to crops, as well as winds, localized flooding, and drought. Aster yellows has been observed in crops. There are links on the Crop Production News page so that interested readers can subscribe to the newsletter or read issues from past years.

Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year). The August 23 issue provides an update on grasshoppers, flea beetles, and bertha armyworm. It also has features insect pests that are often found in storage bins that could affect grain quality and a quiz for identifying butterflies!

Prairie Research: Carabid Beetles that help Manage Weeds

*Text for this post prepared by Daniella Canon-Rubio and Christian Willenborg, University of Saskatchewan.

At the University of Saskatchewan, Christian Willenborg, Khaldoun Ali, and Daniella Canon-Rubio are studying the role of carabid beetles in the biological control of weeds. These remarkable beetles have gained acclaim for their vital ecological role across diverse agroecosystems, including as predators of pest insects and for contributing to weed management by actively reducing the population of weed seeds in agricultural fields.

Stereoscope image of an adult of Pterostichus melanarius. Picture provided by Daniella Canon-Rubio, University of Saskatchewan.

The seed selection process in carabid beetles is a multifaceted phenomenon, subject to the influence of various ecological factors. The objective of Daniella’s study is to examine the effects of imbibition on the preferential tendencies exhibited by Pterostichus melanarius and Amara littoralis carabid beetles towards the seeds of Bassia scoparia (kochia) and Thlaspi arvense (stinkweed).

Stereoscope image of Thlaspi arvense seed eaten by P. melanarius next to an intact seed. Picture provided by Daniella Canon-Rubio, University of Saskatchewan.

Their research will involve conducting field experiments to trap live adult insects using pitfall traps. In the laboratory at the University of Saskatchewan, studies in controlled feeding environments will be conducted with varying imbibition length times to allow for the evaluation of seed preferability and consumption. Seed imbibition occurs when dry seeds take up water. Concurrently, we will utilize an olfactometer to evaluate how the odor emitted by Bassia scoparia and Thlaspi arvense seeds, treated with various imbibition times, influences the seed selection and favorability of Pterostichus melanarius and Amara littoralis. To integrate and analyze the behavioral data obtained from this experiment, we will employ Ethovision, a sophisticated software platform, to track the subjects through video analysis, perform movement analysis, and accurately identify specific behaviors exhibited by the beetles.

Through the implementation of this research on biological control in conservation, our objective is to significantly expand and enrich the knowledge base concerning carabid beetles and their feeding behavior in relation to diverse weed seed characteristics. By fostering a comprehensive understanding, we seek to promote awareness among farmers and fellow researchers about the valuable role carabid beetles play as beneficial organisms in North America. Furthermore, we aim to encourage the utilization of carabid beetles as an alternative approach to weed management.

Pre-Harvest Intervals

It is necessary to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.

Helpful resources include:
• The Keep It Clean website, with information about PHI and Maximum Residue Limits (MRL)
• The Pest Management Regulatory Agency fact sheet, “Understanding Preharvest Intervals for Pesticides”, with a free copy available to download
• Keep It Clean’s “Pre-Harvest Interval Calculator” that will help to accurately estimate PHI for a variety of crops
• The Pre-Harvest Glyphosate Stage Guide
• The provincial crop protection guides include the PHI for every pesticide by crop combination. The 2023 Crop Protection Guides are available as FREE downloadable PDFs for Alberta, Saskatchewan, and Manitoba.

Parasitoids of Wheat Stem Sawfly

Bracon cephi and Bracon lissogaster are the primary parasitoids that attack wheat stem sawfly and help to regulate wheat stem sawfly populations in North America. These closely related parasitoid species are described as idiobiont ectoparasitoids. The parasitoid larva, after hatching from an egg laid on the surface of the wheat stem sawfly larva, consume the entire host except for the host’s head capsule and exoskeleton. Both Bracon species complete their development and pupate inside the wheat stem. Their pupae are generally found inside the exoskeleton or beside the remnants of their consumed wheat stem sawfly host. There are two generations of B. cephi and B. lissogaster per year.  The first generation completes its lifecycle then exits the wheat stem to locate a new host to parasitize.  The second generation overwinters within the wheat stem. 

Adult Bracon cephi parasitoid, pictured inside a vial (hence the artistic effect!) by Dylan Sjolie, AAFC-Saskatoon.

Bracon cephi and B. lissogaster are similar in appearance. The wasps are typically 2-15 mm long and brown in colour. They have a narrow waist connecting the abdomen to the thorax and the combined length of head plus thorax is equal to the length of the abdomen.  These parasitoid wasps have long antennae and two pairs of transparent wings. Females have a noticeable ovipositor protruding from the end of the abdomen. 

Parasitoid population dynamics and efficacy are influenced by crop management practices. Parasitoids can be conserved by increasing the height of stubble when harvesting and reducing insecticide applications in grass ditches where natural enemies of the wheat stem sawfly are abundant. 

For more pictures and information about the natural enemies of the wheat stem sawfly, check out our past Insect of the Week post about Bracon cephi!

Released August 26, 2022

The final WEEKLY UPDATE of the 2022 growing season is here!

Thank you to the many people who performed and supported insect pest monitoring in field crops this year! The Prairie Pest Monitoring Network brings together a unique array of incredible cooperators and collaborators at federal, provincial, regional, post-secondary, and industry levels across western Canada! Thanks to these many individuals! The PPMN also thanks our many contributors to the Weekly Updates and Insect of the Week who stand as co-authors at the top of each Post. Last but not least, a small number of key individuals ensure 16 weeks of pertinent content are available through the growing season on behalf of the PPMN – thank you to Ross Weiss, Tamara Rounce, Serge Trudel, Cynthia Schock, Meghan Vankosky, and Jennifer Otani.

Vital insect pest data originates from in-field observations – that’s THE FOUNDATION – and now, more than ever, researchers need support and permission to continue to collect and build the many integral data sets needed to enable improvements in the detection, monitoring, and management of pest risk in field crops grown across the Canadian prairies! Please, this winter, if you’re a producer, connect with a field researcher and give permission for pests to be monitored in your field. If you’re able to monitor, connect with a field researcher to find out how to help. It’s vital that fields ALL ACROSS the prairies represent Canadian agriculture!

This week includes…..

• Weather synopsis
• Predicted grasshopper development
• Predicted diamondback development
• Lygus bug monitoring
• Predicted wheat stem sawfly growth
• Pre-harvest intervals (PHI)
• West nile virus risk
• Provincial insect pest report links
• Crop report links
• Previous posts
….and review the 2022 Insect of the Week lineup – 16 in total!

Wishing everyone good HARVESTING weather!

To receive free Weekly Updates automatically, please subscribe to the website!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

Weather synopsis

TEMPERATURE: Though average temperatures for the 2022 growing season continue to be similar to long-term average values, August temperatures have been much warmer than normal. This past week (August 15-21, 2022) the average daily temperature for the prairie region was 1.5 °C warmer than the previous week and almost 5 °C warmer than climate normal temperatures for the region. Last week recorded the warmest weekly average temperature of the 2022 growing season so far. The warmest temperatures were observed across southwestern Saskatchewan and southeastern Alberta (Fig. 1).

Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of August 15-21, 2022.

The prairie-wide average 30-day temperature (July 23 – August 21, 2022) was 2 °C warmer than the long-term average value for the same period. Average 30-day temperatures continue to be warmest across southern Alberta and southwestern Saskatchewan (Fig. 2). The average growing season (April 1-August 14, 2022) temperature for the prairies has been similar to climate normal values. The growing season has been coolest in a region extending from Edmonton to the Peace River region (Fig. 3).

Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of July 23 to August 21, 2022.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to August 21, 2022.

PRECIPITATION: This week (August 15-21, 2022), minimal amounts of rain were reported for Alberta and Saskatchewan. The greatest weekly precipitation amounts occurred across southern Manitoba (Fig. 4). The 30-day (July 23-August 21, 2022) rainfall amounts continue to be greatest across eastern Manitoba while dry conditions persist across the southern and central regions of Alberta and Saskatchewan (Fig. 5). Rainfall amounts across southern Alberta and southwestern Saskatchewan have been 40% less than climate normal values.

Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of August 15-21, 2022.
Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (July 23 to August 21, 2022).

Growing season rainfall for the prairies (April 1 – August 21, 2022) has been near normal for Alberta and above normal across southeastern Saskatchewan and Manitoba. Total rainfall continues to be greatest across Manitoba and eastern Saskatchewan and least across central and south-central Saskatchewan (Fig. 6).

Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to August 21, 2022.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 22, 2022) can be viewed by clicking the hyperlinks. Over the past 7 days (August 16-22, 2022), the lowest temperatures recorded across the Canadian prairies ranged from < 0 to >12 °C while the highest temperatures observed ranged from <26 to >34 °C. Review the days at or above 25 °C across the prairies and also the days at or above 30 °C. Access these maps and more using the AAFC Maps of Historic Agroclimate Conditions interface.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be accessed at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network. The AAFC Canadian Drought Monitor also provides geospatial maps updated monthly.

Predicted grasshopper development

The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Model outputs provided below as geospatial maps are a tool to help time in-field scouting on a regional scale yet local development can vary and is only accurately assessed through in-field scouting.

Model simulations were used to estimate grasshopper development as of August 21, 2022. Potential risk continues to be greatest across central and southern regions of Saskatchewan and southeastern Alberta. Simulations indicate that prairie populations are in the adult stage and that females are laying eggs in the soil. Since last week, model simulations indicate that oviposition is now occurring across all of the prairies (Fig. 1). Earlier oviposition can result in above-average production of eggs and increased overwintering survival of eggs.

The oviposition index provides a method to assess where egg production is greatest; higher oviposition index values indicate where egg production is greatest. Model runs for the 2022 growing season (April 1 – August 21) predict that oviposition rates have been greatest across a large region that extends from east of Lethbridge to Regina and north to Saskatoon (Fig. 1).

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 21, 2022 . Higher ovipositional index values indicate greater potential for oviposition.

Grasshopper Scouting Tips:
● Review grasshopper diversity and photos of nymphs, adults, and non-grasshopper species to aid in-field scouting from egg hatch and onwards.
● Access the PPMN’s Grasshopper Monitoring Protocol as a guide to help implement in-field monitoring.
● Review grasshopper lifecycle, damage and scouting and economic thresholds to support sound management decisions enabling the preservation of beneficial arthropods and mitigation of economic losses.

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. Review the historical grasshopper maps based on late-summer in-field counts of adults performed across the prairies.

Predicted diamondback moth development

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Recent warm conditions have resulted in the rapid development of diamondback moth populations. Model simulations to August 14, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across the southern prairies (Fig. 1). DBM development is predicted to be marginally greater in 2022 than expected based on long-term average values (Fig. 2).

Warm conditions during August resulted in rapid development of diamondback moth populations. Model simulations to August 21, 2022, indicate that the fourth generation of non-migrant adults (based on mid-May arrival dates) are currently occurring across most of the prairies (Fig. 1). DBM development is predicted to be marginally greater than long-term average values (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 21, 2022.
Figure 2. Long-term predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of August 21, based on climate normal data.

In-Field Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

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Figure 4. Diamondback moth pupa within silken cocoon.
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Figure 5. Adult diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

Diamondback moth was the Insect of the Week for Wk10 in 2021!

Lygus bug monitoring

On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.

Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps. In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.

Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.

How to tell them apart: The 2019 Insect of the Week’s doppelganger for Wk 15 was lygus bug versus the alfalfa plant bug while Wk 16 featured lygus bug nymphs vs. aphids!  Both posts include tips to discern the difference between when doing in-field scouting!

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.

Predicted wheat stem sawfly growth

Warm, dry weather is conducive to wheat stem sawfly (Cephus cinctus) population growth where they are present. Risk of damage to sawfly host crops is greatest when weather conditions are warmer and drier than normal. Risk associated with wheat stem sawfly can be predicted by calculating growth index values, where the growth index describes the potential for wheat stem sawfly population growth. Where growth risk index values are moderate to high, crop damage is more likely than in areas where growth risk index values are low to moderate. Scouting in moderate and high risk areas this fall (especially where wheat stem sawfly populations are known to be present) will provide valuable information about potential crop yield losses this year and about the risk of wheat stem sawfly population damage in next growing season.

Based on growing season weather in 2022 (April 1 to August 22), predicted wheat stem sawfly growth index values are low to moderate across most of the prairies (Fig. 1). This is due to average (in parts of Alberta) to above-average (in parts Manitoba and southeastern Saskatchewan) precipitation during the current growing season. Growth index values, based on 2022 growing season weather are predicted to be greatest in a region that extends from Swift Current to Saskatoon (Fig. 1). This area has been warmer and drier than the rest of the prairies.

Figure 1. Predicted risk for wheat stem sawfly (Cephus cinctus) across the Canadian prairies as of August 21, 2022.

Access these resources for more information:
• Wheat stem sawfly was the Insect of the Week in 2021 for Week 12.
• Biological and monitoring information (including tips for scouting and economic thresholds) related to wheat stem sawfly is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.
• Refer to the wheat stem sawfly page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
• Review historical survey data for wheat stem sawfly.

Pre-Harvest Intervals (PHI)

One last time….. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop.  The PHI recommends sufficient time for a pesticide to break down. PHI values are both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

Here are a few resources to help:
• Information about PHI and Maximum Residue Limits (MRL) is available on the Keep It Clean website.
• The Pest Management Regulatory Agency has a fact sheet, “Understanding Preharvest Intervals for Pesticides” or download a free PDF copy.
• Use Keep It Clean’s “Spray to Swath Interval Calculator” to accurately estimate:
◦ PHI for canola, chickpeas, lentils, faba beans, dry beans, or peas.
◦ How long to wait, if the crop has already been sprayed.
◦ To find a pesticide to suit your timeline.
• Access the Pre-Harvest Glyphosate Stage Guide.
• And remember Provincial crop protection guides include the PHI for every pesticide x crop combination. The 2022 Crop Production Guides are available as a FREE downloadable PDF for Alberta, Saskatchewan, and Manitoba.

West nile virus risk

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in Figure 1 but the unusual heat across the prairies greatly accelerated mosquito development!

As of August 21, 2022 and where present, C. tarsalis development has progressed. Remember, areas highlighted yellow have accumulated sufficient heat units for the second generation of C. tarsalis to fly. Many areas of the prairies well exceed the 250-300 DD of base 14.3 °C (e.g., areas orange red any any shade of pink) represented in Figure 1. Outdoor enthusiasts falling within areas highlighted yellow, orange, red or pink should wear DEET to protect against WNV! Historically, southern and central regions of the Canadian prairies are at increased risk for WNV from late July but typically peaks over the long weekend in August.

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 21, 2022).

For those following the specifics of the mosquito host-WNV interaction, Figure 2 projects how many days it will take a C. tarsalis female to become fully infective and be able to transmit the virus to another host (bird or human) once the virus is acquired from another bird. This represents the extrinsic incubation period (EIP) of the virus within the mosquito. Figure 2 projects the EIP was approximately 12-14 days in areas highlighted mauve and approximately 22-24 days in areas highlighted light green.

Figure 2. Predicted extrinsic incubation period (EIP) of West Nile Virus within a C. tarsalis female as of August 21, 2022.

The above maps should be compared with historical confirmed cases of WNV. The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date August 13, 2022; retrieved August 26, 2022) and provided below.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (retrieved 25Aug2022).

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

Provincial insect pest report links

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2022 are up and running! Access a PDF copy of the August 24, 2022 issue here. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more!
• Aphids in soybeans and sunflower, Lygus bugs, grasshoppers, and crickets were described in the August 24 issue.

SASKATCHEWAN’S Crop Production News for 2022 is up and running! Access the online Issue #6 (URL retrieved August 25, 2022) and find an update on Diamondback moth. Bookmark their insect pest homepage to access important information!

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information. Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.

Crop report links

Click the provincial name below to link to online crop reports produced by:
• Manitoba Agriculture and Resource Development (or access a PDF copy of the August 23, 2022 report).
• Saskatchewan Agriculture (or access a PDF copy of the August 16-22, 2022 report).
• Alberta Agriculture, Forestry, and Rural Economic Development (or access a PDF copy of the August 9, 2022 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the August 22, 2022 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 23, 2022 edition).
• The USDA’s Weekly International Weather and Crop Highlights (access a PDF copy of the August 20, 2022 edition).

Previous posts

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2022 Posts (organized alphabetically):
• 2021 Risk and forecast maps
• Alfalfa weevil – predicted development (Wk06)
• Aphids in field crops (Wk14)
• Bertha armyworm – predicted development (Wk07)
• Cabbage seedpod weevil monitoring (Wk12)
• Cereal leaf beetle – predicted development (Wk06)
• Crop protection guides (Wk02)
• Cutworms (Wk02)
• European corn borer – Canadian standardized assessment 2.0 (Wk02)
• Extension survey for Albertans (Wk12)
• Field heroes (Wk08)
• Field guides – New webpage to access (Wk02)
• Flea beetles (Wk01; IOTW)
• iNaturalist.ca (Wk02)
• Invasive insect species – Early detection (Wk02)
• Pea leaf weevil monitoring (Wk12)
• Scouting charts – canola and flax (Wk03)
• Ticks and Lyme disease (Wk02)
• Wheat midge – predicted development (Wk12)
• Wind trajectory reports (Wk09)

Weekly Update

Week 16 and this marks the final Weekly Update of the 2021 growing season! Watch the website in late February when 2022 forecast maps will begin to be released and the Weekly Update will return in May 2022. An even easier option is to subscribe to the website to receive updates automatically!

This week, please pay special attention to the Provincial Insect Pest Report section – provincially-led surveys continue for grasshoppers and wheat midge but also find links to permit land access and to help monitor in 2022! Once again, we thank the many folks who participated in insect monitoring in field crops grown across the prairies! We also thank the key individuals who worked to create the data and information presented within the Weekly Updates!

As swathers and combines continue to move across the prairies, we wish everyone good weather and a safe harvest! Be sure to catch the Insect of the Week – it’s the Japanese beetle!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

Weather synopsis

TEMPERATURE: This past week (August 9 – 15, 2021) the prairies continued to experience above-average temperatures and extremely dry conditions. Across the prairies, the average 30-day (July 17 – August 15, 2021) temperature was 1.5 °C warmer than climate normal values. The warmest temperatures were observed across the southern prairies (Fig. 1). A comparison of temperature anomalies (difference between average and observed temperatures) for this period indicated that southern Alberta and northeast Saskatchewan were approximately 3 °C warmer than normal (Fig. 2). Average temperatures around Peace River, Edmonton, and southern Manitoba were most similar to climate normal values.

Figure 1. 30-day average temperature (°C) observed across the Canadian prairies for the period of July 17– August 15, 2021.
Figure 2. Temperature anomalies (difference from climate normal values) for average temperature (°C) observed across the Canadian prairies for the period of July 17 – August 15, 2021.

The 2021 growing season (April 1 – August 15, 2021) has been 1.5 °C warmer than average (Fig. 3). Growing season temperature anomalies indicate that Parkland and Peace River regions have been 1.5-2.5 °C warmer than normal (Fig. 4).

Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 15, 2021.
Figure 4. Temperature anomalies (difference from climate normal values) for average temperature (°C) observed across the Canadian prairies for the period of April 1 – August 15, 2021.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-August 9, 2021) can be viewed by clicking the hyperlinks. Over the past 7 days (August 12-18, 2021), the lowest temperatures recorded across the Canadian prairies ranged from < -1 to >11 °C while the highest temperatures observed ranged from <20 to >37 °C. Check the number of days of >25 °C or >30 °C across the Canadian prairies (April 1-August 11, 2021). Access these maps and more using the AAFC Drought Watch webpage interface.

PRECIPITATION: Weekly (August 9-15, 2021) rainfall amounts were generally less than 5 mm. Rainfall amounts for the period of July 17 – August 15 (30-day accumulation) have been well below average with most of the prairies reporting rain amounts that were less than 40 mm (Fig. 5). Growing season precipitation has been below average across most of the prairies with cumulative rain amounts that have been less than 100 mm. A region extending from Lethbridge to northeastern Saskatchewan has had less than 100 mm of rain (Fig. 6).

Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 17 – August 15, 2021
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – August 15, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

Predicted diamondback moth development

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Model runs based on climate normals data indicate that most DBM populations should be in the third generation with second-generation DBM predicted for areas within the Peace River region and localized areas of fourth-generation DBM occurring across southern Alberta, Saskatchewan and Manitoba (Fig. 1). Model simulations based on current growing season weather indicate that, compared to climate normal results, there has been an additional generation (fourth) of non-migrant adults that are currently occurring across the Canadian prairies (Fig. 2).

Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) that are expected to have occurred across the Canadian prairies as of August 15 (based on climate normals data).
Figure 2. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to occur across the Canadian prairies as of August 15, 2021.

Monitoring: Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 3) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 3. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

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Figure 4. Diamondback moth pupa within silken cocoon.
This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 5. Diamondback moth.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

Predicted grasshopper development

Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development and oviposition as of August 15, 2021. Above-average temperatures during June, July, and early August continue to result in a noticeable increase in the rates of oviposition.

Grasshoppers generally begin to lay eggs in early August. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July. Earlier oviposition can result in above-average production of eggs and increased overwintering survival of eggs. This may result in potential increased grasshopper risk for the 2022 growing season. Model runs for the 2021 growing season (April 1 – August 15) indicated that oviposition should now be occurring across most of the prairies and is predicted to be greatest in southeastern Alberta (Fig. 1).

Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 8, 2021. Higher values indicate greater potential for oviposition.

Grasshopper Scouting Steps:
● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers.
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
● Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
24 per m² – Very severe damage
For lentils at flowering and pod stages, >2 per m² will cause yield loss.
For flax at boll stages, >2 per m² will cause yield loss.
● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

West nile virus risk

The following is offered to help predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies. By this week, all regions across the prairies have now accumulated sufficient degree-day heat units for Culex tarsalis to develop to adult stages, if present in the region (Fig. 1).

As of August 15, 2021 (Fig. 1), C. tarsalis development has now reached the point that adults are predicted to be flying across all areas of the Canadian prairies. Outdoor enthusiasts falling within areas highlighted red OR in areas that have accumulated >400 degree-days for C. tarsalis to emerge should wear DEET to protect against WNV!

Figure 1. Predicted development of Culex tarsalis across the Canadian prairies (as of August 15, 2021).

The Public Health Agency of Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance. Link here to access their most current weekly update (reporting date August 13, 2021; retrieved August 19, 2021). The screenshot below (retrieved 19Aug2021) serves as a reference and reports one human case of WNV, two positive wild birds, and positive mosquito pools in Ontario.

Bird surveillance continues to be an important way to detect and monitor West Nile Virus. The Canadian Wildlife Health Cooperative (CWHC) works with governmental agencies (i.e., provincial laboratories and the National Microbiology Laboratory) and other organizations to report the occurrence of WNV. Dead birds retrieved from areas of higher risk of West Nile Virus are tested for the virus. A screenshot of the latest reporting results posted by Canadian Wildlife Health Cooperative is below (reporting date August 18, 2021; retrieved 19Aug2021) which reports 3 positive birds collected in both Ontario and Quebec.

Anyone keen to identify mosquitoes will enjoy this pictorial key for both larvae and adults which is posted on the Centre for Disease Control (CDC) website but sadly lacks a formal citation other than “MOSQUITOES: CHARACTERISTICS OF ANOPHELINES AND CULICINES prepared by Kent S. Littig and Chester J. Stojanovich” and includes Pages 134-150. The proper citation may be Stojanovich, Chester J. & Louisiana Mosquito Control Association. (1982). Mosquito control training manual. pp 152.

Early detection of invasive insect species

Many of Canada’s economically important species of insect pests originated as invasive species that managed to relocate and establish self-sustaining populations. Over time, they became increasingly widespread and so frequently abundant that they became part of the annual list of species we monitor and attempt to manage.

Examples of invasive species that now exist as part of our field crop landscape include wheat midge, cereal leaf beetle, cabbage seedpod weevil, pea leaf weevil, swede midge – in fact, the list of invasive species is far longer! It’s important to consider the impact of invasive species AND recognize that a growing list of species will likely affect field crops in Canada. Globalization, adaptation, and the development of new cultivars suited to Canada’s growing regions, climate change, plus many other factors will contribute to the reality: we can expect more invasive species to continue to arrive.

Where can you play a role??? Early detection and accurate identification are key steps involved in mitigating the risks associated with new invasive species. Many levels of government are active in the ongoing battle against invasive species. Even so, initial detections often arise from keen in-field scouting by producers or agrologists so access these resources to help identify the “that’s weird” or “I haven’t seen that before”. And be sure to thank the many entomologists – regional, provincial, federal, and some amazing amateurs PLUS the folks at Canadian Food Inspection Agency (CFIA) who ALL work to stand on guard for thee!

• Canadian Food Inspection Agency’s (CFIA) main Plant Health section can be accessed here.

• More specifically, CFIA’s Plant Pests and Invasive Species information is accessible here.

• Did you know…. CFIA’s top field crop invasive species include anything falling under the List of Pests Regulated by Canada which is accessible here. Caveats are that (i) some species may be on the list (e.g., codling moth) that are not necessarily a high priority but remain to maintain regulatory policy or (ii) list may include species yet to be removed.

• Anyone can access diagnostic information for invasive species at CFIA’s Plant Pest Surveillance section accessible here.

• HERE’S WHERE YOU CAN HELP – Experienced producers and agrologists make important discoveries every day! Keep Canadian agriculture strong and support the detection of invasive species using this important information and the three options when encountering unusual damage symptoms or unknown insect species:

Important details to be ready to report: Be ready to include details to make a “report” – Sightings need to be validated so providing as much detail as possible will help the expert confirm identifications and relocate the site, if the issue demands urgent attention.
◦ Date of observation
◦ Nearest town and province
◦ Latitude x longitude values
◦ Host plant(s)
◦ Good photo(s) – lateral, dorsal, damage symptoms, host plant, etc., with some sort of size reference is ideal
◦ Chronological photos (i.e., that tell the story of detection and how and when symptoms or specimen came to your attention)
◦ A specimen may be needed by your provincial entomologist or CFIA

Option 1: Contact your provincial entomologist to confirm identifications and details – they are able to help and historically have acted to triage reports then direct relevant information to CFIA counterparts:
◦ Manitoba (John.Gavloski@gov.mb.ca )
◦ Saskatchewan (james.tansey@gov.sk.ca)
◦ Alberta (shelley.barkley@gov.ab.ca)

Option 2: Alternatively, reports can be sent directly using one of the following paths:
◦ Using CFIA’s Report A Pest website form
◦ Contact a local CFIA office
◦ Or contact CFIA’S general surveillance account email at cfia.surveillance-surveillance.acia@canada.ca
◦ Or contact CFIA’s Survey Biologist for the Western Area (david.holden@canada.ca)

Option 3: Another alternative is to consider documenting your query using iNaturalist.ca (read more here). The basic steps involved are:
◦ Create an account at iNaturalist.ca (https://inaturalist.ca/signup)
◦ Watch your Inbox for a basic how-to guide.
◦ Upload photos or videos (e.g., bird calls) to create an “Observation”
◦ iNaturalist subscribers considered to be experts will help identify your observation.

An APP with a difference – iNaturalist.ca

Smartphones and their evolving photographic capacity continue to enhance our ability to learn about the environment around us. Millions of APPs have been developed to harness information and agriculture continues to benefit.

iNaturalist.ca is beneficial to download. It helps users identify terrestrial organisms by connecting to “experts” who help identify and provide information to users but there’s an underlying secondary benefit: Researchers, institutions, and active research projects can set up Lists and access observations within iNaturalist. As the homepage says, “Every observation can contribute to biodiversity science, from the rarest butterfly to the most common backyard weed.” We reached out to the Canadian Food Inspection Agency (CFIA) who are already using and accessing valuable data from this resource.

What’s best – iNaturalist.ca OR iNaturalist.com? Canadian Food Inspection Agency (CFIA) and the team that focuses on the detection of invasive species generally recommends iNaturalist.ca because it allows Canadians better access to Canadian experts and Canadian data.

Is iNaturalist.ca worth using to identify unknown insects encountered in field crops? iNaturalist.ca is going to be the leader in early detections and is a fairly intuitive and usable tool for everyone. It’s not perfect for all organisms but works well for many. CFIA staff are actively monitoring it and, in the near future, CFIA hopes to set up an account that might allow users to flag observations for their team to see more rapidly.

How does CFIA mine iNaturalist and what is the value? CFIA uses a script through the Intauralist API to query for any mentions of our targeted list under the project here: Important Pest Species List for Canada – Lookout · iNaturalist. CFIA staff members receive a daily email of all the target list mentions (i.e., includes insects, plants, and mollusks). In order to increase early detections, CFIA’s also trying to retrieve data from comments such as when someone mentions a new record or new detection. At this point, only a few pathogens are listed in our pest lookout because many of CFIA’s regulated pests would need more than a picture (so we didn’t add them). CFIA staff believe iNaturalist.ca is a great tool for early detection because the number of observations is very large and growing like crazy AND they are geographically widespread.

The basic steps involved are:
◦ Create an account at iNaturalist.ca (https://inaturalist.ca/signup).
◦ Watch your Inbox for a basic how-to guide.
◦ Upload photos or videos (e.g., bird calls) to create an “Observation”.
◦ iNaturalist subscribers considered to be experts will help identify your observation.

Crop Metrics Application

Reminder – Agriculture and Agri-Food Canada has released the Canadian Crop Metrics application. This product contains useful and interesting information about the current status of crops grown across Canada. The application also presents data for a number of pest insects including bertha armyworm, diamondback moth, grasshoppers and wheat midge.

Read over the synopsis of the Canadian Crop Metrics application to gain a sense of what the resource has to offer and how to optimize access. It allows users to look at specific regions and generate reports, graphs, and tables to compare current conditions to historical conditions for 11 different crop types. Weather data is updated regularly and yield estimates are updated monthly from July to October. Forecasts are made at the beginning of the months of July, August and September for all crops, and an additional forecast is made for corn and soybeans (late season crops) at the beginning of October. Forecasts are jointly produced by Agriculture and Agri-Food Canada and Statistics Canada using historical yield, climate and satellite data as inputs.

Screenshots of the application are below for reference. Get started here!

Provincial insect pest report links

Provincial entomologists provide insect pest updates throughout the growing season so link to their information:

MANITOBA’S Crop Pest Updates for 2021 are now available – access the August 11, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Bookmark their insect pest homepage to access fact sheets and more!
• The late-season grasshopper survey is underway in Manitoba – Anyone interested can access the survey protocol posted here.

SASKATCHEWAN’S Crop Production News is available. Access Issue #5 online which includes information describing supporting pollinators in an agriculture habitat. Be sure to bookmark their insect pest homepage to access important information!
• PLEASE participate in the fall wheat midge soil core survey by registering fields at the pest survey sign-up webpage! – Producers need to sign up to allow access to their land to help build the 2022 forecast map!
• PLEASE volunteer to monitor bertha armyworm in 2022 by emailing pestsurveys@gov.sk.ca – Please state that you would “like to participate in the BAW survey”.

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am (through the growing season).
• Consider getting involved with annual insect surveying by signing up to allow access to your land– Producers who participate help build population maps of pest insects. Email shelley.barkley@gov.ab.ca to sign up for 2022!

Crop report links

Click the provincial name below to link to online crop reports produced by:
• Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the August 17, 2021 report; retrieved 19Aug2021).
• Saskatchewan Agriculture (or access a PDF copy of the August 10-16, 2021 report; retrieved 19Aug2021).
• Alberta Agriculture and Forestry (or access a PDF copy of the August 10, 2021 report; retrieved 19Aug2021).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the August 16, 2021 edition; retrieved 19Aug2021).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the August 17, 2021 edition; retrieved 19Aug2021).

Previous posts

As the growing season progresses, the various Weekly Update topics move on and off the priority list for in-field scouting but they should be kept at hand to support season-long monitoring. Click to review these earlier 2021 Posts (organized alphabetically):
• 2020-2021 Risk and forecast maps
• Alfalfa weevil – predicted development (Wk07)
• Aphids in field crops (Wk09)
• Bertha armyworm (Wk12)
• Bertha armyworm – predicted development (Wk09)
• Cabbage seedpod weevil monitoring (Wk09)
• Calls for survey help (Wk14)
• Cereal aphid manager APP (Wk07)
• Cereal leaf beetle – predicted development (Wk07)
• Crop protection guides (Wk03)
• Cutworms (Wk02)
• European corn borer – nation-wide monitoring project (Wk07)
• Field heroes (Wk15)
• Flea beetles (Wk02)
• Flea beetles – predicted geographic distribution and abundance (Wk04)
• Fuzzy white “eggs” on barley or wheat (Wk13)
• Grasshopper diversity and scouting photos (Wk08)
• Ladybird beetles (Wk03)
• Lygus bug monitoring (Wk15)
• Midges in canola (Wk11)
• Monarch migration (Wk09)
• Pea leaf weevil (Wk03)
• Praire-wide survey of stored grain pests (Wk13)
• Pre-Harvest Intervals (Wk15)
• Scouting charts – canola and flax (Wk03)
• Slugs and their parasites (Wk04)
• Thrips in canola (Wk12)
• Weather radar mapping interface (Wk06)
• Wheat midge – predicted development (Wk08)
• Wheat midge – predicted development (Wk15)
• Wind trajectories for monitoring insect movement (Wk02)
• Wind trajectories – weekly reports (Wk09)
• Wireworms (Wk02)

JAPANESE BEETLE: A COLOURFUL INVADER ON THE PRAIRIES

Japanese beetle (Bruce Marlin CC-BY 3.0)

As the name suggest, the Japanese beetle is native to Japan but has been present in North American since 1916. While an annual trapping program in Canada has been in place since 1939, complete elimination has not been achieved. Fortunately, it has not reached the Prairies yet, but it is found in southern Ontario, Quebec, New Brunswick, Prince Edward Island and Nova Scotia. It has been detected in Vancouver, British Columbia and the CFIA is leading a coordinated eradication program and has implemented efforts to prevent the pest’s spread outside Vancouver. The rest of British Columbia is still considered free of Japanese Beetle. In the USA, eastern states are considered generally infested (from Minnesota south to Arkansas and across to the Atlantic Coast, excluding Mississippi [partial infestation], and Florida and Louisiana [no infestation]); central states are partially infested (from North Dakota south to Texas); and western states (including Alaska and Hawaii) have no infestations (USDA Japanese Beetle FAQ). Quarantine and phytosanitary regulations are in force to limit movement of infested materials from infested states into or through non-infested states to protect the agriculture sector.

Potential host plants on the Prairies include corn and soybean, but the Japanese beetle also targets fruit crops like peach, apple, apricot, cherry and plum, as well as berries like blueberry, raspberry. Damage from adult Japanese beetles includes leaves that have been chewed down to the vein. Damaged leaves turn brown and drop, leaving plants vulnerable to disease and limiting overall growth. Larvae feed on roots, causing additional stunting in addition to potential wilting and sometimes death.

Adults are almost 10 millimetres long and oval. Their abdomen, thorax and head are metallic green with metallic copper-brown wing coverings and white hair along the abdomen. Larvae grow to 25 millimetres and are C-shaped white grubs with a yellowish-brown head. A V-shaped spine arrangement can be seen on the last body segment. 

Japanese beetle larval development (David Cappaert — Michigan State University CC-BY 3.0)

Biological and monitoring information related to Japanese beetles in field crops can be found on our Monitoring page. For more information, visit the Japanese beetle page on the Canadian Food Inspection Agency website.

Weather synopsis

This past week (Aug 4-10, 2020) conditions were generally warm and dry. Weekly prairie temperatures were warmest across Manitoba and Saskatchewan (Fig. 1). Lower temperatures were observed across western and northwestern Alberta (Fig. 1). Though average 30-day (July 12 – August 10, 2020) temperatures continue to be cooler in Alberta than eastern Saskatchewan and Manitoba (Fig. 2), temperature anomalies (mean temperature difference from average; July 14-August 10, 2020) indicate that conditions have generally been warmer than average across most of Alberta as well as Parkland regions of Saskatchewan and Manitoba (Fig. 3).

Figure 1. Observed average temperatures across the Canadian prairies the past seven days (August 4-10, 2020).
Figure 2. Observed average temperatures across the Canadian prairies the past 30 days (July 12-August 10, 2020).
Figure 3. Mean temperature difference from Normal the past 30 days (July 14-August 12, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (12Aug2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Regions in southeastern central and southern Saskatchewan and across southern Manitoba have reported temperatures that have been up to 2 °C cooler than average. Based on growing season temperatures (April 1-August 10, 2020) temperatures were warmest across the southern prairies (Fig. 4). Based on growing season temperature deviations (observed temperatures compared with climate normal temperatures), below average temperatures have been observed across central and western regions of Saskatchewan and central regions of Alberta (Fig. 5). Across southern Alberta and most of Manitoba, temperatures have generally been above average. (Fig. 5)

Figure 4. Observed average temperatures across the Canadian prairies for the growing season (April 1-August 10, 2020).
Figure 5. Observed difference from average temperatures across the Canadian prairies for the growing season (April 1-August 10, 2020).

Most areas reported 7-day cumulative rainfall amounts that were less than 10 mm (Fig. 6). Cumulative 30-day rainfall was lowest across a large area ranging across southern Alberta as well as central and western regions of Saskatchewan (Fig. 7). Growing season rainfall (percent of average) is highly variable across the prairies (Fig. 8). Rainfall has been below normal across most of Saskatchewan as well as southern Alberta, and the Peace River region (Fig. 8).

Figure 6. Observed cumulative precipitation across the Canadian prairies the past seven days (August 4-10, 2020).
Figure 7. Observed cumulative precipitation across the Canadian prairies the past 30 days (July 12-August 10, 2020).
Figure 8. Percent of average precipitation for the growing season (April 1-August 10, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (12Aug2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-August 9, 2020) is below (Fig. 9) while the growing degree day map (GDD) (Base 10 ºC, April 1-August 9, 2020) is shown in Figure 10.

Figure 9. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-August 9, 2020).
Figure 10. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-August 9, 2020).

The highest temperatures (°C) observed across the Canadian prairies the past seven days ranged from <17 to >34 °C (Fig. 11) while the lowest temperatures ranged from <-1 to >13 °C (Fig. 12). So far this growing season (as of August 12, 2020), the number of days above 25 °C ranges from 0-10 days in the west (to west of Calgary, west and north of central Alberta and extending into the south and west of the Peace River region) but extends up to 51-60 days in southern Manitoba (Fig. 13).

Figure 11. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-August 12, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Aug2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 12. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (April 1-August 12, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Aug2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209
Figure 13. Number of days above 25 °C observed across the Canadian prairies this growing season (April 1-August 12, 2020).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (13Aug2020). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Drought Watch Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch website, Environment Canada’s Historical Data website, or your provincial weather network.

Bertha armyworm

Weekly Pheromone-baited Trapping Results – Click each province name to access moth reporting numbers observed in Alberta, Saskatchewan and Manitoba (as they become available). Check these sites to assess cumulative counts and relative risk in your geographic region but remember in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. For convenience, screen shots of the above maps or data have been placed below for Alberta, Saskatchewan, and Manitoba.

Monitoring:

  • Larval sampling should commence once the adult moths are noted.
  • Sample at least three locations, a minimum of 50 m apart.
  • At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae.
  • Count them and compare the average against the values in the economic threshold table below:

Scouting tips:
● Some bertha armyworm larvae remain green or pale brown throughout their larval life.
● Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms.
● Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves.
● Larvae eat the outer green layer of the stems and pods exposing the white tissue.
● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 1) to help identify the economically important larvae.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

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Figure 1. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted diamondback moth development

This week, the DBM model based on Harcourt (1954) was run with a biofix of May 15, 2020. Most of Alberta has had two generations. It is possible that three generations have been completed across Saskatchewan and southeastern Alberta where it has been warmer. Results indicate that a potential fourth generation may be occurring across southern Manitoba. DBM densities generally increase with increasing numbers of generations. Later maturing canola fields may be susceptible to damage resulting from larval feeding.

Figure 1. Using a biofix date of May 15, 2020, the projected number of diamondback moth (Plutella xylostella) generations across the Canadian prairies as of August 10, 2020.

Monitoring:

Remove the plants in an area measuring 0.1 m² (about 12″ square). Beat them on to a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

This image has an empty alt attribute; its file name is DBM_Larva_AAFC.jpg
Figure 2. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.
This image has an empty alt attribute; its file name is DBM_Pupa_AAFC-1.jpg
Figure 3. Diamondback moth pupa within silken cocoon.

Economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

This image has an empty alt attribute; its file name is DBM_adult_AAFC-1.png
Figure 4. Diamondback moth.

Biological and monitoring information for DBM is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.  

More information about Diamondback moths can be found by accessing the pages from the  “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide“.  View ONLY the Diamondback moth page but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted grasshopper development

As of August 10, 2020, the grasshopper model estimates that prairie grasshopper populations are primarily in the adult stage (Fig. 1). Figure 2 provides an overview of where oviposition is predicted to occur based on weather conditions up to August 10. Oviposition is well underway across southern Manitoba and southeastern Saskatchewan (Fig. 2).

Figure 1. Predicted average development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of August 10, 2020).
Figure 2. Predicted oviposition for (Melanoplus sanguinipes) populations across the Canadian prairies (as of August 10, 2020).

Recent warm weather in southwestern Alberta has resulted in increased development rates, resulting in predicted occurrence of oviposition. The three graphs compare grasshopper development at Grande Prairie (Fig. 3), Saskatoon (Fig. 4) and Brandon (Fig. 5). Output suggests that adults are beginning to occur near Grande Prairie but oviposition has yet to begin (Fig. 3). Saskatoon (Fig. 4) and Brandon (Fig. 5) populations should be primarily in the adult stage and oviposition should be well underway.

Figure 3. Predicted grasshopper (Melanoplus sanguinipes) phenology at Grande Prairie AB. Values are based on model simulations (April 1-August 10, 2020).
Figure 4. Predicted grasshopper (Melanoplus sanguinipes) phenology at Saskatoon SK. Values are based on model simulations (April 1-August 10, 2020).
Figure 5. Predicted grasshopper (Melanoplus sanguinipes) phenology at Brandon MB. Values are based on model simulations (April 1-August 10, 2020).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Stored grain insect survey in Manitoba

Entomologists with Agriculture and Agri-Food Canada in Winnipeg are doing a survey in September of insects in farm grain bins. They are looking for 10 farms not far from Winnipeg where they can access grain bins to sample insects. No grain will be removed, just insects. If interested, please contact John Gavloski (John.Gavloski@gov.mb.ca) as soon as possible.

Stored product pests

Reminder – The Canadian Grain Commission’s website has an online key to stored product pests.  Growers managing grain storage can find an online identification tool for stored product pests (e.g., Rusty grain beetle, Red flour beetle, Confused flour beetle, Saw-toothed grain beetle, and more).  The online tool features excellent diagnostic photos.  A screen shot of the Canadian Grain Commission’s “Identify an Insect” webpage is included below for reference.

This image has an empty alt attribute; its file name is 2020Aug06_CGC_Snip-1024x746.png

West nile virus risk

Health Canada posts information related to West Nile Virus in Canada and also tracks West Nile Virus through human, mosquito, bird and horse surveillance.  Link here to access the most current weekly update (reporting date July 12-18, 2020; retrieved Aug 13, 2020). The screenshot below (retrieved Aug 13, 2020) serves as reference but access that Health Canada information here.

This image has an empty alt attribute; its file name is 2020Jun28-Jul04_WNV_Weekly_HealthCanada-1024x593.png

The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas).  As of August 9, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge.  Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!  

Figure 1. Predicted development of Culex tarsalis, across the Canadian prairies (as of August 9, 2020).

Harvest Sample Program

The Canadian Grain Commission is ready to grade grain samples harvested in 2020.  Samples are accepted up to November 30 but growers normally send samples as soon as harvest is complete.

This is a FREE opportunity for growers to gain unofficial insight into the quality of grain and to obtain valuable dockage information and details associated with damage or quality issues.  The data collected also helps Canada market its grain to the world!

More information on the Harvest Sample Program is available at the Canadian Grain Commission’s website where growers can register online to receive a kit to submit their grain.  

In exchange for your samples, the CGC assesses and provides the following unofficial results FOR FREE:

  • unofficial grade
  • dockage assessment on canola
  • protein content on barley, beans, chick peas, lentils, oats, peas and wheat
  • oil, protein and chlorophyll content for canola
  • oil and protein content and iodine value for flaxseed
  • oil and protein for mustard seed and soybean
  • Falling Number for wheat
  • Vomitoxin (deoxynivalenol or DON) for wheat and corn.

It can be helpful to have grade and quality information on samples before delivering their grain. Read brochures produced by the Canadian Grain Commission describing the Harvest Sample Program and details specific to the Western version of the program.

Provincial insect pest report links

Provincial entomologists provide insect pest updates throughout the growing season so link to their information: 

• Manitoba‘s Crop Pest Updates for 2020 are available. Access the August 11 2020 report. The summary indicates that, “Grasshoppers continue to be the insect of greatest concern. The diamondback moth populations in eastern Manitoba that were of concern in some fields a couple of weeks ago seem to have diminished. Spider mites are being noticed in some soybean fields, but no insecticide applications for them have been reported yet.”

• Saskatchewan‘s Crop Production News (for Issue 7). Read Issue 7 which includes articles on Pest Scouting 101- Harvest, Promoting and Enhancing Beneficial Insects, and What to Do with Unwanted Pesticides and Obsolete Livestock Medications. Issue 5 included articles on Bertha armyworm, Cabbage seedpod weevil,  FieldWatch – Fostering Communication Between Applicators and Producers, and Look What the Wind Blew in! Diamondback Moths Arrived Early This Spring. Issue #4 included articles on Pest Scouting 101: Mid-Summer, and The Wheat Midge.

•  Alberta Agriculture and Forestry’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.

Crop report links

Click the provincial name below to link to online crop reports produced by:

• Manitoba Agriculture and Rural Initiatives – Other viewing options include subscribing to receive or access a PDF of August 11, 2020 report.

• Saskatchewan Agriculture  or access a PDF of August 10, 2020 report.

• Alberta Agriculture and Forestry or access a PDF of July 28, 2020 report.

The following crop reports are also available:

• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the August 10, 2020 edition).

• The USDA’s Weekly Weather and Crop Bulletin (read the August 11, 2020 edition). 

Previous posts

Click to review these earlier 2020 Posts (organized alphabetically):

    • 2019-2020 Risk and forecast maps

    • Alfalfa weevil (Wk08)

    • Aphid mummies (Wk15)

    • Aster leafhopper (Wk05)

    • Beetle data please! (Wk03)

    • Bertha armyworm – predicted development (Wk15)

    • Cereal aphid APP (Wk11)

    • Crop protection guides (Wk02)

    • Cutworms (Wk02)

    • Diamondback moth (Wk11)

    • Flea beetles (Wk02)

    • Field heroes (Wk14)

    • John Doane (Wk10)

    • Ladybird beetles (Wk15)

    • Lygus bugs in canola (Wk15)

    • Monarch migration (Wk10)

    • Pea leaf weevil (Wk11)

    • Pea leaf weevil – predicted development (Wk09)

    • Prairie provincial insect webpages (Wk02)

    • Wheat midge (Wk13)

    • Scouting charts – canola and flax (Wk02)

    • Thrips in canola (Wk15)

    • Ticks and Lyme Disease (Wk06)

    • Wind trajectories (Wk09)

    • West nile virus (Wk14)

RYE PESTS / FEATURE ENTOMOLOGIST: HALEY CATTON

This week’s Insect of the Week feature crop is is rye, a cold and drought resistant grain with various uses, including bread and cereal production, and brewing and malting. Our feature entomologist this week is Haley Catton.

Rye – AAFC

A versatile crop, rye grown in the Prairie region has numerous uses, including animal feed production, bread and cereal production and brewing and malting. Rye can also be used as a cover and forage crop. Like wheat, rye comes in winter and spring varieties, with winter rye remaining the most popular across Western Canada. In 2019, rye was grown over 114,100 hectares (281,700 acres) in the Prairies, producing 262,200 metric tonnes (289,000 US tons).

Various pest species target rye. Monitoring and scouting protocols as well as economic thresholds (when available) are found in Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management and the Cutworm Pests of Crops on the Canadian Prairies: Identification and Management Field Guide. Additional monitoring protocols exist to control certain pests.

Rye field – AAFC
Rye Pests
  • Armyworm
  • Black grass bugs
  • Cereal leaf beetle
  • Darksided cutworm
  • Dingy cutworm
  • English green aphid
  • Fall armyworm
  • Fall field cricket
  • Glassy cutworm
  • Grasshoppers
  • Green-tan grass bugs
  • Breenbug
  • Pale western cutworm
  • Rice leaf bug
  • Variegated cutworm
  • Wheat head armyworm
  • Wheat midge
  • Wheat stem maggot
  • Wheat stem sawfly
  • Wireworms
Fall field cricket – Joseph Berger, bugwood.org, cc-by 3.0

ENTOMOLOGIST OF THE WEEK: HALEY CATTON

Name: Dr. Haley Catton
Affiliation: AAFC-Lethbridge Research and Development Centre
Contact Information: haley.catton@agr.gc.ca, 
@haleycatton (Twitter)

How do you contribute in insect monitoring or surveillance on the Prairies?

My team and I often work on developing and refining monitoring methods for certain pests (e.g. wireworms). But, for the past few years we have actively been monitoring one particular tiny little insect – the parasitic wasp T. julis, a natural enemy of the cereal leaf beetle. These beneficial wasps are so small that they are easy to miss with the naked eye, only 2-3 mm long in their adult form! We track them by cutting open cereal leaf beetle larvae to see if they are parasitized. We can find 5-20 little T. julis larvae inside a single cereal leaf beetle larva! For next year, we ask that anyone on the Prairies who sees cereal leaf beetle larvae to send us a sample of 10-30 larvae so we can dissect them. We will tell you if T. julis is on the scene and contributing to management of this potentially damaging pest.

In your opinion, what is the most interesting field crop pest on the Prairies?

That’s tough to pick, all of them are interesting in their own way. But if I have to choose, it will be wireworm. This is a pest made up of several species, with long life spans, lots of host crops, and different behaviours. They can go without food for at least a year, and even moult to become smaller in times of stress. They are a formidable pest, but the more I learn about them, the more interesting the story becomes.

What is your favourite beneficial insect?

Another tough choice. T. julis is pretty spectacular, how it finds its host so effectively, a true “seek and destroy” biological control insect, or Field Hero. We think T. julis is a big reason why cereal leaf beetle has not become a major pest on the Prairies, but that is hard to prove when it is tough to even find larvae to dissect! This “disappearance” phenomenon is a big problem in biological control. When beneficial insects are very successful, the pests are no longer noticeable, and therefore less on people’s minds. The value of the beneficial insects therefore becomes “behind the scenes”, and can be overlooked. This is why more research and awareness are needed on the value and efficacy of beneficial insects, so they can considered and protected.

Tell us about an important/interesting project you are working on right now.

I’m just finishing up a 3-year project on wireworms (funded by AWC and WGRF), and have learned so much. I am working with a team to produce a wireworm field guide for the Prairies, and it is shaping up to be a really nice document. Expected release later this year!

What tools, platforms, etc. do you use to communicate with your stakeholders?

I love giving presentations, going to field days, and talking to farmers. Also, find me on Twitter (@haleycatton), or reach out by email, haley.catton@agr.gc.ca.

Weekly Update

Greetings!

Week 16 and some interesting weather across the prairies!  Please bookmark the Blog or subscribe to receive the latest growing season information!

Please access the complete Weekly Update either as a series of Posts for Week 16 (July 25, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week – the rest of the growing season features doppelgangers to aid in-field scouting!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Meghan Vankosky or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these easy steps!

Weather synopsis

Weather synopsis – Prairie temperatures continue to be cooler than average. This past week (July 15-21, 2019), temperatures were approximately 1 °C cooler than last week (Fig. 1). The warmest temperatures were observed across MB while temperatures were cooler in western SK and AB. 

Figure 1. Average temperature (°C) across the Canadian prairies the past seven days (July 15-21, 2019).
Figure 2. Average temperature (°C) across the Canadian prairies the past seven days (June 21-July 21, 2019).

Across the prairies, 30 day (June 21 – July 21, 2019) average temperatures have been approximately 1 °C cooler than normal (Fig. 3). Temperatures were warmest across MB and eastern SK. Growing season temperatures (April 1-July 21, 2019) have been 1 °C cooler than average; the warmest temperatures were observed across the southern prairies. 

Figure 3. Average temperature (°C) across the Canadian prairies for the growing season (April 1-July 21, 2019).

This past week significant rainfall amounts were reported the parkland region of  SK and AB (Fig. 4).  

Figure 4. Cumulative precipitation observed the past seven days across the Canadian prairies (July 15-21, 2019).
Figure 5. Cumulative precipitation observed the past 30 days across the Canadian prairies (June 21-July 21, 2019).

Across the prairies, rainfall amounts for the past 30 days have been highly variable (Fig. 7). Dryer conditions continue across southern AB. Rainfall was well above average in SK. Growing season (April 1 – July 21, 2019) rainfall amounts have been below average across southern regions of AB, and across MB. 

Figure 6. Cumulative precipitation observed the past 30 days across the Canadian prairies (April 1-July 21, 2019).
Figure 7. Percent of average precipitation observed across the Canadian prairies for the growing season (April 1-July 24, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The growing degree day map (GDD) (Base 5 ºC, April 1-July 21, 2019) is below (Fig. 8):

Figure 8. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-July 21, 2019).

The growing degree day map (GDD) (Base 10 ºC, April 1-July 21, 2019) is below (Fig. 9):

Figure 9. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-July 21, 2019).

The lowest temperatures (°C) observed the past seven days ranged from at least 14 down to at least 2 °C in the map below (Fig. 10).

Figure 10. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to July 21, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The highest temperatures (°C) observed the past seven days ranged from less than 16 up to at least 30 °C in the map below (Fig. 11).

Figure 11. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to July 21, 2019).  
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (125ul2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers can bookmark the AAFC Drought Watch Maps for the growing season.

Wheat midge

Wheat Midge (Sitodiplosis mosellana) – Dry conditions in May and June have resulted in reduced emergence of adult populations across most of SK. Oviposition is well underway and larvae should be developing in wheat heads. Where wheat midge are present, the following maps indicate potential occurrence of eggs (Fig. 1) and larvae (present in wheat heads) across the prairies (Fig. 2). It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.

Figure 1. Predicted  potential occurrence of eggs laid by wheat midge (Sitodiplosis mosellana) across the Canadian prairies (as of July 21, 2019).
Figure 2. Predicted  potential occurrence of  larvae of wheat midge (Sitodiplosis mosellana) across the Canadian prairies (as of July 21, 2019).

Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.

Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage. 

Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10).  Check that post for help with in-field scouting for this economic pest of wheat!  The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11).  Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted grasshopper development

Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).

Cool temperatures continue to result in reduced grasshopper developmental rates. Based on model runs, approximately 68% (50% last week) of the population should be in the 4th-5th instar and adult stages. Based on climate data, 80% of the population would be expected to be in the 4th-5th instar and adult stages. The following map indicates the average instar for grasshopper populations across the prairies (Fig. 1). Development is predicted to be greatest across southern MB and southeastern SK.

Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 21, 2019). 

The Insect of the Week’s Doppelganger featured GRASSHOPPERS for Week 14!!  Check out the excellent nymph photos to help your in-field scouting!

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is available as a free downloadable document in either an English-enhanced or French-enhanced version.

Bertha armyworm monitoring

Bertha armyworm (Lepidoptera: Mamestra configurata) – Predictive model updates are completed for the growing season but can be reviewed here (Wk 14).  

Important – Watch for updates from your provincial monitoring networks who are compiling cumulative pheromone-baited trap interceptions to assess risk levels in Alberta, Saskatchewan (updated 10Jul2019), and Manitoba (look on pg 8).

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 1) to help identify egg masses and the economically important larvae in canola.

Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada).

Now is the time to do in-field scouting for this insect pest.  Review the Insect of the Week which features bertha armyworm and its doppelganger, the clover cutworm!

Lygus in canola

Lygus bugs (Lygus spp.) – Last week’s Insect of the Week’s doppelganger was lygus bug versus the alfalfa plant bug.  This week the doppelganger is lygus bug nymphs vs. aphids!  both include tips to to discern the difference between when doing in-field scouting!

The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
 
Fifth instar lygus bug nymph (3-4 mm long) (photo:  AAFC-Saskatoon).
 

Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. They feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.

Sampling becomes more representative IF repeated at multiple spots within a field.  For lygus bug monitoring, sampling is most accurate when repeated at a total of 15 spots within the field.  Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). 

If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.

Sequential sampling for lygus bugs at late flowering stage in canola.
 

The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted.

Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production.  The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage.  In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.

Table 1.  Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).

1 Canola crop stage estimated using Harper and Berkenkamp 1975).
2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).

Table 2.  Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).

3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).

Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

West Nile Virus and Culex tarsalis

West Nile Virus Risk –  Health Canada posts information related to West Nile Virus in Canada.  Health Canada also tracks West Nile Virus through human, mosquito, bird and horse surveillance.  Link here to access the most current weekly update (July 13, 2019). The screenshot below was retrieved 25Jul2019 as reference but access that information here.

The following is offered to predict when Culex tarsalis will begin to fly across the Canadian prairies (Fig. 1). Protect yourself by wearing DEET!  This week, regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  Areas highlighted yellow in the map below (Fig. 2) are on the verge of approaching sufficient heat accumulation for mosquitoes to emerge.  Areas highlighted lime green should be preparing for C. tarsalis flight.

Figure 1. Predicted development of Culex tarsalis, across the Canadian prairies (as of July 21 2019).

Once adults emerge, the following map demonstrates how quickly a Culex tarsalis mosquito carrying WNV can become fully infective (i.e., when it has accumulated 109 base 14.3° degree days) – it’s a matter of days, depending on the region (Figure 2).

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so we link to their most recent information: 

• Manitoba‘s Crop Pest Updates for 2019 are posted here. Access Issue #10 posted July 24, 2019 noting grasshoppers, cereal armyworms, and lygus bugs. There is a helpful photo of an European corn borer egg mass plus bertha armyworm pheromone trap counts, some of which are categaorized as “uncertain” so in-field scouting is critical.

• Saskatchewan‘s Crops Blog Posts includes a segment on “Economic thresholds” by Kaeley Kindrachuk posted in May 2019. Also access the Crop Production News with Issue #5 (featuring pesticide drift information).

•  Alberta Agriculture and Forestry’s Agri-News includes an insect-related item in the July 8, 2019 edition with an important reminder that field scouting in July can lead to a more successful crop.

Crop report links

Crop reports are produced by:

The following crop reports are also available:

Field Events – Speak to an entomologist

Public summer field events – Coming to a field near you –  Prairie field crop entomologists are already scheduled to be at these 2019 field tour events from May-August (be sure to re-confirm dates and details as events are finalized):

•  August 8, 2019:  2019 Wheatstalk to be held at Teepee Creek AB.  View event info/registration details.   Entomologists tentatively participating: Jennifer Otani, Shelby Dufton, Amanda Jorgensen, Boyd Mori.

•  August 8, 2019. Horticulture School. Agriculture and Agri-Food Canada Research Farm, Portage la Prairie, Manitoba. View event info/registration details.  Entomologist presenting: John Gavloski, Kyle Bobiwash.

Previous Posts

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps – Week 2

Alfalfa weevil – Week 11

Bertha armyworm (predicted development) – Week 12

Cabbage seedpod weevil – Week 11
Cereal aphid manager APP – Week 12
Cereal leaf beetle – Week 9
Crop protection guides – Week 6
Cutworms – Week 5

Diamondback moth – Week 15

Field heroes – Week 6
Flea beetles – Week 5

Grasshoppers – Week 10

Insect scouting chart for Canola – Week 5
Insect scouting chart for Flax – Week 5

Monarch migration – Week 13

Painted lady butterfly – Week 8
Pea leaf weevil – Week 10
Prairie Crop Disease Monitoring Network – Week 11
Preparing grains for market – Week 15

Ticks and Lyme disease – Week 4
Timely IOTW to review – Week 13

Weather Radar – Week 6
Wildfires – Week 8

Wind trajectories – Review Page for list of PDFs for Weeks 1-12

Doppelgangers: Lygus bugs nymphs vs. aphids

The case of lygus bug nymphs versus aphids: Small, green, soft-bodied, sucking insects – at first glance they could be either lygus bug nymphs or aphids. But spend a moment and look for the following characteristics, and you’ll be able to tell which pest you are dealing with.

  • Size: depending on the species, aphids can reach up to 4 mm long, but most will be 1-2 mm. Lygus bug nymphs will be larger, 4-6 mm long
  • Cornicles (small upright backward-pointing tubes found on the back side at the rear of abdomen): aphids have them, lygus bug nymphs do not. In some aphid species, the cornicles or where they attach to the abdomen are black (e.g. corn aphid, English grain aphid).
  • Markings: older lygus bug nymphs have five distinct black dots on their thorax and abdomen; aphids do not.  

For more information about these species and more tips on telling them apart, see our Insect of the Week page! Also, see our Monitoring protocols for lygus bugs in canola. 

Tarnished plant bug nymph – note five black dots on thorax and abdomen – Scott Bauer, USDA
English grain aphid – adult and nymphs – note black cornicles (tubes) sticking out the back – Tyler Wist, AAFC

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Review previously featured insects by visiting the Insect of the Week page.

Insect of the Week – Biological control agents of weeds

As we are nearing the end of the 2018 growing season, we decided to feature something a little bit different for this week’s Insect of the Week: insects that are biological control agents of weeds. Natural enemies of insects include parasitoids and predators that kill insect pests. Natural enemies of weeds include plant pathogens or insect herbivores that impact weed growth and reproduction, thus reducing reduce weed density. There are many insects that may be found in rangeland, forage and crop habitats that are biological control agents of weeds, some of which have been introduced purposely after rigorous testing for safety from places where our invasive plants have originated. Biological control agents of weeds act in two primary ways: plant herbivory and granivory. Plant herbivores consume root, leaves and./or shoots enough to typically reduce its ability to grow and reproduce, and thus its ability to compete with rangeland plants used in cattle grazing or with crops. Granivores or weed seed predators consume high numbers of weed seeds, thus reducing the number of viable weed seeds entering seed banks for germination in future growing seasons.

Ground beetles (Coleoptera: Carabidae) of several genera are known to eat weed seeds within crops, including Harpalus, Amara, Poecilus, and Pterostichus. The diets of some ground beetles almost entirely consist of weed seeds. Other ground beetles are primarily carnivores (i.e., generalist predators of other insects or slugs) that occasionally consume weed seeds. More information about the biology of ground beetles can be found by visiting the Insect of the Week page.

Mogulones crucifer (Pallas) is a biological control agent of hound’s-tongue (Cynoglossum officinale L.), a weedy pest of rangelands in southern British Columbia and southwestern Alberta. The adult stage of this weevil species (Coleoptera: Curculionidae) feeds on leaves of its host while the larvae consume the roots of the host plant. The weevil is highly mobile and has significantly reduced hound’s-tongue densities where it has been released for biological control. For more information about M. crucifer, visit https://www.for.gov.bc.ca/hra/plants/biocontrol/detailed_bioagent_pages/Mogulones_cruciger.htm

Prepared by Dr. Meghan Vankosky

Hound’s-tongue, an invasive species, is a host
plant for Mogulones crucifer
Photo: Jacob W. Frank
Mogulones crucifer adult on hound’s-tongue leaf
photo: Rosemarie De Clerk-Floate
Mogulones crucifer larvae infesting hound’s-tongue root
photo: Rosemarie De Clerk-Floate

Weekly Update

Greetings!

This is the last Weekly Update of the 2018 growing season. It is the 16th week of both the INSECT OF THE WEEK plus WEEKLY UPDATE – hopefully each has supported in-field scouting in our prairie field crops! 

Thank you to our many contributors and sincere appreciation is extended to the many people who repeatedly visited fields all season to support provincial AND prairie-wide insect pest monitoring in field crops in 2018!  

Access the complete Weekly Update either as a series of Posts for Week 16 (August 23, 2018) OR a downloadable PDF version.  Also review the “Insect of the Week” for Week 16!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Meghan Vankosky or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these three steps!

Weather synopsis

Weather synopsis – We close out the Weekly Update for the growing season by looking back at precipitation thanks to the AAFC Drought Watch folks.

This is a map of growing season precipitation (% of normal; Fig. 1):

Figure 1.  Percent of normal precipitation for the growing season (April 1-August 22, 2018) across the Canadian prairies. Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The following map illustrates precipitation (% of normal) for the last 60 days (Fig. 2):

Figure 2. Percent of normal precipitation the past 60 days (as of August 22, 2018) across the Canadian prairies.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Whereas this is the precipitation (% of normal) for the past 30 days (Fig. 3):

Figure 3. Percent of normal precipitation the past 30 days (as of August 22, 2018) across the Canadian prairies.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Here is the accumulated precipitation the past 7 days (Fig. 4)!

Figure 4. Accumulated precipitation the past 7 days (as of August 22, 2018) across the Canadian prairies.
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The map below reflects the Highest Temperatures occurring over the past 7 days (August 16-22, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 5). 

Figure 5. Highest temperature across the Canadian prairies the past seven days (August 16-22, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

 The map below reflects the Highest Temperatures occurring over the past 7 days (August 16-22, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 6). 

Figure 6. Lowest temperature across the Canadian prairies the past seven days (August 16-22, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Normally we share growing degree day maps calculated for the growing season including  March 1, 2018, to the present.  This week we instead reference the AAFC Drought Watch maps.  Below is the growing degree day map (GDD: Base 10ºC for APRIL 1 – August 20, 2018) and is available from Agriculture and Agri-Food Canada (Fig. 7):

Figure 7. Growing degree-day using base 10ºC for across the Canadian prairies for the growing season (APRIL 1-August 20, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Below is the growing degree day map (GDD: Base 5ºC for APRIL 1 – August 20, 2018) and is available from Agriculture and Agri-Food Canada (Fig. 8):

Figure 8. Growing degree-day using base 5ºC for across the Canadian prairies for the growing season (APRIL 1-August 20, 2018). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (23Aug2018).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers can bookmark the AAFC Drought Watch Maps to continue to follow weather conditions during harvest and beyond.

Pre-Harvest Intervals

Reminder – Pre-Harvest Interval (PHI) – Growers with late-season insect pest problems must factor in the PHI which is the minimum number of days between a pesticide application and swathing or straight combining of a crop.  

The PHI recommends sufficient time for a pesticide to break down and a PHI-value is both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

An excellent summary of PHI for various pesticides in their various crops was posted by Saskatchewan Agriculture’s Danielle Stephens in 2016 within their Crop Production News.

In 2013, the Canola Council of Canada created and circulated their “Spray to Swath Interval Calculator” to help canola growers accurately estimate their PHI.  Other PHI are described in your provincial crop protection guides and remember that specific crop x pesticide combinations will mean different PHIs.  

Finally, work towards “Keeping It Clean” so your grain is ready for export!  More information about PHI and Maximum Residue Limits (MRL) is available on the Keeping It Clean site. 

Slugs on wheat

Earlier this month, feeding channels on the upper surfaces of the flag leaf in wheat were reported and evening scouting revealed this culprit!

Figure 1. Deroceras reticulatum, the “grey field slug”, on wheat growing near Crooked Creek AB (August 2, 2018; det. Lien Luong).
Figure 2.  Flag leaf feeding damage  on wheat caused by the grey field slug (Deroceras reticulatum). 
Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.

Field scouting was performed in the evening from 8:30-10:30pm.  As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels.   Wheat was hand-collected by clipping stems ~20cm above the ground to later reveal a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2). 

Specimens were forwarded to L. Luong (U of A) who identified the slugs from the above field as one species, Deroceras reticulatum, the grey field slug.  The majority were juveniles. The grey field slug is the most common to occur in the home garden.

Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops: 

  • Slugs are a complicated problem because most general insecticides don’t work well on them.  
  • Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.  
  • Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.  
  • Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.  
  • Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.  

Health Canada has an overview of snails relating to gardening posted here.

Plant bugs

Bugs of the Family Miridae are also referred to by their common name, “plant bugs”. Prairie growers are familiar with two plant bugs – lygus and alfalfa plant bugs.  

Plant bugs are a very large group of bugs that can include herbivores, omnivores and predators but virtually all are polyphagous which is a term referring to their ability to feed on several species, even Families of other organisms.  Plant bugs are generally very mobile as both adults and nymphs and move readily to feed on different host plants as the season progresses.  Plant bugs can also have different lifecycles with alfalfa plant bugs reproducing as one generation per year whereas lygus bugs can have two to three generations per year.

This season in southern Alberta, first-generation lygus bugs damaged seed alfalfa in June then the second generation damaged canola fields in July and August. High numbers of lygus bugs (10-20 per sweep and higher) were collected in research and demonstration plots of sainfoin, hemp and quinoa in southern Alberta.  

Both lygus and alfalfa plant bugs have sucking mouthparts and the larger, more mature nymphs plus adults are able to penetrate and extract oils from seeds, causing them to shrivel and lose in quality.  Plant bugs feeding in faba beans can cause spotting.

Wasps in the genus Peristenus include native species that attack lygus and alfalfa plant bugs but normally don’t occur in sufficient densities to reduce outbreaking populations of these plant bugs.  The exotic Peristenus digoneutis from Europe, if it could be established and is shown not to interfere with native predators and parasitoids, may increase parasitism to help prevent plant bug outbreaks.  

Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Fifth instar lygus bug nymph (3-4 mm long) (photo:  AAFC-Saskatoon).

Harvest Sample Program

The Canadian Grain Commission is ready to grade grain samples harvested in 2018.  Samples are accepted up to November but send samples as soon a harvest is complete.

This is a FREE opportunity for growers to gain unofficial insight into the quality of their grain and to obtain valuable dockage information and details associated with damage or quality issues.  The data collected also helps Canada market its grain to the world!

More information on the Harvest Sample Program is available at the Canadian Grain Commission’s website where growers can register online to receive a kit to submit their grain.  

In exchange for your samples, the CGC assesses and provides the following unofficial results FOR FREE:

  • dockage assessment on canola
  • unofficial grade
  • protein content on barley, beans, chick peas, lentils, oats, peas and wheat
  • oil, protein and chlorophyll content for canola
  • oil and protein content and iodine value for flaxseed
  • oil and protein for mustard seed and soybean
  • NEW for 2018-19: Participants will receive Falling Number and deoxynivalenol (DON) results for their wheat samples at no cost. This enhancement to the Harvest Sample Program is the first initiative to be funded by the Canadian Grain Commission’s accumulated surplus.

Many producers find having both grade and quality information on their samples before delivering their grain to be helpful.

Stored Product Pests

The Canadian Grain Commission’s website has an online key to stored product pests.  Growers managing grain storage can find an online identification tool for stored product pests (e.g., Rusty grain beetle, Red flour beetle, Confused flour beetle, Saw-toothed grain beetle, and more).  The online tool features excellent diagnostic photos.  A screen shot of the webpage is included below for reference.

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so we link to their most recent information: 

Manitoba‘s Insect and Disease Updates for 2018 can be accessed here. Issue #13 (posted August 22, 2018).

Saskatchewan‘s Crop Production News for 2018 is posted with Issue #7 now available. This issue includes an update from the Crop Protection Lab.

Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Scott Meers. The most recent Call of the Land was posted August 23, 2018.

Crop reports

Crop reports are produced by:

The following crop reports are also available:

Previous Posts

The following is a list of 2018 Posts – click to review:

Abundant parasitoids in canola – Week 10 
Alfalfa weevil – Week 6
Aphid App – Week 12

Bertha armyworm – Week 15

Cabbage seedpod weevil – Week 12 
Cabbage root maggot – Week 11 
Cereal aphid manager (CAM) – Week 2
Cereal leaf beetle – Week 13
Cereal leaf beetle larvae request – Week 8
Crop protection guides – Week 2
Cutworms – Week 4

Diamondback moth – Week 7
Download the field guide – Week 10

Field heroes – Week 8
Flea beetles – Week 4
Flea beetles – Week 15

Grasshopper simulation model output – Week 13

Ladybird beetles – Week 15
Lygus in canola – Week 15

Monarch migration – Week 8

Pea leaf weevil – Week 13

PMRA Pesticide Label Mobile App – Week 4

Scouting charts (canola and flax) – Week 3

Thrips – Week 15
Ticks and Lyme Disease – Week 4

Weather radar – Week 3
West nile virus risk – Week 13
Wheat midge – Week 12

White grubs in fields – Week 8

Wind trajectories – Week 6

Wireworm distribution maps – Week 6

Review the 2018 INSECT OF THE WEEK!

Need a refresher or simply want to keep our 2018 lineup a click away? Here’s the 2018 INSECT OF THE WEEK lineup for the growing season:

Wk01 (May 07, 2018) – Glassy cutworm
Wk02 (May 14, 2018) – Darksided cutworm
Wk03 (21 May, 2018) – Ground beetles: cutworm natural enemies
Wk04 (May 28, 2018) – Flea Beetles
Wk05 (June 4, 2018) – Wireworms
Wk06 (June 11, 2018) – Pterostichus melanarius
Wk07 (June 18, 2018) – Red turnip beetle
Wk08 (June 25, 2018) – Bruner grasshopper
Wk09 (July 03, 2018) – Pea aphid (Hemiptera: Aphididae) 
Wk10 (July 09, 2018) – Natural enemies of pea aphids
Wk11 (July 16, 2018) – The new canola flower midge
Wk12 (July 23, 2018) – Natural enemies of the canola flower midge
Wk13 (July 30, 2018) – Wheat stem sawfly (Cephus cinctus, Hymenoptera: Cephidae)
Wk14 (Aug 07, 2018) – Natural Enemies of the wheat stem sawfly
Extra (Aug 10, 2018) – English grain aphid (Hemiptera: Aphididae)
Wk 15 (Aug 13, 2018) – Twospotted spider mite (Acarina: Tetranychus)
Wk16 (August 20, 2018) – Biological control agents of weeds

Review the WEEKLY UPDATE for 2018 growing season!

Access the WEEKLY UPDATE as either a series of Posts OR downloadable PDF file for the entire 2018 growing season: 

Wk01 – May 10, 2018
Wk02 – May 17, 2018
Wk03 – May 24, 2018
Wk04 – May 31, 2018
Wk05 – Jun 07, 2018
Wk06 – Jun 14, 2018
Wk07 – Jun 21, 2018
Wk08 – Jun 28, 2018
Wk09 – Jul 05, 2018
Wk10 – Jul 12, 2018
Wk11 – Jul 19, 2018
Wk12 – Jul 26, 2018
Wk13 – Aug 02, 2018
Wk14 – Aug 09, 2018
Wk15 – Aug 16, 2018
Wk16 – Aug 23, 2018

Upcoming Meetings and Conferences

Upcoming Meetings and Conferences – The following agricultural insect pest-related meetings and conferences will be held – be sure to re-confirm dates and details as events are finalized:

  • September 27-29, 2018:  The Entomological Society of Alberta Annual Meeting will be held at Edmonton AB and information is available here.
  • October 18, 2018:  The Western Committee on Crop Pests will meet at Lloydminster SK and information is available here.  
  • October 23-25, 2018:  The 11th Canadian Pulse Research Workshop will be held at Edmonton.  More information is available here.  
  • October 23-25, 2018:  The 2018 Canola Discovery Forum will be held at Banff AB.  More information is available here.  
  • November 11-14, 2018:  The Joint Annual Meeting of the Entomological Society of Canada, Entomological Society of America and Entomological Society of British Columbia meets at Vancouver BCand information is available here. 
  • January 15-16, 2019:  CropSphere Agricultural Conference will be held at TCU Place in Saskatoon SK during Crop Production Week.  More information is available at: https://www.cropsphere.com/index.cfm 
  • January 22-24, 2019: The Manitoba Ag Days show will be held at the Keystone Centre in Brandon MB. More information will be available at: https://www.agdays.com/show-info/
  • January 29-31, 2019:  FarmTech 2019 will be held in Edmonton AB and information is available at http://farmtechconference.com/  with registration typically opening early in November.

Please send other IPM-related conference and meetings to jennifer.otani@agr.gc.ca to update this information.

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information: 


● Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and read Issue #13 (posted August 16, 2017) noting soybean aphids as field near the R6 stage and high levels of bertha armyworm larvae from some fields in western Manitoba.

● Saskatchewan’s Crop Production News – 2017 – Issue #5 includes information related to value of late-season disease scouting and record keeping, critical periods for crop water use, and leaving tall-stubble at harvest.

● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (August 17, 2017) provided by Scott Meers. That report notes that diamondback moth are starting to pupate in central and southern fields in the province yet late canola may still need monitoring for DBM larvae, bedstraw hawkmoth larvae (~2.5″ long) have been spotted in canola feeding on volunteer cleavers, the beginning of post-harvest survey for wheat midge and wheat stem sawfly across the province, plus the Agricultural Fieldmen are now ~30% completed the annual grasshopper survey with data coming in already.

Crop reports

Crop reports are produced by:
• Manitoba Agriculture, Rural Development (August 14, 2017)
• Saskatchewan Agriculture Crop Report (August 8-14, 2017)

• Alberta Agriculture and Forestry Crop Report (August 8, 2017)


West Nile Virus and Culex tarsalis

West Nile Virus Risk –  The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below.  As of August 13 2017, areas highlighted in red on the map below have accumulated sufficient heat for C. tarsalis to fly.  Areas highlighted in red, orange and even yellow will have C. tarsalis flying so wear your DEET to stay protected!




The Public Health Agency of Canada posts information related to West Nile Virus in Canada.  In 2016, 104 human clinical cases of West Nile Virus were reported.  The map of clinical cases of West Nile Virus in Canada in 2017 is updated through the summer and three cases of viral West Nile have been reported so far (as of August 5, 2017).  All cases were reported from Ontario (in Timiskaming and Windsor-Essex).

The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds.  As of August 17, 2017, 1113 birds were examined and 48 have tested positive for West Nile virus; one from Saskatchewan, two from Manitoba, 13 from Ontario, and 32 from Quebec.

The Public Health Agency of Canada also monitors and posts updates on the status of WNV in Mosquitoes.  As of July 22, 2017, Quebec, Ontario, Manitoba and Saskatchewan have reports of positive mosquito pools of West Nile Virus.  A total of 47 positive mosquito pools have been found: 

  • 33 from Ontario [Peel Regional (5), Toronto (6), Halton(5), Haliburton-Kwartha-Pine Ridge District(1), Simcoe Muskoka District (1), Windsor-Essex County (6), Eastern Ontario (1), Durham Reginal (1), Hamilton (1), Haliburton-Kawarta-Pine Ridge district (1), Hastings and Prince Edward Countries (2), and York Regional (3)];  
  • 11 from Manitoba [(Winnipeg (3), Southern (2), Interlake eastern (1), and Prairie Mountain(5)]; 
  • 2 from Quebec [Montérégie (1), Laval (1)], and 
  • 1 from Saskatchewan. 

Insect of the Week – Bronzed blossom pollen beetle

This week’s Insect of the Week is the bronzed blossom pollen beetle. They feed on canola and oilseed rape, mustards, bittercress, rockcress, wild radish and dogmustard. They are not known to be established in Western Canada, but are present in Nova Scotia, PEI and Quebec. Adult females lay clusters of 2 to 3 eggs in developing buds and can lay up to 250 eggs in one summer. Once the eggs hatch, larva enter developing flower buds to feed. This feeding can reduce seed production by up to 70%!

For more information on the bronzed blossom pollen beetle, see our Insect of the Week page.

Bronzed blossom pollen beetle – adults (C. Noronha, AAFC)
Bronzed blossom pollen beetle – eggs (C. Noronha, AAFC)



Remember the NEW Cutworm Field Guide is free and downloadable in 2017!

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Weekly Update – Greetings!

Greetings!

Please access the Weekly Update for August 17, 2017 (Week 16), as either a series of Posts  or a downloadable PDF.   


Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Owen Olfert or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these three steps!

Weekly Update – Weather Synopsis

Weather synopsis – Temperature – This week’s temperatures were warmest in southern Alberta and Manitoba (Fig. 1). The 30-day average temperatures were warmest along the border with USA (Fig. 2).

Figure 1. Average precipitation across the Canadian prairies the past
seven days (August 7-14, 2017).



Figure 2.  Average temperature across the Canadian prairies the
past 30 days (July 14-August 14, 2017).





After a fair bit heat across the prairies (Fig. 3), a few of us woke to cooler temperatures (Fig. 4) this week!

Figure 3.  Highest temperatures the past seven days (August  10-16, 2017) across
the Canadian prairies.
Figure 4.  Lowest temperatures the past seven days (August  10-16, 2017) across
the Canadian prairies.



Precipitation – Seven-day rainfall accumulations were greatest in regions north of the Yellowhead highway (Fig. 5). Total 30-day rainfall accumulations indicate that conditions dryer than normal for most of the prairies, particularly southern and central regions of Alberta (Fig. 6). 

Figure 5. Accumulated precipitation the past seven days (August 7-13, 2017).



Figure 6. Percent of average precipitation across the Canadian prairies the 
past 30 days (July 15-August 13, 2017). 



This growing season (April 1 – August 13, 2017), the percent of average precipitation continues to be below average for most of the prairies (Fig. 7).

Figure 7. Percent of average precipitation across the Canadian prairies for the 
growing season (April 1-August 13, 2017). 






The growing degree day map (GDD) (Base 10ºC, March 1 – August 13, 2017) is below:





The growing degree day map (GDD) (Base 5ºC, March 1 – August 13, 2017) is below:






The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.

Weekly Update – Pre-Harvest Intervals (PHI)

Pre-Harvest Interval (PHI) – Growers with late-season insect pest problems will need to remember to factor in the PHI which is the minimum number of days between a pesticide application and swathing or straight combining of a crop.  

The PHI recommends sufficient time for a pesticide to break down and a PHI-value is both crop- and pesticide-specific.  Adhering to the PHI is important for a number of health-related reasons but also because Canada’s export customers strictly regulate and test for the presence of trace residues of pesticides.

An excellent summary of PHI for various pesticides in their various crops was posted by Saskatchewan Agriculture’s Danielle Stephens in 2016 within their Crop Production News.


In 2013, the Canola Council of Canada created and circulated their “Spray to Swath Interval Calculator” which was intended to help canola growers accurately estimate their PHI.  Other PHI are described in your provincial crop protection guides and remember that specific crop x pesticide combinations will mean different PHIs.  More information about PHI and Maximum Residue Limits (MRL) is available on the Canola Council of Canada’s website.


Weekly Update – Crop protection guides

Crop Protection Guides – If you don’t have a copy of your province’s Crop Protection Guide, please make use of these links to access:
• Saskatchewan’s Crop Protection Guide
• Manitoba’s Guide to Crop Protection Guide 
• Alberta’s Crop Protection or Blue Book 
• Western Committee on Crop Pests Guidelines for the Control of Crop Pests


Recall earlier this spring that Health Canada’s Pest Management Regulatory Agency launched a new mobile app to access pesticide labels registered for use in Canada. The App helps homeowners, farmers, industry, provincial and federal organizations access details for pest control products from a smartphone or tablet.  Download it as either:

Weekly Update – Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) – Based on Harcourt (1954), this week the DBM model was run with a biofix date of May 21. The following map illustrates that potentially three generations (after the migratory population) may have been completed across most of the prairies. 



REMINDER – Once diamondback moth is present in the area, it is important to monitor individual canola fields for larvae.  Remove the plants in an area measuring 0.1 m² (about 12″ square), beat them on to a clean surface and count the number of larvae (Fig. 1) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.  The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).


Figure 1. Diamondback larva measuring ~8mm long.
Note brown head capsule and forked appearance of prolegs on posterior.


Figure 2. Diamondback moth pupa within silken cocoon.


Biological and monitoring information for DBM is posted by Manitoba Agriculture, Food and Rural Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, and the Prairie Pest Monitoring Network.  

More information about Diamondback moths can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Diamondback moth page but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Figure 3. Diamondback moth.


Across the prairies, provincial staff coordinate diamondback pheromone trapping during the growing season:
● Low numbers of moths have been reported across Saskatchewan for the 2017 pheromone monitoring.  
● Manitoba Agriculture and Rural Initiatives posted low DBM counts which can be reviewed here.  
● Alberta Agriculture and Forestry has a live 2017 map reporting Diamondback moth pheromone trap interceptions.  A copy of the map (retrieved July 20, 2017) is below for reference.

Weekly Update – Bertha Armyworm

Bertha armyworm (Lepidoptera: Mamestra configurata) – REMINDER – Reporting sites across the prairies have generally reported lower cumulative interceptions and cumulative counts are summarized by provincial staff in Manitoba, Saskatchewan and Alberta.



Scouting tips:
● Some bertha armyworm larvae remain green or pale brown throughout their larval life. 
● Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms. 
● Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. 
● Larvae eat the outer green layer of the stems and pods exposing the white tissue. 
● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.

Monitoring:
– Larval sampling should commence once the adult moths are noted. 
– Sample at least three locations, a minimum of 50 m apart. 
– At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae. 
– Count them and compare the average against the values in the economic threshold table below:  


Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network.  Also refer to the bertha armyworm pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Weekly Update – Lygus in canola

Lygus bugs (Lygus spp.) – Reminder – The economic threshold for Lygus in canola is applied at late flower and early pod stages.  

Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).

Fifth instar lygus bug nymph (3-4 mm long) (photo:  AAFC-Saskatoon).


Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. They feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.

Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.

Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.

Repeat the sampling in another 14 locations. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.

Sequential sampling for lygus bugs at late flowering stage in canola.


The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted.

Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. 

Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production.  The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage.  In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.


Table 1.  Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).

1 Canola crop stage estimated using Harper and Berkenkamp 1975).
2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).


Table 2.  Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).

 3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).


Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.  Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.

Weekly Update – Predicted Grasshopper Development

Grasshopper Simulation Model Output – Based on model output, grasshopper development is slightly ahead of long term averages with approximately 80% of the population in the adult stage.  The following map presents model data for oviposition. Given the warm conditions across the southern prairies, it is not surprising that oviposition rates are predicted to be greatest in southern Alberta and in south-central Saskatchewan.



Grasshopper scouting steps can be reviewed in the previous Week 13 Post.


Reminder:  Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Food and Rural Development, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.

Weekly Update – Time of Swathing for Canola

The Canola Council of Canada created a guide to help growers estimate swathing time in canola.  A screen shot of the downloadable Canola Swathing Guide has been included below for reference.




Weekly Update – Wheat surveying (post-harvest)

Wheat surveying – As wheat is harvested, monitoring can begin for two wheat pests including wheat midge and wheat stem sawfly.  As soon as the combine passes through, in-field monitoring can commence with:
● Soil core sampling is used to assess the densities of wheat midge cocoons set to overwinter, PLUS
● The number of cut stems can be counted to determine the density of wheat stem sawfly.

By January, forecast and risk maps summarizing surveying efforts for the above pests will be available (e.g., check the Risk Map Page).


More information about these pests can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”.  View ONLY the Wheat midge pages or ONLY the Wheat stem sawfly pages.  Remember the entire guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry) or the PPMN protocol. 


Information related to wheat stem sawfly is posted by Alberta Agriculture & Forestry, Saskatchewan Agriculture, Manitoba Agriculture, or the PPMN. 

It’s all about the habitat – The secret life of cattle dung!

Cattle dung provides moisture, nutrients, and shelter for numerous insect species and other arthropods.  Ralf Jochmann’s video magnificently captures some of this diversity, using close-up photography and narration (https://www.youtube.com/watch?v=-l05EHZMmKE).



Adults of the dung beetle Chilothorax (Aphodius) distinctus are common in cattle dung, particularly in September and early October.  Larvae develop in agricultural soils where they can occasionally cause crop damage when present in high densities.  For more information on this occasional pest, click here.

Weekly Update – Previous Posts

The following is a list of 2017 Posts – click to review:

Alfalfa Weevil (Week 11)

Brood X Cicadas

Cabbage seedpod weevil (Week 12)
Canola scouting chart
Cereal leaf beetle
Crickets with your popcorn
Cutworms

Diamondback moth (Week 14)

Flax scouting chart
Flea beetles

Grasshoppers (Week 13)

Iceberg reports
Insects as food (Week 14)

Lily leaf beetle

Monarch migration (Week 10)

Painted lady butterflies (Week 9)
Pea leaf weevil
PMRA Pesticide Label Mobile App

Nysius niger (Week 8)

Ticks and Lyme disease

Weather radar
Wheat midge
White grubs in fields (Week 9)
Wildfires (Week 13)

Wind trajectories

Weekly Update (UPDATED!)

Greetings!

Three sections of the Weekly Update for Week 16 (August 17, 2016) were just updated!  A downloadable PDF copy of the updated Weekly Update can now be accessed here.  

Subscribe to the Blog by following the instructions posted here!  You can receive automatic updates in your inbox through the growing season.



Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Owen Olfert or Jennifer Otani.  Past “Weekly Updates” are very kindly archived to the Western Forum website by webmaster, Dr. Kelly Turkington.  

Weekly Update – Weather Synopsis (updated)

Weather synopsis – The average temperature over the past seven days (August 7-14, 2016) was similar to Long Term Normal (LTN) values.



Across central Alberta, Saskatchewan, and Manitoba,  average cumulative rainfall was well above LTN values.





The average 30 day temperature for July 8-August 7, 2016, was similar to LTN and rainfall was 50% greater than LTN (average across the prairies). The wettest conditions have been in south and central areas of western Saskatchewan and central Alberta.






The average growing season temperature (April 1- August 7, 2016) was marginally warmer than normal. Growing season rainfall has been approximately 28% above average.






The map below shows the modelled soil moisture across the prairies (August 14, 2016).



The updated growing degree day map (GDD) (Base 5ºC, March 1 – August 14, 2016) is below:






While the growing degree day map (GDD) (Base 10ºC, March 1 – August 14, 2016) is below:







The map below shows the Lowest Temperatures the Past 7 Days (August 10 – August 16, 2016) across the prairies:


The map below shows the Highest Temperatures the Past 7 Days (August 10 – August 16, 2016):




The maps above are all produced by Agriculture and Agri-Food Canada.  Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.

Weekly Update – Swede midge (updated)

Swede midge (Contarinia nasturtii) – This growing season, bioclimatic model outputs predicting swede midge development continue to be compared to in-field observations of actual midge in canola in Saskatchewan since the model has yet to be validated with midge data from that region.


The model was run for Melfort SK for April 1 – 14 and the output suggests 4 generations might possibly occur in 2016 in northeast Saskatchewan.

 
Warm, wet conditions are predicted to result in shorter generation times in July and August than May and June.





In-field monitoring continues to be the priority both to detect new populations of swede midge on the prairies but then to validate the number of generations and phenology of this pest relative to canola development on the prairies.    

Swede midge scouting tips for in-field monitoring:
• Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae.
• The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
• Flowers may fail to open.
• Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
• Larvae can be seen with a hand lens.
• Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.