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.
Reminder – Cutworm scouting spans April to late June across the Canadian prairies!
Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow up by walking these areas either very early or late in the day when some cutworm species (or climbing cutworms) move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of symptomatic plants and also any healthy plants immediately adjacent to missing rows or wilting or clipped plants. Some cutworms feed by remaining just below the soil surface, clipping then pulling the plant below as they munch away! If the plant is well-established (e.g., perennial grass or legume), check within the crown plus in the adjacent soil. The culprits could be cutworms, wireworms, or more!
Important: Several species of cutworms (Lepidoptera: Noctuidae) can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. A field guide is available to help growers scout and manage the various species of cutworms that can appear in field crops grown on the Canadian prairies. Cutworm Pest of Crops is available free in either English or French! Download a searchable PDF copy to access helpful diagnostic photos plus a table showing which larvae are active at different points in the growing season!
Other vital resources to scout and manage cutworms include: ● For anyone on the Canadian prairies, Manitoba Agriculture’s Cutworms in Field Crops fact sheet includes action and economic thresholds for cutworms in several crops, important biological information, and great cutworm photos to support in-field scouting. ● For Albertans….. If you find cutworms, please consider using the Alberta Insect Pest Monitoring Network’s “2024 Cutworm Reporting Tool” then view the live 2024 cutworm map updated daily. Review the live map to see where cutworms are appearing then prioritize in-field scouting accordingly. ● Cutworms were featured as 2024’s first Insect of the Week.
Two species, the striped and crucifer flea beetles, are the most chronic and economically important insect pests of cruciferous field crops grown across western Canada. Both species are already active so prioritize field scouting in fields of emerging and seedling canola and mustard. All cruciferous crops and plants of any Brassicaceae are similarly attractive and can suffer damage from crucifer (P. cruciferae) and striped flea beetles (P. striolata).
Damage to emerging crops can progress very quickly when flea beetle densities are high, even within the same day! The cotyledon stage of canola is most vulnerable to flea beetle feeding.
Learn more about flea beetle damage in canola by reviewing the Insect of the Week (Wk 2 released May 13, 2024). Review photos of flea beetle feeding damage posted in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent feeding damage and to apply the action threshold of 25 % leaf area of cotyledons. The Canola Council of Canada’sCanola Encyclopedia also features flea beetles along with an excellent visual guide to help estimate feeding damage.
Conditions in May 2024 have been cooler and somewhat wetter than experienced in May of 2023. These cool, wet conditions could be slowing down the development of grasshopper eggs and grasshopper nymphs. Many factors could influence grasshopper populations in the next few weeks. Because grasshoppers had so much time to lay eggs in summer and fall of 2023, and because the eggs had more time to develop before overwintering, grasshopper risk remains quite high in spring of 2024.
In fact, grasshopper nymphs, including the nymphs of the pest species, have been observed at multiple locations in southern Alberta and southern Saskatchewan. In central Saskatchewan, there are reports of significant grasshopper feeding damage to emerging canola crops.
Scout for grasshoppers to keep informed of their developmental stage and population density.
Tip – younger or earlier instar nymphs are easier to manage but visit sites every few days to stay on top of local field conditions.
Important – A preliminary summary of available thresholds for grasshoppers has been kindly shared by Dr. J. Tansey (Saskatchewan Agriculture) in Table 1. When scouting, compare in-field counts to the available threshold value for the appropriate host crop AND for field or ditch situation. Available thresholds (nominal and economic) help support producers while protecting beneficials (i.e., predators, parasitoids, and pathogens) that regulate natural populations of grasshoppers.
More 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. ● Carefully check roadside ditches and along field edges but also check the edge of the crop and into the actual field. ● A sweep-net can ‘detect’ grasshopper nymphs, however, economic thresholds for grasshoppers are based on the number of grasshoppers per square-metre counts. ● 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.
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.
Earlier this week, Shelley Barkley (Alberta Agriculture and Irrigation) swept a flixweed patch in a ditch and found diamondback moth larvae (Fig. 1) that were nearly ready to pupate! Thus, in some parts of the prairies, the first local generation of diamondback moth is well underway and nearing completion.
Figure 1. Diamondback larvae collected using a sweep-net in flixweed growing near Dunmore AB on May 27, 24. Photo: S. Barkley (Alberta Agriculture and Irrigation).
It’s a busy week in the field, so we do not have a full update on diamondback moth trap captures to share this week. Please check out the Provincial Reports for the most up-to-date information available from the diamondback moth pheromone monitoring program.
Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, 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.
The annual pea leaf weevil survey is getting started! If you are planting field peas this year, please consider volunteering your fields for this survey. The survey is conducted by counting the characteristic ‘u’ shaped feeding notches made by adult pea leaf weevil at several locations along the field edge.
Adult pea leaf weevil could now be dispersing into emerging field pea and faba bean fields. Watch for ‘u’-shaped notches along the leaf margins of emerging seedlings – for more information about the damage caused to crops by pea leaf weevil, check out the Week 4 Insect of the Week post.
Live adult pea leaf weevil are needed for experiments this spring, so if you are finding weevils in your crops, please contact Dr. Meghan Vankosky (AAFC-Saskatoon; meghan.vankosky@agr.gc.ca). Thank you!
Based on long-term data for the prairie region, bertha armyworm pupal development should be 30-75% completed by late May in a normal year (Fig. 1).
Figure 1. Long-term average predicted bertha armyworm (Mamestra configurata) pupal development (% completion) across the Canadian prairies as of May 28, 2023. Model runs were conducted using climate normal data.
Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season will be starting soon, with traps likely to be set up the week of June 10, 2024.
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” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
The Pests and Predators Field Guide (2021) is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields.
Reminder – When scouting, avoid unwanted passengers – remember to watch for ticks at this time of year!Blacklegged (deer) ticks can carry Lyme Disease, anaplasmosis, babesiosis, or Powassan virus. Access information on how to safely remove and identify a tick made available by Health Canada which also recommends these “before you go” ways to help prevent tick bites: • light coloured, long-sleeved shirts and pants help you spot ticks easier. • tuck shirt bottoms into pants and pant cuffs into socks – seal yourself in and ticks out! • closed-toe shoes keep ticks out! • apply an insect repellent containing DEET or Icaridin to clothing and exposed skin (according to product label directions). • wear permethrin-treated clothing (according to product label direction). …. and review the full set of helpful tips!
Continued surveillance is important and enables tracking of Lyme disease incidence and risk. Follow the links to learn more and to submit ticks if you live in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, or Quebec. Access additional information posted by Health Canada related to Lyme disease surveillance which also summarized that, between 2009 and 2023, 19,983 human cases of Lyme disease were reported to provincial public health units across Canada.
Another option is the free eTick APP, a public platform for image-based identification and population monitoring of ticks in Canada. Both Google Play and iOS versions of the App enable users to upload tick photos for help with identification.
Public Health Agency of Canada has a Top 10 Tick Hiding Spots on Your Body available as a poster in multiple languages including Mi’kmaq, Mohawk, Ojibwe (Eastern), French, English, Spanish, Tagalog, Arabic, Punjabi, Chinese (simplified and traditional), and Italien. An example in English is posted below for your quick reference (Fig. 1) so check it, then yourself, and your pets!
Figure 1. Screenshot of Public Health Agency of Canada’s infographic of top 10 tick hiding spots on your body (2020; retrieved 2024May23).
Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:
MANITOBA’SCrop Pest Updates for 2024 have started! Access the online May 23, 2024 report (or review a PDF copy). Bookmark the insect pest homepage to access fact sheets and more! • Diamondback moth pheromone trap monitoring in MB – Dr. John Gavloski (Manitoba Agriculture) reported that, “Diamondback moth have been found in 55 out of 68 traps that counts were reported from. Trap counts have generally been low so far, however, some moderate counts have occurred in the Eastern, Interlake and Central regions. The highest cumulative trap count so far is 69 from a trap near Riverton in the Interlake region.” • True armyworm in MB – Dr. John Gavloski (Manitoba Agriculture) reported that, “A network of pheromone-baited traps are being monitored at 34 locations from early-May until late-July to determine how early and in what levels populations of armyworms have arrive. Some moderate counts have occurred from traps in the Eastern and Interlake regions of Manitoba. The highest cumulative count is 76, from a trap near Riverton in the Interlake region.” • Beneficial insect monitoring in MB – “Weekly monitoring of the levels and stages of five groups of predaceous insects; lady beetles, green lacewings, hover flies, minute pirate bugs and damsel bugs”, will be undertaken using sweep-net sampling.
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #1 report. Bookmark their insect pest homepage to access important information! • Grasshopper hatch in SK – Updates that, ” eggs are being found by agrologists”, “recent rains are unlikely to have a major impact on grasshopper populations”, “nymphs have been found near Outlook, Kindersley, and Regina”, and emphasizes the importance of “producers start(ing) to scout for eggs or nymphs”. • Flea beetle monitoring in SK – Updates that, “fields in northern Saskatchewan have heavy flea beetle feeding on volunteer canola” and recommends, “producers across the province should frequently scout canola and mustard” following seedling emergence. • Also access the Crops Blog Posts that announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).
ALBERTA’SInsect 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. Remember, AAF’s Agri-News occasionally includes insect-related information, e.g., scout for grasshoppers (May 27, 2024), flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024). • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from the 27 reporting sites reflect low or “no risk” while two sites in the Peace River region reflect “elevated risk” (as of May 30, 2024). • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 7 surveyed sites have reported from across the province and all are in southern Alberta.
May was characterized by wonky weather – unseasonably warm days and very little rain. As a result, some prairie insect pests are developing faster than normal.
Grasshoppers thrive in warm, dry conditions and we continue to hear about high numbers of nymphs along roadsides and field edges. Last week, we also observed some third instar grasshopper nymphs, which normally do not appear in the population until mid-June. Diamondback moths that arrived in early May have likely reproduced and adult moths found now could be from the first generation produced on the prairies. Bertha armyworm development is also well ahead of schedule – pupal development could be 90% complete in some areas, so it is probably time to set up pheromone traps for bertha armyworm monitoring in most parts of the prairies. This week, we featured the pea leaf weevil in the Insect of the Week – the annual damage survey for pea leaf weevil is now underway! For more information, check out the posts in the Weekly Update!
Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to plan for in-field scouting, and even thresholds to help support in-field management decisions are all available for review or download.
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.
***Special thanks to Mark Berry, AAFC-Geomatics, for providing up-to-date weather information for the prairies that is summarized here and used to predict insect development***
This past week (May 22-28, 2023), average prairie temperatures continued to be well above average. The prairie average daily temperature was 4°C warmer than normal (Fig. 1). The warmest temperatures were observed across southern regions of Manitoba and Saskatchewan. Even though temperatures have moderated across the Peace River region, temperatures were still 2-3°C warmer than normal for this time of year.
Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of May 22-28, 2023.
Average temperatures over the past 30 days (April 28 – May 28, 2023) have been 4°C above normal (Fig. 2), with the warmest temperatures reported for Alberta and western Saskatchewan.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of April 29-May 28, 2023.
Since April 1, the 2023 growing season has been coolest across eastern Saskatchewan and western Manitoba (Fig. 3). Temperatures have been below normal for many locations across western Manitoba. For example, the average temperature near Melita has been 1.3°C cooler than average. Alberta temperatures continue to be above average. Relative to climate normals temperatures, the warmest and most above average conditions continue to be those in the Peace River region. For example, the growing season temperature has been 5°C warmer than normal at Fort Vermillion, AB.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to May 28, 2023.
Seven-day cumulative rainfall was nominal for most of Alberta and Manitoba last week (Fig. 4). Central Alberta and southern locations in the Peace River region received much need rain. Grande Prairie, Alberta reported 65 mm and Peace River, Alberta reported 59 mm. Saskatoon, Saskatchewan reported 41 mm.
Figure 4. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 22-28, 2023.
Rainfall over the past 30 days has been highly variable across the prairies (Fig. 5). Recent rainfall in the Peace River region has resulted in many locations in that region having rainfall amounts that are 200% of normal. Conversely eastern Alberta and western Saskatchewan have had rainfall amounts that are well below normal. Over the past 30 days rainfall totals are less than 60% of normal across most of Alberta, northwestern and eastern Saskatchewan and Manitoba.
Figure 5. 30-day average cumulative rainfall (mm) observed across the Canadian prairies for the period of April 29-May 28, 2023.
Growing season rainfall has been greatest across southern Saskatchewan and southern areas of the Peace River region; rainfall amounts have been low for most of the southern and central regions of Alberta, western Saskatchewan, and most of Manitoba (Fig. 6). A large region, extending from Lethbridge, Alberta to Edmonton, Alberta and into western Saskatchewan (to about Saskatoon) continues to have well below normal rainfall accumulations. At Hanna, Alberta for example, the total rainfall this growing season is only 40% of what would normally have accumulated by this time of year.
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to May 28, 2023.
‘Reverse trajectories’ refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date. Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating. If diamondback moth adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g., rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data.
More reverse trajectories entered the Canadian prairies between May 25-31 than in the last two weeks (Fig. 1). With more reverse trajectories occurring, we may also see an increase in the introduction or migration of diamondback moths and aster leafhoppers to the prairies.
Figure 1. The average number (based on a 5-day running average) of reverse trajectories (RT) that have crossed the prairies for the period of May 1-31, 2023.
Mexico, California and Texas: Last week no reverse trajectories that entered the prairies that originated from Mexico, California or Texas. In comparison, 37 reverse trajectories from Mexico, California, or Texas crossed into the prairies this week (May 25-31). These trajectories were predicted to cross into southeastern Saskatchewan and Manitoba (Fig. 2)
Figure 2. Total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and May 31, 2023.
Pacific Northwest (Idaho, Oregon, Washington): This week 55 reverse trajectories from the Pacific Northwest were predicted to cross the prairies, which is less than observed last week (n=79). The majority of Pacific Northwest reverse trajectories have been reported to pass over Alberta and western Saskatchewan (Fig. 3).
Figure 3. Total number of dates with reverse trajectories originating over Idaho, Oregon, and Washington that have crossed the prairies between April 1 and May 31, 2023.
Oklahoma and Texas: This past week there were 38 reverse trajectories that originated over Texas and Oklahoma and passed through the prairies, particularly southeastern Saskatchewan and Manitoba (Fig. 4).
Figure 4. The total number of dates with reverse trajectories originating over Oklahoma and Texas that have crossed the prairies between May 1 and May 31, 2023.
Kansas and Nebraska: Since April 1, reverse trajectories originating in Kansas and Nebraska were reported to cross southeastern Saskatchewan and southern Manitoba (Fig. 5). Between May 25 and May 31, 2023 there were 95 reverse trajectories that were predicted to occur. This is a significant increase over the previous week (n=9).
Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between May 1 and May 31, 2023.
Over the past 5-7 days we have conducted a roadside survey for grasshoppers in west-central Saskatchewan. Numbers and development were higher than normal. First and second instar nymphs were found at all locations and many sites had low numbers of third instar grasshopper nymphs. We generally do not see third instars until mid-June! Many locations had high numbers of first instars suggesting that the hatch is still progressing. Melanoplus bivittatus, the two-striped grasshopper, was the most common species at all locations sampled in Saskatchewan in the last five days.
Our observations in the field over the last week agree with the model simulation used to estimate the status of grasshopper development as of May 28, 2023. Grasshopper development is progressing rapidly where temperatures have been well above normal in Alberta and western Saskatchewan. Model runs for 2023 suggest that egg development is 87% complete, on average. At the end of May in an average year, we would expect egg development to be only 72% complete. Recent warm conditions across southern Manitoba have also resulted in faster development rates for eggs.
Grasshopper eggs are now hatching across Alberta and in western and central regions of Saskatchewan (Fig. 1). Hatch rates are well ahead of expected hatch rates based on long-term average weather conditions. In central and eastern regions and across most of Manitoba, hatch is predicted to be less than 15% but hatch rate is increasing (15-45%) in southern Manitoba after some warmer weather last week.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of May 28, 2023.
2023 is shaping up to be an interesting year for grasshoppers and prairie farmers should be prepared to scout for grasshoppers, especially if conditions remain warmer and drier than normal. For more information about grasshopper scouting, biology, and management in your province (Alberta, Saskatchewan, Manitoba), please check out their resources available online.
Diamondback moths (Plutella xylostella) are a migratory invasive species to western Canada. 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, resulting in subsequent non-migrant populations that may have three or four generations during the growing season. DBM development can be rapid during periods of warm weather. Model simulations, initiated in early May and extendingto May 28, 2023, indicate that the first generation of non-migrant adults are currently occurring across the Canadian prairies (Fig. 1).
Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of May 28, 2023.
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 dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Biological and monitoring information for diamondback moth (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Ministry of 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 Field Guides page.
Based on model simulations, development of overwintered bertha armyworm (Mamestra configurata) pupae is rapidly progressing this spring (Fig. 1).
Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development (% complete) across the Canadian prairies as of May 28, 2023.
In fact, development is significantly ahead of normal for most of the prairies (Figs. 2). Models suggest that bertha armyworm pupal development in Alberta is 10-14 days faster than average development for this time of year. There are small areas in Alberta where the model predicts that pupal development may be greater than 90% completed.
Figure 2. Long-term average predicted bertha armyworm (Mamestra configurata) pupal development (% completion) across the Canadian prairies as of May 28, 2023. Model runs were conducted with climate normals data.
Where bertha armyworm are present, adults may be appearing in areas where predicted pupal development is greater than 90% complete. We suggest that bertha armyworm traps should be installed as soon as possible. Many thanks to all of the volunteers across the Prairie region who are hosting BAW pheromone traps in 2023!
Visit the Alberta Insect Pest Monitoring Network page for information about insect monitoring in Alberta, including links for live maps from the 2023 monitoring season for diamondback moth, bertha armyworm, cutworms and others.
Watch for new issues of the Saskatchewan Crop Production News coming soon in 2023 and browse the articles from 2022 for information from the past.
The first Manitoba Crop Pest Update for 2023 was posted on May 24. Watch their website for new Crop Pest Updates as the season continues and check out the archives to read past Updates.
As crops are beginning to pop up – so is the pea leaf weevil (Sitona lineatus). Adults emerge in the spring and feed on legumes, such as field peas, faba beans, alfalfa, beans and lentils (causing characteristic “notching” or “scalloping” on the edges of leaves) before laying their eggs in field peas and faba beans. Each adult female can lay over 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Feeding by adults on the foliage and by larvae on the root nodules contributes to yield losses in field pea and faba bean crops.
Adult pea leaf weevil and a ‘u’-shaped notch resulting from feeding by the adult weevil. Photo credit: Jonathon Williams, AAFC-Saskatoon.
The pea leaf weevil is a slender greyish-brown beetle measuring approximately 5 mm in length. These insects can be distinguished by three light-coloured stripes extending length-wise down the thorax and the abdomen. All species of Sitona, including the pea leaf weevil, have a short or ‘broad’ snout unlike species like the cabbage seedpod weevil that have a long, curved snout. Mature larvae grow up to 3.5-5.5 mm long. The larvae are legless and c-shaped with a brown head.
An adult pea leaf weevil, missing some scales, but showing the stripes extending onto the pronotum/thorax. Photo credit: Jonathon Williams, AAFC-Saskatoon.
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.
TEMPERATURE: Since April 1, the 2022 growing season has been cooler than normal, particularly across Manitoba. Conditions continue to be dry across Alberta and western Saskatchewan while rainfall amounts have been well above normal for eastern Saskatchewan and Manitoba. This past week (May 23-29, 2022) average daily temperatures were significantly warmer than last week. The average temperature across the prairies was 1C warmer than normal (Fig. 1). Temperatures were warmest in an area extending from Saskatoon to Winnipeg.
Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of May 23-29, 2022.
Weekly temperatures continue to be cooler in the Peace River region. Average 30-day temperatures (April 30-May 29, 2022) were similar to climate normal values (Figs. 2 and 4). Temperatures were warmer than normal across most of Alberta and western Saskatchewan. The growing season (April 1-May 29, 2022) has been cooler than average (Fig. 3; Table 1).
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of April 30 to May 29, 2022.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to May 29, 2022.Figure 4. Growing season average temperature anomaly (°C difference from climate normals) observed across the Canadian prairies for the period of April 1-May 29, 2022.Table 1. Growing season temperature and rainfall summary for specific locations across the Canadian prairies (April 1- May 29, 2022).
PRECIPITATION: Seven-day cumulative rainfall ranged between 0 and 67 mm with the highest rainfall amounts occurring across western Manitoba and eastern Saskatchewan (Fig. 5). Conditions continue to be dry across western Saskatchewan and most of Alberta with rainfall amounts that were generally 5 mm or less for the period of May 23-29.
Figure 5. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 23-29, 2022.
Rain (30-day accumulation) amounts have been well above average across the eastern prairies, particularly southeastern Manitoba; rain amounts have been below normal in Alberta and western Saskatchewan (Figs. 6 and 8).
Figure 6. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (April 30 to May 29, 2022).
Growing season rainfall for April 1-May 29, 2022 continues to be greatest across Manitoba and eastern Saskatchewan yet conditions have been well below normal across most of western Saskatchewan and Alberta (Fig. 7; Table 1).
Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to May 29, 2022.Figure 8. Growing season cumulative rain anomaly (% if climate normals) observed across the Canadian prairies for the period of April 1-May 29, 2022.
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. Review lifecycle and damage information for this pest. Review the historical grasshopper maps based on late-summer adult in-field counts performed across the prairies.
Model simulations were used to estimate percent grasshopper embryonic (egg) development as of May 29, 2022. Recent warmer temperatures have resulted in increased rates of egg development. Last week average development was 64 %. This week, average egg development is predicted to be 73 % with a range of 63-82 % (Fig. 1). In comparison, egg development based on long-term climate data is typically 70 % by this week of the growing season (Fig. 2). Cool conditions in Manitoba and the Peace River region continue to result in slower than average development rates in those areas. Across southern Alberta, the simulation indicates that egg development is similar to long-term average values.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development (%) across the Canadian prairies as of May 29, 2022.Figure 2. Long-term average predicted grasshopper (Melanoplus sanguinipes) embryological development (%) across the Canadian prairies as of May 29 based on climate normals data.
Hatch is progressing across southern Alberta and western Saskatchewan (Fig. 3). Last week, grasshopper hatchlings were collected in an area between Saskatoon and Kindersley. Southern Alberta and western Saskatchewan have received the least amount of rain during the growing season. Grasshopper risk can be greater when conditions are warm and dry.
Figure 3. Predicted grasshopper (Melanoplus sanguinipes) grasshopper hatch (%) across the Canadian prairies as of May 29, 2022.
The alfalfa weevil (AAW) (Curculionidae: Hypera postica) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest.
Model simulations for alfalfa weevil (AAW) indicate initial hatch should be occurring across southern and central regions of Alberta and Saskatchewan. First and second instar larvae are predicted to appear in alfalfa fields near Medicine Hat.
The following graphs indicate, based on potential number of eggs, that development is marginally faster near Vauxhall, Alberta (Fig. 1), compared to Saskatoon, Saskatchewan (Fig. 2). Development is similar to long-term average values. The model predicts that first and second instar larval populations may peak over the next 10 days near these two locations.
Figure 1. Predicted status of alfalfa weevil (Hypera postica) populations near Vauxhall AB as of May 29, 2022.Figure 2. Predicted status of alfalfa weevil (Hypera postica) populations near Saskatoon SK as of May 29, 2022.
Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from 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 cereal leaf beetle (CLB) (Chysomelidae: Oulema melanopus) model predicts larval development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest.
Warmer conditions in southern Alberta and southwest Saskatchewan are expected to have resulted in more rapid development of CLB populations in those areas than in southern Manitoba. The model output suggests that CLB hatch should be occurring across southern Alberta and Saskatchewan (Figs. 1 and 2). As a result of cooler conditions, egg development is predicted to be delayed in southern Manitoba (Fig. 3). The simulation predicts that second instar larvae may occur next week in southern Alberta and then 7-10 days later across southern Manitoba.
Figure 1. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Lethbridge AB as of May 29, 2022.Figure 2. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Maple Creek SK as of May 29, 2022. Figure 3. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Brandon MB as of May 29, 2022.
Access scouting tips for cereal leaf beetle or find more detailed information by accessing the Oulema melanopus page from 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.
When considering average versus in-season pupal development, the current 2022 development of overwintered BAW pupae is expected to be significantly delayed for the Peace River region, Manitoba, and southern and eastern regions of Saskatchewan (Fig. 1). Though somewhat delayed, development of BAW pupae in southern and central Alberta and western Saskatchewan will be similar to average.
We recommend BAW pheromone traps be placed in fields when pupal development is 75-80 % to ensure traps are deployed in advance of the emergence of adults. The weather forecast predicts normal temperatures for the next week. This should advance BAW development with rates becoming similar to long-term average values. Based on current runs, it is advisable that Alberta and Saskatchewan traps be placed in fields by the end of next week (June 6-10). Traps in MB and the Peace River region should be put out one (Manitoba) or two (Peace River region) weeks later.
Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development (%) across the Canadian prairies as of May 29, 2022.
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” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
1. REVERSE TRAJECTORIES (RT) Since May 1, 2022, the majority of reverse trajectories crossing the prairies originated from the Pacific Northwest (Idaho, Oregon and Washington) (Fig. 1). Relative to previous weeks, this past week (May 24-30, 2022) there was a significant increase in the number of trajectories (PNW, OK/TX and NE/KS) that passed over the prairies.
Figure 1. Average number (based on a 5-day running average) of reverse trajectories (RT) crossing the prairies for the period of May 1-30, 2022.
a. Pacific Northwest (Idaho, Oregon, Washington) – The majority of Pacific Northwest reverse trajectories have been reported to pass over southern and central Alberta and western Saskatchewan (Fig. 2).
Figure 2. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and May 30, 2022.
b. Mexico and southwest USA (Texas, California) – This past week there have not been any reverse trajectories that originated from Mexico, California or Texas. Since April 1, reverse trajectories were reported for Manitoba (Portage, Selkirk, Brandon, Carman, Russell) and eastern Saskatchewan (Gainsborough, Grenfell) (Fig. 3).
Figure 3. The total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and May 30, 2022.
c. Oklahoma and Texas – Since April 1, reverse trajectories were reported for Manitoba and eastern Saskatchewan (Fig. 4). This past week (May 24-30, 2022) there was an increase in the number of reverse trajectories that have crossed over southeastern Saskatchewan (Weyburn and Gainsborough) and Manitoba (Portage and Brandon) relative to previous weeks.
Figure 4. The total number of dates with reverse trajectories originating over Texas and Oklahoma that have crossed the prairies between May 1 and May 30, 2022.
d. Nebraska and Kansas – Reverse trajectories, originating from Kansas and Nebraska have crossed southeastern Saskatchewan and southern Manitoba (April 1 – May 23, 2022) (Fig. 5). This past week (May 24-30, 2022) there was an increase in the number of reverse trajectories that have crossed over eastern Saskatchewan and Manitoba relative to previous weeks.
Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between April 1 and May 30, 2022.
2. FORWARD TRAJECTORIES (FT) The following map presents the total number of dates (since April 1, 2022) with forward trajectories (originating from Mexico and USA) that were predicted to cross the Canadian prairies (Fig. 6). Results indicate that the greatest number of forward trajectories entering the prairies have originated from the Pacific Northwest (Idaho, Oregon, Washington), Montana and Wyoming.
Figure 6. Total number of dates with forward trajectories, originating from various regions of the United States and Mexico, crossing the prairies between April 1 and May 30, 2022.
View historical PPMN wind trajectory reports by following this link which sorts the reports from most recent to oldest.
The Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download a free copy to arm your in-field scouting efforts!
Review the Sweep-net Video Series including: • How to sweep a field. Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • What’s in my sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • Why use a sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020.
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
MANITOBA’SCrop Pest Updates for 2022 are up and running! Access a PDF copy of the June 1, 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! • Diamondback moth pheromone trap monitoring update for MB – “So far, diamondback moth has been found in 24 traps. Levels are generally very low, with the exception that some moderate counts have occurred in the Eastern region, particularly over the past two weeks. The highest cumulative trap count so far is 50 from a trap near Hadashville in the Eastern region” Review page 4 of the above report for greater detail and regional counts.
ALBERTA’SInsect 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. • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, low numbers of diamondback moth have been intercepted across the province. • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, no cutworms have been reported on the live map.
Continuing our series on Prairie wireworms, this week we highlight the Prairie grain wireworm, Selatosomus aeripennis destructor.
This species is native to the Prairies and is the second most abundant wireworm in Prairie crop fields, but it likely causes the most damage. This wireworm is big and beefy, it grows up to 23 mm long when mature and has a stout build. Its aggressive feeding style can destroy 10 times as many seeds as its cousin, Hypnoidus bicolor, a species that is often found together within the same fields.
Size of resident wireworms can vary with species. Selatosomus aeripennis destructor (left) and Hypnoidus bicolor (right). Photo: W. van Herk, AAFC Agassiz . Photo taken from the Pest Wireworm Guide
Interestingly, click beetles of this species rarely fly, they mostly walk to find mates and choose locations to lay eggs. A new pheromone has recently been discovered by researchers at Simon Fraser University and AAFC that can be used to attract male beetles. This pheromone will help monitoring efforts.
AAFC has recently released a new field guide on Prairie pest wireworms. It has information on biology, monitoring and management and research on wireworms on the Prairies.
Free digital copies in both official languages can be downloaded at these links.
See this week’s wireworm information in the free, downloadable guide: English ; French
Did you know?
Prairie grain wireworm has a closely-related subspecies called Puget sound wireworm (Selatosomus aeripennis aeripennis). This species looks almost identical to Prairie grain wireworm and can be a pest in the Aspen Parkland Ecoregion.
Reference:
Gries, R., van Herk, W., Alamsetti, S.K., Catton, H., Meers, S., Otani, J., Gries, G. (2022) (Z,E)-a-Farnesene – sex pheromone component of female click beetle Selatosomus aeripennis destructor (Brown) with intra- and inter-sexual communication function. Entomologia Experimentalis et Applicata. 170:344-351. https://doi.org/10.1111/eea.13142
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.
Access background information for how and why wind trajectories are monitored in this post.
1. REVERSE TRAJECTORIES (RT) Since May 1, 2021 the majority of reverse trajectories that have crossed the prairies originated from the Pacific Northwest (Idaho, Oregon and Washington). For the past two weeks there have been an increasing number of reverse trajectories that moved north from Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Compared to previous years, the number incoming trajectories (May) has increased. Though these US regions can be a source of diamondback moths, the ECCC models predict air movement, not actual occurrence of diamondback moths. It should also be noted that host plants of diamondback moth include all plants in the Brassicacea family, including cruciferous weeds and volunteer canola. These plants are suitable hosts until canola emerges.
Figure 1. The average number (based on a 5 day running average) of reverse trajectories that have crossed the prairies for the period of May 1 – 27 2021.
a. Pacific Northwest (Idaho, Oregon, Washington) – This week there have been 36 trajectories (44 last week) that have crossed Alberta, Manitoba and Saskatchewan. In previous years, the majority of Pacific Northwest reverse trajectories usually have been reported to pass over southern Alberta. This growing season, PNW trajectories have crossed all parts of the prairies (Fig. 2). Compared to this time last year there has been a significant increase in the number of trajectories that have crossed Manitoba and eastern Saskatchewan.
Figure 2. Total number of dates with reverse trajectories originating over Pacific Northwest (Idaho, Oregon, and Washington) and have crossed the prairies between March 24 and May 27, 2021.
b. Mexico and southwest USA (Texas, California) – Compared to previous years, there has been a noticeable increase in number of trajectories from the southern US. This week there have been 54 trajectories (15 last week) that originated in Mexico and the southwestern US that have crossed the prairies (Fig. 3).
Figure 3. The total number of dates with reverse trajectories originating over Mexico, California and Texas and have crossed the prairies between March 24 and May 27, 2021.
c. Oklahoma and Texas – This week there have been 51 trajectories (16 last week) that have passed over Manitoba, Saskatchewan and eastern Alberta that originated in Oklahoma or Texas (Fig. 4).
Figure 4. The total number of dates with reverse trajectories originating over Oklahoma and Texas and have crossed the prairies between March 24 and May 27, 2021.
d. Kansas and Nebraska – This week there have been 63 trajectories (35 last week) that originated in Kansas or Nebraska that have passed over the prairies (Fig. 5). Relative to the reverse trajectories associated with Oklahoma and Texas, the trajectories from Kansas and Nebraska have crossed further into Alberta.
Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska and have crossed the prairies between March 24 and May 27, 2021.
2. FORWARD TRAJECTORIES (FT) a. Forward trajectories, originating from Mexico and USA, have crossed a number of prairie locations since May 1, 2021. This week there has been a decrease in the number of trajectories that are predicted to cross the prairies (Fig. 6). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line). The data suggests that, compared to this week, there may be increased potential for the introduction of DBM to the prairies.
Figure 6. The average number (based on a 5-day running average) of forward trajectories that have crossed the prairies for the period of May 1- 27, 2021.
TEMPERATURE: This past week (May 17-23, 2021) began with hot dry conditions followed by cool/wet conditions (mid-week reports of snow and minimum temperatures less than 0 °C). Most of the prairies had significant rainfall over the weekend. The average temperature across the prairies was 1 °C cooler than normal (Fig. 1). For the second week temperatures were warmest across Manitoba. Temperatures were coolest across western Saskatchewan and most of Alberta.
Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of May 17-23, 2021.
The prairie-wide average 30-day temperature (April 24- May 23) was 0.4 °C less than climate normal values. The warmest temperatures were observed across the southern prairies (Table 1; Fig. 2). The 2021 growing season (April 1 – May 16) has been characterized by near-normal temperatures. Temperatures have been similar across the prairies (Table 2; Fig. 3).
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of April 24-May 23, 2021.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1-May 23, 2021.
The growing degree day map (GDD) (Base 5 ºC, April 1-May 24, 2021) is provided below (Fig. 4) while the growing degree day map (GDD) (Base 10 ºC, April 1-May 24, 2021) is shown in Figure 5.
Figure 4. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-May 24, 2021). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=trueFigure 5. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-May 24, 2021). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Many were uttering the f-word this past week… several areas were on the receiving end of frost and many folks are still watching to see how their crops recover. The lowest temperatures recorded ranged from <-14 to >0 °C (Fig. 6) while the highest temperatures (°C) observed across the Canadian prairies the past seven days ranged from <11 to >25 °C (Fig. 7).
Figure 6. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (May 20-26, 2021). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=trueFigure 7. Highest temperatures (°C) observed across the Canadian prairies the past seven days (May 12-18, 2021). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (19May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
PRECIPITATION: This week average precipitation for the prairies was 17 mm (Fig. 8). Last week the average was less than 2 mm. Conditions continued to be dry in a large region bounded by Swift Current, Saskatoon and Vegreville as well as central and northern areas of the Peace River region. Rainfall amounts for the period of April 24-May 23 (30-day accumulation) were 88 % of long-term average values. Rainfall was greatest for large areas of Alberta, southern Saskatchewan and southern Manitoba (Table 1; Fig. 9). Average growing season (April 1 – May 23) precipitation was 86 % of normal (Table 1; Fig. 10). The map indicates that conditions continue to be very dry across the Peace River region, east-central Alberta, and west-central Saskatchewan.
Figure 8. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 17-23, 2021.Figure 9. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of April 24-May 23, 2021.Figure 10. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-May 23, 2021.
Access Environment and Climate Change Canada’s weather radar mapping interface. Options to access preceeding precipitation events include clicking off either an 1 or 3 hours time interval, using an 8-colour or 14-colour index. or changing the base map.
Two species, Phyllotreta striolata and P. cruciferae, are the most chronic and economically important flea beetle pests of cruciferous crops in western Canada. Bioclimate simulation models for the two flea beetle species were developed to assess how climatic factors influence shifts in their geographic distribution and relative abundance. Economic risk was associated with populations in the orange and red zones (Figs. 1-4). It is crucial to note that the following information is NOT based on flea beetle densites BUT IS INSTEAD reflecting the suitability of environmental factors for P. striolata and P. cruciferae to prosper in highlighted areas of the following maps.
This spring has been approximately 1 °C cooler than normal. Recent rain (May 23-24) has resulted in precipitation amounts that are normal to above normal (30-day total) across Alberta and Saskatchewan. Simulations were run to determine how the two flea beetle species might respond to cooler, wetter conditions (compared to average growing seasons). Based on average temperature and precipitation (based on long term climate normals) risk associated with P. cruciferae is most prevalent across the southern prairies and risk related to P. striolata tends to be greatest across the Parkland and Peace River regions (Figs. 1 and 2).
Figure 1. Predicted risk for P. cruciferae, for model simulations based on long term climate normals. Red and orange regions may be associated with economic crop losses.Figure 2. Predicted risk for P. striolata, for model simulations based on long term climate normals. Red and orange regions may be associated with economic crop losses.
For both species, cooler/wetter conditions generally could result in reduced risk and southward shifts in distribution (Figs. 3 and 4). Cooler and wetter than average growing seasons were predicted to have less negative impact on P. striolata than P. cruciferae. For example, Peace River populations of P. striolata are predicted to present reduced risk with cooler, wetter conditions (compared to average climate). Under similar conditions, P. cruciferae was predicted to have significantly reduced risk in the Peace River region. Wetter than average conditions in Manitoba may result in reduced risk from P. cruciferae and P. striolata. Olfert et al. (2017) reported that both species were more sensitive to temperature than moisture. Potential risk related to warmer temperatures was greater for P. cruciferae than P. striolata. Producers should monitor flea beetle species composition, crop stage and weather to assess potential flea beetle risk to cruciferous crops.
Figure 3. Predicted risk for P. cruciferae, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.Figure 4. Predicted risk for P. striolata, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.
If flea beetle densities are high, seedling damage levels can advance quickly – even within the same day! The cotyledon stage of canola is vulnerable to flea beetle feeding. Review photos of flea beetle feeding damage posted earlier in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent defoliated and to apply the action threshold of 25 % leaf area of cotyledons consumed plus flea beetles were the Insect of the Week (Wk 02 – May 10)!
The cereal leaf beetle (CLB) model output predicts that egg hatch may be starting across the prairies. The graphs provide a comparison of development at Saskatoon (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that second instar larvae may occur during the last week of May near Saskatoon and Lethbridge.
Figure 1. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Saskatoon, SK as of May 23, 2021 (projected to June 7, 2021).Figure 2. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Lethbridge, AB as of May 23, 2021 (projected to June 7, 2021).
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the midvein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.
Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 4. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Model simulations for alfalfa weevil (AAW) predict that oviposition should be well underway across the prairies. The following graphs indicate that development is similar near Swift Current SK (Fig. 1) and Brandon MB (Fig. 2). The model predicts that that hatch may occur during the last week of May and that second instar larvae could be present during the first week of June.
Figure 1. Projected predicted status of alfalfa weevil (Hypera postica) populations near Swift Current SK as of May 23, 2021 (projected to June 7, 2021).Figure 2. Projected predicted status of alfalfa weevil (Hypera postica) populations near Brandon MB as of May 23, 2021 (projected to June 7, 2021).
The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3). The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long.
Figure 3. Developmental stages of the alfalfa weevil (Hypera postica). Composite image: J. Soroka (AAFC-Saskatoon).
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).
Model simulations to May 23, 2021, indicate that overwintered BAW pupal development (Fig. 1, C) varies across the prairies. Development is predicted to be greatest across the southern prairies (Fig. 2). Based on current development, adult emergence is projected to occur in mid-June.
Figure 1. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).Figure 2. Predicted bertha armyworm (Mamestra configurata) pupal development across the Canadian prairies as of May 23, 2021.
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.
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).
Model simulations were used to estimate grasshopper egg development as of May 23, 2021. Average development of eggs is 73 % and is well ahead of the long-term average of 62 %. Since last week, developmental rates increased at all locations. Recent warm conditions across southeastern Saskatchewan and southern Manitoba have been responsible for the advanced development of eggs near Regina, Brandon and Winnipeg (Fig. 1). The simulation predicted that development was greatest across most of the southern prairies (Fig. 2).
Figure 1. Predicted percent embryonic development of grasshopper eggs (Melanoplus sanguinipes) across the Canadian prairies as of May 23, 2021.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 23, 2021.
The model was projected to June 7 to determine potential development at Winnipeg and Lethbridge over the next two weeks (Figs. 3 and 4). Results suggest that by June 7 hatch could be at 20 % for Lethbridge and approximately 35 % near Winnipeg. Drought conditions tend to favour development of grasshopper populations while delaying crop development. If dry conditions persist, crop development may be delayed across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as the hatch progresses in late May and early June.
Figure 3. Projected predicted development of M. sanguinipes populations near Winnipeg, Manitoba as of May 23, 2021 (projected to June 7, 2021).Figure 4. Projected predicted development of M. sanguinipes populations near Lethbridge, Alberta as of May 23, 2021 (projected to June 7, 2021).
Researchers based at the University of Alberta are conducting a survey of pestiferous slugs and their associated nematode parasites from agricultural fields of Alberta. Last year, a peer-reviewed article was published (Nematology2020) which reported for the first time the presence of a parasitic nematode in Canada. The parasite can kill slugs and could have a role as a potential biocontrol agent against slug populations.
The slug survey continues this summer with researchers hoping to connect with producers who are interested in participating. If interested, please contact researchers at slugs@ualberta.ca now to participate by: ● Either allowing U of A staff to collect slugs from fields (1-2 times/month) or ● Arranging to send live slugs encountered in the field (please email first to obtain detailed collection instructions).
Figure 1. 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.
Diamondback moth pheromone trap monitoring update for MB – Refer to the summary updated twice a week. So far extremely low numbers have been intercepted in only sixteen traps (e.g., when present, only max. of 8 moths per site) in Manitoba. Read the details on page 5 of the May 26, 2021, report.
Diamondback moth pheromone trap monitoring update for SK – follow this link to find current DBM counts. At this point, extremely low numbers have been intercepted but monitoring continues. Seven moths were reported across the entire province so far (2021May19 Carter, pers. comm.).
• ALBERTA’SAlberta Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. Reminder – NEW for 2021 – AAF’s Shelley Barkley has gathered and streamlined information into a Major Crops Insect webpage. The new webpage does not replace the Alberta Insect Pest Monitoring Network page. However, the new Major Crops Insect webpage serves as a table of contents, connecting users to crop insect pest information on alberta.ca. It offers links to specific insect identification, life cycle, damage, monitoring and management. Users will hopefully find pertinent insect information with fewer clicks! Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.
Diamondback moth pheromone trap monitoring update for AB – Refer to the Live Map which reports 12 sites, each with extremely low numbers, for a total of only 15 moths intercepted (as of 27May2021).
Cutworm reporting tool for AB – Refer to the Live Map which reports two sites with cutworms (as of 27May2021).
This week’s “Insect of the Week” is the Pea Leaf Weevil. Larval hosts are field peas and faba beans. Adults can spread to other cultivated and wild legumes, such as alfalfa, beans and lentils. Each adult female lays up to 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Adults feed on leaves and growing points of seedlings, causing notches in leaf margins.
Adult pea leaf weevil damage, showing crescent shaped notches on the leaf margin (AAFC)
The pea leaf weevil is a slender greyish-brown insect measuring approximately 5 mm in length. These insects can be distinguished by three light-coloured stripes extending length-wise down the thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout. Mature larva grow up to 3.5-5.5 mm long, and are legless and c-shaped with a brown head.
Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.
The phenology models used to predict insect staging and associated risk to field crops on the Prairies is a complex system with multiple moving parts. Last week, phenology model output and map development was not available owing to the detection of an error in one of the underlying datasets required to run the models. We are pleased to report that the error has been resolved for this week.
At this moment, segments of earlier 2020 Weekly Updates have been pulled back. The phenology models for Wk01 and Wk02 will be reposted once we have had opportunity to re-run the models with the correct datasets and re-map the model outputs. Stay tuned and thank you for your patience!
This week’s Insect of the Week feature crops are chickpea and lentil and Erl Svendsen is our feature ‘entomologist.’
Lentil Plant cc by 3.0 Christiaan Kooyman
Lentils (green, red, black beluga, French green, Spanish brown) and chickpeas (desi, kabuli) are important Prairie crops introduced to the region in the 1970s and 1980s. These crops are good options to include in your rotation. Except for a few acres in Ontario, lentils and chickpeas are grown in Alberta and Saskatchewan, with Saskatchewan accounting for 90% of production. In 2019, lentils were grown on 1.5 million hectares (3.8 million acres) and yielded 2.2 metric tonnes (2.4 US tons). Chickpeas were grown on 160,000 hectares (390,000 acres) and yielded 250,000 metric tonnes (280,000 US tons). Over 70% of production is exported.
How do you contribute in insect monitoring or surveillance on the Prairies?
Full disclosure: I am not an entomologist by any stretch of the imagination. But much of my recent work was been to support the communications efforts by the real entomologists of the network. I was the co-lead for the Cereal Aphid Manager app, and have edited done the layout and design of the recent insect field guides. More recently, I’ve been working with a great team to develop the new PPMN website, to be launched soon. I am also responsible for putting out the Insect of the Week post.
In your opinion, what is the most interesting field crop pest on the Prairies?
Considering I knew very little about the life histories of many of the pest and their natural enemies when I started working the entomologists 7 years ago, it’s hard to pick a favourite. Back to the wall, I would have to say the lowly cutworm. Who knew there were so many pest species with very different behaviours. Which makes them a challenging group to manage.
What is your favourite beneficial insect?
I’ve always had a special place in my heart for ladybird beetle. Not only are they beautiful and brightly coloured (orange with black spots), they are voracious, gobbling down hundreds (if not thousands) of aphids and other soft-bodied pests in their short lifespan. And unlike many other natural enemies, both the adult and the larva are mighty hunters.
Tell us about an important project you are working on right now.
I am working with Drs. Haley Catton, Wim van Herk and Julien Saguez on a new Wireworm Field Guide for the Prairies. It summaries all the wireworm research conducted on the Prairies since the 1910s as well as pulling in relevant research from other regions. And of course there will be high quality images throughout. Look for an announcement and download links later this summer.
What tools, platforms, etc. do you use to communicate with your stakeholders?
In addition to the PPMN blog (new website to be launched soon), I work with the entomologists to develop manuals and factsheets. I use Twitter (@ErlSv) and have a booths at several extension events throughout the year to promote the PPMN and other AAFC research programs.
Weather synopsis – Temperatures (30 day average) continue to be warmest in southern AB and western SK (Fig. 1). Across the prairies, the monthly average temperature was slightly cooler than normal.
Figure 1. Average temperatures across the Canadian prairies (°C) from March 31-April 30, 2019.
Rainfall (30 day accumulation) amounts have been well below average for most of the prairies (Figs. 2 and 3). Rainfall amounts (30 day) across southern SK are normal to above normal.
Figure 2. Accumulated 30 day cumulative rainfall (mm) across the Canadian prairies from March 31-April 30, 2019. Figure 3. Percent of average precipitation across the Canadian prairies from March 31-April 30, 2019. Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (01May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
On March 27 and 28 significant snowfall amounts were reported for a number of locations across AB and southern SK (Table 1; Fig. 4). This has resulted in improved soil moisture amounts for the southern SK (Fig. 5).
Figure 4. Observed 7-day cumulative rain (mm) across the Canadian prairies (April 23-30, 2019). Figure 5. Modeled soil moisture (%) across the Canadian prairies (as of April 30, 2019).
Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s. Trajectory models are used to deliver an early-warning system for the origin and destination of migratory invasive species, such as diamondback moth. In addition, plant pathologists have shown that trajectories can assist with the prediction of plant disease infestations and are also beginning to utilize these same data. We receive two types of model output from ECCC: reverse trajectories and forward trajectories.
‘Reverse trajectories’ (RT) refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date. Of particular interest are those trajectories that, prior to their arrival in Canada, originated over northwestern and southern USA and Mexico, anywhere diamondback moth populations overwinter and adults are actively migrating. If diamondback adults are present in the air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over our area (e.g. rain showers, etc.). Reverse trajectories are the best available estimate of the ”true” 3D wind fields at a specific point. They are based on observations, satellite and radiosonde data.
‘Forward trajectories’ (FT) have a similar purpose; however, the modelling process begins at sites in USA & Mexico. The model output predicts the pathway of a trajectory. Again, of interest to us are the winds that eventually end up passing over the Prairies.
Ross Weiss (AAFC), Meghan Vankosky (AAFC) and Serge Trudel (ECCC)
DATE: APRIL 30, 2019
1. Reverse trajectories (RT)
a. Pacific Northwest (PNW) – For the period of April 24-30 there have been 18 RTs (originating over ID, OR and WA) that have crossed over prairie locations. By comparison, for the period of April 17-23 there were 51 RT’s. The majority PNW RTs have been reported to pass over southern AB. Since March 23rd Lethbridge AB has reported the highest number of PNW RTs (n=22), Beiseker AB (n=15) and Olds AB (n=31).
Figure 1. Daily total number of reverse trajectories (RTs) originating over Idaho, Oregon, and Washington that have crossed the Canadian prairies as of April 30, 2019. Figure 2. Total number of dates with PNW reverse trajectories originating over Idaho, Oregon, and Washington that have crossed the Canadian prairies (since March 23, 2019). Figure 3. List of PNW (Idaho, Oregon, and Washington) reverse trajectories that have crossed the prairies (since March 23, 2019).
b. Mexico and SW USA (TX, CA) – No trajectories, originating over Mexico or southwest USA have crossed the prairies for the period of April 24-30, 2019. Since March 23, 2019 there have been 5 reverse trajectories that originated over Mexico, CA and TX. All five occurred on April 7.
c. Texas and Oklahoma – No trajectories, originating over TX or OK have crossed the prairies for the period of April 24-30, 2019. Since March 23, 2019 there have been 18 reverse trajectories that have originated over OK and TX. Most of these trajectories have crossed eastern SK and MB.
2. Forward trajectories (FT) –
The following table reports the origin of forward trajectories predicted to cross the prairies over the next five days (Note: ‘InitialDate’ refers to when the forward trajectory crossed the source location. Trajectories are predicted to cross prairie locations within five days of the initial date).
In a continuing effort to produce timely information, wind trajectory reports will be available both DAILY and WEEKLY:
DAILY REPORTS, as they can be generated, will be put up as a downloadable PDF file on this page.
Cutworms (Noctuidae) – A field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is available for free in either English or French and is posted on the Cutworm Field Guide page!
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops.
Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.
Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “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.
Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015). Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae.
The AAW model runs indicate that oviposition has begun in fields near Swift Current SK (Fig. 1). Compared to last week, oviposition rates are predicted to have increased.
Figure 1. Predicted AAW adults near Swift Current SK as of April 30, 2019.
The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhancedor French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model was run for Red Deer AB (Fig. 1) and Saskatoon SK (Fig. 2). The output suggests that PLW are beginning to become active and will begin to fly on warmer days (Figs. 1 and 2).
Figure 1. Predicted overwintered PLW adults near Red Deer AB as of April 30, 2019. Figure 2. Predicted overwintered PLW adults near Saskatoon SK as of April 30, 2019.
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 3, Left).
The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
Figure 3. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.
Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.
Cereal leaf beetle (Oulema melanopus) – Model output indicates that CLB adults have begun to oviposit eggs near Lethbridge AB (Fig. 1).
Figure 1. Predicted CLB adults near Lethbridge AB as of April 30, 2019.
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 2). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 2. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.
Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 3). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 3. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.
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).
This week we observed an adult grasshopper (female), Arphia conspersa, in Saskatoon. Model runs were conducted for Grande Prairie, Saskatoon, Swift Current and Lethbridge.
As of April 30, 2019, predicted development was 60% and is similar to long term average values. The following graph illustrates development for 4 prairie locations (Fig. 1). Hatch is expected to occur during the 3rd week of May (Saskatoon, Swift Current and Lethbridge) and early June in Grande Prairie.
Figure 1. Percent predicted embryological development of M. sanguinipes at Grande Prairie AB, Saskatoon SK, Swift Current SK, and Lethbridge AB as of April 30, 2019 (Weiss, Olfert, Vankosky [AAFC] 2019).
Reminder – The Prairie Pest Monitoring Network’s 2019 Grasshopper Forecast Map was released in March. Review all the risk and forecast maps by linking here. While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, areas highlighted orange or red in the 2019 forecast map should be vigilant this spring by performing in-field scouting to assess nymph densities.
Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.
We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.
What an incredible mix of weather this week – flooding, dangerously dry, blizzards that shut highways and airports! Even so, seeding is underway in parts of the prairies!
Weather synopsis – Weather conditions continue to be warmer and dryer than average across most of the prairies. This past week, (May 22 – 29, 2018) the average temperature was approximately 4 °C warmer than long term average (Fig. 1). The warmest weekly temperatures occurred across MB.
Figure 1. Weekly (May 22 – 29, 2018) average temperature (°C) .
The 30-day average temperature (April 29 – May 29) was approximately 2 °C warmer than long term average (Fig. 2).
Figure 2. The 30-day (April 29 – May 29, 2018) average temperature (°C).
Weekly precipitation was below average and 30-day total rainfall was approximately 50% less than average (Figs. 3 and 4).
Accumulated precipitation for the growing season (April 01-May 30, 2018) is shown below.
The map below reflects the Highest Temperatures occurring over the past 7 days (May 24-30, 2018) across the prairies.
The map below reflects the Lowest Temperatures occurring over the past 7 days (May 24-30, 2018) across the prairies – it got a bit chilly for our newly seeded crops!
The growing degree day map (GDD) (Base 10ºC, March 1 – May 30, 2018) is below:
The growing degree day map (GDD) (Base 5ºC, March 1 – May 30, 2018) 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.
Background: Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories to deliver an early-warning system for the origin and destination of migratory invasive agricultural pests.
We receive two types of model output from ECCC: reverse trajectories (RT) and forward trajectories (FT):
(i) ‘Reverse trajectories’ (RT) refer to air currents that are tracked back in time from specified Canadian locations over a five-day period prior to their arrival date.
(ii) ‘Forward trajectories’ (FT) have a similar purpose; however, the modelling process begins at sites in USA and Mexico. The model output predicts the pathway of a trajectory. Again, of interest are the winds that eventually end up passing over the Prairies.
Current Data
Since May 21, 2018, the number of incoming trajectories (RTs) crossing the prairies has increased, particularly from California, Texas and Mexico (Fig. 1). The increased number of reverse trajectories could result in increased introductions of insects into the prairies.
Figure 1. Daily total number of reverse trajectories, originating over the Pacific Northwest AND Southwest of the USA, that have entered the Canadian prairies (May 1-28, 2018).
Flea Beetles (Chrysomelidae: Phyllotreta species) – The Insect of the Week features flea beetles!
Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “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.
Cutworms (Noctuidae) – A field guide is available to help growers scout and manage Cutworms! Cutworm Pest of Crops is available for free in either English or French and is posted on the Cutworm Field Guide page! Also be sure to check the Insect of the Week through May – it highlights cutworms. Several species of cutworms can be present in fields. They range in colour from shiny, opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. The following page extracted from the new “Cutworm Pests of Crops on the Canadian Prairies” (Floate 2017; Page 5) shows the seasonal occurrence of lifecycle stages for different species of cutworms. To aid scouting, the seasonal chart outlines what time of year larvae of different pest species are present (i.e., when to scout) but it also describes larval feeding habit (i.e., where to look for them relative to the plant host). For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2018 Cutworm Reporting Tool”. Once data entry occurs, growers can view the live 2018 cutworm map which is updated daily (see below for screenshot of map retrieved June 5, 2018).
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).
Above normal temperatures have advanced grasshopper development (Figs. 1 and 2). As of May 28, 2018, predicted hatch was 31% (up from 6% last week).
Figure 1. Grasshopper embryological development (%) based on model simulations (April 1-May 28, 2018).
Figure 2. Grasshopper hatch (%) based on model simulations (April 1-May 28, 2018).
Reminder – The Prairie Pest Monitoring Network’s 2018 Grasshopper Forecast Map was released in March (Fig. 3). Spring temperatures, soil moisture conditions, and precipitation all have an impact on survival of overwintered grasshopper eggs. Growers in areas highlighted orange or red in the map below should be vigilant this spring.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that oviposition is occurring across southern and central regions of the prairies (example Swift Current – Fig. 1).
Figure 1. Predicted pea leaf weevil phenology at Swift Current SK.
Values are based on model simulations (April 1-May 28, 2018 and projected to July 1, 2018).
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 2, Left). The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
Figure 2. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June. Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in
peas grown in Alberta and Saskatchewan in 2017.
Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.
Cereal leaf beetle (Oulema melanopus) – Model output indicates that CLB are primarily in the larval stage (example Lethbridge – Fig. 1).
Figure 1. Predicted cereal leaf beetle phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 28, 2018 and projected to June 21, 2018).
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 2). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 2. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 3). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 3. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.
Alfalfa Weevil (Hypera postica) – The AAW model runs for Swift Current SK indicate that oviposition is well underway in southern Saskatchewan (Fig. 1). Larvae should be primarily second and third instars. Fourth instar larvae may be occurring as well.
Figure 1. Predicted alfalfa weevil phenology at Swift Current SK.
Values are based on model simulations (April 1-May 28, 2018 and projected to June 21, 2018).
Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015). Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below (Fig. 2).
Figure 2. Predicted development of alfalfa weevil as of May 30, 2018.
The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.
Use the photo below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhancedor French-enhanced version.
Updated phenology models for insect pests on the Canadian prairies will be posted to our new Predictive Model Update page during the growing season, as they become available. This information is intended to supplement the Weekly Updates while providing the most current information to further support in-field scouting.
Whenever items are posted to this page, @vanbugsky will be Tweeting and using #PPMNblog to help users access this most up-to-date information.
This week, an updated table of predicted emergence dates for bertha armyworm was posted for across the Canadian prairies (May 30, 2018). Those in charge of coordinating deployment of pheromone traps will need to pay particular attention to these dates.
Bertha armyworm (Lepidoptera: Mamestra configurata) – The BAW model is predicting that pupae are developing rapidly in the soil and that development is well ahead of average (Fig. 1). Development is expected to be 5 – 6 days faster than average.
Figure 1. Predicted bertha armyworm pupal development (as of May 30, 2018).
Pupal development is approximately 72% (long term average is 47%). Model output predicts that emergence may begin as early as June 6, 2018 (Table 1).
Table 1. Projected dates for bertha armyworm adult emergence as of May 28, 2018 and projecting to June 30, 2018.
Reminder – Review the 2017 bertha armyworm distribution map for the Canadian prairies which reports cumulative pheromone trap counts intercepting male moths during the 2017 growing season.
Cabbage seedpod weevil (Ceutorhynchus obstrictus) – There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.
Monitoring: ● Begin sampling when the crop first enters the bud stage and continue through the flowering. ● Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location. ● Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field. ● Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur. ● An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). ● Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators. ● High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod. There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season these new adults migrate to overwintering sites beyond the field.
As the spring weather improves and people are active outdoors, remember to watch for ticks. Blacklegged (deer) ticks are important because they can carry Lyme Disease. Continued surveillance activities conducted by Health Canada and the provinces remain important and you can help by identifying / removing / submitting your ticks!
Remember – Health Canada’s Pest Management Regulatory Agency launched a 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 (Fig. 1). Users can save searches, download product labels to their ‘Favourites’ which can even be accessed while offline. ‘Favourites’ will also auto-update when accessed online. Pesticide labels can be searched based by product name or active ingredient (e.g., to review detailed explanations on proper product use and necessary precautions). Users can download the app on their mobile device. If you have any questions, please contact the PMRA’s Information Service.
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 2018 will be posted soon. Review the most recent updated (May 30, 2018) prepared by John Gavloski and Holly Derksen. The insect update notes flea beetles in canola and cutworms. Saskatchewan‘s Crop Production News for 2018 is now posted. Access Report #1 posted May 31, 2018, and be sure to review the articles posted for flea beetles and pea leaf weevils to prepare for field scouting. Also know that Saskatchewan growers can review diamondback moth pheromone trap counts in the upper right of the diamondback moth page. Access Alberta Agriculture and Forestry’s Call of the Land for insect pest updates from Scott Meers. The most recent Call of the Land (posted on May 31, 2018) and highlights scouting for flea beetles with the warmer weather, glassy cutworms in perennial forages crops and more recently in the irrigated acres to the south of the province (please report using online cutworm reporting tool), relatively low numbers of diamondback moth on pheromone traps in the 4th week of monitoring and relatively low pea leaf weevil numbers so far based on field assessments completed in southern Alberta to date.
Crop reports are produced by: • Manitoba Agriculture, Rural Development (May 28, 2018) • Saskatchewan Agriculture Crop Report (May 22-28, 2018) • Alberta Agriculture and Forestry Crop Report (May 22, 2018) The following crop reports are also available: • The United States Department of Agriculture (USDA) produces a Crop Progress Report (view the May 29, 2018 edition).
We again track the migration of the Monarch butterflies as they move north by checking the 2018 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 29May2018) but follow the hyperlink to check the interactive map!
Visit the Journey North website to learn more about migration events in North America and visit their monarch butterfly website for more information related to this fascinating insect.
This week’s Insect of the Week is the Flea Beetle (Phyllotreta species). This group of beetles is typically oval and 2-3 mm long. In canola, the most common flea beetles are either bluish black (crucifer flea beetle or Phyllotreta cruciferae) or black with two wavy yellow lines running down the length of its back (striped flea beetle or Phyllotreta striolata). They overwinter as adults under plant material along field margins and females lay eggs in the soil near the host plants. Striped and crucifer flea beetles feed on canola, mustard and related cruciferous plants and weeds. Their damage results in a shot-hole appearance in cotyledon leaves. They also feed on stems under windy or damp conditions, causing wilting or breakage. Remember, the Action Threshold for flea beetles on canola is when 25% of cotyledon leaf area is consumed.
For more information on flea beetles, refer to the Insect of the Week page!
For many, seed isn’t even in the ground yet, but the cutworms are ready for it when it is. So the time to start scouting for cutworms is now! Even if it is too wet to seed, consider checking volunteer plants for cutworms or feeding damage. General cutworm monitoring protocols can be found on the Monitoring Protocols page. Species-specific protocols can be found in the new Cutworm Pests of Crops on the Canadian Prairies (see below for download details).
There are over 20 cutworm species that may cause economic damage to your crop, each with different feeding behaviour, preferred hosts and lifecycle. This is why species identification is so important: it helps growers understand what they are up against: determining how and when to scout, knowing whether the cutworm species is found above-ground (climbing) or below-ground, recognizing damage, choosing control options. Species also impacts the most appropriate time of day for monitoring and applying controls.
Action and economic thresholds do exist for many of the cutworm species – please use them. This will help control costs by eliminating unnecessary/un-economic sprays and reduce your impact on non-target insects – insects that include cutworm natural enemies that work in the background to control cutworm populations.
This week’s Insect of the Week is the dingy cutworm. This is an above ground climbing species. Crops are at greatest risk in the spring when partially mature larvae emerge to feed primarily on leaves. The name ‘dingy cutworm’ is generally applied to three closely related species with similar appearance and life cycles.
For more information about dingy cutworms, go to the Insect of Week page.
Dingy cutworm larva (cc John Gavioski, Manitoba Agriculture)
Weather synopsis – This week’s average temperatures were approximately 3°C cooler than normal (Fig. 1) and seven day precipitation accumulations were above normal. The 30-day rainfall amounts were below average in eastern Saskatchewan and Manitoba (Fig. 2).
The map below reflects the Accumulated Precipitation for the Growing Season so far for the prairie provinces (i.e., April 1-May 24, 2017):
The map below shows the Lowest Temperatures the Past 7 Days (May 18-24, 2017) across the prairies:
Whereas the map below shows the Highest Temperatures the Past 7 Days (May 18-24, 2017):
The updated growing degree day map (GDD) (Base 5ºC, March 1 – May 22, 2017) is below:
While the growing degree day map (GDD) (Base 10ºC, March 1 – May 22, 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.
THE WEEK OF MAY 23, 2017: Wind trajectory data processing by AAFC-Saskatoon Staff began in April. Reverse Trajectories track arriving air masses back to their point of origin while Forward Trajectories predict favourable winds expected to arrive across the Canadian Prairies for the week of May 23, 2017: Reverse trajectories (RT) Between May 16 and 23 there were 57 RT’s from the Pacific Northwest of USA that crossed the prairies. The first chart (Fig. 1) indicates site specific results for PNW RT’s for each day of the past week. Values reflect the fact that PNW RT’s were lower this week than previous weeks. The greatest number of PNW RT’s continued to be across southern AB (Fig. 2).
Figure 1. Cumulative number of Reverse Trajectories (RT) originating from the Pacific Northwest arriving across the Canadian prairies from May 16-23, 2017 (Olfert et al. 2017).
Figure 2. Number of Reverse Trajectories (RT) originating in the Pacific Northwest that arrived at sites across the Canadian prairies from April 1-May 23, 2017.
Forward trajectories (FT) No FTs originating from Mexico or southwest USA/Mexico are predicted to cross the prairies over the next 5 days. The following map provides an overview of FTs that have crossed the prairies during the 2017 growing season.
Figure 2. Total number of reverse trajectories originating from the Pacific Northwest of the USA arriving at sites across the Canadian prairies (April 1-May 23, 2017).
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from 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.
Cutworms (Noctuidae) – NEW – Just in time for spring scouting! A new field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is now available for free in either English or French and is featured at our newCutworm Field Guide! Also be sure to check the Insect of the Week throughout May – it highlights cutworms! Be sure to read more about Dingy cutworms.
Dingy cutworm larva (cc John Gavloski, Manitoba Agriculture)
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to the Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Keep an eye on fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2017 Cutworm Reporting Tool”. The map now has reports of pale western and redbacked cutworms in central and southern Alberta so view the live 2017 cutworm map.
Cereal leaf beetle (Oulema melanopus) – As of May 22, 2017, the CLB model indicates that oviposition is well underway across the southern prairies. Compared to southern Alberta and Saskatchewan, populations in southern Manitoba are predicted to be delayed by approximately five days (Fig. 1). Compared to 2016, development in 2017 is approximately 1 week later. Hatch is predicted to occur in isolated areas.
Lifecycle and Damage: Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 2). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 2. Adult Oulema melanopus (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 3). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 3. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.
Pea Leaf Weevil (Sitona lineatus) – The pea leaf weevil simulation model will be used to monitor weevil development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of weevil development stages based on biological parameters for Sitona lineatus.
The PLW model was run for Lethbridge AB and Saskatoon SK. Meteorological data (April 1 – May 15, 2017) and climate data (May 16- June 30) were used to predict PLW phenology. Output indicates that PLW oviposition in Lethbridge is approximately one week earlier than Saskatoon.Reminder – Access last week’s PLW model output predictions here.
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 1, Left). The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
Figure 3. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.
Alfalfa Weevil (Hypera postica) – The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long. Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).
Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models. Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below.
This week, embryological development is greatest across south and central regions of Alberta and Saskatchewan and across southern Manitoba. Early hatch is predicted to occur in a region near Brooks AB and Regina SK and south to the USA border.
Use the figure below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhancedor French-enhanced version.
