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Growing season temperatures have been marginally warmer than average while rainfall amounts continue to be well above average. Manitoba continues to have warm temperatures and above normal precipitation. The average 30 day temperature (May 25 – June 23, 2024) was 13.2 °C and was 0.8 °C cooler than the long term average temperature. Warmest temperatures were observed across Manitoba and the southern prairies (Figure 1). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Rainfall amounts have been greatest in eastern regions and continue to be driest across most of Alberta (Figure 2). Average cumulative rainfall (mm) over the past 30 days was 71 mm and was 138 % of climate normal values (164 % last week). Provincial 30 day values were 54 mm, 73 mm and 97 mm for Alberta, Saskatchewan, and Manitoba, respectively. What a difference a year makes; In 2023 the average temperature for May 27 to June 25 was 17.6 °C (4.4 °C warmer than 2024) and the prairie-wide average cumulative rainfall was 56 mm (104 % of climate normals).
Since April 1, the 2024 growing season average temperature has been similar to climate normal values. Warmest average temperatures were observed across a region extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Growing season rainfall has been above normal across most of the prairies (Figure 4). Near normal precipitation amounts occurred across western Alberta and western areas of the Peace River region. During May rain amounts were well above average. Over the past few weeks, rainfall amounts have been moving closer to long term normal values. Although rainfall amounts continue to be above average, precipitation amounts (relative to climate normal) are lower in late June than mid-May. For example, as of May 12, rain amounts were 221 % of long term average values. Current rain amounts have been 168 % (191 % last week) of climate normals. Cumulative rainfall has been lowest for a large region than is west of a line that extends from Regina to Grande Prairie (Figure 5).
Soil moisture values, particularly near the soil surface, can impact the development of soil-borne insect stages (e.g., overwintered or spring stages of eggs, larvae or pupae). Figure 6 presents data to show soil moisture levels (averaged for June 17-23, 2024) in the top five centimeters of soil in western Canada. Driest soil moisture conditions were observed for western regions of Saskatchewan and eastern regions of Alberta. Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan. The data is produced from passive microwave satellite data collected by the Soil Moisture and Ocean Salinity (SMOS) satellite and converted to soil moisture using the SMOS soil moisture processor. The data are produced by the European Space Agency. Satellites are used to sense the strength of radiation emitted from the surface of the earth. There is a strong difference in the signals emitted by dry soil and wet soil. This relationship is used to calculate surface soil moisture using a model that incorporates land cover, vegetation content, surface roughness, soil texture and other factors that influence the satellite sensor. The satellite collects data every one to three days over Canada (Satellite Soil Moisture – agriculture.canada.ca).
Damaging populations of grasshoppers have been reported in some parts of the prairies this spring. Insecticides have been applied to protect seedlings from grasshopper nymphs.
Scout for grasshoppers to keep informed of their developmental stage and population density.
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. ● It is best to scout on warm days when grasshopper nymphs are more active and easier to observe. ● Carefully check roadside ditches and along field edges but also check the edge of the crop and into the actual field. ● Younger or earlier instar nymphs are easier to manage – visit sites every few days to stay on top of local field conditions. ● 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.
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 situations. Available thresholds (nominal and economic) help support producers while protecting beneficials (i.e., predators, parasitoids, and pathogens) that regulate natural populations of grasshoppers.
Soil moisture conditions in May and June significantly impacts wheat midge emergence. Where wheat midge cocoons are present in soil, the 2024 growing season’s rainfall during May and June will determine if overwintered larvae will terminate diapause then move to the soil surface to pupate. Pupae develop near the soil surface with adults emerging to seek flowering wheat plants.
Although the PPMN is unable to model and predict wheat midge development as in previous years, accumulated precipitation levels during May and June do provide guidance in terms of in-field scouting. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. The Olfert et al. (2020) model indicated that dry conditions may result in: (a) Delayed adult emergence and oviposition, and (b) Reduced numbers of adults and eggs.
In 2024, the accumulated precipitation levels over past 60 days (April 25 to June 24, 2024) were mapped in Figure 1 and ranged from 45-250 mm across the prairies. Areas in Figure 1 receiving substantial rainfall this spring need to plan to scout for wheat midge now as adults typically emerge and seek wheat in late June and early July. In contrast, midge emergence may be delayed or erraticwhere rainfall fails to exceed 20-30 mm during May and June.
Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of wheat midge on plants are carefully compared to the economic thresholds.
Soil core sampling to assess the densities of larvae were collected across Saskatchewan and Alberta post-harvest in 2023 (Fig. 2). Fields where cultivars that are susceptible to wheat midge were grown were targeted so densities of overwintering larvae (and respective parasitism) could be determined to help estimate risk for 2024. Although the 2023 survey found relatively low densities of wheat midge in most sampled fields, be mindful – wheat midge larval cocoons can survive for several years in the soil, waiting for wet spring conditions.
This means, producers opting to grow cultivars that are susceptible to wheat midge need to be mindful that any historically elevated density of wheat midge occurring over the past one or even possibly six years across the prairies that also has received substantial rainfall since May of 2024, warrants in-field monitoring now. Review the past wheat midge maps here in relation to your fields THEN compare the historical densities to areas of high precipitation in Figure 1.
In-Field Monitoring:When scouting wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 3). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) To maintain yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and larval damage.
Wheat midge was featured as the Insect of the Week in 2023 (for Wk08). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – not all flying insects are mosquitoes nor are they pests! Many are important parasitoid wasps that regulate insect pest species in our field crops OR pollinators that perform valuable ecosystem services!
Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
The cereal leaf beetle (Chrysomelidae: Oulema melanopus) has a broad host range. Wheat is the preferred host, but adults and larvae also feed on leaf tissue of oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Yield quality and quantity is decreased, if the flag leaf is stripped. Fun fact: Cereal leaf beetle larvae carry their own fecal waste above their body to help protect themselves from predators.
Fortunately, the parasitoid wasp, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is an important natural enemy of cereal leaf beetle larvae. Learn more about this beneficial insect species featured in Week 9 of 2023’s Insect of the Week!
Cereal Leaf Beetle Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 1). 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.
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. 2). When the larva completes its growth, it drops to the ground and pupates in the soil.
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.
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.
There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo). Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.
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.
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.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jun27).
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.
By this week, a second generation of adult diamondback moth should be active in parts of the prairies.
Pheromone-baited delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.
Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of the diamondback moth.
Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 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.
Similar to diamondback moth, the true armyworm, or just armyworm (Mythimna unipuncta or Pseudaletia unipunctata) is a migratory pest in Canada. After arriving from the United States, true armyworm can have two generations of larvae before cool temperatures in the fall stop their development. True armyworm caterpillars feed along leaf margins of their hosts, leaving damage that could be misdiagnosed as grasshopper or bertha armyworm damage. Preferred hosts include native grasses, wheat, rye, corn, oats, and barley. Other hosts can include crucifer vegetables (e.g., cabbage) and alfalfa.
Phermone traps have been deployed by the Saskatchewan Ministry of Agriculture and Manitoba Agriculture and by their collaborators and volunteers in both provinces to detect the arrival of immigrating true armyworm. In Saskatchewan, true armyworm have been caught by pheromone traps in the northeast and central parts of the province. In Manitoba, true armyworm have been caught in all five regions.
The economic threshold for true armyworm larvae in cereals is 10 larvae/m2. If scouting in the evening or at night, beat plants in a 1 m2 area and count the dislodged larvae. True armyworm larvae are more likely to be on the ground during the day, so look under leaf litter and other debris around the plants in a 1 m2 area and count the larvae. For more information and tips for scouting, refer to the armyworm pages of 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 OR access Manitoba Agriculture’s scouting guide.
Track the migration of the Monarch butterflies as they move north by checking the 2024 Monarch Migration Map! A screenshot of Journey North’s “first sightings of adults” map was featured last week. This week, the map of “first sightings of LARVAE” has been placed below (retrieved 27Jun2024) but follow the hyperlink to check the interactive map. Larvae have been spotted in Manitoba so far!
Reminder – Last week, the Prairie Crop Disease Monitoring Network (PCDMN) launched a new website at PrairieCropDisease.com. The PCDMN is a coordinated field crop disease monitoring program for the Prairies, focusing on providing timely information about crop diseases and highlighting effective disease management strategies.
“We are really excited to be launching this new website,” said project lead Dr. Kelly Turkington, Plant Pathologist at Agriculture and Agri-Food Canada, Lacombe Research and Development Centre. “The goal of the network has always been to provide important and timely information to growers and agronomists. By enhancing the functionality of our PCDMN Blog, this new website will greatly improve our communication and engagement, ensuring that stakeholders have access to the latest research and disease management strategies.”
The PCDMN is composed of field crop pathologists who conduct research and actively monitor field crop diseases on the Canadian Prairies. The network includes researchers from Agriculture and Agri-Food Canada, Manitoba Agriculture, Saskatchewan Ministry of Agriculture, Alberta Agriculture & Irrigation, and Prairie-based universities.
“The PCDMN is a valuable resource for farmers, agronomists, and scientists,” says Wayne Thompson, Executive Director of the Western Grains Research Foundation (WGRF). “We are proud to have funded the development of this new website. With this launch, WGRF has successfully developed websites for the three major pest monitoring networks in Western Canada—Insects, Weeds, and Disease. These networks play a crucial role in providing the information needed to anticipate and manage major crop threats.”
The PCDMN also provides weekly updates via email during the growing season. The updates alert subscribers to crop disease risks and management. To view the new site and to sign up for weekly updates please visit PrairieCropDisease.com
Many other organizations have been involved over the years to support this valuable initiative with the 2023-2028 funders including Agriculture and Agri-Food Canada, WGRF, Alberta Canola, Alberta Grains, Alberta Innovates, Manitoba Crop Alliance, Manitoba Pulse and Soybean Growers, Manitoba Canola Growers, Prairie Oat Growers Association, RDAR, Sask Canola, Saskatchewan Ministry of Agriculture, Saskatchewan Pulse Growers, and the Saskatchewan Wheat Development Commission.
Jennifer Otani, John Gavloski, Shelley Barkley, James Tansey and Carter Peru
Categories
Week 8
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 are available. Access the online June 27, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Flea beetles – Dr. J. Gavloski reported that, “foliar insecticide applications were reported from all agricultural regions over the past week”. • Cutworms – “Cutworms are still sporadically affecting canola and sunflowers in the Central region. Insecticides were applied to control true armyworms in some forage seed fields in the Interlake. Larvae of true armyworms have also been noticed in cereals in the Central region, but at numbers below threshold.” • Alfalfa weevil – “some spraying” in the Interlake region. • Grasshoppers – “field edge control” in the Central region. • Bertha armyworm pheromone trap monitoring – Access the PDF copy of the June 27 report. • Diamondback moth pheromone trap monitoring – Reports that moths were present “in 75 out of 92 traps” and that, “trap counts have generally been low so far in the Northwest and Southwest regions” but “some moderate to high counts have occurred in the Eastern, Central, and Interlake regions”. The highest cumulative trap count so far is 233 from a trap near Riverton in the Interlake region.” Access the PDF copy of the June 27 report. • True armyworm in MB – “Counts have been low so far in the western regions of Manitoba, with some moderate counts in the Central region” but “higher counts have occurred in some of the traps in the Eastern and Interlake regions”. “The highest cumulative count is 434 from a trap near Riverton in the Interlake region” and “there are areas in the Central, Eastern, and Interlake regions where cereals and forage grasses would be good to prioritize” for armyworm larvae. Access the PDF copy of the June 26 report. • Released a revision of the fact sheet, “Maximizing the value of beneficial insects on the farm“.
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #3 report. Bookmark their insect pest homepage to access important information! A brief summary of the week was provided by Dr. J. Tansey (as of June 27): • Insect pests to watch – “Flea beetles were reported as minor to moderate issue throughout the province with spraying reported in NW and some serious issues reported from a small number of sites in SW”. There was “some minor root maggot damage reported in EC and NE” and “limited moderate wireworm problems in the SW and EC”. “Cutworm pressures were generally low but moderate pressures were reported in the SE”. More recently this week, “barley thrips activity” was reported. • Grasshopper nymphs – “Grasshopper issues were sporadic but moderate pressures were reported in central regions and limited severe pressure in SW.” • Diamondback moth – Preliminary cumulative count data from pheromone traps across the province can now be reviewed online. • Also access the Crops Blog Posts that released a grasshopper activity update, 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., soil moisture, wheat midge and other insect pests (June 24, 2024), scout for grasshoppers and other insect pests (June 17, 2024); how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024); 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). • Bertha armyworm 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 210 trap locations are all reporting “low risk” category as of June 27, 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 have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of June 27, 2024). Four trap locations have caught > 25 adult diamondback moths; sites fall within the County of Grande Prairie (as of June 8, 2024), County of Warner (as of June 15, 2024), Vulcan County (as of June 15, 2024), and County of Barrhead (as of June 15, 2024). • Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.