Welcome to Week 16 – the final Weekly Update of the 2024 growing season! We wish everyone good harvest weather AND a speedy, amicable resolution to the rail labour dispute that started Thursday morning. This week includes: • Weather synopsis • Pre-harvest intervals (PHI) • Bertha armyworm • Diamondback moth • Grasshopper • Crickets • West nile virus • Provincial insect pest report links • Crop report links • Previous posts
Catch Monday’s Insect of the Week for Week 16 – What’s eating my crop? Wheat stem sawfly
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.
When it comes to wildfire smoke and air quality indices – did you know you can click to find…. • 72 hr projections of Ground Level Wildfire Smoke Fine Particulate Matter (PM 2.5) for the Canadian prairies using this link • Tabular summaries of Air Quality Heatlh Index values and forecast maximums for the provinces of Manitoba, Saskatchewan, Alberta, or British Columbia.
As harvest approaches, remember to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific. Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.
Access the Provincial Insect Pest Report for Wk16 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk16 for updates for this economic insect pest.
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.
Access the Provincial Insect Pest Report for Wk16 for updates for this economic insect pest.
Two species of crickets of agricultural significance can be found in more southern regions of the Canadian prairies. The Mormon cricket (Anabrus simplex Haldeman) is typically active as an adult from late June to mid-September. Technically not a true cricket, Mormon crickets are katydids as they belong to the Family Tettigoniidae). Host plants for the nymphs and adults include broad-leafed plants but they will also feed on sagebrush, grasses and small shrubs, as well as wheat, barley, alfalfa, sweet clover, some forages and garden vegetables plus other insects.
True crickets include the field, ground, camel and tree crickets which belong to the Family Gryllidae. Fall field crickets (Gryllus pennsylvanicus Burmeister) are normally observed from late July to the end of September. Fall field crickets (nymphs and adults) can feed and affect seed yields in forages grown for seed, cereals, and some small fruits when they occur at high densities, however, fall field cricket adults are predators of grasshopper eggs.
Many species of crickets are distributed across the Canadian prairies. In addition to the Mormon cricket, 17 species of true crickets can be observed in Manitoba! The Mormon cricket was featured as the Insect of the Week back in 2021 and images of the fall field cricket can be viewed online at Bug Guide. Check out the Bug Guide link to the “Singing insects of North America” to learn more about fall field crickets!
Biological and monitoring information for fall field cricket (Gryllus pennsylvanicus Burmeister) and Mormon cricket (Anabrus simplex Haldeman) are described in the cricket 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.
While the PPMN no longer predicts the development of Culex tarsalis, the dominant vector for West Nile Virus(WNV), areas of the Canadian prairies in 2024 have received high levels of precipitation. This is noteworthy because the larvae of C. tarsalis can develop in, “agricultural tailwater, alkaline lake beds, fresh and saline wetlands, secondary treated sewage effluent and oil field run-off” (Centre for Vector Biology URL retrieved 2024Jul04).
Culex tarsalis have a base developmental threshold of 14.3 °C. Across the Canadian prairies, WNV transmission is of greatest concern as the second generation of C. tarsalis females begin to fly (by 250-300 degree days). In fact, an additional 109 degree days (using Base 14.3 °C) is required within a given mosquito population for virus development to complete to the point that transmission might occur.
Historically, by mid-July, C. tarsalis adults begin to fly in southern parts of the Canadian prairies. By August, protect yourself from mosquitoes when outdoors – this is the window when mosquitoes are most numerous plus have the greatest chance of carrying WNV. Field scouts and outdoor enthusiasts should wear DEET to protect against C. tarsalis and WNV.
For reference, the following table of data was quickly generated using AAFC Drought Watch Historical Daily Air Temperatures since April 1, 2024:
Location
Degree Days (base 14.3 °C) as of August 21, 2024
Observed date heat units >200 Degree Days
Potential date when >390 Degree Days attained
Winnipeg
384.0
July 20
August 24
Brandon
302.8
July 27
Unable to project
Regina
352.9
July 26
September 2
Saskatoon
320.4
July 29
Unable to project
Lethbridge
331.2
July 25
Unable to project
Edmonton
205.9
August 20
Unable to project
Grande Prairie
239.2
August 11
Unable to project
Note: Potential dates calculated using daily mean of 18°C until August 30, 2024, then daily mean of 15°C for September 1-30, 2024.
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 August 15, 2024 report (or access the PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights reported by Dr. J. Gavloski include: • Aphids – “Soybean aphids levels are high in some areas” with “insecticides applied to a few soybean fields in the Eastern region” but “a lot of lady beetles” have been reported from some soybean fields. The report includes photos of lady beetle larvae to help producers identify sevenspotted, multicoloured Asian, thirteenspotted, and sevenspotted larvae. An action threshold for soybean aphids (R1-R5 growth stages) is an average of >250 aphids per plant but is no longer applicable past the R5 stage. Access the Manitoba Pulse Growers “soybean growth staging guide” to differentiate plant stages. • Other aphid predators – Photos of a hover fly larva, damsel bug adult, green lacewing larva, and minute pirate bug adult are featured in the report. • Grasshoppers – The annual grasshopper survey is underway now. Interested participants can find the protocol, data sheet, and steps to submit data in the newly updated protocol.
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, AAI’s Agri-News occasionally includes insect-related information, e.g., diamondback moth and bertha armyworm (August 6, 2024); aphids in field crops, canola flower midge scouting (July 29, 2024); assessing and a description of missing pods on canola (July 22, 2024); scout for wheat midge (July 15, 2024); the right canola crop stage to spray for lygus bugs (July 8, 2024); 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of August 1, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map (as of August 8, 2024). • Diamondback moth monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of July 4, 2024). Remember to scout fields for larvae. • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of August 8, 2024). Remember to scout fields for larvae.
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.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk15 to remain alert to areas and crops suffering from aphid pest pressure.
Figure 1. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.
Alternatively, several aphid pest species are described in the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) and is accessible as a free downloadable PDF in either English or French on our Field Guides page. PDF copies of the individual pages have been linked below to access quickly: • Corn leaf aphid or Rhopalosiphum maidis (Fitch) • English grain aphid or Sitobion (Macrosiphum) avenae (Fabricius) • Oat-birdcherry aphid or Rhopalosiphum padi (Linnaeus) • Pea aphid or Acyrthosiphon pisum (Harris) • Potato aphid or Macrosiphum euphorbiae (Thomas) • Soybean aphid or Aphis glycines (Matsumura) • Turnip aphid or Lipaphis erysimi (Kaltenbach) • Sugar beet root aphid or Pemphigus betae Doane • Russian wheat aphid or Diuraphis noxia (Mordvilko)
Access the Provincial Insect Pest Report for Wk15 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk15 for updates for this economic insect pest.
Access the Provincial Insect Pest Report for Wk15 for updates for this economic pest.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
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.
Access the Provincial Insect Pest Report for Wk15 for updates for this economic insect pest.
Two species of crickets of agricultural significance can be found in more southern regions of the Canadian prairies. The Mormon cricket (Anabrus simplex Haldeman) is typically active as an adult from late June to mid-September. Host plants for the nymphs and adults include broad-leafed plants but they will also feed on sagebrush, grasses and small shrubs, as well as wheat, barley, alfalfa, sweet clover, some forages and garden vegetables plus other insects. Fall field crickets (Gryllus pennsylvanicus Burmeister) are normally observed from late July to the end of September. Fall field crickets (nymphs and adults) can feed and affect seed yields in forages grown for seed, cereals, and some small fruits when they occur at high densities, however, fall field cricket adults are predators of grasshopper eggs.
Biological and monitoring information for fall field cricket (Gryllus pennsylvanicus Burmeister) and Mormon cricket (Anabrus simplex Haldeman) are described in the cricket 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.
While the PPMN no longer predicts the development of Culex tarsalis, the dominant vector for West Nile Virus(WNV), areas of the Canadian prairies in 2024 have received high levels of precipitation. This is noteworthy because the larvae of C. tarsalis can develop in, “agricultural tailwater, alkaline lake beds, fresh and saline wetlands, secondary treated sewage effluent and oil field run-off” (Centre for Vector Biology URL retrieved 2024Jul04).
Culex tarsalis have a base developmental threshold of 14.3 °C. Across the Canadian prairies, WNV transmission is of greatest concern as the second generation of C. tarsalis females begin to fly (by 250-300 degree days). In fact, an additional 109 degree days (using Base 14.3 °C) is required within a given mosquito population for virus development to complete to the point that transmission might occur.
Historically, by mid-July, C. tarsalis adults begin to fly in southern parts of the Canadian prairies. By August, protect yourself from mosquitoes when outdoors – this is the window when mosquitoes are most numerous plus have the greatest chance of carrying WNV. Field scouts and outdoor enthusiasts should wear DEET to protect against C. tarsalis and WNV.
For reference, the following table of data was quickly generated using AAFC Drought Watch Historical Daily Air Temperatures since April 1, 2024:
Location
Degree Days (base 14.3 °C) as of August 13, 2024
Observed date heat units >200 Degree Days
Potential date when >200 Degree Days attained
Potential date when >390 Degree Days attained
Winnipeg
330.6
July 20
—
August 28
Saskatoon
266.2
July 29
—
Unable to project
Lethbridge
294.7
July 25
—
Unable to project
Edmonton
188.6
—
August 18
Unable to project
Grande Prairie
220.9
August 11
—
Unable to project
Note: Potential dates calculated using daily mean of 18°C until August 30, 2024, then daily mean of 15°C for September 1-30, 2024.
As harvest approaches, remember to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific. Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.
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 August 15, 2024 report (or access the PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights reported by Dr. J. Gavloski include: • Bertha armyworm – “Continues to be noticed at high levels in some canola fields in the Southwest region and western part of the Central region. Access Manitoba’s fact sheet for this insect to support in-field scouting for larvae now. • Lygus bugs – “High levels were noted in some canola fields in the Northwest and Easter regions”. Review the report for scouting tips and photos of lygus bug adults and nymphs. • Aphids – “Soybean aphids have been increasing in some areas but no reports yet of economic levels or insecticide applications” being applied so far. • Green caterpillars in canola – Review the report for tips and photos to differentiate a number of species that can be present now in canola. • Grasshoppers – The annual grasshopper survey is underway now. Interested participants can find the protocol, data sheet, and steps to submit data in the newly updated protocol. • Reminder – Insects in Stored Grain – AAFC in Winnipeg is seeking producer participation for grain bin monitoring in September-October 2024. Learn more here and find out how to participate.
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, AAI’s Agri-News occasionally includes insect-related information, e.g., diamondback moth and bertha armyworm (August 6, 2024); aphids in field crops, canola flower midge scouting (July 29, 2024); assessing and a description of missing pods on canola (July 22, 2024); scout for wheat midge (July 15, 2024); the right canola crop stage to spray for lygus bugs (July 8, 2024); 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of August 1, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map (as of August 8, 2024). • Diamondback moth monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of July 4, 2024). Remember to scout fields for larvae. • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map (as of August 8, 2024). Remember to scout fields for larvae.
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.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk14 to remain alert to areas and crops suffering from aphid pest pressure.
Figure 1. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.
Alternatively, several aphid pest species are described in the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) and is accessible as a free downloadable PDF in either English or French on our Field Guides page. PDF copies of the individual pages have been linked below to access quickly: • Corn leaf aphid or Rhopalosiphum maidis (Fitch) • English grain aphid or Sitobion (Macrosiphum) avenae (Fabricius) • Oat-birdcherry aphid or Rhopalosiphum padi (Linnaeus) • Pea aphid or Acyrthosiphon pisum (Harris) • Potato aphid or Macrosiphum euphorbiae (Thomas) • Soybean aphid or Aphis glycines (Matsumura) • Turnip aphid or Lipaphis erysimi (Kaltenbach) • Sugar beet root aphid or Pemphigus betae Doane • Russian wheat aphid or Diuraphis noxia (Mordvilko)
Access the Provincial Insect Pest Report for Wk14 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk14 for updates for this economic insect pest.
Access the Provincial Insect Pest Report for Wk14 for updates for this economic pest.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
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.
Access the Provincial Insect Pest Report for Wk14 for updates for this economic insect pest.
As harvest approaches, remember to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific. Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.
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 August 8, 2024 report (or access the PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights reported by Dr. J. Gavloski include: • Bertha armyworm – Some control of bertha armyworm has occurred in several fields in Southwest Manitoba. Some evidence of diseased bertha armyworms has also been observed. Access Manitoba’s fact sheet for this insect to support in-field scouting for larvae now. • Lygus bugs – A couple of canola fields in the Eastern region were sprayed for Lygus bugs. Lygus near threshold in sunflowers was reported from the Southwest region. • European corn borer – A field of corn in the Eastern region was sprayed for European corn borer. Access Manitoba’s fact sheet for this insect. • Aphids – Aphids are being noticed in some fields of peas (pea aphid), soybeans (soybean aphid), cereal crops (a complex of cereal feeding aphids) and on canola leaves in some area. Currently, in most instances, these are not at economic levels, or the crops are beyond the more susceptible stages. Noticeable levels of predators of aphids, and evidence of parasitism, have also been reported in some areas. • Thrips – High levels of thrips in barley were reported from the Northwest region. • Sunflower midge – Some damage from sunflower midge was noticed along the edges of a sunflower field in the Eastern region. • Insects in Stored Grain – AAFC in Winnipeg is seeking producer participation for grain bin monitoring in September-October 2024. Learn more here and find out how to participate.
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, AAI’s Agri-News occasionally includes insect-related information, e.g., diamondback moth and bertha armyworm (August 6, 2024); aphids in field crops, canola flower midge scouting (July 29, 2024); assessing and a description of missing pods on canola (July 22, 2024); scout for wheat midge (July 15, 2024); the right canola crop stage to spray for lygus bugs (July 8, 2024); 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 37 trap locations are reporting; 11 sites in central Alberta are “high” and in the Peace River region 21 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of August 1, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of August 8, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 272 trap locations are all reporting “low risk” across the province while 1 trap location near Fairview, plus 3 trap locations in southern Alberta (2 in Vulcan County plus 1 near Lethbridge) are reporting “medium risk” as of August 8, 2024). Remember to scout fields for larvae.
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.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk13 to remain alert to areas and crops suffering from aphid pest pressure.
Figure 1. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.
Alternatively, several aphid pest species are described in the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) and is accessible as a free downloadable PDF in either English or French on our Field Guides page. PDF copies of the individual pages have been linked below to access quickly: • Corn leaf aphid or Rhopalosiphum maidis (Fitch) • English grain aphid or Sitobion (Macrosiphum) avenae (Fabricius) • Oat-birdcherry aphid or Rhopalosiphum padi (Linnaeus) • Pea aphid or Acyrthosiphon pisum (Harris) • Potato aphid or Macrosiphum euphorbiae (Thomas) • Soybean aphid or Aphis glycines (Matsumura) • Turnip aphid or Lipaphis erysimi (Kaltenbach) • Sugar beet root aphid or Pemphigus betae Doane • Russian wheat aphid or Diuraphis noxia (Mordvilko)
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
Compare canola flower midge damage to the closely related Swede midge which was featured as Wk12’s Insect of the Week.
Access the Provincial Insect Pest Report for Wk13 for updates for this economic insect pest.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk13 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk13 for updates for this economic insect pest.
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
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.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
As harvest approaches, remember to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific. Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.
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 August 1, 2024 report when it comes online later this week (access the PDF copy). Bookmark the insect pest homepage to access fact sheets and more! In the meantime: • European corn borer – Review the report for tips to scout for egg masses in corn, hemp, quinoa, potatoes and other host crops. Access both the updated fact sheet and request to report by downloading and using the free Survey123 App. • Bertha armyworm pheromone trap monitoring – Reports that this week all bertha monitoring sites fall within the “low risk” category, except one site that falls in the “uncertain risk” category. So far, there are no reports of economic levels of bertha larvae.
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, AAI’s Agri-News occasionally includes insect-related information, e.g., aphids in field crops, canola flower midge scouting (July 29, 2024); assessing and a description of missing pods on canola (July 22, 2024); scout for wheat midge (July 15, 2024); the right canola crop stage to spray for lygus bugs (July 8, 2024); 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 37 trap locations are reporting; 11 sites in central Alberta are “high” and in the Peace River region 21 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of August 1, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of August 1, 2024). Sweep samples collected across the province and processed by S. Barkley are now completed; there was nothing exciting or concerning in the samples but also no samples had really high diamondback moth larval numbers – which is good news! • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 267 trap locations are all reporting “low risk” across the province while 1 trap location near Fairview, plus 3 trap locations in southern Alberta (2 in Vulcan County plus 1 near Lethbridge) are reporting “medium risk” as of August 1, 2024). Remember to scout fields for larvae.
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.
Last week (July 8-14, 2024), average cumulative 7 day rainfall was 5 mm (Figure 1) and was well below the previous week (July 1-7) that experienced an average cumulative rainfall value of 16.7 mm. The average 30 day (June 14 – July 14) temperature was 0.5° C warmer than long term average values. Most of the prairies reported 30 day rainfall amounts ranging from normal to above normal. A region from Saskatoon to Oyen has had uncharacteristically high rainfall; Kindersley and Oyen had greater than 250 % of normal precipitation (Figure 2). Driest conditions were observed near Edmonton and the western areas of the Peace River region. Since April 1, the 2024 growing season average temperatures have been 0.5° C greater than climate normal values. Most of the prairies have had above normal to above normal (157 %) rainfall (Figure 3).
Figure 1. 7 day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 8-14, 2024.Figure 2. 30 day percent of normal rain (%) observed across the Canadian prairies for the period of June 14-July 14, 2024. Figure 3. Growing season percent of normal rain %) observed across the Canadian prairies for the period of April 1 – July 14, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for the eastern and Peace River regions of Alberta and southern regions of Saskatchewan (Figure 4). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan.
Figure 4. 7 day average saturated soil moisture (% soil moisture for the surface layer, <5 cm depth) for the period of July 8-14, 2024.
Relative to climate normal values, average temperatures have increased over the past four weeks. The 7 day average temperature for July 14-20, 2024 was 20.5 °C and was 3.3 °C warmer than normal. Warmest temperatures were observed for northern regions of the Alberta Peace River region, eastern regions of Alberta, and southern regions of Saskatchewan (Figure 1).
Figure 1. Seven day average temperature (°C) observed across the Canadian prairies for the period of July 14-20, 2024.
The 30 day (June 21-July 20) average temperature (18.4 °C) was 2 °C warmer than average (Figure 2). Growing season (April 1 – July 20) average temperatures were 0.7 °C warmer than average (Figures 3 and 4, respectively).
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of June 21 – July 20, 2024.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – July 20, 2024.Figure 4. Growing season average temperature anomalies (°C) observed across the Canadian prairies for the period of April 1 – July 20, 2024.
Last week (July 14-20, 2024) average cumulative 7 day rainfall was 4.4 mm (Figure 5). Most of the prairies reported 30 day rainfall amounts that were normal to above normal (Figure 6). Rainfall amounts have been above normal for the majority of Manitoba and normal to below normal for most of Alberta. Driest conditions were observed near Edmonton and the western areas of the Peace River region. Rainfall values (June 21-July 20) have been highly variable across Saskatchewan. Growing season (April 1 – July 20) precipitation has been above normal to above normal (147 %) rain (Figure 7).
Figure 5. 7 day cumulative rainfall (mm) observed across the Canadian prairies for the period of July 14-20, 2024.Figure 6. 30 day percent of normal rain (%) observed across the Canadian prairies for the period of June 21 – July 20, 2024.Figure 7. Growing season percent of normal rain (%) observed across the Canadian prairies for the period of April 1 – July 20, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for eastern and Peace River regions of Alberta and southern regions of Saskatchewan (Figure 8). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan.
Figure 8. 7 day average saturated soil moisture (%) for the surface layer (<5cm)) for the period of July 14-20, 2024.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Access the Provincial Insect Pest Report for Wk12 to remain alert to areas and crops suffering from aphid pest pressure.
Figure 1. Pea aphid adults (each 3-4 mm long) and nymph. Photo: M. Dolinski.
Alternatively, several aphid pest species are described in the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) and is accessible as a free downloadable PDF in either English or French on our Field Guides page. PDF copies of the individual pages have been linked below to access quickly: • Corn leaf aphid or Rhopalosiphum maidis (Fitch) • English grain aphid or Sitobion (Macrosiphum) avenae (Fabricius) • Oat-birdcherry aphid or Rhopalosiphum padi (Linnaeus) • Pea aphid or Acyrthosiphon pisum (Harris) • Potato aphid or Macrosiphum euphorbiae (Thomas) • Soybean aphid or Aphis glycines (Matsumura) • Turnip aphid or Lipaphis erysimi (Kaltenbach) • Sugar beet root aphid or Pemphigus betae Doane • Russian wheat aphid or Diuraphis noxia (Mordvilko)
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
Compare canola flower midge damage to the closely related Swede midge which was featured as Wk12’s Insect of the Week.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
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.
Access the Provincial Insect Pest Report for Wk12 for updates for this economic insect pest.
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 July 25, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Aphids – Dr. J. Gavloski reported that, “Pea aphids in peas” remained a concern that resulted in “some control in the Southwest, Central and Interlake regions”. Additionally, “aphids in cereal crops are becoming more noticeable in some areas” but there also were “reports of aphid mummies (parasitized aphids), lacewings and lots of lady beetles in some fields of wheat.” • True armyworm – “True armyworms were still noted in forage grasses in the Central and Interlake regions. There were no reports of control of true armyworms over the past week, and levels of larvae may be declining as they turn to pupae. Review the cumulative pheromone trap counts in the July 24, 2024 report. Also find reports of natural enemies of armyworm in this report. • Grasshoppers– Reports that, “grasshoppers are more noticeable in crops in some areas, while in other areas grasshopper activity is mainly limited to field edges or is of less concern. There was a report of a number of dead grasshoppers clinging to the top of wheat heads (a sign of a fungal pathogen) in the Southwest region.” • Canola flower midge – “Unopened buds, a result of canola flower midge, is noticeable in some canola fields in the Northwest region.” • European corn borer – Review the report for tips to scout for egg masses in corn, hemp, quinoa, potatoes and other host crops. Access both the updated fact sheet and request to report by downloading and using the free Survey123 App. • Corn rootworm – Review the report for tips to scout for both the northern and western corn rootworm. • Bertha armyworm pheromone trap monitoring – Reports moths in “79 of 82 traps” although “counts have been low so far”. So far, the highest cumulative count reported is “290 from a trap near Killarney in the Southwest region”. Access the PDF copy of the July 25 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
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, AAI’s Agri-News occasionally includes insect-related information, e.g., assessing and a description of missing pods on canola (July 22, 2024), scout for wheat midge (July 15, 2024), the right canola crop stage to spray for lygus bugs (July 8, 2024), 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from 37 trap locations are reporting; 10 sites in central Alberta are “high” and in the Peace River region 22 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 25, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 18, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 266 trap locations are all reporting “low risk” across the province while 1 trap location near Fairview, plus 3 trap locations in southern Alberta (2 in Vulcan County plus 1 near Lethbridge) are reporting “medium risk” as of July 25, 2024). • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 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 – Cumulative counts arising from weekly data are available so refer to the Live Map. 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.
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.
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.
Producers opting to grow cultivars 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.
Figure 3. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.Figure 4. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.
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.
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.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk11 for updates for this economic insect pest.
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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.
Aphid populations can quickly increase at this point in the season and particularly when growing conditions are warm and dry. Over the years, both the Weekly Updates and Insect of the Week included aphid-related information so here’s a list of these items to access when scouting fields:
The European skipper (Hesperiidae: Thymelicus lineola) is a diurnal, bright orange butterfly (Fig. 1). The predominantly green defoliating larvae can cause economic levels of damage in timothy. The larvae also feed on other species of grasses and winter wheat.
Figure 1. European skipper (Thymelicus lineola) adults on timothy seed seeds. Photo: S. Dufton, AAFC-Beaverlodge.
There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. Host plants include timothy (Phleum pretense), cocksfoot (Dactylis glomerata), couch or quack grass (Agrophyron repens), perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis), orchardgrass (Dactylis glomerata).
Early in July, butterflies feed on nectar, mate, and lay eggs. Females lay vertical rows or “strings” of groups of ~30 eggs on the inside of grass leaf sheaths, seed heads or on the stem of a host plant. By late July, larvae develop within the eggs yet they remain safely enclosed to overwinter inside the egg shell. Eggs can be transferred in both hay and seed as seed cleaning will not remove all eggs. Early the following May, the overwintered larvae emerge from the shell, crawling up growing grass blades to feed. Five larval instar stages cause damage by defoliation of the upper leaves of timothy.
Larvae are leaf-tyers that spin and attach silk ties across the outer edges of leaves to pull them together (Figs. 2-5). The silk ties hold the leaf in a tight furl enclosing the larva within a leafy tube then it moves up and down the tube to feed. The tying behaviour and camouflaged green body (marked longitudinally with two white lines) make larvae hard to locate when scouting. Even larger larvae with their brown head capsules are surprisingly difficult to locate because the larva will lie lengthwise, along the base of the leaf fold yet the larva remains very still until touched. When high densities of European skipper larvae are present, leaf tying goes out the window and larvae feed in more exposed areas, often amidst rapidly disappearing foliage.
Adult wingspans range from 19-26 mm but they have bright brassy orange wings with narrow black borders and hindwing undersides that are pale orange and greyish. Nectar sources for adults include orange hawkweed, thistles, oxeye daisy, fleabane, white clover, red clover, common milkweed.The typical flight season extends from early June to mid-July but will vary regionally with southern parts of the Canadian prairies starting earlier than more northern regions.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Cultural control strategies for European skipper include separating timothy from nectar sources to avoid attracting adults which will mate then oviposit in the same field. Another strategy is the removal of cut grass or bales.
In terms of chemical control, an action threshold of six or more larvae per 30 cm x 30 cm area is recommended to mitigate losses but emphasis should be placed on scouting and managing early instar larvae. If the need arises, chemical control in timothy involves using a higher water volume (e.g., 300 L H2O/ha) to adequately cover the thicker canopy.
Figure 2. Early instar larva feeding along edge of timothy leaf. Photo: A. Jorgensen, AAFC-Beaverlodge.Figure 3. Larva resting in fold of timothy leaf formed by silken tie. Photo: K. Pivnick. AAFC-Saskatoon.Figure 4. Larval feeding damage and silken ties on timothy leaf. Photo: K. Pivnick, AAFC-Saskatoon).Figure 5. In situ camouflaged larvae and feeding damage in timothy. Photo: S. Barkley.
The European skipper was introduced to North America at least a century ago and has moved west and north in its distribution across western Canada even though its area of origin is recognized as Eurasia and northwestern Africa. The initial report of European skipper in Canada is from 1910 and cites it being imported on contaminated timothy seed near London, Ontario.
Distribution records for T. lineola can be reviewed on the Butterflies of North America website. In western Canada, T. lineola established in parts of Saskatchewan by 2006. In 2008, butterflies were collected near Valleyview, Alberta (Otani, pers.comm.), and in 2015 larvae were observed feeding in the flag leaves of winter wheat near Mayerthorpe, Alberta (2015 Meers, pers. comm.). Specimens confirmed as T. lineola were collected in 2016 near Valleyview, Donnelly, and High Prairie, Alberta (2017 Otani and Schmidt, pers. comm.) with additional specimens confirmed from Baldonnel and Clayhurst, British Columbia in 2021 (2021 Otani and Schmidt, pers. comm.).
The European skipper was the Insect of the Week in 2022 (Wk10).
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect that focuses feeding activities on developing buds, pods and seeds. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Recent research in Alberta has resulted in a revision to the thresholds recommended for the management of Lygus in canola. Under ideal growing conditions (i.e., ample moisture) a threshold of 20-30 lygus per 10 sweeps is recommended. Under dry conditions, a lower threshold may be used, however, because drought limits yield potential in canola, growers should be cautious if considering the use of foliar-applied insecticide at lygus densities below the established threshold of 20-30 per 10 sweeps.In drought-affected fields that still support near-average yield potential, a lower threshold of ~20 lygus per 10 sweeps may be appropriate for stressed canola. Even if the current value of canola remains high (e.g., >$19.00 per bu), control at densities of <10 lygus per 10 sweeps is not likely to be economical. Research indicates that lygus numbers below 10 per 10 sweeps (one per sweep) can on occasion increase yield in good growing conditions – likely through plant compensation for a small amount of feeding stress.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continues until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes Lygus bugs. The Flax Council of Canada includes Lygus bugs in their Insect Pest downloadable PDF chapter plus the Saskatchewan Pulse Growers summarize Lygus bugs in faba beans.
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 in 2023 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
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 July 18, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Aphids – Dr. J. Gavloski reported, “control of aphids in field peas from the Southwest (Boissevain area), and Central region (Notre Dame de Lourdes, Starbuck and Fannystelle areas)”. Access the Aphids on Peas fact sheet. • True armyworm – Reports that, “true armyworms remain at high levels in some areas, and control was reported from the Interlake and Central regions. There is also some evidence of parasitism of true armyworms starting to become visible (pupal clusters of a parasitic wasp called Cotesia).” Access the PDF copy of the July 10 report. • Grasshoppers– Reports, “some grasshopper control in soybeans and cereal crops occurred in the Central region”. • Sunflower bud moth – “Has been noticeable in many sunflower fields” and is featured in the July 18th report. • Bertha armyworm pheromone trap monitoring – Reports moths in “66 of 79 traps” although “counts have been low so far”. Where present, “eggs are now starting to hatch”. Access the PDF copy of the July 10 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #4 report which includes sections covering thrips in small grains cereal crops, cabbage seedpod weevil, and mid-season gopher control. Bookmark their insect pest homepage to access important information! • Insect pests to watch – A brief summary of the week was provided by Dr. J. Tansey (as of July 17) – “The prevalent story this week was pea aphid in lentils. Diamondback moth larvae were numerous in a smattering of fields in the southwest and monitoring is warranted. A few pockets of grasshoppers remain in southwest and east-central regions of Saskatchewan and populations of two-striped are reaching adulthood this week.” • Diamondback moth – Pheromone trapping is complete for 2024 and can be reviewed online. A total of 24 sites intercepted a cumulative total of ≥25 moths so in-field monitoring for larvae should be prioritized in those areas. • Bertha armyworm – Cumulative catches in phermone-baited unitraps “continue to increase slowly with one trap in east central reporting more than 300”. • Also access the Crops Blog Posts that released a grasshopper activity update (June 2024), 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 wheat midge (July 15, 2024), the right canola crop stage to spray for lygus bugs (July 8, 2024), 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Shelley Barkley reported that, “midge numbers are increasing in the Edmonton and Peace region”. So far, cumulative trap counts from 35 trap locations are reporting; 10 sites in central Alberta are “high” and in the Peace River region 21 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 18, 2024). • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then the data populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 18, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 265 trap locations are all reporting “low risk” while 1 trap location near Vulcan plus 1 trap location near Lethbridge are both reporting “medium risk” as of July 18, 2024). • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 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 – 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.
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.
Although the PPMN is unable to model and predict wheat midge development as in previous years, accumulated precipitation levels during May and June provide guidance in terms of in-field scouting. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Important– the accumulated precipitation levels over past 60 days (May 5 to July 3, 2024) were mapped in Figure 1 and ranged from 60 to >250 mm across the prairies, well beyond the 45 mm threshold that facilitates larvae to exit their cocoons to pupate in the soil then emerge. 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 early July.
Figure 1. 60 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 5 -July 3, 2024.
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.
Producers opting to grow cultivars 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.
Figure 3. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.Figure 4. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. Photo: AAFC-Beav-S. Dufton.
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.
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.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
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.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.
The economic threshold for immature and flowering canola is 100-150 larvae per metre2.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
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 2024Jul04).
Weekly Pheromone-baited Trapping Results – Early season detection of bertha armyworm is improved through the use of pheromone-baited unitraps traps deployed in fields across the Canadian prairies. Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Remember: in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.
Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).
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 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. 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:
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. 1). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 1. 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.
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 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 2. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
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.
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. Access the Provincial Insect Pest Report for Wk09 for updates.
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.
This week, European skipper was reported in the northeast of Saskatchewan where more forage crops are grown.
The European skipper (Hesperiidae: Thymelicus lineola) is a diurnal, bright orange butterfly (Fig. 1). The predominantly green defoliating larvae can cause economic levels of damage in timothy. The larvae also feed on other species of grasses and winter wheat.
Figure 1. European skipper (Thymelicus lineola) adults on timothy seed seeds. Photo: S. Dufton, AAFC-Beaverlodge.
There is one generation per year of European skipper but butterfly oviposition or egg laying largely dictates where damage occurs the following summer. Host plants include timothy (Phleum pretense), cocksfoot (Dactylis glomerata), couch or quack grass (Agrophyron repens), perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis), orchardgrass (Dactylis glomerata).
Early in July, butterflies feed on nectar, mate, and lay eggs. Females lay vertical rows or “strings” of groups of ~30 eggs on the inside of grass leaf sheaths, seed heads or on the stem of a host plant. By late July, larvae develop within the eggs yet they remain safely enclosed to overwinter inside the egg shell. Eggs can be transferred in both hay and seed as seed cleaning will not remove all eggs. Early the following May, the overwintered larvae emerge from the shell, crawling up growing grass blades to feed. Five larval instar stages cause damage by defoliation of the upper leaves of timothy.
Larvae are leaf-tyers that spin and attach silk ties across the outer edges of leaves to pull them together (Figs. 2-5). The silk ties hold the leaf in a tight furl enclosing the larva within a leafy tube then it moves up and down the tube to feed. The tying behaviour and camouflaged green body (marked longitudinally with two white lines) make larvae hard to locate when scouting. Even larger larvae with their brown head capsules are surprisingly difficult to locate because the larva will lie lengthwise, along the base of the leaf fold yet the larva remains very still until touched. When high densities of European skipper larvae are present, leaf tying goes out the window and larvae feed in more exposed areas, often amidst rapidly disappearing foliage.
Adult wingspans range from 19-26 mm but they have bright brassy orange wings with narrow black borders and hindwing undersides that are pale orange and greyish. Nectar sources for adults include orange hawkweed, thistles, oxeye daisy, fleabane, white clover, red clover, common milkweed.The typical flight season extends from early June to mid-July but will vary regionally with southern parts of the Canadian prairies starting earlier than more northern regions.
Access the Provincial Insect Pest Report for Wk09 for updates for this economic insect pest.
Cultural control strategies for European skipper include separating timothy from nectar sources to avoid attracting adults which will mate then oviposit in the same field. Another strategy is the removal of cut grass or bales.
In terms of chemical control, an action threshold of six or more larvae per 30 cm x 30 cm area is recommended to mitigate losses but emphasis should be placed on scouting and managing early instar larvae. If the need arises, chemical control in timothy involves using a higher water volume (e.g., 300 L H2O/ha) to adequately cover the thicker canopy.
Figure 2. Early instar larva feeding along edge of timothy leaf. Photo: A. Jorgensen, AAFC-Beaverlodge.Figure 3. Larva resting in fold of timothy leaf formed by silken tie. Photo: K. Pivnick. AAFC-Saskatoon.Figure 4. Larval feeding damage and silken ties on timothy leaf. Photo: K. Pivnick, AAFC-Saskatoon).Figure 5. In situ camouflaged larvae and feeding damage in timothy. Photo: S. Barkley.
The European skipper was introduced to North America at least a century ago and has moved west and north in its distribution across western Canada even though its area of origin is recognized as Eurasia and northwestern Africa. The initial report of European skipper in Canada is from 1910 and cites it being imported on contaminated timothy seed near London, Ontario.
Distribution records for T. lineola can be reviewed on the Butterflies of North America website. In western Canada, T. lineola established in parts of Saskatchewan by 2006. In 2008, butterflies were collected near Valleyview, Alberta (Otani, pers.comm.), and in 2015 larvae were observed feeding in the flag leaves of winter wheat near Mayerthorpe, Alberta (2015 Meers, pers. comm.). Specimens confirmed as T. lineola were collected in 2016 near Valleyview, Donnelly, and High Prairie, Alberta (2017 Otani and Schmidt, pers. comm.) with additional specimens confirmed from Baldonnel and Clayhurst, British Columbia in 2021 (2021 Otani and Schmidt, pers. comm.).
The European skipper was the Insect of the Week in 2022 (Wk10).
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 Wk07. This week, the updated map of “first sightings of LARVAE” has been placed below (retrieved 11Jul2024) but follow the hyperlink to check the interactive map. Larvae have been spotted in Manitoba and now Saskatchewan!
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 July 11, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include: • Pea aphids – Dr. J. Gavloski reported, “high levels of pea aphids in peas from fields in the Norte Dame de Lourdes area of the Central region, and the Hamiota / Oak River area of the Southwest regions”. The report includes the economic threshold for pea aphids to be checked at the beginning of flowering for field peas. • True armyworm in MB – Reports, true armyworms in some forage grass fields in the Interlake requiring insecticide treatments”. The highest cumulative trap count so far is 435 from a trap near Riverton in the Interlake region.” Scouting for larvae in cereals and forage grasses is still recommended in areas of the Central, Eastern, and Interlake regions. Access the PDF copy of the July 10 report. • Grasshoppers– Reports, “high levels of grasshoppers in wheat in the Central and Northwest regions”. • Bertha armyworm pheromone trap monitoring – Reports moths in “66 of 79 traps” although “counts have been low so far”. Where present, “eggs are now starting to hatch”. Access the PDF copy of the July 10 report. • Diamondback moth pheromone trap monitoring – Trapping is complete for 2024 (as of Wk 09; access the PDF copy of the July 4 report).
SASKATCHEWAN’SCrop Production News is back for the 2024 growing season! Access the online Issue #4 report which includes sections covering thrips in small grains cereal crops, cabbage seedpod weevil, and mid-season gopher control. Bookmark their insect pest homepage to access important information! A brief summary of the week was provided by Dr. J. Tansey (as of July 10): • Insect pests to watch – “Diamondback moth were detected in several sites”. In canola, “some lygus were detected” but “significant cabbage seedpod weevil were observed near Swift Current”. There were “several reports of barley thrips in wheat and durum”. “Pea aphid were reported in pulses”. Also, “several sites in southern and central regions have suffered ground squirrel damage to canola” with “major sections completely cleaned off”. • Grasshopper nymphs – “Grasshopper pressures have diminished considerably”. • Diamondback moth – Pheromone trapping is complete for 2024 and can be reviewed online. A total of 24 sites intercepted a cumulative total of ≥25 moths so in-field monitoring for larvae should be prioritized in those areas. • 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., the right canola crop stage to spray for lygus bugs (July 8, 2024), 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). • Wheat midge monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Shelley Barkley reported that, “midge numbers are increasing in the Edmonton and Peace region”. So far, cumulative trap counts from 26 trap locations are reporting; 6 sites in central Alberta are “high” and in the Peace River region 18 sites are reporting “high”, 2 sites are “medium”, and 2 sites are “low” (as of July 11, 2024). • Grasshoppers – Shelley Barkley reported that “nymphs are around but no adult pest grasshoppers have been seen yet” but that “(they) may be seen soon with the hot weather this week and expected for the next week or so”. • Cabbage seedpod weevil monitoring – Sweep-net count data can be reported here then populates the Live Map. So far, a total of 16 sites in southern Alberta are reporting; there are 14 “low risk” plus 2 “high risk” reports as of July 11, 2024). • Bertha armyworm pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts from 251 trap locations are all reporting “low risk” while 1 trap location near Vulcan is reporting “medium risk” as of July 11, 2024). • Armyworm moths – Shelley Barkley reported that, “Lindgren traps have been catching high numbers of armyworm moths (Miller moths) in the last week; in her experience, high moth numbers in traps in summer are indicative of high levels of cutworm damage the following spring”. • Diamondback moth pheromone trap monitoring – Cumulative counts arising from weekly data are available so refer to the Live Map. Cumulative trap counts have been recorded from 32 reporting sites and 28 remain in the “no risk” category as of July 4, 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 – 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.
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.
Last week (Jun 24-30, 2024), a number of locations had 7 day rainfall amounts that exceeded 50 mm. Most of the rain was observed across the central prairies extending from Oyen to Brandon. Beaverlodge and Grande Prairie had rain amounts that exceeded 45 mm. Growing season temperatures have been similar to climate normal values while rainfall amounts continue to be well above average. Manitoba continues to have warm temperatures and above normal precipitation.
The average 30 day temperature (June 1 – 30, 2024) was 13.9 °C and was almost 1 °C cooler than long term average temperatures. 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. Average cumulative rainfall (mm) over the past 30 days was 86 mm (71 mm last week) and was 150 % of climate normal values. Rainfall amounts have been greatest for Manitoba as well as central and Parkland regions of Saskatchewan (Figure 2). Rain amounts for the area extending from Saskatoon to Kindersley has been 250 % of normal for the past 30 days while cumulative 30 day rain totals for southwestern Saskatchewan and southern Alberta have been less than 65 % of normal.
Figure 1. 30 day average temperature (°C) observed across the Canadian prairies for the period of June 1-30, 2024.Figure 2. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 1-30, 2024.
Since April 1, the 2024 growing season average temperature (10 °C) has been marginally greater than 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 (prairie wide average) was 194 mm and has been above normal across most of the prairies (Figure 4). Regions around Brandon and Saskatoon have been particularly wet. Near normal precipitation amounts occurred across southern Saskatchewan, western Alberta and western areas of the Peace River region. Current rain amounts have been 175 % 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).
Figure 3. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 30, 2024.Figure 4. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 30, 2024.Figure 5. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 30, 2024.
Soil moisture conditions (top 5 cm) continue to be driest for western regions of Saskatchewan and eastern regions of Alberta (Figure 6) and is similar to the 30 day cumulative rainfall map (Figure 4). Soil moisture values were greatest for Manitoba and the Parkland region of Saskatchewan. Lowest values occurred across southern and central regions of Alberta as well as southwestern Alberta.
Figure 6. 7 day average saturated soil moisture (% soil moisture for the surface layer, <5 cm depth) for the period of June 24-30, 2024.
