Weekly Update (May 21, 2020; Wk 04) Otani, Weiss, Rounce, Trudel, Svendsen, Turkington, Olfert, Vankosky

The phenology models used to predict insect staging and associated risk to field crops on the Prairies is a complex system with multiple moving parts.  Last week, phenology model output and map development was not available owing to the detection of an error in one of the underlying datasets required to run the models.  We are pleased to report that the error has been resolved for this week.

At this moment, segments of earlier 2020 Weekly Updates have been pulled back.  The phenology models for Wk01 and Wk02 will be reposted once we have had opportunity to re-run the models with the correct datasets and re-map the model outputs.  Stay tuned and thank you for your patience!

Access information to support your in-field insect monitoring efforts in the complete Weekly Update either as a series of Posts for Week 4 OR  a downloadable PDF.

Stay Safe!

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

Subscribe to the Blog by following these easy steps!

Wind Trajectories

Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.

The entire list of 2020 Wind Trajectory Reports is available here.
→ Read the WEEKLY Wind Trajectory Report for Wk04 (released May 18, 2020).
→ Read the DAILY Wind Trjectory Reports for Wk04 (released May 20 and May 21).

Weather synopsis

Weather synopsis –  This week, May 12-18, 2020, cool, dry conditions continued to occur across the prairies. Early growing season daily average temperatures continue to be cooler than normal (Fig. 1). 

Figure 1. Mean temperature difference from Normal across the Canadian prairies the past 30 days (April 21-May 18, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18May2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

This past week the average temperature was approximately 1 °C cooler than normal (Fig. 2). The warmest temperatures were observed near Lethbridge, Regina and Saskatoon.  

Figure 2. Observed average temperatures across the Canadian prairies for the past seven days (May 12-18, 2020).

Average 30 day (April 19-May 18, 2020)  temperatures were marginally warmer than average (Fig. 3). Across the prairies, average temperatures were warmest in Alberta and western Saskatchewan. 

Figure 3. Observed average temperatures across the Canadian prairies for the past 30 days (April 19-May 18, 2020).

Conditions continue to be dryer than normal (Fig. 4).  Seven day cumulative rainfall indicated that minimal rain was observed across large areas across the prairies (Fig. 5). Most locations reported less than 5 mm. Rainfall amounts for the past 30 days have been approximately 77 % of normal (Fig. 6). 

Figure 4. Percent of average precipitation the past 30 days (April 19-May 18, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18May2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

Figure 5. Observed cumulative precipitation across the Canadian prairies for the past seven days (April 26-May 4, 2020).

Figure 6. Observed cumulative precipitation across the Canadian prairies for the past 30days (April 19-May 18, 2020).

The growing degree day map (GDD) (Base 5 ºC, April 1-May 18, 2020) is below (Fig. 7):

Figure 7. Growing degree day map (Base 5 °C) observed across the Canadian prairies for 
the growing season (April 1-May 18, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18May2020).  
Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 10 ºC, April 1-May 18, 2020) is below (Fig. 8):

Figure 8. Growing degree day map (Base 10°C) observed across the Canadian prairies for 
the growing season (April 1-May 18, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (18May2020).  
Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The lowest temperatures (°C) observed the past seven days ranged from <-10 to >2 °C in the map below (Fig. 9).

Figure 9. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (May 14-20, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (20May2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The highest temperatures (°C) observed the past seven days ranged from <10 to >28 °C in the map below (Fig. 10).

Figure 10. Highest temperatures (°C) observed across the Canadian prairies the past seven days (May 14-20, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (20May2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

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

Cutworms

Cutworms (Noctuidae) – Several species of cutworms can be present in fields and scouting should begin before seeding and continue in to June on the Canadian prairies!  Access tools including the Cutworm Field Guide, photos and descriptions for glassy, darksided, pale western, dingy and some of the natural enemies that attack cutworms plus scouting tips to help identify cutworms in field crops.  

Figure 1. Dingy cutworms (photo: J. Gavloski, Manitoba Agriculture and Resource Development).

Flea beetles

Flea Beetles (Chrysomelidae: Phyllotreta species) – The Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed.  Watch for "shot-hole" feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.  Link here to review photos and scouting tips for flea beetles in canola (Wk03).

Figure 1.  Flea beetle feeding on leaves canola seedling resulting in "shot-hole" damage plus girdling of stem (left) plus dorsal view of striped flea beetle (right).

Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) - Once diamondback moth is present in the area, it is important to monitor individual canola fields for larvae.  Warm growing conditions can quickly translate into multiple generations in a very short period!

Wind Trajectory Updates - This week, wind trajectory models used to deliver an early-warning system for the origin and destination of migratory invasive species indicated arrival events of air currents potentially carrying migrating diamondback moths from more southerly regions.  Both Weekly (released May 18, 2020) and Daily reports (released May 20 and May 21) indicated multiple trajectories originating over Mexico, California, and Texas crossing locations in Manitoba, Saskatchewan.

Weekly Pheromone-baited Trapping Results - Early season detection of diamondback moth is improved through the use of pheromone-baited delta traps deployed in fields across the Canadian prairies.  As they become available, moth reporting numbers observed in Alberta, Saskatchewan and Manitoba will be linked here.

Monitoring:
Remove the plants in an area measuring 0.1 m² (about 12" square), beat them on to a clean surface and count the number of larvae (Fig. 1) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

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

Figure 2. Diamondback moth pupa within silken cocoon.

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

Figure 3. Diamondback moth.

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

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

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9 °C are produced to predict the development of Alfalfa weevil (AAW) across the prairies.  The model is updated weekly to help growers time their in-field scouting for second-instar larvae. 

Model output indicates that oviposition is well underway and initial hatch should occur over the next 7-10 days  (Fig. 1). Compared with long term normal weather data, egg development is 1 – 2 days later than average.  Based on the alfalfa weevil degree day model (Soroka et al. 2020), AAW development is most advanced across southern AB.

Figure 1. Predicted alfalfa weevil (Hypera postica) phenology at Saskatoon SK.
Values are based on model simulations (April 1-May 18, 2020).

Figure 2. Predicted development of populations of alfalfa weevil (Hypera postica) across

the Canadian prairies as of May 18, 2020. 

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 33, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) - The CLB simulation model will be used to monitor this insect pest's development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of development stages based on biological parameters for this species.  

The cereal leaf beetle (CLB) model indicates that oviposition is well underway (Fig. 1 and 2). First instar larvae should be appearing within the next 7-10 days.

Figure 1. Predicted cereal leaf beetle phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 18, 2020).

Figure 2. Predicted cereal leaf beetle phenology at Winnipeg MB.
Values are based on model simulations (April 1-May 18, 2020).

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 4). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  

Figure 4. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 5).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 5.  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.

NEW for Manitobans - Dr. John Gavloski is looking for samples of cereal leaf beetle larvae this growing season to determine their range across Manitoba, their population density, and the rate at which larvae are parasitized. Please contact John (John.Gavloski@gov.mb.ca) or @JohnTheBugGuy if you observe cereal leaf beetles in your fields. 

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" available as a free downloadable document in either an English-enhanced or French-enhanced version.

Predicted grasshopper development

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

As of May 18, 2020, predicted embryonic development was 66% and is similar to long term average values.  Development was greatest in a region from Regina to Saskatoon and southwest to Lethbridge.  

Figure 1. Grasshopper embryological development (%) based on model simulations using
current environmental conditions (May 18, 2020).

Embryonic development at Winnipeg, Brandon and Grande Prairie is expected to be seven to ten days slower than for Saskatoon, Swift Current and Lethbridge (Fig. 2). Based on these locations, Winnipeg (Fig. 2) was the only site with embryonic development predicted to be slower than long term average (Fig. 3).  

Figure 2. Grasshopper embryological development (%) based on model simulations using
current environmental conditions (as of May 18, 2020) for sites across the Canadian prairies.

Figure 3. Grasshopper embryological development (%) based on model simulations using current environmental conditions (blue bars) compared to long-term normal (red bars) as of May 18, 2020.
*LTN = long term climate normals, used for comparison of current year development (OBS)

This week initial hatch is predicted to occur in southern Alberta (Fig. 4). Across the prairies, results indicated that eggs should begin to hatch during the next two weeks (Fig. 4). 

Figure 4. Predicted percent of grasshopper (Melanoplus sanguinipes) population at first instar stage across
the Canadian prairies (as of May 18, 2020). 

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

Field Heroes

Reminder - The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Review all the info posted in Wk03!

Spring threshing surprise - Seeking beetle data please!

Reminder - Large numbers of adult Amara ground beetles are being reported this spring (Fig. 1) in canola fields left unharvested last fall. These are non-pest beetles.  Adults feed on seeds, particularly those of cruciferous plants.  Larvae eat pest insects (e.g., grasshopper eggs).

Figure 1. An aggregation of Amara littoralis near Pickardville, AB. This was one of several outbreaks of
carabids observed in central Alberta in the autumn of 2010.  Photo B. Berry.

Read the full post and find a request for beetles posted in Wk03!

Provincial Insect Pest Reports

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

• Manitoba's Crop Pest Updates for 2020 are available. Access the May 20, 2020 report. The first report for the 2020 growing season includes cutworms, flea beetles and diamondback moth information.

• Saskatchewan's Crops Blog Posts can include insect pest information. Also access Crop Production News. Issue 1 is now available. Articles include Pest Monitoring in Saskatchewan - how and why, Early-Season Scouting of Cutworms, Flea Beetles in Canola, plus Pea Leaf Weevil Season Is Starting Soon.

•  Alberta Agriculture and Forestry's Agri-News occasionally includes insect-related information. Read about overwintered canola and ground beetles.  

Bookmark prairie provincial insect pest pages

Find insect pest monitoring fact sheets and information from your prairie provincial experts posted in Wk02.

Prairie Crop Disease Monitoring Network - Turkington

The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of  prairie pathologists working together to support in-field disease management in field crops.  Information related to trajectory events based on forecast and diagnostic wind fields and cereal rust risk is experimental, and is offered to the public for informational purposes only.  Read the OVERVIEW describing the collaborative nature of this effort and the methods employed.  

Wind trajectory and cereal rust risk assessment and need for in-crop scouting in the Prairie region, May 12-18, 2020

1. Pacific Northwest (PNW) – There were a number of reverse wind trajectories that passed over the PNW region and into the prairies.  However, currently there is limited stripe rust development in the PNW, cool dry Prairie weather conditions, and early stages of Prairie crop development.  Thus, as of May 18, 2020 the risk of stripe rust appearance from the PNW is limited and scouting for this disease is not urgent.  

2. Texas-Nebraska corridor – Currently, there is limited leaf and stripe rust development in this corridor.  Moreover, there were a relatively low number of recent wind trajectories from this area, and cool Prairie weather conditions and early stages of Prairie crop development.  Thus, as of May 18, 2020 the risk of leaf and stripe rust appearance from the Texas-Nebraska corridor is limited and scouting for these diseases is not urgent

3. Where farmers or consultants noticed stripe rust development on winter wheat in the fall of 2019, it is recommended to scout winter wheat fields that have resumed growth this spring.  Scouting is especially critical where the variety being grown is susceptible to stripe rust.  Currently, there are no early spring reports of stripe rust on winter wheat.

4. Read the full report here.  

Crop reports

Click the provincial ministry name below to link to online crop reports produced by:
• Manitoba Agriculture - Other viewing options include subscribing to receive or access a PDF of May 19, 2020 report.
• Saskatchewan Agriculture  or access a PDF of May 12-18, 2020 report.
• Alberta Agriculture and Forestry or access a PDF of May 12, 2020 report.

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the May 18, 2020 edition).

• The USDA's Weekly Weather and Crop Bulletin (read the May 19, 2020 edition). 

Scouting Charts - Canola and Flax

Click here to access TWO generalized insect pest scouting charts (with hyperlinks to the insect guide) intended to aid in-field scouting on the Canadian prairies.

Crop protection guides

Crop Protection Guides – Manitoba, Saskatchewan and Alberta guides were included in Wk01. Find PDF copies or access their homepages.

Insect Pest of the Week and the Entomologists that Study Them (May 19): Chickpea and lentil pests / featuring Erl Svendsen

This week's Insect of the Week feature crops are chickpea and lentil and Erl Svendsen is our feature 'entomologist'.

Migratory grasshopper (cc-by Joseph Berger, bugwood.org)

Note: 

This year, we're doing things a bit differently for our Insect of the Week. Instead of focussing on a single insect (pest or natural enemy), we're looking at it from a crop perspective. Each week, we'll pick a crop and list the insects that attack it along with additional helpful information. The insect list is based on the information found in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. The field guide offers information describing lifecycle, damage description, monitoring/scouting strategies, economic thresholds (where available) and control options) for each economic pest.

In addition to an Insect of the Week, we'll also feature one of the entomologists that help support the PPMN, either directly or indirectly.