Weekly Update (May 7, 2020; Wk 02) Otani, Weiss, Rounce, Svendsen, Olfert, Vankosky

Spring has sprung!

Equipment is moving in fields across the prairies this week.  In addition to the Weekly Update, the Insect of the Week is back for 2020's growing season.  Please access the complete Weekly Update either as a series of Posts for Week 2 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.

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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.

Find the first WEEKLY report (available 11 May 2020).

Weather synopsis

Weather synopsis –  Though still early, the 2020 growing season has been cooler and dryer than normal. This past week (April 28-May 4, 2020), the average temperature was approximately 2 °C warmer than normal (Fig. 1).  

Figure 1. Observed average temperatures across the Canadian prairies for the past seven days (April 28-May 4, 2020).

Conversely, the average 30 day temperature (Fig. 2) was 2 °C less than climate normal values (Fig. 3). April temperature anomalies were greatest in a region extending from Edmonton to Saskatoon to Regina (Fig. 3).

Figure 2. Observed average temperatures across the Canadian prairies for the past 30 days (April 5-May 4, 2020).

Figure 3. Mean temperature difference from Normal across the Canadian prairies for the growing season (April 1-28, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (29May2020).  

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

Seven day cumulative rainfall (April 28-May 4) reveals that minimal rain was observed in central Saskatchewan, southern Alberta and the Peace River region (Fig. 4).  Rain (30 day accumulation) amounts have been well below average for most of the prairies (Fig. 5).

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

Figure 5. Observed cumulative precipitation across the Canadian prairies for the past 30 days (April 5-May 4, 2020).

 The growing degree day map (GDD) (Base 5 ºC, April 1-May 4, 2020) is below (Fig. 6):

Figure 6. Growing degree day map (Base 5 °C) observed across the Canadian prairies for 
the growing season (April 1-May 4, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (07May2020).  
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 4, 2020) is below (Fig. 7):

Figure 7. Growing degree day map (Base 10°C) observed across the Canadian prairies for 
the growing season (April 1-May 4, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (07May2020).  
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 <-9 to >0 °C in the map below (Fig. 8).

Figure 8. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (April 30-May 6, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (07May2020).  

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 <8 to >25 °C in the map below (Fig. 9).

Figure 9. Highest temperatures (°C) observed across the Canadian prairies the past seven days (April 30-May 6, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (07May2020).  

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) – A field guide is available to help growers scout and manage Cutworms.  Cutworm Pest of Crops is available for free in either English or French and is posted on the Cutworm Field Guide page!  

Several species of cutworms can be present in fields (Refer to downloadable PDF below).  They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning.  Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol.  Also refer to Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. 

In the past, the Insect of the Week featured economically important species of cutworms and some of the important natural enemies that help regulate these pests:
     Glassy cutworm - Wk01 (May 07, 2018)
     Darksided cutworm - Wk02 (May 14, 2018)
     Pale western cutworm - Wk01 (May 1, 2017)
     Dingy cutworm - Wk04 (May 23, 2017)
     Cutworm natural enemies - Wk03 (21 May, 2018)

Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look.  Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed.  Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant.  If the plant is well-established, check within the crown in addition to the adjacent soil.  The culprits could be wireworms or cutworms. 

 

For Albertans..... If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2020 Cutworm Reporting Tool” then view the live 2020 cutworm map which will be updated daily.

Flea beetles

Flea Beetles (Chrysomelidae: Phyllotreta species) – As canola seedlings emerge, scout for flea beetle damage on cotyledons but also on the stem (Fig. 1, left).  Two species, Phyllotreta striolata (Fig. 1, right) and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola seedlings.

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).

Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed.  Watch for "shot-hole" feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.

Estimating flea beetle feeding damage can be challenging.  Using a visual guide to estimate damage can be helpful.  Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon)  - take it scouting!

Figure 1. Canola cotyledons with various percentages of leaf area consume owing to 
flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).

Figure 2.  Percent leaf area consumed by flea beetles feeding on canola seedlings 
(Photo: Soroka & Underwood, AAFC-Saskatoon).

Refer to the flea beetle page 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.

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. 

As of May 4, 2020, AAW model simulations indicate that oviposition should have begun across central and western areas of the prairies.  The following graphs indicate, based on potential number of eggs, that development is more advanced near Lethbridge (Fig. 1) than Brandon (Fig. 2).

Figure 1. Predicted alfalfa weevil (Hypera postica) phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 4, 2020).

Figure 2. Predicted alfalfa weevil (Hypera postica) phenology at Brandon MB.
Values are based on model simulations (April 1-May 4, 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. 3, 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.  

As of May 4, 2020, the cereal leaf beetle model indicates that overwintered adults are active and  oviposition is underway across the prairies. The graphs provide a comparison of development for Swift Current (Fig. 1) and Saskatoon (Fig. 2). Reproductive adults appeared earlier in southern Saskatchewan, resulting in earlier oviposition.

Figure 1. Predicted cereal leaf beetle phenology at Saskatoon SK.
Values are based on model simulations (April 1-May 4, 2020).

Figure 2. Predicted cereal leaf beetle phenology at Swift Current SK.
Values are based on model simulations (April 1-May 4, 2020).

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than 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 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the 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. 4).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

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 4, 2020, grasshopper embryonic development is marginally ahead of long term normals.  Development has been greatest across Saskatchewan and Alberta (Table 1, Fig. 1).


Table 1. Predicted percent embryonic development of M. sanguinipes populations at selected sites across the Canadian prairies as of May 4, 2020.

Figure 1. Grasshopper embryological development (%) based on model simulations using
current environmental conditions (as of May 4, 2020).

Reminder - The Prairie Pest Monitoring Network's 2020 Grasshopper Forecast Map was released last week (Fig. 2) in the 2019-2020 Risk and Forecast Maps.  Spring temperatures, soil moisture conditions, and precipitation all have an impact on survival of overwintered grasshopper eggs. Growers in areas highlighted orange or red in the map below should be vigilant this spring.

Figure 2.  Grasshopper forecast map (M. sanguinipes) for 2020 growing season (released January 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.

Crop protection guides

Crop Protection Guides – If you don’t have a copy of your province’s Crop Protection Guide, please make use of these links to access the PDF version of the:
• Manitoba's Guide to Crop Protection Guide  or access via their homepage
• Saskatchewan's Crop Protection Guide or access it via their homepage
• Alberta's Crop Protection or Blue Book or access it via their homepage

• Pest Management Regulatory Agency's online pesticide label search application
• Western Committee on Crop Pests Guidelines for the Control of Crop Pests

Bookmark prairie provincial insect pest pages

Reminder - Looking for insect pest monitoring fact sheets and information from your prairie provincial experts?

Access Manitoba Agriculture and Resource Development here.

Access Saskatchewan Agriculture here.

Access Alberta Agriculture and Forestry here.

Scouting Charts - Canola and Flax

Reminder - Field scouting is critical - it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.

We offer TWO generalized insect pest scouting charts (with hyperlinks) to aid in-field scouting on the Canadian prairies:

1. CANOLA INSECT SCOUTING CHART



2. FLAX INSECT SCOUTING CHART




These charts feature hyperlinks directing growers to downloadable PDF pages within the "Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide".

Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.

Good luck with scouting!

Crop reports

Crop reports are produced by:
• Manitoba Agriculture (May 5, 2020 report accessible to email subscribers)
• Saskatchewan Agriculture (May 6, 2020 report accessible but check online).
• Alberta Agriculture and Forestry (not yet available).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the May 4, 2020 edition).

• The USDA's Weekly Weather and Crop Bulletin (read the May 6, 2020 edition). 

Previous posts

Click to review these earlier 2020 Posts:

2019-2020 Risk and forecast maps

Insect Pest of the Week and the Entomologists that Study Them (May 4): Canola and mustard pests / featuring Dr. Owen Olfert

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.

This week's feature crops are the Brassica oilseeds (mustard and canola) and Dr. Owen Olfert is our starring entomologist.

Crucifer flea beetles on canola seedling