This past week (Aug 4-10, 2020) conditions were generally warm and dry. Weekly prairie temperatures were warmest across Manitoba and Saskatchewan (Fig. 1). Lower temperatures were observed across western and northwestern Alberta (Fig. 1). Though average 30-day (July 12 – August 10, 2020) temperatures continue to be cooler in Alberta than eastern Saskatchewan and Manitoba (Fig. 2), temperature anomalies (mean temperature difference from average; July 14-August 10, 2020) indicate that conditions have generally been warmer than average across most of Alberta as well as Parkland regions of Saskatchewan and Manitoba (Fig. 3).
Regions in southeastern central and southern Saskatchewan and across southern Manitoba have reported temperatures that have been up to 2 °C cooler than average. Based on growing season temperatures (April 1-August 10, 2020) temperatures were warmest across the southern prairies (Fig. 4). Based on growing season temperature deviations (observed temperatures compared with climate normal temperatures), below average temperatures have been observed across central and western regions of Saskatchewan and central regions of Alberta (Fig. 5). Across southern Alberta and most of Manitoba, temperatures have generally been above average. (Fig. 5)
Most areas reported 7-day cumulative rainfall amounts that were less than 10 mm (Fig. 6). Cumulative 30-day rainfall was lowest across a large area ranging across southern Alberta as well as central and western regions of Saskatchewan (Fig. 7). Growing season rainfall (percent of average) is highly variable across the prairies (Fig. 8). Rainfall has been below normal across most of Saskatchewan as well as southern Alberta, and the Peace River region (Fig. 8).
The growing degree day map (GDD) (Base 5 ºC, April 1-August 9, 2020) is below (Fig. 9) while the growing degree day map (GDD) (Base 10 ºC, April 1-August 9, 2020) is shown in Figure 10.
The highest temperatures (°C) observed across the Canadian prairies the past seven days ranged from <17 to >34 °C (Fig. 11) while the lowest temperatures ranged from <-1 to >13 °C (Fig. 12). So far this growing season (as of August 12, 2020), the number of days above 25 °C ranges from 0-10 days in the west (to west of Calgary, west and north of central Alberta and extending into the south and west of the Peace River region) but extends up to 51-60 days in southern Manitoba (Fig. 13).
Weekly Pheromone-baited Trapping Results – Click each province name to access moth reporting numbers observed in Alberta, Saskatchewan and Manitoba(as they become available). Check these sites to assess cumulative counts and relative risk in your geographic region but remember in-field scouting is required to apply the economic threshold to manage both this pest and its natural enemies. For convenience, screen shots of the above maps or data have been placed below for Alberta, Saskatchewan, and Manitoba.
Larval sampling should commence once the adult moths are noted.
Sample at least three locations, a minimum of 50 m apart.
At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae.
Count them and compare the average against the values in the economic threshold table below:
Scouting tips: ● Some bertha armyworm larvae remain green or pale brown throughout their larval life. ● Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms. ● Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. ● Larvae eat the outer green layer of the stems and pods exposing the white tissue. ● At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.
This week, the DBM model based on Harcourt (1954) was run with a biofix of May 15, 2020. Most of Alberta has had two generations. It is possible that three generations have been completed across Saskatchewan and southeastern Alberta where it has been warmer. Results indicate that a potential fourth generation may be occurring across southern Manitoba. DBM densities generally increase with increasing numbers of generations. Later maturing canola fields may be susceptible to damage resulting from larval feeding.
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. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
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).
As of August 10, 2020, the grasshopper model estimates that prairie grasshopper populations are primarily in the adult stage (Fig. 1). Figure 2 provides an overview of where oviposition is predicted to occur based on weather conditions up to August 10. Oviposition is well underway across southern Manitoba and southeastern Saskatchewan (Fig. 2).
Recent warm weather in southwestern Alberta has resulted in increased development rates, resulting in predicted occurrence of oviposition. The three graphs compare grasshopper development at Grande Prairie (Fig. 3), Saskatoon (Fig. 4) and Brandon (Fig. 5). Output suggests that adults are beginning to occur near Grande Prairie but oviposition has yet to begin (Fig. 3). Saskatoon (Fig. 4) and Brandon (Fig. 5) populations should be primarily in the adult stage and oviposition should be well underway.
Entomologists with Agriculture and Agri-Food Canada in Winnipeg are doing a survey in September of insects in farm grain bins. They are looking for 10 farms not far from Winnipeg where they can access grain bins to sample insects. No grain will be removed, just insects. If interested, please contact John Gavloski (John.Gavloski@gov.mb.ca) as soon as possible.
The following is offered to predict when Culex tarsalis, the vector for West Nile Virus, will begin to fly across the Canadian prairies (Fig. 1). This week, regions most advanced in degree-day accumulations for Culex tarsalis are shown in the map below (yellow, orange then red highlighted areas). As of August 9, 2020 (Fig. 1), areas highlighted yellow and more imminently orange are approaching sufficient heat accumulation for mosquitoes to emerge. Areas highlighted red NOW HAVE Culex tarsalis flying (Fig. 1) – protect yourself by wearing DEET!
The Canadian Grain Commission is ready to grade grain samples harvested in 2020. Samples are accepted up to November 30 but growers normally send samples as soon as harvest is complete.
This is a FREE opportunity for growers to gain unofficial insight into the quality of grain and to obtain valuable dockage information and details associated with damage or quality issues. The data collected also helps Canada market its grain to the world!
More information on the Harvest Sample Program is available at the Canadian Grain Commission’s website where growers can register online to receive a kit to submit their grain.
In exchange for your samples, the CGC assesses and provides the following unofficial results FOR FREE:
dockage assessment on canola
protein content on barley, beans, chick peas, lentils, oats, peas and wheat
oil, protein and chlorophyll content for canola
oil and protein content and iodine value for flaxseed
oil and protein for mustard seed and soybean
Falling Number for wheat
Vomitoxin (deoxynivalenol or DON) for wheat and corn.
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
• Manitoba‘s Crop Pest Updates for 2020 are available. Access the August 11 2020 report. The summary indicates that, “Grasshoppers continue to be the insect of greatest concern. The diamondback moth populations in eastern Manitoba that were of concern in some fields a couple of weeks ago seem to have diminished. Spider mites are being noticed in some soybean fields, but no insecticide applications for them have been reported yet.”