Bertha armyworm: Time to scout

James Tansey, provincial entomologist with the Saskatchewan Ministry of Agriculture, posted this tweet on August 4:

Peak bertha emergence occurred between July 15 and July 22 in most regions of SK. Time to scout for larvae

— Dr. James Tansey (@dr_tansey) August 4, 2020

Here are the latest trap updates:

• Alberta. Alberta has quite a few locations with moth trap counts in the “medium” risk level and three in the “high” risk level. Those three are all in the southern part of the province. See the map.
• Saskatchewan. Counts were low for most of the province, with just a couple of sites moving into moderate or higher risk levels. The only orange spot on the map (July 22) is south of Humboldt. See the map.
• Manitoba. This is from the August 5 report: “No traps were in the moderate or high risk categories. Highest counts were in the western part of the central region and the northwest. The highest trap count is 485 near Dunrea in central Manitoba.” See the report.

Larvae start small but will grow quickly in warmer weather. This article from last week has details on how to scout and thresholds.