Reports are coming in late last week of fields in Eastern Ontario reaching well above threshold levels for soybean aphids. Just a few weeks prior, these fields had only 30 to 40 per plant. I suspect other fields in even Central and Southern Ontario will also experience this kind of rapid increase as daytime and more importantly night time temps are now back down to a level that is more ideal for these aphids. If not enough natural enemies are there to take them down, the aphids reach threshold quite quickly.
Scouting soybeans at least once a week from now until fields are into the R6 stage is advised. Particularly since other pests are also active in the fields now including spider mites, defoliators like Japanese beetles, red-headed flea beetles and bean leaf beetle which the latter are also starting to feed on the pods and clip some pods off plants in some fields.
Besides…aren’t soybeans a lot easier to scout than corn fields this time of year? Just saying…..