Soybean Aphids
August 22, 2008
There's still a lot of soybean aphid activity in the fields, which brings up questions about management. Remember that the economic threshold is 250 aphids/plant with a growing population. That number allows the grower several days to get the aphids controlled before yield loss may occur. Beneficial insects like lady beetles, if in plentiful supply, can keep the aphid population from exploding. But you generally can't rely on the lady beetles to move into a field and reduce an aphid population that's already beyond the threshold.
When using insecticides, be sure your applicator is following label instructions. Most products require at least 2+ gpa by air or 15 gpa by ground. I've heard of some applications not controlling the aphids; but the aerial spray volume was only 1 gpa. It may not sound like much, but its only 50% of the require quantity. That's a big difference.
Scouting and management/control has proven to be beneficial until R6 (full seed) stage. Little to no yield loss (due to soybean aphid) has been noted beyond that point.
At some point in time the soybean aphid population may transition to having wings. The winged aphids will migrate out of the soybean field and fly to buckthorn trees in the tree lines.