July 25, 2008

Several growers and consultants have called this week with reports of soybean aphids in fields. They have usually described the fields as having low numbers, with "hot spots" of 50 to 100 square feet where aphids are at or near threshold levels.

Remember, the economic threshold is an average of 250 aphids per plant over the entire field. Hot spots come and go, so don't jump the gun and treat when the field average is below 250.

That being said, aphids can reproduce very rapidly and the field should be checked at least twice a week. The 250 threshold should give producers five to seven days of lead time before average numbers hit 600, which is about the point where yield loss begins. Aphids will be active though August, so now is the time to devote scouting efforts to this sometimes major pest.

Keith Jarvi
Integrated Pest Management
Northeast REC, Norfolk