My graduate student Erin Hodgson and I just returned from a soybean sampling trip in SE Minnesota (Houston County) (12 June 2001). We visited fields adjacent to where aphids had caused substantial plant damage last August and where we found aphids colonizing Buckthorn in October of 2000. We sampled four fields this afternoon, one was conventional soybeans planted in 7" rows, three fields were Round Up Ready fields planted in 20", 30" or as drilled beans. All fields had active aphid colonies, that appear to be soybean aphids.

Roughly a 10% infestation was seen (10% of random plants sampled had at least 1 aphid). The actual numbers were 3/30, 4/30, 5/30, and 3/30 (plants with aphids/total no. random plants sampled). It appears that field edges were more readily colonized and fields closest to wood lots with buckthorn had higher aphid densities. We will grid sample those same fields later this week to see if we can discern a pattern of colonization. All putative soybean aphids were found on the uncurled trifoliate or newly expanded trifoliate. Colonies varied in size from a few aphids (<10) to nearly 50 aphids. Four alates were found and we will send those off for confirmation as soon as we can. Fields were either V-1 or V-2 stage in development.