David Owens, Extension Entomologist, owensd@udel.edu
Soybean
Continue scouting double crop soybeans for stink bug activity. At R6, pods with full seed, the threshold starts to increase from 5 to 7 bugs per 15 sweeps. Many second generation stink bugs are molting to adults now and beginning to move in the landscape. For this reason, their populations can increase in double crops. Also make mental notes of fields in which you see a large amount of flagged petioles which can be indicative of a Dectes infestation. Fields with the greatest number of Dectes stem borer should be prioritized for as timely a harvest as possible.
Alfalfa
A report came in earlier this week of significant defoliation from alfalfa webworm. An insecticide may be warranted if 25% of terminals are infested and alfalfa will not be cut in the next two weeks. Otherwise, early harvest is a great option. Scout alfalfa for defoliation.
Sorghum
I consider most of our late sorghum fields to be worm safe by this point. However, they are not sugarcane aphid safe. We scouted a field earlier this week with some concerning levels of sugarcane aphid. Threshold through the soft dough stage is 30% infested plants with localized areas of honeydew present. Insecticide options include Sivanto Prime (3-7 fl oz), Transform (0.75 to 1.5 oz), and Sefina (6 fl oz).