I looked at two soybean fields (one in Cherokee County and one in Cullman County) planted behind wheat on Thursday, September 1 and found high numbers of velvetbean caterpillars (VBCs) and stink bugs. Some growers were caught off-guard in September of 2020 and had almost 100% defoliation of their late-planted soybeans from VBCs.
We do not need a repeat of 2020 with the high soybean prices and excellent yield potential of these late-planted soybeans. Growers need to be scouting their fields (there is a real threat from VBCs if they have not been sprayed with Dimilin). Stink bugs, mostly green and brown marmorlated , are also being found in very high numbers in many of these fields.
A pyrethroid at a high rate will do an excellent job controlling both the VBCs and stink bugs (green and brown marmorlated).
VBCs start at the top of the plants and can quickly defoliate a field ( in 10-14 days soybeans can go from no foliage damage to 100% loss). They have been an infrequent pest but are becoming more prevalent in North Alabama. They have four sets of prolegs (the middle set of legs) and move rapidly if disturbed. The legs near the head are true legs.
The green cloverworm comes earlier in the season and have three sets of prolegs and also move rapidly when touched. Green cloverworms are usually not a major defoliator and should not be confused with VBCs.
Dimilin will give season-long control of VBCs and green cloverworms on foliage where it is sprayed.
We have also been picking up soybean loopers in low numbers, not enough to trigger a spray which is much more expensive than a pyrethroid. They start feeding at the bottom of the plant and have two sets of prolegs. Dimilin is not very effective on soybean loopers, and they have developed a resistance to many insecticides including the pyrethroids.
Intrepid Edge or Prevathon would be best options for soybean loopers but they will not control stinkbugs so it would be wise to add a pyrethroid if either Intrepid Edge or Prevathon is applied.
VBCs can also be a major defoliator of peanuts so any peanuts not sprayed with Dimilin should also be scouted.