Posted: 08 Sep 2016 04:33 PM PDT
If you are growing soybeans or alfalfa on the Texas High Plains it would be a good idea to scout for green cloverworms. I was in a soybean field near Ralls earlier in the week that had approximately 8 larvae per plant, and I just got a call about soybeans near Clarendon that were heavily infested.
In both cases the people making the reports thought the worms were soybean loopers. It is easy to tell the two caterpillars apart because loopers have two pairs of prolegs on the abdomen while the green cloverworm has three pairs. Loopers are fairly lethargic, but green cloverworms hop around quickly when disturbed.
Green cloverworm larvae near Ralls
Typical defoliation in soybean caused by green cloverworm
Fortunately the green cloverworm is only a leaf feeder in soybean and it does not damage pods. For alfalfa here is a quote the Oklahoma guide, "These defoliators are rarely a significant problem in established alfalfa, although seedling stands can be heavily damaged by their feeding." However, if there are enough of them present they can cause defoliation, which in turn will reduce the amount of nutrients the plants can store for overwintering.
For soybeans, University of Tennessee has good list of insecticides in their publication here. Oklahoma State University has control suggestions for alfalfa here.
Friday, September 9, 2016
Dr. Pat Porter reported yesterday about heavy infestations of the green cloverworm in alfalfa and soybeans (http://focusonagriculture.blogspot.com), The following is the article that he published in "Focus on Entomology". One of the fields he got a call about was near Clarendon. Blayne Reed, Extension Agent - IPM, also, reported finding heavy infestations in soybean fields in Floyd county. I have not heard of any other fields in the Panhandle but there is high probability that the fields are infested.