Green cloverworms in alfalfa and
soybeans
We
are having some more ‘excitement’ on the pest front this week, this time on
soybeans. There are not many acres of
soybeans in the area, and we have none in our scouting program, but this pest
looks to be very serious. The following
was released by Dr. Pat Porter, District 2 Entomologist, earlier today on the
districts Focus on Entomology blog:
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 in Floyd
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.
Thanks Pat!
In a jaunt through Floyd today, every soybean
field I came across that was not maturing passed damage (5 total fields) has
these green clover worms at the same high level. Here are some additional photos from the damage in Floyd that I took today, 9/8/2016.
Blayne
