Stink Bugs Quiet, Fall Armyworms Defoliating Entire Plants

Walking The Field Recommended

MILAN, TENN.
   It has been a quiet year for insects in soybeans this year according to Dr. Scott Stewart, University of Tennessee, Extension Entomologist, “very quiet; unusually quiet. We have had probably the lightest year since I have been here. We have had isolated problems with fall armyworm, early season, some corn earworm lately, but stink bugs got a slow start this year. We are just now getting some calls about stink bugs once plants reach R6 in development.”
   Producers need to scout their fields. “Everybody wants to quit and go to the house but we have got a lot of late planted and late maturing beans out there that are still quite susceptible.”
   Stewart was asked why he is seeing fewer insects. “Well, if I could figure that kind of stuff out I would make a lot more money. It is very common for insects to go through cycles, just like other animals, you have up and down years and this is clearly a down year. Green stinkbugs are our predominant pest species and when it has a down year, we are just not going to have many stink bugs. We have had our normal year with the three-cornered alfalfa hopper, bean leaf beetles but usually it is the stink bug we will spray the most acres for.”
   Stewart added fall armyworms have created problems. “I would say the most impressive problem we had this year was during early August. We had fall armyworms virtually defoliate entire fields. Fortunately, this was only some fields, mostly late planted, and fields where grassy weeds got fall armyworm infestations started. This pest will feed on grasses and move to soybean plants, particularly after Roundup applications take out the weeds.” Defoliation can occur quickly according to Stewart. “It can happen in four or five days.”
   Net sweeps were catching five caterpillars per sweep in some cases. Stewart said, “they will just defoliate the entire plant. This happens every year somewhere. It does make the point that if you are not looking at your field every seven to ten days you can get caught. A farmer on a hi-boy driving through a field will not notice the fall armyworms or other pests until it’s too late. By simply walking through the fields and being observant, you can pick up potential problems before they cause yield loss.” However, Stewart strongly recommends using a sweep net while scouting your fields.
   Stewart has seen producers increase scouting efforts. “It is increasing quite a bit, particularly with soybeans, less so with corn. It is increasing in part because we are losing cotton acres so we have professional consultants that are available to check other crops. The price of soybeans has gone up. It is becoming more of a cash crop and growers are a little more interested in taking care of it.”
   Stewart said, “unfortunately, many folks still do not scout or hire a consultant. However, we can’t afford not to manage insects in soybeans, particularly late maturing fields. In most years, late maturing fields will benefit from insecticide applications for one or several late season pests including stink bugs, threecornered alfalfa hoppers or soybean loopers.” Δ
   REGINA LAROSE: Associate Editor, MidAmerica Farmer Grower

Dr. Scott Stewart, University of Tennessee, Extension Entomologist, explains this year was a very quiet year for insects. Photo by John LaRose