Many peanut fields in Georgia received much needed rain over the past two weeks. This does not mean that lesser cornstalk borers (LCB) will be gone from those fields. Rain DOES NOT kill LCBs. Cool moist conditions are not favorable for the pest, but in situations where populations are already high, sporadic rainfall will have little effect on infestations. The bottom line is that peanut fields should be scouted soon and scouted every week to determine if LCB is present and if an insecticide application is needed. The reports I have gotten, and the results of my own trials, indicate that the insecticides recommended by UGA Extension for LCB management are doing a good job against the pest. When scouting for LCB, be certain to check plants randomly. Stopping to check only plants in skips or those with wilted leaves will bias the count and could result in an unnecessary insecticide application. Finding a live LCB larva at 3 out of 10 stops in a field (checking 3 feet of row at each stop) is enough to warrant a spray.
Foliage feeding caterpillars continue to exceed thresholds in peanut fields across the state. Though caterpillar populations are made up of several species, it is the beet armyworm (BAW) that has been present at much higher than “normal” levels. County agents, growers, and consultants across the state have reported problems controlling BAW with products containing the active ingredient chlorantraniliprole (Vantacor, Besiege, and Shenzi). The UGA Peanut Entomology program conducted a trial over the last week to test the efficacy of several different insecticide active ingredients against BAW. Caterpillar mortality in the chlorantraniliprole treatments did not differ from the non-treated check. The products Intrepid and Intrepid Edge resulted in 91% and 100% mortality respectively at 5 days after treatment.
The next few weeks will be critical for setting this year’s crop; lets make sure we do not suffer any unnecessary losses from LCB or foliage feeding caterpillars. Fields need to be scouted regularly and treated when thresholds are reached. If you have questions about caterpillar management or any other pest concerns in peanut, please contact your local UGA County Extension agent.
