Chinch Bugs are showing up in high numbers in seedling corn and rice in Arkansas. Chinch bugs are one of those insects that can sneak up on a grower and cause significant damage. They feed on grasses, so corn, grain sorghum and rice are the crops we are primarily concerned with when it comes to this pest. Most of the calls we are receiving about chinch bugs in corn are from the central portion of the state, primarily Prairie County. Chinch bugs are tiny black insects that will feed on the stem of the plant behind the leaf sheath or below the soil line on corn and grain sorghum. Because these insects are so small and often feed out of sight, they are easy to miss when scouting a field. When checking plants, pull back leaf sheaths and also pull soil back from the base of the plant. We are getting reports of up to 2 adults per plant on corn in some areas. Adults and large nymphs are the most damaging stages of this pest. Chinch bugs inject a toxin as they feed. Feeding damage may show up as yellow streaking or reddening of leaves. Leaves may also begin to look twisted. Two or more adults feeding on a small seedling can cause plant death. Because corn is sensitive to stand loss, it is very important that growers scout fields for these insects at this time. High numbers can cause significant stand loss.
The Good News….the majority of our corn was planted with a seed treatment (Poncho or Cruiser). Both of these seed treatments will give suppression of chinch bugs. The level of this suppression is related to the seed treatment rate. Cruiser 500 and Poncho 500 will give better control than the 250 rates of these seed treatments. If adults are being found in corn with these seed treatments, but no damage is showing up, it is recommended that the grower wait and recheck the field in a few days. The bugs do have to feed on the plant before the seed treatment will kill them, so it is possible to find adults that have recently entered a field but have not fed yet. If there are still chinch bugs in the field and damage is beginning to show up on some plants, growers should treat with a labeled insecticide. MP 144 “Insecticide Recommendations in Arkansas” gives a list of recommended insecticides. The method of insecticide application is more important for chinch bug control than the actual choice of insecticide. They all give good control, but because these insects feed behind the leaf sheath and below the soil line, a high volume of water is usually required to get adequate control. Last week we were seeing cutworms showing up in some fields, primarily in south Arkansas (Akin – Cutworms Surfacing in Corn). If chinch bugs and cutworms are present, a Pyrethroid would be recommended to control both pests. Growers also need to watch out for stink bugs in seedling corn at this time (see Lorenz – Stink Bugs).
Rice – we are getting reports of chinch bugs in high numbers in rice in Louisiana and south Arkansas. The message is the same here as it is in corn. If a seed treatment (Cruiser or Nipsit Inside) is on the crop, it should give control of chinch bugs in rice. Fields should still be checked and if seedlings are dying and chinch bugs are present – treat the field.