After thrips, foliage feeding caterpillars are the most often treated insect pest in Georgia peanut fields. While it is certainly not uncommon for caterpillar infestations to reach the economic threshold (the threshold ranges from 4 to 8 caterpillars per row foot depending on crop condition), not every peanut field in the state will need to be treated. We are now in the second week of August, and reports of velvet bean caterpillars (VBC) and soybean loopers (SBL) have started coming in right on schedule. VBC moths were abundant in some of my plots this morning in Tift County, and I saw near threshold populations of caterpillars in a commercial field near the Florida line yesterday. That field had a mix of SBL and corn earworm/tobacco budworm.
The best way to preserve yield and avoid spending money unnecessarily is to scout peanut fields every week. This means walking or riding the field and stopping an average of 10 times per field to assess caterpillar populations. Vigorously shaking 3 feet of row at each location in the field to dislodge pests onto the ground or a beat sheet and counting the number of caterpillars will provide the information needed to make a timely and wise management decision. The following link is for a video that shows how to sample caterpillars in peanut: https://www.youtube.com/watch?v=WIVal7queaI&t=87s.
If you are a grower and you do not have a scout or consultant, it will be important to keep an eye on your fields over the next few weeks. VBC is a voracious feeder and can quickly defoliate a peanut field. Many of our fields got off to a slow start in 2023, and we do not need to prolong the season by letting VBC take all of the foliage during peak pod fill. The good news is that VBC is typically easy and cheap to kill (see the Georgia Pest Management Handbook for available options). Soybean looper, on the other hand, is neither cheap nor easy. SBL caterpillars tend to start feeding deep in the crop canopy where it is difficult to reach them with insecticides. As they grow they will move up to feed on leaves higher in the canopy. Many of the complaints I have received about control problems involving SBL over the years were due to inadequate coverage of the lower canopy. With that said, insecticide resistance is a real concern for almost all of the caterpillar species that occur in peanut. If you experience a control failure, please report it to your local UGA county Extension agent.
A final word of caution regarding the use of pyrethroid insecticides in peanut. There are a lot of two spotted spider mites in the South Georgia landscape right now. Conditions in many places have not been favorable for mite population development in peanut (i.e. hot and dry), but that could change in as little as a week if there is no rain. Because pyrethroid use increases the risk of mites in peanut, I urge growers to avoid this class of chemistry in non-irrigated fields.
If you have questions about caterpillar management or any other insect management concern in peanut, please contact your local UGA county Extension agent.