We currently have a diverse mix of foliage feeding caterpillars in GA peanut fields. Right now, the heliothines (tobacco budworm and corn earworm) are most common, but beet armyworm, fall armyworm, soybean looper, cutworms, and even some velvet bean caterpillars have been reported. Several species are commonly found in the same field. Fields where granular chlorpyrifos (e.g. Lorsban 15G) was applied should be monitored closely for foliage feeders.
Thresholds for foliage feeders remain 4 to 8 caterpillars per row foot. It seems a lot of folks start to get nervous when we get close to 4 larvae per foot. Peanut can tolerate a significant amount of defoliation with no impact on yield, but when we start to see ragged leaves, it becomes difficult to hold back. We do not want to be spraying peanuts just because everyone else is if there are only one or two larvae per foot of row.
Caterpillars feeding on blooms. Bloom feeding has been observed in peanut for a number of years, and current thresholds do not take this type of damage into account. Peanut produces a lot of blooms, and not all of them will result in harvestable pods even in perfect conditions. The impact of caterpillar feeding on blooms is not known. I think it is reasonable to be more aggressive in making treatment decisions when significant bloom feeding is observed. What is “significant bloom feeding”? That is a question that will have to be answered on a case by case basis taking into account the condition of the field, number of caterpillars, maturity of the crop, and personal experience.
Fortunately we have some very good options for caterpillar control that will not completely eliminate beneficial insects.