MARIANNA, Fla. — Over the past week reports have been surfacing across Georgia and in the Florida Panhandle of increased populations of caterpillars. Scout your soybean and peanut fields! This message is focusing largely potential peanut pitfalls and options. The caterpillar threshold in peanut is 4-8 caterpillars per row foot, and the number used for threshold varies by field based on growth stage, stress, and how quickly they are growing. Lapped rows are generally on the higher end of that threshold, especially irrigated fields. Dryland fields under heat stress may use a lower number, 5-6 depending on how fast they are growing and the expected weather. Several caterpillar species may be present, and certain chemistries are more effective on specific species. If you notice higher levels or have sprayed and still see caterpillars contact the extension office regarding species identification and control options! DO NOT spray a pyrethroid in your dryland field and risk flaring spider mites, they are extremely expensive and hard to control.
Velvetbean caterpillars are one of the most severe when it comes to rapid defoliation, Dimilin works well at controlling this species and if you have been adding it to your fungicide sprays you may be in good shape. For irrigated fields where spider mites may not be such a high risk, pyrethroids (Asana, Mustang, Warrior, etc.) are cheap and effective or premix products that include pyrethroids (such as Besiege). Dryland fields are more at risk of spider mite issues and pyrethroids should be avoided. Vantacor would be a good dryland non-pyrethroid option for a faster kill, Dimilin, or Diamond are good options as well, but insect growth regulators tend to have a slower kill and if defoliation is a problem you may want to use something that works faster. Generally, soybean loopers can be harder to control and require more than say Dimilin, but they generally do not defoliate fields as quickly as velvetbean caterpillars. Armyworms may be present, and with corn harvest well underway, corn earworms will be picking up too. Lesser cornstalk borer’s like hot and dry weather (similar to spider mites), keep an eye out. Lesser’s can be treated effectively with products such as Diamond or Vantacor. Keep in mind that your spray will likely not kill ALL caterpillars in the field, the goal is to keep your field under damaging levels (that caterpillar threshold). Call the extension office for questions on insect identification or product recommendations.
Dr. Mark Abney’s UGA Peanut Blog can be found here- https://site.extension.uga.edu/peanutent/2023/08/check-fields-for-velvetbean-caterpillars-today/
Dr. Scott Monfort has a cool “All About the Pod” podcast here- https://podcasters.spotify.com/pod/show/allaboutthepod
–Ethan Carter, UF/IFAS
