Mid-Season Arthropod Issues Peanut Notes No. 157 2020
Midsummer Pests are Getting Active
Entomology Extension Specialist
Insect and mite activity has begun to increase in the past week in peanuts. We are in the very early stages of seeing caterpillars or worms in a few fields. Not enough to spray, but a few of them are beginning to show up. Keep your eyes open.
We are also seeing some fields with the typical “V” shaped yellow area on the leaf tip that is characteristic of leafhoppers. This pest is one that we struggle to understand when to treat and if we should treat. Historically, when we treated a high percentage of our acreage with Lorsban, we knocked out the leafhoppers at the same time. It is easy to control with inexpensive pyrethroid insecticides, but if it’s hot and dry, we can cause spider mite outbreaks with these insecticides. While they are cheap, they can cost us more in the long run if we have to spray for mites. Other products are listed in our control recommendations that can control leafhopper but they are more expensive. My thoughts are that you have to see a lot of yellowing, more than 25% of the leaflets showing damage, and see an active population in the field (lots of small flying leafhoppers when you shake the vines) before you can justify a treatment.
Finally, we have seen rainfall that is not uniform throughout eastern North Carolina. This is typical and as a result we have some dry areas and we are seeing some aggressive populations of spider mites. Keep your eyes open for this pest. We have limited products available. Comite is the standard but in recent years it has become very difficult to find. Danitol does a good job but both of these products need to be applied twice about 3-5 days apart unless we get some cooler, rainy weather. Brigade is also labeled for spider mite control, but I only recommend its use late in the summer. It can reduce the populations at a very reasonable cost, but has a tendency to allow the mite population to bounce back if the weather stays hot. So I like to see this product only used late in the season.