Spider Mites After Tropical Storm Peanut Notes No. 167 2020

— Written By

Spider Mite Status in Peanuts
Rick Brandenburg
Entomology Extension Specialist

July was a very hot month and some insects such as leafhoppers showed up in higher numbers. I think most of those populations have declined, but some fields still have healthy populations. Due to the wide range of rain we saw in July, some fields are very dry and spider mites have begun to show up and some fields have really high populations and visible damage. We’ve all seen rainfall set a mite population back. However, a tropical storm or hurricane can REALLY knock the infestation off its feet and it’s just not the direct effect of the rain. Research conducted in North Carolina decades ago demonstrated that two consecutive days of cooler temperatures (below 87 F), cloudy conditions, and some rain over a 40 plus hour time period will almost always result in a rapid decline of spider mites. That’s what is happening right now. This is due to the rapid growth of a fungal pathogen that attacks mites under those cooler, wet conditions. Virtually the whole mite population can be wiped out.

Once the storm passes and things dry out a bit, don’t assume that field where mite damage was occurring is still a problem. Nature may have taken care of it for you.