Entomologists: Persistent drought can lead to spider mites in the Midwest

With drought taking over a lot of farm country, crop entomologists are warning of spider mites, particularly in the Midwest.

They thrive on stressed plants and typically take a liking to soybeans but experts say corn growers should also be on alert. The first sign of trouble is yellowing leaves, and as the damage gets worse, they begin to turn brown and necrotic.

The mites can be hard to spot, however, but a closer look should show webbing as they leave behind a coating on the leaves. Experts say there are not a lot of options for getting them out of the fields.

“Mites are not an insect. They’re an arachnid. One of the consequences of that is a lot of insecticides don’t do a very good job of controlling spider mites. We’ve got a relatively limited number of pesticides that we can use a few insecticides, in particular bifenthrin and dimethoate. Will have an effect on them. In both cases, you’re not going to have any effect on the eggs at all, and the materials don’t last very long, so it might take multiple applications with material like that to get good control. We also have dedicated miticides like agromet, and avermectin for instance. There’s a number of others as well. Those tend to be a little bit more expensive, but they will likely do a better job of control.”

Seiter warns against using a broad-spectrum insecticide because it could kill off any predators of the mites and do more harm than good.