Heads Up for Spider Mites in Soybeans

June 25, 1999

· Spider mite problems are showing up in soybeans in Ohio.

· Watch for spider mites building up at the edges of soybean fields.

No, we haven't received any reports of twospotted spider mites showing up in soybeans, but I thought you might want to know what's happening in at least one nearby state. Ron Hammond, research entomologist at Ohio State University, contacted me on June 21 to find out if we were experiencing dry weather and spider mite problems associated with droughty conditions. I told him that we had had plenty of moisture in most areas of Illinois and had not heard anybody talking about spider mites. Ron informed me that much of Ohio is dry and that spider mites are showing up in isolated areas of soybean fields throughout the state. He indicated that this early incidence of spider mites in soybeans was reminiscent of occurrences in 1988.

Most of us will not soon forget the devastation caused by twospotted spider mites in 1988. Although I am not suggesting that anything like 1988 will happen again in Illinois in 1999, I do want to make you aware of developments to the east so that you can be vigilant. If rainfall ceases, spider mite populations can build rapidly, especially if the weather gets hot. As you scout soybeans for other pests and problems, always give a look to the plants near the edges of the fields. If spider mite densities begin to increase, you should notice them first at the field edges. Look for yellowing plants that appear sandblasted, and then look for the mites and webbing on the undersides of the leaves. If you think you have found some spider mites, let us know right away; we would want to get the word out quickly.--Kevin Steffey

Author: Kevin Steffey