WOOSTER, Ohio — The soybean aphid is not the only insect pest Ohio growers have to keep a close eye on this growing season.
The two-spotted spider mite, a sapsucker that can kill soybean plants if in high enough numbers and left untreated, may be a potential problem thanks to hot, dry weather in certain areas of the state.
"When it was so hot and dry I was concerned about the two-spotted spider mite. Now knowing that rain moved through the state and the forecast is for cooler temperatures, I'm more worried about the soybean aphid," said Ron Hammond, an Ohio State University research entomologist. "But we are telling growers that they have the potential for both of these problems, so they should keep watch on both of them and know which one is causing problems if a problem does occur."
The two-spotted spider mite is a pest that generally causes little problems for Ohio growers. It's most significant during hot, dry summers, especially late in the season. This year, however, it's making an early appearance.
"When the mite gets started this early, it tends to spread throughout the field, rather than just the field edges," said Hammond, with the Ohio Agricultural Research and Development Center. "Growers need to be checking their entire fields now and spraying if the mites are found in high enough populations."
Hammond suggests that growers use plants injured by the mites as a marker for determining how severe of an infestation they might have.
"The mites will feed on the underside of the leaves and cause a yellow speckling on the upper surface of the leaves," said Hammond. "If populations are heavy in a field, the whole plant will take on that speckled look."
Growers shouldn't wait until they notice a "bronze" appearance to their soybean plants before taking action, as the plant is beyond recovery once it reaches that stage of damage.