Although it’s late in the season, alfalfa growers in Kansas will want to take a close look at their fields to determine if potato leafhoppers or aphids might still be present, says Jeff Whitworth, crop entomologist with Kansas State University Extension.

Whitworth took several calls from growers and consultants earlier this month reporting unusual insect activity and signs of plant damage, including yellowing and wilting. After surveying several fields in the south-central and north-central parts of the state, he concluded most of the problems were being caused by potato leafhoppers.

“The surprising thing about that is (the leafhoppers) were still feeding on the alfalfa. Normally, they come in between the second and third cuttings in the summer. Then, by late August or early September, they migrate out of the state.”

Whitworth was more concerned with the signs of aphid activity, also unusual for this time of year. Yet he stresses he’s not recommending treatment for either insect this fall. “If they’re potato leafhoppers, they’ll be going away soon. If it’s aphids, they won’t be causing any more problems once it gets fairly cold in a week or two.”

The important thing for growers to know? Aphids do overwinter in the state, and that could lead to problems early in spring. Beneficial insects usually do a good job of controlling aphids, but a mild winter could allow the aphids to build up more quickly than the beneficials, Whitworth notes. “There’s usually a time lag of two to four weeks.”

Growers make want to take early action next spring before the insects cause too much damage, the entomologist suggests.