First noticed in Michigan in 2007 and blamed for damage caused to winter wheat in Idaho in 2009, large numbers of the “gregarious” species were seen in the fall, an entomologist at Oregon State University reported. She urged golf course superintendents to scout for the worms in the spring, which “could be a big feeding time” for them.
Oregon State University (OSU) is warning that a relatively new pest, winter cutworms, could be poised to damage grass-seed crops, grains, golf courses and lawns, the Capital Press of Salem, Ore. reported.
The cutworm was noticed in large numbers in the fall, the Press reported. It moves in packs and can quickly damage crops, lawns or turf by “mowing, clipping and cutting off” plants at ground level, Amy Dreves, an OSU assistant professor and research and Extension entomologist, told the Press.
The cutworm is “gregarious,” meaning hundreds of worms can be found together, eating their way across fields, the Press reported.
“The question of the day is what to expect in the spring,” Dreves said. “Spring could be a big feeding time.”
Dreves urged growers, golf course superintendents and homeowners to scout for cutworms in March and April, the Press reported.
An integrated pest management approach might be the best way to handle them, OSU recommended in a bulletin issued in February.
“Reduced risk” insecticides should be used rather than broad-spectrum products, OSU said, and rotating among products reduces the chance that winter cutworms will develop resistance to the insecticides, the Press reported.
Growers also should consider rotating crops and removing weeds and plant residue along the edges of fields, to reduce egg-laying and feeding sites, according to OSU.
A light tilling exposes overwintering pupae and larvae to birds and other predators, Dreves said. Other types of cutworms are somewhat controlled by parasitic wasps, flies, nematodes and bacterial and viral diseases in addition to general predators, and that may help against winter cutworms, according to OSU.
Winter cutworms are a Eurasian pest and may have hitchhiked to North America with plant shipments or other trade items, the Press reported. They were first blamed for U.S. damage in 2007, when large numbers were found in hayfields and around homes in Michigan.
They then were blamed for damaging winter wheat in Idaho in 2009. The first damage reported in Oregon was to grass-seed fields, golf course greens and lawns last fall.
Winter cutworms are up to 2 inches long and can be identified by black dashes down their sides, with a light-colored underline, the Press reported. The pupae are reddish-brown; the moth that emerges is called the large yellow underwing moth.
The moth is a strong migratory flier, capable of traveling 80 miles in a year, Dreves said. While the moths have been present in Oregon for at least a decade, they were primarily considered a nuisance until the damage caused by crawling larvae last fall. Mild winters may have contributed to their increased numbers, the Press reported.