New, cold weather-tolerant pest invades county

by Peter Jakey– Managing Editor

If Presque Isle County producers haven?t had enough on their minds this year with alfalfa weevil last spring and no rain during most of the summer, now a new pest has arrived in northern Michigan, bringing with it a host of problems and questions. Winter cutworms have been found in large numbers this fall in central and northern Michigan, including Presque Isle County, where early reports have the large caterpillar-like creatures in front yards and fields in areas south of Rogers City. MSU Extension agents reported thousands of the pests around homes and in hay fields in the region. ?We started hearing about it three weeks ago,? said Ben Bartlett, Cheboygan County MSU Extension agent, who has been serving as Presque Isle County?s interim director.

?IT?S NOT an exotic or a new species, but it is something we haven?t seen before,? said Bartlett. Winter cutworms have been confirmed near the Cliff Wilk farm near 634 Highway and South Rogers Road and in the front yard of Carrie Thornton?s home on Swan River Road. She found 10 to 15 of them in a three-by-three area under some leaves. ?You?ll drive by every day and (the winter wheat field) looks fine, and then one day you drive by and it?s gone,? said Bartlett, ?Literally gone.? ?Or it?s half gone, and you drive out there and look at it, and part of it is brown, and part of it is green, and there is this whole line of worms eating their way across the field.?

The host range is wide and includes beets, cabbage, carrots, grape, grasses, lettuce, potato, strawberry, and tomato, as well as numerous ornamental plants and weeds. In Michigan, feeding was reported on alfalfa and grass hay, Swiss chard, squash, and sugar beets.

?IT IS A worm that is active in cold weather, which is unusual,? said Bartlett. They have been reported to emerge in the winter and will crawl across snow to feed. They are closely related to other cutworm species found in agricultural fields, feeding at the base of plants and sometimes moving up onto foliage. In large numbers, caterpillars move across fields and roads, similar to the armyworm. The impact of caterpillar feeding in the fall likely depends on local weather conditions after defoliation. If mild temperatures continue, the alfalfa may regrow, depleting root reserves and reducing spring regrowth and yield. If temperatures turn cold and alfalfa does not re-grow, there is little stubble to trap snow, increasing the chance for winter injury. Feeding is of even greater concern in new seedings than in established stands.

OF MAJOR concern are the farmers who already have contracted for wheat, according to

area producer Mike Tulgestke. ?Come next spring, if they don?t have that wheat that they were relying on, they may have to buy that contract out, or fill it somehow,? said Tulgestke. ?It could be a sad state of affairs.? There are no thresholds for winter cutworm in hay fields, but MSU officials suggest following guidelines for armyworm management (four to six per square foot). MSU Extension advises producers to check labels, because insecticide choices differ depending on if the stand is primarily alfalfa or a legume/grass mixture. Bartlett has emailed an MSU specialist to get some answers for mounting questions.

?We want to know what it is going to look like in the spring.? The extensive defoliation of hay is one of the first confirmed reports of economic damage attributed to the insect in the U.S.