Staff Writer
PRESQUE ISLE – Officials with the University of Maine Cooperative Extension are warning area farmers that cutworms have been found feeding on potatoes in several fields in southern and central Aroostook and on canola in the central part of the county.
Contributed photo
Cutworms have been found feeding on potatoes in several fields in southern and central Aroostook and on canola in the central part of the county. Here, a cutworm cuts down a potato plant.
“It’s been about two weeks that we started seeing some minor activity,” said Jim Dwyer, crops specialist/extension professor. “About three weeks ago, we had some reports of some cutworm activity in the central Maine area, so we used that as an alert system for us. When we start seeing things there, usually within one to two weeks we’ll start seeing it up here. It gives us somewhat of an early warning system of what to be looking for.”
In addition to potatoes and canola, cutworms can affect soybean, corn and sunflowers.
“The cutworm is the larval form of a moth,” said Dwyer, “and typically what the grower will see is a branch that’s cut off or a plant that’s wilted down, and if you dig around the base of the plant, you’ll find a cutworm.
“At this point in time,” he said, “the cutworms are about a half-inch long and not quite the diameter of a pencil, but almost. When you pick them up, they’ll curl right up and form a C-shape. They vary a little bit, but they’re dark colored.”
The Cooperative Extension is dealing with two types of cutworms – the black cutworm, which is more nocturnal and tends to cut plants off, and the variegated cutworm, which is also known as the climbing cutworm.
“They tend to climb up a plant and cut leaves off,” said Dwyer. “They’re both nocturnal, and you’ll see a lot more activity at night.”
Damage usually will exhibit an “edge effect” initially as the insects move into a field. There are no established threshold levels for cutworms in potatoes. Growers finding cutworms will need to make a determination as to whether or not a treatment is warranted. Many times an edge or spot treatment may be sufficient for economical control in potatoes and other crops.
“Growers with crops such as corn, canola and soybeans should be actively scouting for cutworm damage at this time,” said Dwyer, noting that North Dakota State University is currently using the following recommendations for cutworm thresholds:
• Canola: an average of one cutworm/square foot.
• Corn: 3 to 6 percent of the plants cut off.
• Soybean: 1 or more larvae per 3 feet of linear row or 20 percent of the plants cut.
• Sunflower: an average of one cutworm/square foot.
Generally treatments are more effective if applied later in the day.
“There are several options that growers can use,” said Dwyer. “They can make the chemical applications themselves.”
Growers are urged to read and follow all label instructions when using any pesticide product.
Home gardens can also be affected by cutworms.
“What will happen is the adult moths get distributed on wind currents,” Dwyer said. “It varies from year to year as whether we’ll see very much cutworm activity or not; in this area, it’s probably been five or six years since we’ve seen very much activity.
“I think the cold, wet spring tends to precipitate it a little bit,” he said.
Since the Cooperative Extension tries to track pest patterns, Dwyer said he would encourage growers who find cutworms to call his office at 764-3361.
