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IPM, Cornell on front lines of armyworm invasion

By HEATHER SWANSON | Published here with permission of the Finger Lakes Times

GENEVA — An ill wind has blown an unwelcome infestation of pests into the Finger Lakes.

A widespread infestation of true armyworms has blanketed New York state, with known cases throughout the region.

The insects make sporadic appearances in the area. The last infestation was a few years ago, but none as severe as this, said Mike Stanyard, an entomologist and Cornell Cooperative Extension's Western New York area field crops specialist.

"We have never seen something this widespread across the state," he said, noting he has received dozens of calls from concerned farmers and spent hours in the field assessing the situation.

The true armyworm is, in fact, a caterpillar, explained Keith Waldron, field crop Integrated Pest Management coordinator at the Geneva IPM. Waldron said the name is something of a misnomer, although the pests do move in unison, much like an army.

While the caterpillars will soon become moths, in the interim they consume field crops, grass and other plants.

Because the insects do not winter here, Stanyard believes the moths traveled north by way of a storm front, possibly arriving with the flux of Red Admiral butterflies that passed through the region in early May. While the colorful butterflies created a stir, the moths are nocturnal and likely went unnoticed, Stanyard explained.

The early spring is also to blame, he said, saying the moths were able to build up in the south earlier than they typically would.

The crops and plants at most risk include grass or mostly grass hayfields and pastures; corn fields that were late planted into grass fields; no-till or reduced tillage fields; corn planted into small grain (especially rye grass) cover crops; and corn fields with grassy weed pressure. Small grains like wheat and oats are at risk, too, as are golf courses and lawns. The armyworms will eat bean, cabbage, carrot, onion, pea, pepper and radish leaves as well.

Cornfields should be monitored most closely now, Stanyard said. He added that hay yet to be harvested has largely been ruined, and wheat is nearing maturity.

"Walk the edge of your cornfield," he advised.

Waldron encouraged people to look for the pest in the early morning and evening — that's when they're most active.

True armyworm larvae appear smooth, cylindrical and pale green to brownish in color when they are small. Mature larvae are smooth and marked with two orange, white-bordered stripes on each side.

Larvae range in size from an eighth of an inch when they first hatch to 1 1/2 inches long at the end of three weeks. Their appetite increases with their size.

In addition to looking for the insects, farmers should be wary of the damage they cause, Waldron said.

"I'd be looking for signs of feeding on the grass," he advised. "I'd be looking on the ground underneath some of the litter and debris that might be on the ground."

"It looks like the yard is moving," said Carol Harris, who lives on a Yellow Tavern Road farm in Fayette with her husband, Allen.

The armyworms targeted the Harris' fields first, then moved into the yard.

"It looks like it's liquid — that's how many of them there are," Carol Harris said.

"When they move into a lawn they really can decimate it," added Jennifer Grant, co-director of the Geneva IPM and Community IPM coordinator. "The weeds are left standing."

Measures homeowners can take to control the pests on lawns are not the same as the steps farmers can take in fields, Grant cautioned. Pesticides must be specifically designed for lawn use. Additionally, those a homeowner can apply differ from those a professional can.

"This is a situation where I think it's a good idea to hire a professional," she said.

Should homeowners choose not to apply pesticides, Grant said the grass will return but has to be watered to prevent sun damage that could kill it.

"In most cases, I expect it to come back eventually," she said, adding that applying additional grass seed later in the season may be necessary for some.

Mark Lott, a Seneca Falls farmer, has found armyworms on his County House Road property and has been assisting other farmers in the area in spraying for the pests.

"If you don't treat it, it can wipe the crop out," he said.

Lott said heavy infestations can often be spotted right away.

"You stand back in some wheat crops and you'll see them without even bending over to look for them," he said.

Hoards of the insects will cross roads to reach neighboring fields.

Though the armyworm would typically trouble farmers for only about three weeks before transforming into moths, that appears unlikely this time, Stanyard said. The reason: Small, three-quarters-of-an-inch armyworms are in the fields with half-inch armyworms, indicating staggered hatching times.

"This is going to go on the rest of the month," Stanyard predicted.

Natural parasites and pathogens may prove a saving grace, though. The armyworms are typically targeted by a parasitic fly that kills them, as well as a viral infection that could wipe them out.

"Those do have a tendency to come to our assistance," Waldron agreed.

Signs of the fly have yet to appear, but Stanyard believes the pathogen may have arrived. Samples were sent to Cornell University for confirmation. It is also possible a second generation of the armyworm will make an appearance sometime in July. Although second generations are typically not problematic, Stanyard believes that may not be the case this time because of the extent of the current infestation.

    — Heather Swanson