Warm — in some cases downright hot — late winter and early spring weather has brought a wave of new insect pests marching into the North Country.
”Because they feed at night, armyworms may inflict much injury before they are detected,” warned New York State Agriculture Commission Darrel Aubertine. “Having exhaused a current food supply, the worms migrate as an ‘army’ to new host plants. Fields adjacent to or harboring lush grass are most commonly attacked.”
This was an unwelcome surprise for dairy farmer James Normandin of Star Road in Ellenburg Center, who last week had just burned a pile of 40 to 50 pounds of worms that had accumulated on top of his hay mower. “They were five inches thick on top of the discbine,” he said.
All told, he lost probably 9,000 to 10,000 square bales of hay.
”I’ve been pretty stressed the past few days,” he said. “In about 72 to 86 hours, they had already chewed up 50 acres,” Normandin said, adding that it’s a problem he’s never had before in his 26 years of farming, although he’s had a neighbor who had an outbreak 10 or 12 years ago.
”You can hear them chew, like borers in a log,” he said. “One day they weren’t there, and the next day they were.”
It was the last of his hay that he uses for heifer feed, and now it’s going to have to go for bedding and fertilizer.
”You keep your fingers crossed they don’t eat the second cut, too,” he said.
Armyworms primarly attack hay, stripping the leaves from the stalk. While they don’t like alfalfa or clover, they can attack corn, too, especially if it is adjacent to infested hay fields.
So far, that hasn’t happened on Normandin’s farm. The insects don’t like dirt, heat or direct sunlight, so a well-tilled cornfield is more protected. No-til corn can be susceptible, though. A large flock of a birds in a hay field is not a good sign, indicating the pests may be present.
The solution, said Normandin, who’d been up all night running his equipment bringing in hay, is to take the food source away. “Cut everything you can as fast as you can cut it,” he said.
In the time it would take to spray, he said, the crop would be gone.
Insects can blow in from the south as egg-laying moths or in other forms during unusual weather conditions, like Tropical Storm Irene or during the 80-degree heat wave in March.
Paul Peterson, Northern New York regional field crop specialist with Cornell Cooperative Extension, said armyworms have created quite a stir, but they’re not the only new invader.
”It’s been the buzz, but there’a a new pest that’s around,” he said.
This has been the potato leafhopper, which is not a threat to corn or hay, but zeros in on forage leaf crops. “Alfalfa is one of its favorite hosts,” he said.
As the name implies, the pest can affect potatoes, too. Peterson has seen it all across the four Northern New York counties he serves.
While the armyworms have been spotty, they have hit pretty hard in the areas they’ve affected, such as the Normandin farm.
”The armyworm arrives as a moth from the south,” Peterson said, explaining that it can be blown in during hot spells on a stiff southerly breeze. “They like thick grass areas.”
The migrating moths lay eggs resulting in the worm infestation.
“The actual pest is the larval stage or the caterpillar,” he said of the one-and-one-half to two-inch long worms.
They live for about a week and munch, potentially doing tremendous damage, before pupating and going into a dormant phase.
”They can really sneak up on a person,” Peterson said. “You can wipe out a field overnight.”
Peterson said he believes this particular type of armyworm, the true armyworm, is a variety that likely will not go through a second damaging cycle later in the season, although it can happen in some instances.
”The second generation isn’t as successful up here,” Peterson said.
Fortunately, he said, armyworms seem to be coming to the end of being an issue, at least for now. Whether they will become a more common problem in the North Country due to possible climate changes has yet to be seen.
”It’s definitely associated with the weather we’ve had this spring,” he said. “Whether that’s related to a long-term change, I don’t know.”
Not letting hay go too long before cutting and cutting it fast are the best defenses.
”By all means, get that cut in as soon as possible,” Peterson said.
As far as the potato leafhopper, the damage is different and harder to spot.
”It also does blow up from the south, but it hangs around a little longer,” he said.
The adults are winged bugs, comparable to the moth stage of the armyworm. The young versions aren’t caterpillars, but nymphs, too small to see, but both phases can do harm.
“The damage appears as yellowing of leaves and a stunting of the plant,” Peterson said, explaining that the pests suck sap from the host and feed on the underside of leaves, emiting a toxin.
The symptoms can be mistaken for drought stress.
“I would wager this is more common than the armyworm,” Peterson said.
The W.H. Miner Agricultural Research Institute in Chazy is providing information about genetic experiments with resistant alfalfa plants, and resistant seed is available for future plantings, a better alternative to chemicals.
“Insecticides are a great tool, but they’re such a broad spectrum you can take out what you don’t want,” Peterson said.
While infestations may be the worst in St. Lawrence County, the pest is very widespread in Cliinton and Franklin counties as well.
“When the damage becomes visible, it’s really too late to do anything for this harvest,” Peterson said.
Clipping it down or grazing it and monitoring the new growth may work about 50 percent of the time. The second growth may have to be sprayed.
Sweep nets can be used to confirm an infestation and the number of insects found can determine if it meets the economic threshold to spray.
“The main issue would be to get out in the fields and look and see if you’ve got damage occurring,” Peterson said. “It just kind of take diligence.”
He said there can also be stress in the alfalfa stands due to the unseasonably warm and unpredictable winter with temperatures jumping up and down.
“It can confuse the plant,” he said.
According to Commissioner Aubertine, armyworms have severely impacted Western New York counties as well, including the Finger Lakes.
The state’s last significant infestation was in 2008 and prior to that 2001.
“By some accounts, this year’s infestation is surpassing those experiences,” he said in a news release.
For more information, visit the CCE Northern New York website at www.ccenny.com.