The alfalfa snout beetle is a root-feeding weevil that mimics winterkill and a host of other problems. That means it can easily hide in alfalfa fields for 10 to 20 years.
The rest of the bad news? At this point, it's impossible to eradicate.
The good news is that New York is the only state the pest has been introduced into, and then only in selected counties.
Yet it's infested an estimated 13% — 500,000 acres — of New York's cropland since 1995. And it has recently spread from eight to nine counties.
“It could be in every state around us; we just don't know,” cautions Elson Shields, Cornell University extension entomologist. “It's such a subtle thing. It causes tremendous stand loss, but there are so many things that cause alfalfa stand loss that unless somebody is aware of it, they miss it for years.”
Shields has battled the pest since 1988, but has been slowed by limited funding. Financial support from the Northern New York Ag Development Program, however, has allowed him and alfalfa breeder Don Viands to make progress.
The entomologist believes the snout beetle — whose larvae can severely damage alfalfa taproots while the adults do minimal damage feeding on leaves and stems — can be controlled using a two-pronged strategy.
“It will probably take a good effort in both biological control and resistant alfalfa to bring snout beetle under control,” he says.
In 2002, after 10 years of work, the researchers came up with a greenhouse screening method. Viands can now screen thousands of plants for genetic resistance to the pest.
“We have some interesting selections (of seedlings), so there is some promise,” Shields says. But snout beetle-resistant alfalfa is still a long way from being developed, he notes.
In 2000, in an effort to find a biological control, Shields and Gabor Neumann, a Hungarian graduate student, started researching why the snout beetle, which is native to Hungary, doesn't damage alfalfa there.
“We've done surveys for biological control there and imported a Hungarian strain of nematode, which seems to be the key factor. It's the same species that we've been working with here, but it's a strain from Hungary.”
Right now, rotation is growers' only tool to control the pest.
“Rotating crops keeps the population down,” Shields explains. “But snout beetle does well on Queen Anne's lace or wild carrot, which we have no shortage of in New York. It also does okay on dandelion, and there is no shortage of dandelions where alfalfa grows. You almost need to rotate on a three-year basis, and farmers cannot really do that economically.
“So farmers learn to grow grass,” Shields adds. “They learn to make milk on grass rather than on alfalfa.”
The insect spreads slowly, unless it is moved by human activity and transport. New infestations have have been found where beehives had been used to pollinate apples and other fruits, and when farm equipment and tiling equipment traveled in from infected areas. The pest doesn't fly and its population is almost entirely confined within the Lake Ontario and Lake Champlain drainage systems.
“When this insect comes to a stream or river, it balls up and floats, and all the water flows into the area already infested,” Shields says. “So we're not getting any water spread within New York.”
Hitching a ride on machinery is most likely the way the snout beetle will travel out of New York, he says. And it would only take one beetle to infest a field; all adults are female.
Cornell University scientist Janice Thies is taking a different approach. She's trying to develop a microbial control that farmers could apply to infested fields.
Shields doesn't believe farmers can afford to control snout beetle with a commercial product, even a one-time application.
“I believe that the solution is to re-establish classical biological control,” he says. “We need to find out why it's not a problem in Europe. We need to import the biological control and release it in New York.”