MONTPELIER -- Northeast berry growers are learning ways to combat an invasive fruit fly that wiped out 80 percent of some farms' late-season fruit two years ago, forcing some small growers out of business.
The tiny spotted wing drosophila arrived in the U.S. from Asia in 2008 and turned up in the Northeast two years later.
The pest tends to make its way to New England in mid-August and lays its eggs in blueberries and raspberries. The population is expected to build until late September.
"We've seen noticeable impacts since 2012," said Adam Hausmann of Adam's Berry Farm in Charlotte. "It's definitely a game changer for late-season soft-bodied fruit."
Many farms are harvesting the berries as soon as they ripen or even before and refrigerating them to prevent damage. Other growers are spraying fruit with an organic or conventional insecticide. Some organic growers have switched from fall raspberries to spring raspberries and are placing nets over the plants.
Adam's Berry Farm has moved its fall raspberries into hoop houses covered with fine insect netting. It lost about 60 percent of its fall raspberries and late-season blueberries in 2012 and 2013.
Hausmann decided against using insecticide.
"For us as a farm, and managing the farm and the pest, we didn't feel comfortable with that, so we decided to go with covering them," Hausmann said. "This will be the first year that we've done it so I'm curious to see the impact."
The farm also planted more summer raspberries and sold a couple hundred mature late-season blueberry plants.
Two farms in eastern New York tried netting, insect trapping and weed mats as part of a research project. The project found success in netting smaller plants, especially for organic growers, said Laura McDermott, Cornell Cooperative Extension Fruit and Berry Specialist with the Eastern New York Commercial Horticulture Program.
Vern Grubinger, a vegetable and berry specialist for the University of Vermont Extension, said it's also crucial to pick the berries as soon as they're ripe and to refrigerate them to stop the decay.
"Those two things alone are really helpful, especially for small-scale producers," Grubinger said.
Still, growers like Walker Farm in Dummerston, Vermont, picked their ripe fruit and placed it into refrigeration and still lost about 10 to 20 percent of its berries last year.
Bigger growers, including those in Maine, the country's largest producer of wild blueberries, are spraying and harvesting sooner and planting earlier varieties.
"You take a loss, but the loss is on green berries rather than having to put more pesticides out there," said Jim Dill, pest management specialist at the University of Maine Extension.