published Monday, October 21st, 2013

New Asian fruit fly poses threat to Tennessee crops

This undated photo provided by the University of Maine Cooperative Extension shows spotted-wing drosophila, which have invaded East Tennessee and is harming a variety of fruit crops.
This undated photo provided by the University of Maine Cooperative Extension shows spotted-wing drosophila, which have invaded East Tennessee and is harming a variety of fruit crops.
Photo by Associated Press /Chattanooga Times Free Press.

It's difficult to say, and even tougher to get rid of. It didn't even exist in the United States five years ago.

The "Drosophila suzukii," or spotted-wing drosophila, is looming as a new fruit fly threat to Eastern Tennessee's crops, particularly berries. The invasive pest with a serrated tail lays microscopic eggs in fruit, which hatch in as soon as 12 hours.

Within days, a healthy batch of fruit can become an infested, smelly mess.

"It's attacking a bunch of things out there, and we don't know the half of it," said Frank Hale, a University of Tennessee at Knoxville entomology professor who has studied the bug as his personal project.

He says scientists would be glad to help battle the bug -- if they knew more about it.

The fly is native to Japan, where it found a modest living on Asian produce. It immigrated to the United States in a batch of imported fruit that landed in California in 2008.

The pests quickly traveled east, reaching Florida within one year, and showed up in Tennessee in 2011, when an outbreak struck Unicoi County's blueberries. Warren County fell victim in 2012.

This year, the bugs have appeared in more than 10 East Tennessee counties including Coffee, Franklin, Grundy, Polk and Rhea. There's no signs that the drosophila's rapid spread is slowing, and the constantly reproducing flies are at their worst in the fall, Hale says.

"The pest has been damaging in Japan, sure, but over here, it's the land of plenty," Hale said. "We've got all this ripe and wild fruit. It's going to be a huge problem to anybody growing berries in Tennessee."

Fruit farming, Hale said, used to be a lot simpler: Berry-eating birds and occasional droughts were Tennessee's most threatening problems.

But now afflicted farmers are losing entire crops, and this summer's record-setting rainfall seems to be a key factor. Each new storm washed off the most recent pesticide spray.

And since Tennessee received more than 20 inches of rain over the state average this summer, according to the National Weather Service, farmers' lines of defense were dismantled early and often.

"We've had reports this summer of blackberry growers who have lost half their crop, even with spraying on a weekly basis," Hale said. "They actually lost all their crop at one point, but were able to grow some back on a second batch as rain became less frequent."

The consequences of the drosophila infestation can spread to more than just farmers: Eating the bugged fruit might make people sick. And with less high-quality fruit on shelves, consumers could expect to see higher produce prices. Even if quality isn't compromised, farmers are needing to buy new pesticides, which raises their overhead costs.

Wooden's Apple House in Bledsoe County got out of the tomato game this year for that very reason.

With peaches, cabbage, bell peppers -- and, of course, apples -- Wooden's has managed to thrive despite nearly 40 years of farm threats. When pesticides grew costly and profits withered, the homegrown juggernaut gave up on tomatoes altogether, especially as new rain washed their spraying efforts away.

"All it takes is one storm and you're done," said Lebron "Chubby" Smith, a fruit packer at Wooden's. "The expense and cost of growing them anymore is just a bad investment."

Hale said that the drosophila threat can be managed, but it takes a meticulous attitude. Farmers, whether backyard or big-field, need to apply pesticides every week, and especially after it rains. The effort needs to be maintained during Tennessee's mild winters, since the bug can continue to reproduce in 50-degree weather.

"This is a pest that works on so many things, we're just starting to learn what it can do," Hale said. "It's the biggest thing I've seen on small fruit in my career."

Contact staff writer Jeff LaFave at or 423-757-6592.

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