Growers battle stinkbug
Mid-Atlantic growers reacted aggressively this year after huge losses in 2010.
Eastern peach growers report having greater success in controlling the brown marmorated stinkbug this year than they did in 2010.
Rice Fruit Company installed new defect sorting equipment in its apple packing operation earlier this year—making a sizable investment in anticipation of another onslaught from brown marmorated stinkbug.
“We’re hoping it’s unnecessary,” said John Rice, vice president of sales and marketing for the company. “We don’t know yet. It’s late August, and the worst damage last year occurred late in the season.”
Located in Gardners, Pennsylvania, just slightly north of the core stinkbug infestation, Rice Fruit got a rude wakeup call last fall.
“We quite honestly were not anticipating the kind of damage we saw,” Rice said. “We were surprised by how much damage there was in the fruit our growers put into storage. We could see how prominent the stinkbug became the last few weeks of the season. Our windows here at the packing plant were covered with the bugs, and we knew the situation growers were facing.”
Mark Seetin, the director of regulatory and industry affairs for the U.S. Apple Association, pegged damage to the 2010 apple crop in the Mid-Atlantic states at $37 million after a survey of storages last winter.
“The worse damage was to the south of us,” Rice said. “There, some growers had 70 to 80 percent of their fruit damaged—and whole lots went straight to juice. Other growers had less injury. Overall, 10 to 15 percent of our apples were damaged.”
Seetin estimated apple losses in the region at 18 percent of the crop—ranging from 5 to 10 percent to almost 100 percent in some orchards. Like Rice, he said the bug exploded in 2010, after some years of a slow buildup and reports of scattered damage in 2009.
Stinkbug damage on apples shows up as visible, darkened depressions in the skin underlain with corky tissue that can penetrate deep into the apple. This made damaged apples unsuitable for processing into slices and sauce, Rice said. Luckily, the market for juice apples last year was better than it had been in some time.
The new sorting equipment can detect those damage spots, making it possible to salvage good apples from damaged lots. Last year, sorting was done by hand.
A wet May this year resulted in more apple scab lesions than usual, Rice said, so the equipment will be a good investment, whether or not the stinkbug does damage.
Several things contribute to the nerve-wracking situation this year. According to Pennsylvania State University entomologists Dr. Larry Hull and Dr. Greg Krawczyk, fresh injuries from stinkbug feeding are initially almost undetectable, but become apparent after a few days. Since they feed under the skin of the fruit, it is only after the affected cells start drying that the symptoms of their feeding (corking) become visible. If feeding occurs just before harvest, the symptoms might not be apparent until after the fruit is in storage.
A second concern is the lack of an effective and standardized monitoring tool, according to entomologist Dr. Chris Bergh at Virginia Polytechnic Institute and State University. Growers and researchers have used various kinds of traps, but the number of captures hasn’t been translated into damage estimates or action thresholds. This year, growers reacted by aggressively spraying when the bug was first detected. Researchers are looking for effective pheromone lures and studying the reaction of the bugs to various intensities and wavelengths of light.
A third concern going into this season was the lack of field testing on insecticides. Growers entered the season armed with insecticides tested only in laboratory bioassays. “None had been systematically tested,” Bergh said. It also wasn’t known how long a residual effect insecticides might have.
Growers reacted by increasing the frequency of sprays and depended on contact to kill the bugs, which was probably the best approach, Bergh said. “In our preliminary studies, we didn’t find insecticides with good residual activity.”
Bergh thought growers had achieved better levels of control this year. “For many, however, it inflated their insecticide costs 25 to 30 percent and more. Is that a sustainable cost? That’s a good question. But it gave them some confidence that the bug can be controlled.”
Another concern was preharvest interval. The clearance of dinotefuran early in 2010 gave growers a tool they could use up to three days before harvest. Under the Section 18 emergency registration, it can be used only twice in a season and only until October 15.
Most insecticides with significant activity against the stinkbug have at least a seven-day preharvest interval.
Sources of optimism
One source of optimism was the early success growers had controlling the bug in peaches. “We’re not seeing the kind of damage we got last year,” said Jerry Frecon, the Rutgers University agriculture agent in New Jersey.
“This year, so far, it’s better,” added Rutgers entomologist Dean Polk. Last year, he said, every peach grower had damage, in some cases more than 50 percent and up to 90 percent damage.
“This year, it looks like we have about 5 percent damage—after spending a lot of money,” he said. In a normal IPM spray program, he said, growers would use an alternate-row-middle spray program for diseases and insects, spraying every ten days and skipping every other insecticide application once the oriental fruit moth season was over.
This year, they used the alternate-row-middle program with a five- to seven-day interval and used insecticide every time—harder insecticides like endosulfan, lannate, and pyrethroids. Only endosulfan seemed to have any residual activity, he said, and the registration for that material—and its entire insecticide class—will end midseason next year.
Bob Black at Catoctin Mountain in Maryland said some growers used border sprays effectively. They could use a nonlabeled insecticide like orthene on fence rows and woodlots bordering orchards.
Black’s orchards were among the hardest hit last year. “We’re doing okay this year,” he said. “We were very aggressive in our spring program on peaches. While we spent quite a few more dollars, we’re keeping them in check.
“I’ve been living on the sprayer. I spray every night and sometimes in the morning, and we’re going against what we’ve been doing in the past. All this spraying is not the answer. Pyrethroids used to be a no-no in our IPM program, and we’re using them now. Imidan was a standard insecticide, and it doesn’t do anything to stinkbugs.
“On the positive side, I still see green lacewings in the orchards, so we’re not killing all our predators.”
Tracy Leskey, U.S. Department of Agriculture entomologist at the Appalachian Fruit Research Station in Kearneysville, West Virginia, who heads the nationwide team effort aimed at developing controls for brown marmorated stinkbug, said that growers were happier this year that they had fruit to sell—using a fairly aggressive insecticide management program that is 25 to 35 percent more expensive.
She expects the team will have much more to say this winter at the horticulture meetings.
“This last year has been our first full year experiencing this insect,” she said. We have learned a lot. By this winter, we should have a program growers can use in 2012.”