Crop-damaging fly on the prowl
Researchers at Oregon State University are predicting record levels of the invasive pest, which wreaks havoc on blueberries, raspberries, blackberries, strawberries, cherries, peaches, prunes and other popular fruits. “The climate is absolutely perfect in many ways, at this stage,” said horticultural entomologist Vaughn Walton.
Numbers swelled last year throughout the Willamette Valley, and a mild winter ensures an unusually high survival rate, Walton said. Adding to the threat, “Now, we’re going into this abnormally warm spring period,” he said.
He said, “It doesn’t necessarily mean growers will lose money for their crops.” But he said it suggests they will have to spend more to maintain control.
“Everybody is on alert,” said Extension Service horticulturist Jeff Olsen. “It’s an invasive pest. It’s an issue throughout the Willamette Valley, and Yamhill County is part of that.
“They’re in the orchard areas. Cherries are the most affected.”
What makes this fly different from others, Olsen said, is a serrated oviposit allowing females to saw into fruit to lay their eggs. It doesn’t require soft, overripe fruit in order to give its eggs a ready-made food supply, he said.
Walton said, “This bug is everywhere where small and stone fruits are being produced.” But he said it has not been an issue with wine grapes, and isn’t expected to become one.
The fly is native to southeast Asia. Its lifespan can be anywhere from a few weeks to ten months, with a female laying as many as 300 eggs during its life. Its American invasion was recorded in California in 2008.
“At this stage, the only option we have is pesticide applications,” Walton said. But he said, “We are working on alternative methods of control.”
He said control sprays have to be applied pre-harvest. For more detail, visit http://horticulture.oregonstate.edu/group/spotted-wing-drosophila.