Cherry growers take the bait
A new cherry fruit fly control has saved millions of dollars and reduced worker exposure to pesticides.
An insecticide-laced bait that is squirted on trees to control cherry fruit fly has saved growers an estimated $2.75 million over the past three years, Tim Smith, Washington State University Extension agent for north central Washington, reported during the annual Stone Fruit Day in Wenatchee.
The GF-120 bait, which is applied in small amounts from an all-terrain vehicle, has enabled growers to reduce their pesticide costs, as well as the amount of labor needed to apply pesticides.
“Squirting a little goo on your trees seems like an odd way to control a serious pest,” Smith acknowledged. “But it’s being used a lot now.”
It’s being used by organic and conventional growers alike and has proven a boon for cleaning up infested trees.
“This is one of the most exciting things I’ve ever been associated with,” Smith said. “There’s no doubt this product works under heavy pressure. It’s become the most-used insecticide on cherries in the state of Washington.”
Smith figures that the bait has resulted in a 70,000-pound reduction in use of organophosphate insecticides in Washington State, and a reduction of at least 8,000 hours of applicator exposure to organophosphates or carbamates.
“It’s easy to apply, and your workers tend to argue about who gets to put it on because they like driving the four-wheelers,” Smith said. “And there’s a lot of money to be saved.”
Guthion (azinphos-methyl) used to be the mainstay of an early-season cherry fruit fly control program, but the product is being phased out over the next five years, and many growers have already stopped using it, Smith said.
The list of materials used to target the pest has changed over the past few years. Methyl parathion is no longer registered; dimethoate is under the scrutiny of the U.S. Environmental Protection Agency, as is Sevin (carbaryl), a carbamate insecticide that is widely used in apple production as a thinner. Diazinon does not have a tolerance in some overseas cherry markets.
However, several new materials that have come onto the market are very effective fruit fly controls and don’t require cholinesterase testing of workers, Smith said. The neonicotinyl pesticides Assail (acetamiprid), Actara (thiomethoxam), and Calypso (thiacloprid) all work well when applied at 10-day intervals, but not when the interval is stretched to 14 days, his research shows. The spinosyn insecticides Success (which is the active ingredient in the GF-120 bait) and the organic version Entrust are also effective. Dow AgroSciences LLC will launch a related product called Delegate next year. The new product, which has a much longer residual effect, is designed as a replacement for Guthion in apples, but appears to be an effective fruit fly control, Smith said.
DuPont will launch a new product called Altacor (rynaxypyr) for control of codling moth in apples and pears. Smith said cherry growers should be able to use the product at half the codling moth rate for cherry fruit fly, making it more affordable. It’s an effective insecticide but very safe for humans.
Smith has also tested the insect growth regulator Rimon (novaluron) and had good results when he used it in with a bait as an attract-and-kill product.
Options for organic cherry production include the GF-120 bait, Entrust, Pyganic (pyrethrum) and Neem (azadirachtin). Smith said that in his trials Pyganic has suppressed cherry fruit fly but not controlled it. Most organic growers in the Pacific Northwest use the bait and are no longer having difficulty controlling the pest.
Smith urged growers using the bait to check for nearby infested trees that could be sources of infestation. A mature female can enter the orchard and might lay eggs before she finds the bait and eats it. “It’s not lethal the minute she flies into your orchard,” he stressed. “Find those trees, clean them up, and then get rid of them. Don’t cut them down without cleaning them up first.”
For postharvest control, Provado (imidacloprid) is an alternative to dimethoate.