It’s the apple growers’ latest weapon against the intrepid coddling moth, their greatest enemy.
By confusing the male moths with a synthetic female sex hormone, growers can drive the gray-winged little menaces to distraction. Fewer moths mate and no larvae are born to spoil the apples.
It’s called “mating disruption” and it seems to work.
“There’s no doubt,” said Grant Daniels, an East Wenatchee orchardist in his sixth year of using the technique to control the coddling moths in his orchard.
“I don’t know if I’m really saving money,” he said. “But after I started using mating disruption, I’ve had less problems because of insects.”
By tying wires coated with the synthetic sex hormone in their trees, orchardists cut back on pesticide applications and at the same time combat the most destructive apple and pear pest in the world.
“The coddling moth is public enemy number one for orchards,” said Ted Alway, a pest management consultant with Washington State University. “It does great here.”
An immigrant from Central Asia, the half-inch long coppery-gray insect lays its larva on ripening apples. As the larva matures, it burrows into the fruit to eat the seeds. They’re the worms apple eaters fear finding.
Conventional control of the moths involves at least three pesticide applications each season. Unfortunately the chemicals also kill good insects, like ladybugs, that prey on other orchard pests.
At the same time, the moths develop immunities to the pesticides, reducing control effectiveness.
With mating disruption, the male moth is confused by synthetic pheromones a thousand times stronger than the female’s and he can’t find his way to a mate.
Overwhelmed, the male moth gives up. Fewer eggs are fertilized and the number of wormy apples decreases.
Recognizing its success, Washington growers are picking up the pace with mating disruption. “We’ve got these in 25,000 to 30,000 acres,” Alway said.
In some areas, neighboring orchardists collaborate to use mating disruption techniques to cut the moth populations. They install between 120 and 400 dispensers per acre.
Daniel spends up to $95 an acre to use mating disruption. It enables him to cut back on pesticide use.
“In the old days I would spray every 21 days,” he said. “This year, on 70 acres, I used exactly enough spray to cover two acres of orchard only once.”
This bodes well with environmental groups who encourage growers to cut back on chemical applications, Alway said.
Though it doesn’t eliminate the coddling moths, it does dampen their passion and diminishes their return, he said. “There’s no one silver bullet. Still, the main industry likes it and the environmental groups like it. It’s a win-win type of thing.”