An areawide effort to control codling moth without organophosphate chemicals has resulted in better control of both codling moth and pear psylla as well as lower pesticide costs for a group of pear growers in Hood River, Oregon.
Many of them are no longer applying pesticides for either pest during the growing season. The project was launched in 2007 with a U.S. Environmental Protection Agency grant and has been managed by the Columbia Gorge Fruit Growers Association working with Oregon State University faculty.
It started out with 11 growers on more than 600 acres in the Dee Flat area of Hood River. Two years later, another 13 growers with 650 acres of pears in nearby Odell joined the project.
Growers are expected to apply a full label rate of pheromone dispensers on all their apples and pears, and to use alternatives to azinphos-methyl or phosmet if supplemental sprays are needed. Treatment decisions are based on codling moth monitoring using one trap for each three to five acres—a higher number of traps than previously used.
Growers have been meeting with pest control advisors, OSU faculty, and Columbia Gorge Fruit Growers Association staff to review monitoring results and population trends, and to learn about the biology of the pest and the treatment options. They also meet after harvest to review the results.
Previously, many of the growers had used mating disruption and softer pesticides for codling moth control, but the pheromone dispensers had often been applied at lower than recommended rates and applied in a piecemeal manner, said Dr. Steve Castagnoli, OSU extension agent in Hood River. While this addressed concerns about the environmental and human risks of pesticides, growers had varying levels of success in managing codling moth.
Barriers to long-term adoption of alternative codling moth management strategies include the high cost of pheromone dispensers, which is about $120 per acre, and the perception that more fruit will be damaged, Castagnoli said. The EPA Strategic Agricultural Initiative grant, which was designed to help growers transition away from pest management programs relying on organophosphates, provided a subsidy to growers of about $30 per acre for the first three years. Grant funds were also used to pay wages and mileage for a field technician who checked the codling moth traps weekly and evaluated fruit for damage after harvest.
Erick Von Lubken, a grower at Dee Flat, said codling moth was a serious concern before the project began, and some growers were applying as many as four cover sprays. Now they’re applying none. Sprays are used for pear psylla at the dormant through bloom stage, but no summer sprays are needed because the absence of organophosphate cover sprays allows natural enemies to control psylla.
Grower Steve Hunt, who joined the project in 2007, had been using pheromones on his 50 acres of pears since 2000, but it was not effective because of the small area treated. Mated moths are able to move in from neighboring blocks. The areawide approach is the key to making it work, he said.
“If you start hanging pheromones in enough acres, it works. We’ve known that all along. If you do it in isolated blocks of 15 acres, it’s tough to eliminate the border effects.”
Once his neighbors were also using mating disruption, Hunt saw his codling moth trap catches drop from 82 moths during the 2007 season to only 2 in 2009.
Once codling moth populations are reduced, mating disruption can be a stand-alone control, he said.
Castagnoli reports that during the 2007 season, a total of 2,726 codling moths were caught in traps in the Dee Flat area. Last season, only 11 moths were caught.
The cost of a standard pear pest management program is about $900 per acre, he calculates. By year four, some growers were able to reduce the cost to about $600 per acre with no increase in fruit damage by eliminating codling moth cover sprays and late-season pear psylla and mite sprays. The fungicide mancozeb is included in the cost estimates because it is widely used for pear scab early in the season and has some effect on pear psylla.
After the EPA grant expired, the Oregon Department of Agriculture subsidized the cost of mating disruption for the 2010 season. During the 2011 season, about 96 percent of the growers continued to use pheromones, even though cost-share funds were no longer available.
Hunt said growers who have used mating disruption realize that overall insect control becomes cheaper. “In the first few years, when we were applying cover sprays, it was more expensive, but now it’s cheaper,” he said. “We don’t need any inducements to do it.”
Organophosphates are cheap, but they put workers at risk, and the reentry intervals are getting longer, said Hunt, who believes that eliminating those pesticides is fundamentally the right thing to do.
“If doing the right thing costs a little more for two to three years, you’re going to do it,” he said. “Now, we’re getting paid back in spades.”
Hunt said it takes a critical mass of acreage, but it doesn’t necessarily take a formal areawide program to have success with mating disruption. “If you can have cooperation with your neighbors, you don’t have to have a program like this. If you have 200 acres and get together with a couple of other guys in basically the same place who have 200 acres, you have a big enough area to make it work.”
Orchardists are independent, and everyone wants to spray their own materials and control pests their own way, Hunt acknowledged. But the areawide project demonstrates that, with a little cooperation and organization, the benefits of working together can outweigh those of the individual approach.
Hunt said that “It’s a triumph of cooperation over rugged individualism.”