A SPECIAL GROWERS’ REPORT OF AG ALERT ® CALIFORNIA Trees & Vines ®
Pest control advisor Mike Devencenzi shows off a codling moth pheromone dispenser, or puffer. It releases synthetic female pheromones that confuse male codling moths, disrupting mating habits.
Walnut researchers seek remedies to orchard pests By Vicky Boyd Randy Rajkovich, who grows walnuts and apples near Stockton, remembers when integrated pest management came of age in the 1990s. how blocks planted to cover crops may benefit web-spinning mite control by providing habitat for predators compared to blocks without the planted habitat.
In the blocks, CAFF also released predatory mites in hopes that they will help con- trol plant-damaging Pacific spider mite and twospotted spider mite. Last year, crews released them by driving through the orchard. They saw no significant differences between treated and untreated blocks, said Hanna Kahl, CAFF ecological pest man- agement specialist. This year, they used a drone to apply the predatory mites to tree canopies where mites frequent. Because mites typically don’t begin to cause problems in walnuts until later in the season, Kahl said they hadn’t yet assessed their effectiveness. Mites are a concern because heavy populations can cause defoliation, reducing the amount of photosynthesis and tree vigor. Leaf loss also can expose walnuts to sunburn. The Stockton demonstration and work at four other sites are also examining codling moth control using mating disruption. The approach involves blanketing an area with synthetic female pheromones. As a result, males become confused and can’t find females with which to mate, significantly reducing the population. In the Stockton demonstration, dispensers that resemble timed-release air freshener
The holistic approach enlists growers and pest control advisers to maximize crop health, scout and monitor for pests, consider nonchemical controls and apply pesti- cides only when there is a potential economic threat. When they do opt for chemical measures, IPM encourages using the least toxic materials and considering their impacts on predators and other biological controls. Rajkovich and his PCA, Mike Devencenzi, are part of a Biologically Integrated Orchard Systems demonstration that hopes to show how to take IPM to the next level. “I’m always looking for better ways to do things,” Rajkovich said. “I thought if they come here to do this study and work with beneficial insects and we can reduce the number of spray applications, it’s a plus economically and environmentally.” Led by the nonprofit, the Community Alliance with Family Farmers, the project involves three walnut growers and their PCAs in the northern San Joaquin Valley and three in the Sacramento Valley. It is funded by the California Department of Food and Agriculture and is in the second year of a two-year study. CAFF representatives held a demonstration field day in Rajkovich’s walnut orchard to update area growers and PCAs on their progress. The demonstration is comparing
See PESTS, Page 8
September 14, 2022 Ag Alert 7
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