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A L M O N D O R C H A R D 2 0 2 5 G O A L S PEST MANAGEMENT Almond Board of California 6 labels require applications be made at windspeeds of less than 10 mph to reduce offsite drift. Spraying at night in the summer is further supported as there is generally less wind at that time. Noting wind direction and knowing what is located downwind should also be considered prior to every spray. If the wind is likely to pick up during a spray, consider starting the spray near locations where you want to minimize spray drift. Similarly, survey the orchard's surroundings before spraying, paying attention to areas such as water ways, buildings and streets to see if you need to buffer certain zones or spray inward down certain rows. Impacts of responsible sprays "Paying attention to spray drift is critical," Niederholzer said. "Growers can do many things to dramatically lower the amount of drift, and if these aren't put into action, legislation is going to do it for them." Growers and applicators have multiple resources available to guide them through the process of properly calibrating their equipment: PCAs, university experts and consultants from equipment companies can offer input and counsel. In addition, UCCE and UC IPM recently developed a comprehensive online course 4 for applicators, application supervisors, growers and PCAs on how to calibrate air blast sprayers. The Almond Board continues to invest in research on improving spray efficacy, and findings are routinely presented at The Almond Conference. Mark your calendar for Dec. 8-10 for The Almond Conference 2020, held in a virtual conference setting, to hear the latest ABC-funded research on a variety of production topics. Visit almondconference.com to register and for more information. Almond Hulls, Shells Help Fuel an Alternative to Fumigation Three years ago, when Chico almond grower Rory Crowley decided to replace an old walnut orchard with almonds, he knew he needed to take measures to get rid of a particularly nasty soil pest: Pratylenchus vulnus, or root lesion nematode. These tiny worms burrow into the tender roots of young trees, causing damage that can impact their growth and yields for decades. "With trees, like kids, the early years are so important," Crowley said. "When we can kill the nematodes right from the beginning, the trees are healthier for the rest of their lives." But Crowley had limited options for battling nematodes. Over decades, his family had watched the urban area grow ever closer to their orchard. Now, houses and a daycare center stood nearby the 50-acre block where he was trying to replant, and therefore risks to neighbors coupled with regulatory restrictions made use of conventional fumigants out of the question. "We're hemmed in here. But it's not just here and it's not just about this block. Growers are facing headwinds everywhere," Crowley said. "Efforts to get rid of fumigants are gaining traction in California, both in legislation and regulation. We need alternatives." Find an alternative, he did. Crowley saw an opportunity to try a different method to control nematodes and other soil pests in the practice of biosolarization. He began working with University of California (UC), Davis, researcher Christopher Simmons, Ph.D., to test if the idea was more method or madness. Biosolarization involves adding organic materials – in this case, coarsely ground almond hulls and shells – to the soil, covering them with plastic to seal out air and promote solar heating, adding water (under the plastic) via drip tape, and then allowing the sun to heat the soil. In just a few days, solar heat and moisture trigger microbial action, fermenting and breaking down the hulls and shells and releasing organic acids and other compounds that act as natural biopesticides to suppress nematodes and other soil pests. Tough on nematodes, sweet on soil Research from Crowley's orchard shows use of biosolarization with almond hulls and shells was able to achieve nematode kill as high as 84-100%, making its effectiveness comparable to fumigation. And while effective in killing nematodes, biosolarization does not pose a hazard for humans, Simmons said. "There's really nothing there at any level that we would expect to pose a risk for anybody in the field," Simmons said, pointing out that the broken-down products released from decomposing hulls and shells include natural compounds like acetic acid, the primary ingredient in vinegar. "We consume, as a food product, acetic acid at greater levels than what we generate in the soil during biosolarization," Simmons said. "It's potent for knocking out a broad spectrum of pests in the soil, but inherently it's much more innocuous for human beings compared to conventional fumigants." Biosolarization isn't just tough on nematodes while being safe for humans 4 https://campus.extension.org/enrol/index.php?id=1787 A L M O N D O R C H A R D 2 0 2 5 G O A L S ZERO WASTE Continue on page 7