How We Grow

2019 Nov/Dec How We Grow

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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 9 point, mummy nuts will have absorbed some moisture, making them heavier and more likely to fall. Once on the ground, mummy nuts should be blown from berms, swept into rows and destroyed using flail mowers or disking. It's time- and labor-intensive, but it's proven to work, and again, proven to put more money back in growers' pockets the following crop year. Weather is also on the grower's side: Once the mummies hit the ground, wet orchard floors and even cover vegetation can increase the mortality rate for overwintering NOW. "The goal is to destroy nuts before larvae can grow into moths," Haviland explained. "Eggs laid in September and beyond become larvae that overwinter in the kernels. You want to destroy them before spring." The Almond Board continues to be at the forefront of NOW research and remains committed to providing growers with as many research-based IPM solutions as possible. This past year, the Almond Board joined with the pistachio industry to fund a multimillion-dollar research project exploring the use of Sterile Insect Technique (SIT), which looks to mass-produce sterile NOW adults and release them into the orchard. When a sterile NOW mates with a wild NOW, the offspring are no longer viable. "The Almond Board has spent decades researching NOW to better understand how growers can combat this pest," said Josette Lewis, director of Agricultural Affairs at ABC. "Research confirms the importance of winter sanitation. "Still, there's more work to be done and the Almond Board looks forward to partnering with researchers, the almond industry and the broader ag community in exploring this sterile insect opportunity for NOW control." Can winter ground cover increase the mortality of overwintering NOW in mummy nuts? With funding provided by the Almond Board, researcher Houston Wilson and his team are working to evaluate this hypothesis. Continued from page 8 Can cover crops play a role? Efficient mummy nut removal is a key component of the California almond industry's effort to improve environmentally friendly pest management tools by 25%, one of its four Almond Orchard 2025 Goals. To enhance NOW IPM, an additional tool under study involves the role cover crops may play in winter sanitation. At first glance, that premise may seem odd: If a cover crop is grown in windrows, wouldn't mummy nuts be lost in the foliage and hard to reach with flail mowers? The answer, explained UC Riverside faculty Houston Wilson, is yes — but, as he's exploring in his team's research, mowing may not be necessary. The hypothesis under evaluation is to understand to what extent winter ground covers increase mortality of overwintering NOW in mummy nuts. "There's evidence from pistachios that shows what happens to mummies when they sit in a cover crop. It's colder, it's wetter, it's a different environment in there, and evidence suggests that type of atmosphere may lead to increased NOW mortality," said Wilson. However, Wilson is quick to recognize that winter cover crops will likely interfere with traditional sanitation efforts, making it more difficult to sweep and destroy mummies lodged in the ground cover. "We're trying to understand that tradeoff between reduced efficiency of traditional sanitation and increased NOW mortality in mummies within the ground cover," he said. Wilson and Haviland both said integrating cover crops into winter NOW management might be more practical in the northern parts of the state, where rain is more plentiful. "This concept is definitely not to be exercised to the exclusion of winter sanitation," Wilson said. "We're trying to create a cost-benefit analysis of cover crops' potential role here and address the concept in a comprehensive way."

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