Top left: An orchard in late fall, when mummy shake would occur Top right: A thick cover crop stand
are not intended to replace traditional orchard sanitation practices entirely. Winter sanitation remains crucial for removing mummy nuts that remain after harvest.³ To address concerns about cover crop interference during mummy nut removal, farmers can adopt a strategic planting approach. Some farmers plant cover crops in alternate rows while leaving adjacent rows bare to allow for effective winter sanitation efforts without compromising cover crop establishment. You want to plant the cover crop early enough to have a floral load in time for the bees’ arrival prior to bloom. Other farmers elect to plant the cover crop immediately before or shortly after completing winter sanitation.² Cover crops can have an indirect influence on some of the underlying causes of sticktights (unharvested nuts which will become mummy nuts).¹ ² Some of these causes include nutrient or water stress, which leads to uneven ripening of nuts. This situation puts the farmer in the uncomfortable position of shaking some nuts too early or risking NOW infestation of ripe nuts.¹ Cover crops increase water infiltration, boost soil microbial communities, and improve the availability of some plant nutrients. These improved soil conditions can have a compounding effect over time, boosting orchard health.² Again, integrating cover crops into almond orchards does not replace sanitation, but it can be beneficial to NOW suppression. By accelerating mummy nut decomposition, increasing predation, and hiding mummy nuts from female moths, cover crops contribute to reducing pest pressure early in the almond growing season. This integrated approach enhances the effectiveness of NOW control measures while supporting soil and orchard health. Farmers are encouraged to consider these findings when developing comprehensive pest management plans that integrate both cover crops and traditional sanitation practices. Blue Diamond farmers can experiment with cover crops and get technical support at no cost through the Blue Diamond Growers Advancing Markets for Producers Grant program. This is an ongoing Federal USDA grant. To qualify, growers need to meet the following criteria: have and maintain a current contract with Blue Diamond , be a participant in the Blue Diamond Orchard Stewardship Incentive Program (OSIP) with a completed CASP
progress report, and an orchard map and associated paperwork from the FSA. The details can be found at www.bluediamondgrowers.com
Resources: ¹ Almond Board of California (2021) Navel Orangeworm best management practices. (490) Navel Orangeworm Best Management Practices — YouTube ²Wauters, V., & et al. (2023) Developing cover crop systems for California almonds: Current knowledge and uncertainties. Journal of Soil and Water Conservation . Developing cover crop systems for California almonds: Current knowledge and uncertainties | Journal of Soil and Water Conservation (jswconline.org) ³Wilson, H., & et al. (2022) Winter cover crops reduce spring emergence and egg deposition of over wintering Navel Orangeworm (Lepidoptera: Pyralidae) in almonds. Environmental Entomology . Winter Cover Crops Reduce Spring Emergence and Egg Deposition of Overwintering Navel Orangeworm (Lepidoptera: Pyralidae) in Almonds | Environmental Entomology | Oxford Academic (oup.com) ⁴Wilson, H., Burks, C., Reger, J., and Wenger, J. (2020) Biology and management of Navel Orangeworm (Lepidoptera: Pyralidae) in California. Journal of Integrated Pest Management . pmaa025.pdf (silverchair.com) ⁵Wilson, H., Rijal, J., and Haviland, D. (2023) New pest infesting almonds and pistachios in the San Juaquin Valley. UC Division of Agriculture and Natural Resources . New pest infesting almonds and pistachios in the San Joaquin Valley — Food Blog — ANR Blogs (ucanr.edu)
Tom Johnson, Seeds for Bees ® Grower Relations Manager, Project Apis m.
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