How We Grow

2021 Nov/Dec How We Grow

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Added benefit increases value Especially in dry years, it can be difficult to shake all the mummies out of the trees. Labor is then needed but it can be expensive to pay hand crews to finish effective sanitation. There is side benefit to mummy removal however, adding value to a practice that can already save a grower from an unexpected drop in crop value at the huller. "Mummy shaking should not only be thought of as a tool to mitigate NOW, but to also reduce the inoculum load of hull rot going into the next cropping year," Wolter explained. He said the two pests are closely linked and can actually make each other worse. "Nuts affected by hull rot are much harder to shake off the trees at harvest, leading to an increased mummy load post-harvest," Wolter said. "These same mummies, to a varying degree, serve as an inoculum source for hull rot the following year." Labor is expensive and can be hard to find sometimes for growers, especially in California. But when you add the possible decrease in profit plus the increased control of hull rot, good winter sanitation pencils out to be a smart investment. Almond growers are encouraged to learn more about controlling navel orangeworm at Almonds.com/NOW. ABC has presentations from its Navel Orangeworm Summit, information about aflatoxin and short videos with UC ANR advisors describing the different tools for both monitoring and mating disruption. Year-round Approach to NOW Management The Halloween season might be over, but navel orangeworm concerns can haunt growers throughout the year. Given the dollar amount per acre in potential revenue losses and added management tools available to growers, NOW integrated pest management (IPM) can be viewed as a continual practice. Drew Wolter, ABC's senior pest management specialist, said the present day phenological calendar for NOW IPM starts in February or March and ends after mummy shaking the trees. "You've got monitoring, mating disruption, nitrogen management, possible applications, more monitoring and mummy shaking. There is a lot going on in regard to NOW management throughout the year," he said. The newest practice to help control the pest is mating disruption, which coincides with monitoring practices. Wolter said if a grower is implementing all the tools available, their year looks like this. FEBRUARY/MARCH - Egg traps are deployed to set a biofix. That's when the first NOW eggs show up in an orchard and becomes a grower's reference point when deciding if sprays are necessary later in the season. MARCH - Mating disruption and pheromone trap monitoring begins. It's important to note some considerations when using both practices as the prior might interfere with the latter. Wolter said there are easy ways to fix the problem – referred to as "Trap Shutdown" – and pest control advisors are aware of the issues. MAY/JUNE - Look at managing nitrogen. Wolter said research shows that avoiding excess applications of nitrogen 45 to 60 days before hull split makes them easier to shake out of the tree at harvest and during winter sanitation. JULY - Think about strategic deficit irrigation and monitoring leaf nitrogen content. Wolter also notes that these practices between can help NOW management because they aid timely harvest and lessen hull rot. July is also when growers can look at insecticide applications. Growers can use the biofix established in March, combined with insect population data and monitoring, and decide if an application is needed for the second generation of moths. AUGUST - Harvest the nuts in a timely manner and continue to monitor for late varieties as they can be susceptible to a third generation of NOW. Wolter noted that a second spray could be warranted for later varieties that still have nuts on the trees. DECEMBER /JANUARY - Get the mummies out of the trees. Winter sanitation (mummy shaking) remains the foundation of a sound IPM program for navel orangeworm. The UC IPM website recommends getting mummies out of the tree and mowing or discing them before spring. Wolter added that this practice gives growers a head start on management for the next season and should be done before February 1. ALMOND ORCHARD 2025 GOAL "Mummy shaking should not only be thought of as a tool to mitigate NOW, but to also reduce the inoculum load of hull rot going into the next cropping year," — Drew Wolter Almond Board of California 8

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