May Almond Orchard Management Considerations

Luke Milliron, UCCE Orchard Systems Advisor; Butter, Glenn, and Tehama Counties
Franz Niederholzer, UCCE Farm Advisor, Colusa, and Sutter/Yuba Counties
Katherine Jarvis-Shean, UCCE Orchard Advisor, Sacramento, Solano, and Yolo Counties

Please note that the following are general recommendations intended to help you keep track of regular practices in a busy time; the optimal timing for management practices may vary based on specific location and conditions.

  • Navel orangeworm: Track NOW populations and develop a hull split/harvest timing NOW plan. Egg traps can be used to project when egg laying is likely to begin for later generations once a biofix is obtained in spring. Pheromone traps (catch males, ineffective near mating disruption products) and bait-bag traps (catch females) can be used to track flights and relative pest levels.
  • Spider mites: Monitor for spider mites and their predators (especially six-spotted thrips) at least weekly, watching hot spot areas that are often dusty or water-stressed. Be wary that a greater reliance on groundwater this year may result in increased irrigation salinity (EC) induced water stress, and therefore increased mite pressure. Early abamectin (AgriMek®, etc.) sprays provide excellent spider mite control for roughly 60 days if carefully applied but can create mite flaring going into harvest as the abamectin wears off, mites move in and if predators are absent. More information on the prophylactic vs. threshold approaches in our article on Approaches to Spider Mite Management in Almonds.
  • Nitrogen (N): Reassess your crop set and consider leaf sample results from last July and/or this spring and adjust the amount of nitrogen application needed before harvest – up or down depending on all information. Nuts use 80% of annual N budget by June.
  • Potassium (K): Maintain leaf K levels in the adequate range (1.4%) through July to minimize spur death and reduced flower number (crop loss potential) next year. Almonds absorb K up to hull split, so the window for K fertilization is wider than N. Learn more from our Article on Potassium Management for Sustained Almond Yields.
  • Diseases: Monitor for alternaria, rust, scab and anthracnose and treat if needed. If orchard history and conditions indicate high vulnerability, consider a rust treatment before symptoms are visible. Rotate the material’s site of action (FRAC Group) to avoid development of pesticide resistance (see efficacy and timing tables in this newsletter). Be aware of changes possibly affecting propiconazole (Tilt®, etc.) use for nuts exported to the EU. Consult with your processor/marketer regarding propiconazole use. See disease management details at UC IPM for Almonds.
  • Weeds: Survey to see which weeds were not controlled by fall or winter treatment. The UC Weed ID Tool can help with identification. This info will be very helpful in planning for next fall/winter weed management.
  • Bugs: Monitor for leaffooted and stink bugs. Info at UC IPM for Leaffooted Bugs and UC IPM for Stink Bugs.


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