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    California Almonds: Management Considerations – Spring, Early Summer

    Almonds at hull split. ©Sara Savary, AgFax Media

    APRIL

    • Irrigation: Wherever possible, keep orchard water stress low (for example, 1-2 bars below baseline on pressure chamber readings) early in the season. Use plant and/or soil monitoring to know when and how long to irrigate. Pressure chambers are more accurate in measuring water status under saline soil/water conditions than soil moisture or ET. A free, UC drought management in almond publication is available on-line.
    • Water Quality: Obtain water analysis for salinity, chloride, sodium and boron as all change with source (well to well) and time of year as drought conditions worsen. Add nitrate to the analysis to see if “free” nitrogen is available with irrigation water.
    • Disease: Assess orchards for alternaria, rust, scab, and anthracnose symptoms and treat as needed. Consider a rust treatment before symptoms are visible if orchard history and conditions indicate high vulnerability. Rotate the material’s site of action (FRAC Group) to avoid development of pesticide resistance. Check with your processor about status of different fungicides in the EU market.
    • Insects/mites:
      • Monitor for navel orangeworm (NOW) and peach twig borer (PTB). Hang mating disruption dispensers.
      • In drought stressed orchards, spot check for spider mites.
      • Monitor for leaffooted and stink bugs.
    • Gopher monitoring: Severe gopher damage can kill trees. Also, a combination of gopher mounds and close mowing equates to more dust and increased spider mite pressure. Manage gophers before their reproductive pulse – usually between March and May. For best results, use multiple control strategies including trapping, fumigation or baiting. See free video showing steps to gopher trapping with Dr. Roger Baldwin, UC Extension Specialist for great tips and review of trapping procedure.
    • Nitrogen: This is a critical time for assessing crop size and fertilizer budget adjustments. See detailed information on nitrogen management in almonds is available, free from The Almond Board of California.

    MAY

    • Irrigation: Wherever possible, maintain adequate orchard moisture using plant and/or soil monitoring.
    • Nitrogen and Potassium: Keep up with orchard nitrogen (N) and potassium (K) demand. Nuts use 80% of annual N budget by June, May is a time of high N use in orchards with a good cropload. Maintain leaf K levels in an adequate range (>1.4%) to reduce spur death and crop loss potential next year.
    • Mites: monitor orchards weekly and treat if pest and “friendly” mite numbers show a need.
    • Bugs: Continue monitoring for leaffooted and stink bugs.
    • Disease: Monitor for rust, scab, anthracnose and alternaria, treat as necessary.
    • Gophers: Continue to monitor closely.

    JUNE

    • Irrigation: If an orchard has been fully irrigated, a strategic irrigation deficit at the onset of hullsplit offers Rhizopus hull rot management and a shorter, cleaner shake at harvest. Reduce irrigation set length as kernel fill completes. Deep, heavy soil with micro-sprinkler or solid set irrigation have more soil water available and so respond more slowly to reduced irrigation compared to lighter soil with drip irrigation. For two to three weeks, beginning at the onset of hull split (late June or early July), SWP levels of 4 to 8 bars drier than the baseline (generally -14 to -18 bars) will promote hull split and uniform nut maturity leading to timely harvest.
    • Fertilizer application: Apply potassium as needed to maintain 1.4% range through July. Assess K fertilizer need using current crop set, last year’s leaf analysis results, plus orchard observation. Finish nitrogen application in June
      Continue pest monitoring:
    • Ants: Contact your PCA, check for ants and find a treatment plan. Some application programs start 10 weeks ahead of planned harvest. Apply bait promptly after purchase to dry ground to increase efficiency- product opened for 1-2 weeks no longer works.
      Continue scouting for spider mites and their predators.
    • NOW: Check for hull split in the upper southwest canopy of edge trees. Early is better than later for hull split sprays.
    • Hull rot: Best control combines adequate N management (2.4-2.6% N in summer leaf samples), moderate water stress (-14 to -18 bars on the pressure chamber) between kernel fill and end of early hull split, and 1-2 fungicides in June or early July. In a drought year, reducing irrigation may not be needed/recommended.
      • Monilinia: For best control of Monilinia hull rot, present as a tan lesion on the outside of the hull, spray in early June as hull split timing does not effectively control this hull rot pathogen.
      • Rhizopus: For orchards with a history of Rhizopus (black spores) hull rot, spray a fungicide at early hull split timing (tank mix with NOW insecticides).
      • Aspergilus niger: Fungicides are more effective once the hulls have actually split.
    • Equipment preparation: Time and money can be saved by checking harvest equipment before hull split and harvest. Plan for a low-dust harvest.



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