California Almonds: Pre- & Post-Harvest Orchard Management Considerations


    Valley smoke: Wildfire smoke blocks sunlight from reaching the ground and increases relative humidity. Consult with your PCA/CCA to plan ahead to head off possible trouble this summer due to wildfire smoke. Possible problems for almond growing include personal safety for anyone working outside without an N95 mask, increased risk of hull rot due to a higher relative humidity, and slower nut drying on the orchard floor (increased ant feeding and more orchard water stress due to delayed nut pickup).


    Navel Orangeworm (NOW) & Peach Twig Borer (PTB): Continue monitoring for NOW and PTB to determine when and how to manage these pests in your orchard. Consider an edge spray (end of June/early July) when sound nuts in edge trees reach hull split Stage 2C, and a full spray once nuts in the upper canopy of trees within the orchard reach that same stage. Consult with your PCA when making decisions about NOW and PTB management. Switch insecticide chemistries between generations.

    Stage 2C of hull split. This is the critical time for NOW insecticide and Rhizopus hull rot fungicide applications. The orchard is ready for harvest when all nuts are at Stage 2C.

    Mites: Extensive leaf drop (defoliation) at harvest due to mite damage can lead to slower nut drying on the orchard floor this year and reduced yield and shoot growth the following year. Continue weekly monitoring for mites and mite predators throughout your orchard as hull split approaches. For more monitoring and treatment information, see the hull split spraying article in this newsletter and the UC IPM site for spider mites in almonds.

    Ants: Monitor for protein feeding ants and consult with your PCA about ant bait materials and application timing. If present, protein feeding ants can damage almonds on the orchard floor.

    Regulated Deficit Irrigation (RDI): RDI can promote an earlier, more even hull split in a normal rainfall year and can help with NOW and hull rot control. However, using this practice during a drought in already water stressed trees may lead to a yield reduction.

    How can you tell if RDI is a good option this year? At the start of hull split, check stem water potential (SWP) using a pressure chamber to see if the SWP is already in the RDI target range (-14 to -18 bars). If trees are drier than -14 bars (for example, -15 bars) then there is no need for further water reduction to manage hull split. If SWP is wetter than -14 bars (for example, -12 bars), there might be slight water savings in reducing irrigation run-time, so that SWP is in the target range as nuts enter hull split.

    During initial hull spilt, hold SWP in the range of -14 bars to -18 bars for two weeks and then return to full irrigation (100% ETc) for the last two weeks of hull split prior to preharvest irrigation cut off. This advanced strategy (in a drought year) should be approached with caution and precision.

    Leaf Samples: Take July leaf samples and submit for lab analysis to 1) evaluate your nutritional program for this year, 2) plan your nutrition program for next season, and 3) monitor for possible toxic element (chloride, sodium and/or boron) accumulation in the orchard. To learn more about July leaf analysis sampling procedure and interpretation see this article from The Almond Doctor.

    Harvest prep: Prepare shakers, sweepers and pickup machines for harvest. Equipment distributors may have preharvest “tune up” specials that can be scheduled to ready essential equipment for the long harvest season. To limit dangerous and damaging dust at harvest, review Almond Board of California information/videos on dust management.


    NOW Management in pollinizers: After Nonpareil harvest you may want to spray pollinizer varieties for NOW management. In a tight money year, this may not be an attractive option, but should be considered depending on the conditions in the field. The decision to spray or not should be based on the following: existing NOW damage observed in your Nonpareil almonds, progression of the third NOW generation, and timing the start of the fourth-generation egg laying.

    If you do choose to spray, plan your application timing based on when you expect to harvest your pollinizers, remembering that pre-harvest intervals are based on the date that you shake—not the date that you pick up the almonds from the orchard floor. A timely harvest is the least expensive option (shake vs spray and wait the PHI to shake) and can be very effective in limiting NOW damage.

    Hull Boron Samples: Boron accumulates in almond hulls, making hulls (not leaves) the best source of information about boron levels in your trees. To check orchard boron status, collect hull samples at harvest (from the windrows) and submit them to an analytical lab for boron analysis. For more information, see the article from the Almond Doctor on hull sampling for boron analysis.

    Nitrogen application: Use July leaf sample results to decide if any additional fertilizer N is needed this year. If the July leaf levels are adequate à high, research indicates no further N application is needed. If leaf levels are low à deficient, additional N may be needed. If leaf levels show additional N is needed, consider irrigation water nitrate levels when deciding on N fertilizer rates.

    For more information about N application in almonds and how to calculate lb N/acre in irrigation water from lab results see the new publication “Nitrogen Best Management Practices” from the Almond Board of California.


    When to start? Trees are ready for harvest when 100% of nuts in the orchard are at least at Stage 2C of hull split (see image in the July section, above) and test trees shake clean. This will minimize NOW damage on the harvested nuts.

    Dust: Dust at harvest can create unhealthy conditions for workers and community members in and around almond orchards. Plan to minimize dust at harvest by adjusting sweeper head heights, blower spout angles, and fan speed. See link to resources in the July section.

    Shaker damage: Shaker damage can be a major cause of orchard decline. Limit shaker damage (“barking” trees) by making sure all trees in the orchard are ready to shake when starting harvest. Test-shake trees in areas that are the most vigorous and where nuts “stay green” the longest. Where possible, clamp closer to the scaffold crotch rather than lower down on the trunk to minimize root damage and get the best shake to the canopy. Be extra careful when shaking in young (third and fourth leaf) orchards.

    Nut Damage Analysis: Nut damage analysis (harvest samples) can help reveal the primary sources of nut damage in the orchard and assist in planning for reducing that damage next year. Collect 500 nuts throughout your orchard after shaking and before sweeping for analysis. Use the UC IPM Harvest Sample resource and our article on Harvest Damage Evaluation for Almonds to conduct your damage analysis. If there isn’t time to crack out nuts at harvest, they can be frozen for later crack out.

    Don’t stockpile wet nuts: Nuts with hull moisture above 12%, kernel moisture above 6%, or total fruit (hull and kernel) moisture above 9% shouldn’t be stockpiled. Nut quality declines with mold and conceals damage. When sampling for moisture ahead of nut pickup in the orchard, make sure to sample from the top and bottom of the windrow, as nuts on the bottom tend to have higher moisture content than those on the top of the windrow. See the 2021 article on pickup and stockpile practices for further information.


    Post-harvest irrigation: Return irrigation to your trees as quickly as possible after harvest to minimize water stress. Water stress in August-October can interfere with bud development for the next crop. Dry trees after harvest = fewer flowers next spring.

    Post-harvest hull rot and shaker damage assessments: Check for hull rot and shaker damage on your trees after harvest. More information about hull rot assessment and management can be found on the UC IPM website for hull rot management in almonds.

    Plan fall Zn and B sprays: Use your plant tissue analysis results to determine whether you need to apply foliar Zn and B this fall. See our Postharvest Nutrition Review article to learn more about when and how to apply these nutrients.

    Plan for your fall potassium application: If applying fall potassium is part of your orchard nutrient management program, start preparing for application. Banded or targeted broadcasting down the tree row applications are good options for getting your money’s worth out of a fall potassium application. See the Postharvest Nutrition Review article for more information.

    Plan for improved rainwater infiltration: Consider a filter strip of vegetation (cover crop or natural vegetation) around the field edge to slow and help capture runoff water. One easy way to help do this, depending on the year and site, is to shut off herbicide booms as soon as the sprayer leaves the orchard row.

    Cover crops reduce orchard runoff, improve soil health, and/or provide pollen for bees. If you’re considering planting a cover crop this year, you’ll want to get the seed in the ground by the end of October. Start considering your options now using the UC-Almond Board Cover Crop Best Management Practices guide.

    Consider using organic soil amendments (almond shells, compost, etc.) to protect the orchard floor from sealing off due to rain drop impact and slow runoff.

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