Shelling Out Useful, Real-World Almond Knowledge
Tthe time to start planning is now. Every month brings new needs and new possibilities to your orchard, so we’ve done our best to put together the following advice for your almonds.
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Spring Nitrogen Applications
As the almond crop transitions from pollination and early fruit set to leaf-out and canopy expansion, nitrogen demand begins in earnest. As a reminder when building your nitrogen budget for the year, almonds remove about 70 pounds of nitrogen per 1000 pounds of nutmeat. Thus a 3000-pound crop removes about 210 pounds of nitrogen. Nitrogen Uptake Efficiency (NUE) also needs to be taken into consideration when calculating proper nitrogen application rates. In drip and micro-sprinkler irrigated almonds NUE is estimated to be 75-85%, which is high, so assuming a NUE of 75-85%, the total amount of N that should be applied over the course of the season is estimated at about 250-280 lbs./acre.
Timing of N applications to match tree demand is important to maximize NUE and minimize costly losses to the environment. Mature trees need more nitrogen in early spring during these periods of active shoot growth, leaf activity and photosynthesis. Shoot growth is vital for canopy development and the creation of fruiting spurs for next year's crop. Almond nuts and shoots use about 80% of the season’s total nitrogen demand between bloom and mid-June. Split applications of nitrogen are favored to further maximize NUE as follows below:
20% February-March
30% April
30% May
20% September - Early October
The chart below was developed by the CDFA in cooperation with UC Davis and can be found on the Fertilizer Research and Education Program website.
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In the next Almond Newsletter, we will introduce a fantastic tool to improve NUE during the late spring and summer months - NDURE DCD. This product is a proven nitrogen stabilizer that keeps applied N in its ammonium form to reduce both nitrate leaching losses and nitrogen metabolism energy expenditures.
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What About Potassium?
Potassium is required at high rates in almonds. About 75 pounds of K or 90 pounds of fertilizer K2O is required for every 1000 pounds of nut meat produced. K uptake is linear with about 70% of the season's total K accumulation occurring by Mid-June. Fertigation and foliar K applications should commence starting at about 30 days after bloom while canopy expands and transpiration rates increase. According to the work of Brown and Weinbaum, peak demand for K occurs between about March 20 through May 20 (about 2.5 lbs. K2O/acre/day). By about 120 days after bloom, 75% of the K has already accumulated in the fruit. This coincides with mid to late June, depending on growing area and variety. It is always best to get ahead of crop demand rather than attempt to play catch up later in the season.
 Wilbur-Ellis offers TILL-IT REKOIL as a preferred liquid potassium fertilizer designed for in-season fertigation of fruit and nut crops. TILL-IT REKOIL has an analysis of 0-0-19-5S and is formulated with potassium carbonate and potassium thiosulfate to provide a finished product that will have a net neutral effect on soil pH. TILL-IT REKOIL contains 2.05 lbs. K2O per gallon and is recommended at 10-30 gallons per acre per application starting at canopy expansion and again every 3-4 weeks as needed.
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Prepare for Nut Drop
Nut drop in almonds is a natural phenomenon that has a variety of influencing factors. Almonds produce far more flowers than can possibly be carried to final yield and on average the percentage of flowers that do produce a harvestable nut range between about 15-40%.
Early drop occurs shortly after bloom when defective flowers and flowers that were not pollinated are shed from the tree. The second period of fruit drop in almonds occurs about a month later and involves fruit that was pollinated but not fertilized (germ tube did not reach the ovary) as well as some larger developed nuts that were fertilized.
The typical “June drop” causes the greatest concern amongst growers and advisors since it is the most visible of all three drop periods, but it is actually the least of the three in terms of the total number of fruit aborted. Losses at this stage are largely due to depletion of carbohydrates and mineral resources leading to competition for these limited resources. Proper irrigation and nutrition to maximize photosynthesis and tree health are suggested to help reduce this June drop.
 In 2019 four replicated trials were conducted to evaluate the effects of different foliar nutrient applications on June drop. Though results were not spectacular, there was a slight increase in fruit retention (+ 2.1%) in trees treated with NDEMAND ENTOURAGE K plus PURIC PRIME (2 gallons plus 1 pint per acre) compared to the untreated control. A single application was made Mid-May.
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Be on the Lookout for Leaffooted Plant Bugs
Though of sporadic nature, damage caused by this relatively new pest of almonds can be significant. Over-wintering populations may be moving into orchards this time of year and scouting should be conducted to look for this elusive pest or damage cause by their feeding behavior. Look for dropped nuts (particularly on softer shelled varieties) with signs of gummosis. Nuts showing gumming should be cut across the damaged area to look for puncture marks from their long, piercing, sucking mouthparts.
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Leaffooted Plant Bug Adults (left) and Nymphs (right) – courtesy of UC ANR
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Keep Our Bees Safe
Move Them Out Before Applying Insecticides
Now that our friends, the Western Honeybee, have done their job setting California almond growers up for an excellent year, let’s return the favor and make sure all hives are removed from almond orchards before commencing with early insecticide or miticide applications (i.e., Leaf Footed Plant Bug).
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To learn more about which products are right for you, visit almonds.wilburellis.com, or contact your local Wilbur-Ellis PCA/Agronomist
Stay tuned for next month’s newsletter and remember,
You Can’t Win Them All, But You Can Win Your Almonds
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This newsletter is for information purposes only and is not an offer to sell or buy any products or services. Prior to use, always read applicable labels, terms and conditions, and related documents for complete instructions, proper usage, and limitations.
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