February 2020, Issue 3
Shelling Out Useful, Real-World Almond Knowledge

Almond Bloom is or will soon be in full swing. So, the 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.

Frost Protection

Almond bloom is or will soon be in full swing and a topic that should be on every grower’s mind this time of year is the potential for frost damage and the steps to take to mitigate yield loss from frost damage.

Though the weather outlook does not call for widespread frost events like we have experienced in prior years, it is always best to keep a close eye on the weather and take the steps now to get ahead of damaging frost.

During full bloom, frost injury can occur when temperatures in the orchard drop to 27-28OF.  Almonds become even more sensitive to frost damage when leaf out and early nut development begins.

Common practices to prevent or reduce losses to frost damage include:
  1. Irrigate prior to frost event. Moist soils retain daytime heat which is then radiated back into the orchard at night. Dry soils increase susceptibility to frost damage. 
  2. Irrigate during actual frost event. Micro sprinklers and solid set sprinklers are very effective at raising nighttime temperatures in orchards as heat will be released into the air by the cooling sprinkler droplets.
  3. Mow existing ground vegetation as low as possible and irrigate if soils are dry.  Cover crops or other vegetation prevent radiant heat from leaving orchard floors at night.
  4. Air movement by either air machines or helicopters can be effective tools that mix warmer air with colder air for an overall increase in orchard temperature.
For even more information on frost injury in almonds click the button below
Frost Prevention Link

Early-Season Nitrogen Management

Early season growth in almonds (and other deciduous tree crops) is wholly dependent upon nitrogen stored within the tree from the following season.  Late-winter soil applications of nitrogen have absolutely no effect on almond bloom or early growth.  Not until the canopy begins to develop and transpiration of soil moisture to the canopy begins does nutrient uptake occur to any significant amount.

Almond trees take up about 70 pounds of nitrogen for every 1000 pounds of nut meat produced and 80% of the total amount of N taken up by almonds occurs between bloom and mid-June. Applying the right form of nitrogen for early application (about 20% of the total amount for the season) may be as important as applying the right amount. 

When soils are cold, conversion of ammonium from urea or UAN applications to the nitrate form is very slow because this process of “nitrification” is temperature-dependent and mediated by soil bacteria. The chart below presents nitrification rate versus soil temperature. As can be seen when soil temperature is at about 50OF, six weeks may be required for just 50% of the ammonium to convert to nitrate, which is the dominant form of N take up by plants.
Select a nitrogen source that has a high nitrate content for maximum availability in the early spring before soil temperatures have warmed.


Calcium and Early-Season Root Growth

Calcium is an essential nutrient that has a variety of functions in plants including cell wall structure and strength, cell membrane function and others. Calcium is unique in that it is both required for new root growth and is only taken up directly behind the root cap of new roots. Having ample soluble calcium in the immediate root zone prior to and during the critical spring root flush may aid in enhancing calcium uptake and storage in the tree and facilitating a strong spring root flush. A variety of calcium sources are available depending upon the specific need to be addressed but for early season nutritional applications one that also contains a high percentage of nitrate-nitrogen would be preferable.
Sources: IPNI and Yara Brazil/Adubox Trevo; Citrus

Another concept that is gaining attention and interest is the use of humic acids for stimulation of soil microbial activity and enhanced soil nutrient uptake, notably for phosphorus and micronutrients. But until now, growers had no means of combining liquid calcium fertilizers with humic acids due to incompatibility and immediate fall-out. 

Until now, that is. Wilbur-Ellis formulation chemists have developed a patent-pending process for manufacturing liquid humic acid that is compatible with liquid calcium fertilizers. Introducing PURIC Salute, the most advanced liquid humic acid product on the market offering unheard of before compatibility with calcium and acid fertilizers. PURIC Salute contains 8% humic acid and will not fall out of solution when mixed with calcium fertilizers.


Bloom-Time Foliar Nutrition

In the last newsletter, we discussed why foliar applications of boron during bloom is not a good agronomic practice. However, bloom is an ideal time to include foliar calcium and zinc with your bloom fungicide program. Almonds pollinate many more flowers than can make it to yield and drop of both unpollinated flowers and a portion of pollinated flowers is a natural occurrence in almonds that cannot be eliminated. However, timely applications of foliar fertilizers containing calcium and zinc may reduce drop or increase set leading to higher yields.

See below for yield results from a foliar nutrition trial in almonds that looked at 7 different bloom fungicide programs either with or without FoliGro Ca-Zn added at 2 quarts per acre. The objectives of this trial were twofold:
  1. Evaluate differences in efficacy on almond bloom diseases between the different fungicide programs.
  2. Determine if the addition of FoliGro Ca-Zn provided any benefit. 
As is presented below, yields were elevated in six out of the seven fungicide treatments when FoliGro Ca-Zn was included with an average yield gain of 359 pounds nut meat per acre. There was virtually no disease pressure during the year of this trial (you can omit the text at the bottom of the snip)
To learn more about which products are right for you, visit, 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

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.
Copyright © 2020 Wilbur-Ellis Company, All rights reserved.

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