development of fruiting buds. UC Davis recommends the potassium range for summer leaf samples be between 1.4%- 2.0%. In my experience, orchards always did better at the 2%-2.2% range. There are multiple forms or ways potassium can be applied. The main ways are soil applied using Sulfate of Potash (SOP) or fertigation using liquid Potassium Carbonate. In a perfect world you would use a combination of the two. I like to think of my soil application as my savings account for potassium nutrition. It keeps the soil level up but does take time to become plant available. The fertigation of liquid application is more of a checking account. It is a quick way to raise tissue levels of potassium and can correct deficiencies. All three of these macronutrients are vital but the need for each one will differ for each situation. Micronutrients also play a pivotal role in the production of almonds. The three I am going to break down today are calcium, boron and zinc . Having sufficient calcium levels can help prevent disease by strengthening the cells within the plant. Calcium is also crucial in new root growth, especially at the time of root flush. The second micronutrient is boron . Boron is needed for flower production, which ultimately leads to good production. Boron levels need to be checked by taking a hull sample around the time of harvest. Boron accumulates in the hulls themselves and will give the best representation of the levels in the orchard. Boron deficiency can also be identified as what I call a “rat tail.” In Figure 2 you can see what looks to be normal growth followed by a blank area and ending with a new tuft of growth. Boron can be applied on the soil or foliage to treat deficiencies. Monitor levels after application to make sure the pendulum does not swing in the opposite direction leading to boron toxicity. Zinc is the last of the micronutrients that I am going to go over today. Zinc is important in the growth process of the tree and is apparent especially in the new growth. Zinc deficiency can be identified by the tree having tightly stacked nodes at the end of a shoot. When I was working as a PCA, I would say it looked like a “Chia Pet” because of all the growth being stunted at the end of the shoot. Zinc can be applied with soil and foliar applications. Foliar applications are an easy way to show a quick response within the tree. Other
Figure 2 Boron deficiency by Yara
forms of zinc can be mixed with common nitrogen sources like UN-32 and applied through fertigation. As with the macronutrients all these micronutrients are needed for optimal plant health, but each orchard is different and will require its own unique nutrition program. We all know health and wellness are important. As farmers, you have an even better understanding of this concept. If the nutritional balance of an orchard is not correct, it can lead to stunted growth, higher disease and insect impact and an overall loss in yield. Nutrition is a cornerstone for a successful and sustainable yield for every grower’s almond orchard.
Trent Voss, Regional Manager, Blue Diamond Member Relations
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MAY–JUNE 2024
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