Enhance walnut yields through soil and foliar nutrient program

Due to continuing concerns about the use of phosphite based inputs in walnuts and other nut crops as a result of European Union regulations, Agro-K, in 2015 began multi-year trials with two independent contractors, Brooks Bauer with Two Bees Agricultural Research & Consulting, Escalon CA and Steve Deitz of Sawtooth Ag Research, Woodlake, CA, to demonstrate that a comprehensive Agro-K soil and foliar nutrition program without phosphite based materials can improve nut meat yield.

These multi-year trials were initiated in 2015.  They were conducted as randomized complete blocks. The trials consisted of multiple tree plots of ‘Chandler’ trees replicated four to six times.  The foliar materials were applied at 100 GPA.  BioMax Dual Action + was applied to the top of the soil and watered-in. Agro-K nutrient materials were applied at key points during the season based on plant physiology and peak nutrient demand timing.

The Agro-K program resulted in increases in the nut meats of 702 and 384 lbs/ac  ( 547 lbs/ac average) compared to the standard grower program in each location.   The Agro-K program is meant to compliment a comprehensive agronomical sound soil program which is the foundation to overall tree health and consistent above average annual yields.  The trials will continue in 2016 and possibly 2017 to observed long-term yield and tree health benefits of the program.

Maximizing profitability in your walnut orchard starts with maximizing nut set every year. Achieving consistency in set and minimizing alternate bearing cycles is the key to consistent above average yields, increased nut meat quality and higher profits. The secret is ensuring the tree has the right nutrients at the right time in the right forms and right mix.  Agro-K’s carbohydrate based foliar line including:  Vigor-SeaCal, Zinc Plus +4 DL and Micro-Mix DL are designed to help growers meet peak nutrient timings in the crop cycle.

BioMax Dual Action + is a unique soil applied product that has a dual purpose.  The first is to directly feed existing beneficial microbial populations (like Mychorrizae) in the rhizosphere to increase native populations that help to naturally compete against soil borne pathogens.   The second purpose is to encourage root growth and increase root mass to improve nutrient foraging and uptake from the soil to support tree health while maximizing long-term tree growth and productivity.

Agro-K nutrient programs are based on a SCIENCE DRIVEN approach with a clear understanding of the walnut tree physiology and meeting the tree’s peak nutrient demands throughout the season.  With bud break happening in the near future, the focus needs to be on early season nutrient demands and the environmental dynamics of the season.

While more is needed, the walnut growing regions have been fortunate to receive much needed rains this winter.  Ken Dart, Agro-K’s National Technical and Marketing Manager states – “because of the rains we can expect cool wet spring soils to limit nutrient availability, root activity and nutrient uptake to be minimal.  Growers that are interested in maximizing yield (consistently year over year) and quality will work to address spring nutrient needs by managing and meeting peak nutrient demand timings all season long so that the tree has reserves ready, but will also supplement with early spring sprays.  You never want the tree to lack nutrients at critical physiological timings.”

“In the spring, due to poor nutrient availability in the soil the tree will support its needs by utilizing nutrients stored in the roots and wood.  Foliar applied nutrients early season are needed to fully support the tree’s need and to ensure more uniform bud break and faster early growth with larger leaves that have more photosynthetic capability,” says Dart.

Dart cites these important nutritional facts:

• The process of breaking dormancy is a very zinc-intensive process.
• Walnut trees have a very large demand for zinc due to the very large and extensive root, leaf and vascular systems. All these tissues require zinc to function and grow.
• The best nut set and yields won’t happen without molybdenum for pollen production and pollen performance, and boron for pollen tube development and phosphate for cell division for good nut size.
• The full potential of a good nut set won’t happen with small leaves and poor chlorophyll. Leaf size is dependent on adequate zinc levels while the leaves are forming – early peak nutrient demand. The key to making this work is having zinc in the buds, roots and vascular tissues applied at a time, and in a form that will be taken in, stored in these tissues and ready to go when dormancy breaks in the spring.
• Chlorophyll production takes place as the leaves expand and requires Manganese, Magnesium, Iron, and Sulfur. If these are deficient as the chlorophyll forms, the leaves will not be effective in capturing the light for photosynthesis (especially in the lower canopy) which leads to smaller nuts, weak lower limbs and terminals that are more vulnerable to the complex of diseases leading to lower limb die back.

For more information on Agro-K’s walnut trial research, fertility programs and Agro-K’s products contact your local dealer or Agro-K today. 1-800-328-2418 or email info@agro-k.com.