Post Harvest Nutrition

As we enter the harvest season in trees and vines, we should be considering post harvest nutrition. For instance, the bloom season this year in almonds was very fair and nut set was very good. Because soils were not charged well with rainfall, and irrigation was in some cases lackluster, our trees are finishing
off stressed, leading to the potential for poor nut set and yields next year. This can be seen across all the perennial crops being farmed in California.

For those who have been practicing post harvest nutrition in your trees and vines, the crops looked
better this year than they ever have. There are several nutrients to consider when planning your strategy: nitrogen, phosphorous, potassium, zinc and boron. Nitrogen is an important fuel at this time because it helps revive your trees and vines following the stress of the harvest period. Phosphorous is an essential nutrient necessary for fall root flush development and an important energy source when the crop comes out of dormancy next season. Potassium in the plant provides a growth regulator effect which aids in water uptake, nutrient acquisition and assimilation and cell reproduction. Zinc
aids in the crops ability to synthesize auxins (IAA), which results in increased cellular division for strong, uniform bud burst, fruit set, retention and sizing. The main function of boron is the development of healthy floral parts, particularly pollen tubules.  Boron also aids in the translocation of calcium.

So what are the most efficient means to deliver these nutrients to the crop? Since crops came off early this year, there should still be a pretty good canopy following harvest.  With a fall root flush to be expected, roots should have a good opportunity to tale up nitrogen, phosphorous and potassium. An application of 10 or more units of nitrogen via UN-32 is great. Our Nucleus® products are a great source for re-charging the crops with phosphorous and potassium in an early fall application. Remember that our crops are stressed and nutrient delivery from the soil can be tough. Two great tools for enhancing plant health and nutrient acquisition are Viva® and Essence™ 6. Viva helps crops handle
stress better,  encourages root growth and helps nutrient assimilation. In field studies conducted in almonds last year, it was observed that three times as much potassium and a 16% increase of zinc
in leaf nutrient content where Viva was included in soil blends. Essence 6, with its organic solubilizing acids and fulvic acid, improved nutrient availability in the soil. This has been documented with Mehlic Extraction tests.

When considering micronutrients, the best results for acquisition and assimilation can be achieved with foliar nutrition. Foliar applications should be made as soon after harvest as possible so that they are applied to a healthy canopy.  Again we must consider that the crop will be recovering from a stressful period of growth. Foliar nitrogen can help revive the crop from this stress.  CoRoN® 25-0-0 is a great fit for this application. Megafol® can also help relieve crop stress and improve nutrient uptake. Utilize® PK can also improve nutrient acquisition by inducing the plant to produce enzymes responsible for Nitrogen and Phosphorous uptake, namely nitrate reductase and phosphatase.  It also improves chlorophyll production. This helps the plant build energy reserves to store in its buds, limbs, trunk and
roots.

When planning your fall fertility strategies, remember that what you are doing now will have a positive impact on next year’s crop. Many tools are available to help you achieve this goal.

- Dave Cheetham, Product Manager, Northern California