Welcome to the Ultra Gro Agronomy Letter!
Welcome to the May/Memorial Day edition of the Ultra Gro Agronomy Letter. During this holiday, we honor the men and women who made the ultimate sacrifice for our freedom, along with their families. We also want to say thank you to our Veterans and current men and women in the armed forces that have dedicated their lives to protecting our nation and people.  Thank you and God Bless America!

In this issue, we speak to three timely topics: 1) foliar sprays and their benefits in helping us save money and play catch-up, 2) bud retention in pistachios, and 3) “Excite” dry-powder kelp!  Teaser alert: we will be sending another Agronomy Letter asap regarding the almond crop estimates.  Happy Memorial Day.
To Foliar Feed, Or Not to Foliar Feed?
By Robert Smith, Agronomist
Decisions continue to be made about whether to go with May/June sprays on almonds. As always, opinions vary, depending on an orchard’s history, sanitation efforts, trap counts and other points like mating disruption strategies. Pistachio growers are applying foliar nutrients – mainly zinc and copper while adding magnesium and micro blends as needed, based on leaf analysis. Now is the time to maximize your nutrient program with a well-timed foliar spray application.

Foliar nutrient applications to tree, vine and nut crops have become a normal practice in production agriculture during the past 20 years—by definition, foliar feeding is the application of crop nutrients in a liquid form onto the plant’s leaf surface. The foliar nutrients enter the plant through the leaf stomata, leaf cuticle, and hydrophilic pores in the leaf cuticle (not just through leaf stomata).

The effectiveness of foliar applied nutrition early studies concluded that foliar applied nutrients were 8-10 times more effective in supplying the required nutrients than soil applied nutrients. Other work has established the equivalency of foliar applied nutrients to be up to 40 times more effective than soil applied nutrition. 

As growers are looking to maximize net returns and nutrient efficiencies, the application of foliar nutrition is making its way into many of the progressive growers’ crop nutrition programs. Growers are experiencing the positive effect this strategy has on increasing crop yields, nutrient efficiencies and reducing the impact that environmental factors impose on their nutrient programs.

Here are a few of the possible benefits and concerns around foliar feeding.

Benefits of foliar feeding
  • Nutrient efficiency with foliar applications is more efficient than soil-applied fertilizer (due to insect root damage, soil drainage, drought conditions, soil pH and other soil stresses).
  • Eliminates soil interaction with the nutrients being applied—foliar feeding is not affected by soil pH.
  • A convenient way to apply small amounts of certain micronutrients that roots cannot supply from the soil.
  • Speed of reaction time to correct deficiencies—plant response time is quick to address symptoms.
  • Corrects nutrient shortages for maximum production after plant growth has begun.
  • Is used as a supplemental fertility program following a regular soil and/or tissue test.
  • More Bang for the Buck (always take advantage of a free ride!)…we can use less material upstairs and achieve equal results

The initial benefit of a foliar application is an increase in chlorophyll synthesis which can often result in leaves turning a darker green. The increase in photosynthetic activity will stimulate extra root growth; in turn the root hairs excrete excess sugar which stimulates microbial colonies. These bacterial colonies provide auxins and other root stimulating compounds. With the increase in cellular activity gas exchange increases the uptake of water. As the roots take up more water, they also bring in more of the nutrients from the soil solution. The foliar application stimulates the entire “pumping system” in the plant to increase the uptake of the base (soil) applied nutrition.

Tissue testing helps ID nutrient deficiencies before you see them in the field…
Tissue tests taken on a growing crop can identify nutrient deficiencies before you see them and help determine if your crop might benefit from a foliar fertilizer application. Most tissue tests are not taken until some type of deficiency has been seen—tissue tests are sometimes used as a follow-up step to confirm results of soil test results—but it is more effective to conduct tissue tests proactively to find out if your crop is experiencing a micro-nutrient shortage. At the end of the day, we have found that proactively addressing these deficiencies can really make a difference…and using a foliar is often the fastest way to get the job done.
Pistachio Nutrition and Bud Retention for Next Year's Crop
by Robert Smith, Agronomist
Pistachio growers need to manage three physiological conditions. The first is alternate bearing, an annual fluctuation of large crops with poor crops. The second is the production of blank, or unfilled nuts. The third is non-split nuts, nuts that fail to split along. All three problems seem to be related to crop load and are consequently related to carbohydrate and nutrient competition.

Pistachios bear on 1-year-old shoots from ancillary buds produced the previous year. As the trees age, they develop an alternate bearing pattern with “on and off” years. Evidence suggests that it is a problem of carbohydrate and nutrient competition. During the period of nut fill in July, the fruit buds opposite to fruit clusters die and abscise. The heavier the currently borne crop, the greater the subtending bud abscission. Thus, following an “on” crop year, an individual branch may bear no fruit. Only pistachios possess the phenomenon of premature bud abscission being the cause of alternate bearing.

Alternate bearing can be initiated by climatic conditions that result in a low yielding off-crop year, such as insufficient chilling that results in a low number of flowers at bloom, or temperature extremes during flowering, fruit set or June drop that result in excessive flower or fruit abscission. Conversely, when these factors are optimal and little flower or fruit abscission occurs, a heavy on-crop results. For pistachio, the mechanism by which fruit number one year influences the return bloom and yield the next year was identified more than 30 years ago (Crane and Nelson). During the on-crop year, excessive abscission of floral buds beginning with the initiation of embryo growth in June and intensifying during the period of rapid embryo growth.

This year seems to be a heavy nut set “on” year, so what can you do to retain the buds for next year’s crop and mitigate alternate bearing the following year? The more fruit present on shoots or branches, the more buds drop. Fruit load on a branch can also affect the bud abscission on a neighboring branch. It was also found that even 20 fruits per shoot can induce up to 100% bud abscission (Crane and Nelson, 1971; Porlingis, 1974).

Alternate bearing is due to excessive abscission of floral buds for next year’s crop during the heavy on-crop year. Floral bud abscission begins with the initiation of embryo development (June) and proceeds through the period of rapid embryo growth (July).

Lovatt, Daoudi, and Ferguson demonstrated successfully increased pistachio bud retention approximately three-fold with the use of foliar applications of L.B. urea and seaweed extract (cytokinin) applied in early June and again in early July, vs the “untreated control”. This treatment also significantly increased the number of split nuts.

Concentrations of cytokinins decreased 40% from the initiation of embryo growth in June to early in the period of rapid embryo growth in July. Cytokinins are well known for their role in maintaining sink strength and in preventing senescence. Reduced cytokinin concentrations would likely contribute to “weakening” the sink strength of floral buds making them less able to compete for resources against the developing fruit. In addition, low cytokinin concentrations in the floral buds might contribute to their senescence and, hence, abscission.

In their 5-year trial the use of 0.25% N as L.B. urea and 1% seaweed extract in early June and again a month later gave the greatest benefit.
Ultra Gro has acquired the trade name and exclusive marketing rights to “Excite” soluble seaweed powder. Formerly owned and developed by Tulare Ag-Products, Excite is a tried and true dry-powder kelp product that has a large following, across multiple crop-types.  We are grateful to Carl Gwilliam for the opportunity to take over this product and build the market.

Excite soluble seaweed extract powder 0.5-0.17 contains a complex mix of synergistic bioactive compounds that allow plants to reach their full yield potential. Excite is derived exclusively from Ascophyllum Nodosum, it is produced using leading edge technologies that extract, preserve and create bioactive components of this seaweed extract.  It improves plant quality and productivity by enhancing root growth, improving overall plant nutrition, and bolstering tolerance to challenging growing conditions.

Increase your pistachio yields by driving strong early growth, nutrition uptake and stress management with Excite. Working at the cellular level, it reduces the negative effects of stress and increases carbohydrates production and for pistachios, less bud abscission. You will see better yields not just this season, but next year too (proven benefits for bud retention)!

Excite enhances your nutritional program by improving crops’ nutrient uptake. When you apply Excite as part of your regular application program, you’re putting nutrients on the fast track and ensuring your plants get the most out of every ounce of fertilizer. Strong growth throughout the season ensures large, quality fruit. Excite contains natural complexing sugars which bind to micronutrients, thereby improving their bioavailability and translocation within the plant.

  • Improves plant establishment, development, and growth — Improves root initiation, elongation, and branching, leading to improved plant establishment and greater uptake of water and nutrients.
  • Maximizes crop potential during stress conditions — Activates antioxidant production and increases water retention, which reduces the impact of environmental stresses including drought, salinity, heat, and chill.
  • Improves plant nutrient uptake — Containing natural chelators that bind to micronutrients, improves the bioavailability and transport of nutrients within the plant.
  • Improves crop size and uniformity — Improves photosynthesis for greater plant productivity by increasing chlorophyll production within the plant.
  • Enhances yield — helps plants produce energy. Its components act as precursors that encourage plants to produce new active compounds, which in turn boost crop quality and yield.
  • High in Cytokinins

Excite soluble seaweed extract powder is widely used as a plant bio-stimulant, which aim to promote plant growth, enhance abiotic stress tolerance, improve nutrient uptake as well as including antioxidant properties. CHECK IT OUT…Call your UG Crop Advisor…
Please call your Ultra Gro Crop Advisor if you have any questions.
Thank you!