David Doll4 CommentsMarch 6, 2022General

Considerations for March 2022

March is a month full of surprises. Weather can be highly variable, with rain, risk of frost, and heat waves all being possible. Below are some points to consider as the season progresses. Ongoing frost concerns. Frost conditions can occur through the end of March. Maintain a watchful eye on the weather conditions to reduce the risk of any frost event. Critical temperatures after petal fall are around 28F (-2.2C), and temperatures at or below 28F for an extended period will cause crop loss. Micro-irrigation can increase orchard temperature by a few degrees, with higher flows of water providing a greater warming effect. More on frost mitigation can be found here. With irrigation occurring during multiple frost events, it is common to see trees push slow and with pale green growth. This is due to saturated rootzones that lead to loss of fine feeder roots and low micronutrient uptake. Soil irrigation levels should be monitored, and irrigation withheld until stored soil moisture begins to drop. Furthermore, nitrogen applications should not occur during the period of frost risk as running water for extended periods of time will leach nitrogen out of the rootzone. Crop losses from frost are hard to define in early March. Frost affected flowers will have blackened tissue inside the ovary, or flowers may appear blighted and remain on the tree. Trees will slightly compensate for loss of flowers with a slight increase in fruit set percentage of the remaining flowers as well as greater nut size. Therefore, in areas of minimal damage, the impacts might not be observed. In areas with losses greater than 10%, yield reductions should be expected. If frost damage is suspected, it is important to contact any insurance company as soon as possible and trim the early season fertilizer applications until a better

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David Doll0 commentsSeptember 19, 2017Nutrient

Almond Postharvest Management: Nitrogen Considerations

Written by David Doll (UCCE Merced) and Franz Niederholzer (UCCE Yuba-Sutter-Colusa) Applications of nitrogen in the postharvest period have been promoted as a good farming practice.* Trees utilize nitrogen at this time to rebuild nitrogen stores and provide nutrients for bud development. Research from the Kern County nitrogen trials found that trees can absorb approximately 15% of annual nitrogen demand in the 8 weeks after harvest (30-45 lbs/acre, excluding application inefficiencies). This work was done in a highly productive orchard (3000+ lbs/acre) and applications were applied as multiple fertigation events through the entire year. Fertilizer nitrogen applications should be made as soon as possible after harvest to allow the trees the most time to absorb fertilizer nitrogen before the leaves drop, when root nutrient uptake essentially stops. Whole almond tree nitrogen need after harvest is much less than in the spring (no shoot growth or crop), therefore fall fertilizer nitrogen needs are relatively minor compared with leaf out to hull split.  Fall nitrogen fertilization need is further reduced by remobilization of leaf nitrogen into woody tissue storage as trees prepare to drop their leaves in November (if they are not burned off with zinc sulfate.) Interestingly, recent research suggests that late postharvest fertilization (October) can be skipped if mid-July leaf nitrogen levels are adequate (over 2.5% nitrogen). This work by Franz Niederholzer conducted at the Nickels Soil Lab in Colusa County has found no negative impact on yields when skipping postharvest nitrogen applications within orchards over the past two years. In this trial, trees had mid-July leaf nitrogen values of 2.55% or greater. Trees receive 0 or 30 lbs/acre of postharvest nitrogen in mid October. Trees didn’t receive late zinc sulfate foliar spray and maintained leaves up to or through Thanksgiving. Over the past two years, there were no differences

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David Doll6 CommentsMarch 7, 2014Nutrient

Almond Nitrogen Uptake: Seasonal Perspective

There has been a lot of workshops and seminars discussing nitrogen management in almond. The data and conclusions discussed from these trials has been thought provoking, and has provided information to help better manage almond orchard nitrogen.  One particular slide has caught my attention – and provides the basis of nitrogen timings for almond orchards.

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Franz Niederholzer1 CommentSeptember 9, 2013Nutrient

Sustainable Nutrient Management: a Review.

Almond harvest looks to be progressing well (knock, knock).  Orchard fertility/nutrition planning for the 2014 is beginning.  Now is a good opportunity to review the basics of almond orchard nutrient management.  While some of what follows will be review for many readers, a quick review may be of value. Sustainable nutrient management comes down to the four R’s – the Right Rate, the Right Time, the Right Place, and the Right Material.  A sustainable approach to orchard nutrition is intended to optimize crop production and maximizing net profit while reducing the risk of environmental contamination.

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David Doll8 CommentsAugust 17, 2013Nutrient

Postharvest Fertilization – Q&A

Q. How much nitrogen should be applied in the postharvest period? A. This depends.  This should be based upon the current tissue N levels detected from mid-July sampling. If within the prescribed ranges of leaf N (2.2-2.5%), 20% of the budget should be planned for application. If richer (>2.5%), slightly less can be added. If really high N leaf levels are observed (>3.0% in mid-July), postharvest fertigation may not be needed. 

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Franz Niederholzer0 commentsApril 20, 2013Nutrient

A quick review of UC ESP sampling for accurate almond orchard nitrogen fertilization.

This is the first year that the UC Early Season Protocol (UC ESP) model for predicting July almond leaf nitrogen (N) levels from April leaf samples, has been available for public use.  This model was developed by UC Davis researchers led by Dr. Patrick Brown.  Based on calls to several reputable ag labs and questions from PCAs, there seems to be some uncertainty about availability and use of the new model.  Where is the model?  How does is it used?  Who should use it to develop the July leaf N prediction and what should be done with the results?  Does an analytical lab run it for growers and PCA/CCAs?  If the lab doesn’t do it, should/can the grower or their PCA/CCA to do it, and, if so, where is the model?  This blog post is intended to answer these questions and help interested almond industry members use the UC ESP model.

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