January 2021, Issue 8

Shelling Out Useful, Real-World Almond Knowledge

As we continue to move into almond bloom, the time to start is now. Every month brings new needs and new possibilities to your orchard, so we’ve done our best to put together the following advice for your almonds
Frost Damage & Protection in Almonds
A great set of written resources on the topic of frost damage and protection in almonds can be found at this site. The basics involve mowing any cover crop and irrigation to warm the microclimate within orchards. The decision about when to start and stop irrigation for frost protection should be based on both expected low temperature and humidity in the orchard.
The objective of irrigating during potentially damaging frost events is to warm the air by two different processes. First, water within the soil retains heat that is then radiated back into the trees when temperatures drop. Secondly, as water freezes, heat is released in the orchards. Please read the article from Dr. Richard Snyder, UC Davis Bio-meteorologist, for more detailed information. As can be seen in the table below, almonds are quite tolerant to cold temperatures during bloom until temperatures drop to the 26-27OC range, then crop loss can be very significant. Almonds are most sensitive to frost damage later during leaf out and small nut stage.
Weather permitting, the Wilbur-Ellis Western Research Team will be working with a foliar nutritional product that has been observed to provide very favorable frost protection in a commercial citrus grove.  Studies on almonds are planned for 2021 to determine both efficacy and crop safety during this sensitive growth period. We have every expectation for success, but research is needed before we can move forward with confidence. Stay tuned!
Click Here for the Almond Doctor Resource
Carl Bruice, Wilbur-Ellis National Nutrition Technical Manager
Micronutrients in Almonds
As many growers and PCA’s are looking forward to almond bloom, focus is typically centered around fungicide timing as well as FRAC Group selection. Bloom time fungicide applications are vital in protecting the initial development of the crop but many agronomists and PCA’s would argue that bloom time foliar nutrition is just as important.
Last year’s heavy crop load consumed large amounts of nutritional resources, particularly from nut fill through the post-harvest period, likely affecting this year’s bloom. Injecting micronutrient nutrition into developing buds and nuts through foliar nutrition will be critical this year as trees recover from these record crops. Micronutrient nutrition during the bloom period can be viewed as an opportunity for cost savings but is actually a very important opportunity to start orchards off on the right foot.  

The most impactful micronutrients during this period are boron and zinc. Boron plays an important role in both meristematic cellular differentiation and pollen tube elongation.  Zinc is an important nutrient for flowering, pollination, and is an activator of various enzymes. Both nutrients are critical while flowers are being pollinated, embryos are being developed through mitosis and meiosis, and while leaves are starting to emerge and expand. Micronutrient leaf tissue analysis during the mid-late summer period in 2020 can be an important indicator of zinc and/or boron need during this year’s bloom period. Other indicators such as hull boron analysis, high soil pH, or high phosphorous application rates (zinc) should be considered, as well when developing a foliar bloom plan.  

*It is important to note that iron (Fe) is a difficult nutrient to assess via leaf tissue analysis because symptoms can still appear when tissue levels are adequate.
** Copper (Cu) is not a common nutrient applied during the bloom period but can be addressed through spring soil-applied fertilizer blends or as chelated copper injected into irrigation systems.

The table above represents almond leaf tissue samples (900+ samples) taken throughout the Northern San Joaquin and Sacramento Valleys with the percentage of samples found outside of the appropriate mid-summer sufficiency range. This macro view of nutrient status indicates that it is quite common for insufficient zinc and boron levels to be found across these growing regions. The table shows 47% of the sample set were below the adequacy level for boron (~40 ppm), while 35% of the sample set were outside the sufficiency range for zinc (20 ppm). This tells us that a significant number of growers could greatly benefit from the application of foliar micronutrient fertilizers when applied in conjunction with fungicides during the pre-bloom (pink bud) period. When such applications are made prior to flower opening, growers can meet the steep nutrient demand by trees during this time. Wilbur Ellis’ research indicates that foliar applications of boron to open flowers do not provide the same yield-enhancing benefits when compared to pre-bloom applications. 
Matt Comrey, Wilbur-Ellis Technical Nutrition Agronomist
Making Wave with Nutritional Efficiency
FOLI-GRO® TIDALWAVE is a seaweed-based nutritional product that can act as a food source for soil microbial populations.
Download Sell Sheet
Effectively Control Naval Orangeworm
Spear Lep is a peptide-based bioinsecticide that provides broad-spectrum Lepidopteran control and the superior safety profile of a biological product but has the efficacy and specificity of a synthetic product on tree nuts. Spear-Lep is a novel mode of action IRAC Group 32 biological product that can be used as a resistance management tool for the stewardship of certain major synthetic chemistries while still allowing growers to maintain biological safety profiles and lepidopteran control.
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To learn more about which products are right for you, visit, or contact your local Wilbur-Ellis representative today.

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