Zinc is a critical micronutrient for all deciduous crops. It is a component of chlorophyll, which serves as the mechanism converting sunlight into carbon to enable nut development. Retired UC Farm Advisor Bob Beede spoke about the importance of zinc at the recent Central Valley Almond Day, hosted by West Coast Nut. “If you get deficient in zinc, you’re going to find yourself behind the 8-ball,” Beede noted.
Zinc is a critical element of the enzyme system regulating fruit set and flower bud formation. Zinc is crucial to cell elongation which is a precursor to the development of auxin. A lack of zinc will ultimately result in auxin deficiency which will prevent cell enlargement in stems and leaves.
Beede served Kings County as a horticulture specialist for over 35 years. He noted that “first and foremost, growers need to have their feet in the furrows,” to identify zinc deficiency. Symptoms include small, narrow and pointed leaves, along with the failure of internodes to elongate and poor fruit set. Growers should also be on the lookout for the cessation of terminal growth.
Deficiencies can be the result of several different causes including the regular use of manure in orchards. High phosphate concentrations in cow manure can be problematic when almonds are planted in ground that has had routine applications. Those high phosphate levels essentially trap zinc in the soil, preventing it from being used for plant growth.
Listen to Bob’s full interview.