California Citrus Newsletter

January 2025

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Increase Fruit Set with Citrus Winter Fertilization

 

As the demand for early citrus varieties slows down after peaking a couple of months ago, growers seek alternatives to secure better returns, especially those with larger fruit sizes. There are big citrus crops this year which have caused there to be a lot of smaller fruit coming to the market. A large citrus crop most definitely requires more nutrition, particularly when trying to maximize fruit size and quality.

Fall Tissue Analysis: Time to Act Upon Results

Did you remember to take or recommend a fall tissue analysis? This analysis is both a snapshot of what has happened and an indication of what we can anticipate to happen com springtime. Deficiencies noted or visually seen need to be addressed. Visit your 2024 executed plan and make notes for 2025 improvements. Look at nutrient demand curves for your citrus and make sure you meet these timely nutrient needs.  

california citrus orchard

The goal of balanced N, P, K, Ca, Mg, and micros nutrition is one of the most important factors that affect quality, set, size and yield, and storage potential of citrus fruit. A solid citrus crop fertilizer program that provides all essential nutrients when the crop demands them is critical.

Winter Pre-bloom Fertilizer Applications

January to mid-February is the best time to apply foliar nitrogen to citrus. Foliar applications of low-biuret urea made during this time have been shown to increase fruit set, ultimately yield. Based on Dr. Carol Lovatt’s research, just 0.35 lbs N/tree has been shown to increase yield (set and size) in mature navel orange trees. These applications have already started for the 2025 season with most citrus growers applying anywhere from 25lbs to 50lbs/acre.  

california citrus harvested

 A combination of lo-bi urea with other essential nutrients and crop protection products (phosphites) applied via foliar can be more effective than just applying a single nutrient. This is a great way to get ahead and stay ahead of any deficiencies that might be present and also to boost tree health before flowering. There are many nutrients that must work together during the growing season, but especially keep an eye on those needed early on. All micronutrients play a crucial role in overall citrus health and productivity. They enhance the accessibility and movement of macronutrients and keep the entire tree physiology functioning at a high level.  

Manganese supports photosynthesis, enzyme activation, and plant protein metabolism. Manganese deficiencies-chlorosis in citrus are very common and can decrease optimum photosynthesis.

Zinc is used for hormone production, protein synthesis and carbohydrate metabolism. Deficiency symptoms are most obvious in the early season. Trees that are deficient will have slow leaf out, reduced leaf size, and stunted shoot growth (rosetting).  

Yara's solution providing foliar Mn and Zn:
Nutra Spray ZM 
10% Ca, 18.5% Zn, 7% Mn   
 

Getting citrus trees off to a strong start begins with lo-bi urea and a foliar micronutrient product containing Mn and Zn!  


Vanessa Vicencio

Sales Agronomist at Yara North America - South Central Valley, California

vanessa.vicencio@yara.com


 

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