{Theobroma cacao}

Boron Deficiency in Cocoa

One of the first signs of boron deficiency is profuse chupon formation and the appearance of a few curled leaves which are almost normal green in color. When the deficiency is mild, normal and boron-deficient flushes may alternate. As the deficiency progresses, leaves on the new shoots become very chlorotic and are distorted and twisted. Most of the leaves that are formed under conditions of acute boron deficiency fall before they harden. The leaves that mature become brittle and rough; they remain green but the formation of necrotic patches at the leaf tips is common and is the most typical symptom. Suberization of the veins also occurs.

Profuse flowering on the main stems and branches can be expected and the flower cushions may swell. Ultimately, the terminal buds die as may the axillary shoots which subsequently develop. The growth habit becomes bushy. The trunk and branches may crack and tend to bleed.

Boron is essential for normal flower formation and especially for seed set. Pollen viability and growth of pollen tubes can be reduced by boron deficiency resulting in parthenocarpy and distorted pods; the vascular traces in the pods may become brown and necrotic. Care must be taken to confirm a boron deficiency that is suspected on the basis of pod distortion and to eliminate from consideration the insect Bathycoelia thalassina, which can also cause pod malformation.

Boron deficiency is more readily shown in Amazon cocoa than Amelonado. This may be associated with the more rapid growth and high yields of Amazon cocoa which, being a more shallow feeder, may be more susceptible to drought-induced boron deficiency.

Spotting Boron Deficiency in Cocoa

U.S. Borax Products

15% Boron |  | OMRI Certified
Optimum product for suspensions

A fine crystalline borate ideal for NPK compound fertilizers and suspensions. Manufactured as free-flowing granules, Fertibor is easily handled and offers superior flow and consistency.

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15% Boron |  | OMRI Certified
Made especially for bulk blenders

A pure, 100% water-soluble micronutrient that meets boron demand during the growing season. Made especially for bulk blenders, Granubor helps to ensure uniform distribution in nutritional blends and in the field.

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20.5% Boron |  | OMRI Certified
Product of choice for foliar applications

A concentrated, highly soluble, and fast dissolving powder that is ideal for foliar and other sprays. With the highest concentration of boron in any approved product, Solubor is an economical choice for nutritional formulations.

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20.8% Boron
Boron for fertilizer manufacturing

This refined U.S. Borax product is made from the dehydration and fusion of borax. Depending on the grade, Anhybor can be used to produce boron-enriched compound fertilizers or to coat different fertilizer products, such as NPK blends with the aid of a binder.

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10% Boron
Solubor Flow
For fertigation or hydroponic growing

First and only aqueous suspension of sodium borate microcrystals.

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14.5% Boron | 29% Zinc
Perfect combination of zinc and boron

Because zinc and boron deficiency are widespread around the world, a product with both nutrients is a good fit in many regions. Zincubor brings these two important micronutrients together in one product.

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Soil Application (Suggested rates of application)

  Granubor Fertibor
LBS/ACRE 18-36 18-36
KG/HA 20.25 - 40.50 20.25 - 40.50

Foliar Application (Suggested rates of application)

LBS/ACRE 12-25
KG/HA 13.5 - 28.125
Value in Use
Current Yield (Per Acre)
Expected Sale Price

U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles. Learn more about Rio Tinto.

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