{Gossypium spp.}

Boron Deficiency in Cotton

Boron has been universally recognized as the most important micronutrient for cotton production. It is essential at all stages of plant growth, and critically so during fruit development—especially with today’s fast-fruiting, high-yielding varieties. University research shows that using as little as 1 lb of boron fertilizer for cotton plants can increase seed cotton yield by more than 500 lbs per acre.

Boron is an essential element that cotton needs during all stages of growth and fruiting. Supplying adequate boron fertilizers will help cotton:

  • Develop and retain more squares
  • Increase cotton plant bloom pollination and boll set
  • Move nutrients and sugars from leaves to the fruit
  • Produce strong, well-developed fibers
  • Speed maturity

Symptoms of boron deficiency in cotton

Severe symptoms of boron deficiency in cotton appear infrequently. However, boron deficiency without the appearance of any visible foliage and flower symptoms can significantly limit the yield of seed cotton. 

Apart from flower and boll shedding in cotton, many symptoms on the leaves, petioles, flowers, and bolls have been described. However, don’t expect to see all of the symptoms simultaneously in any one field.

One characteristic symptom of boron deficiency is the development of bands (often excessively hairy) on the petioles. The tissue there is typically dying. As a result, the terminal bud often dies. Many lateral branches with short internodes and enlarged nodes then develop. The leaves, which usually do not show any malformation, remain green until the first frost. In cases of severe boron deficiency in cotton, excessive and abnormal vein development results in leaves buckling and irregular leaf shapes.

The cotton plant petals are frequently crumpled and misshapen. Excessive boll shedding in cotton can occur, in both squares and young bolls.

Discoloration of the extrafloral nectaries in cotton is also common due to boron deficiency. Cracks may develop on the stems, at the base of the squares or bolls, and drops of fluid may leak out.

Spotting Boron Deficiency in Cotton

How much boron is enough?

  • Since boron is essential for the transfer and assimilation of sugars and nitrogen into complex carbohydrates (fiber) and protein, demand for this element is greatest during lint and seed development
  • It is also during this time that boron is actually least available in non-irrigated soils due to dry conditions
  • Cotton is especially vulnerable to boron deficiency during a drought that was preceded by heavy rainfall
  • Cotton is also vulnerable after a drought is broken, when there is sudden flush of growth and fruiting—especially if nitrogen is plentiful

Your boron fertilizer options

  • Granubor® is an ideal material for dry blends that are applied broadcast preplant or sidedressed
  • Fertibor® works best in fertilizer suspensions for preplant broadcasts, sidedressing or band sprayed over the pre-emergent seed row
  • Solubor® allows you the most flexibility for applying boron. It can be dissolved alone in water or in liquid fertilizers and/or pesticides and then applied to the soil or directly onto the foliage*

*Foliar sprays should not exceed 0.5 lbs/acre of boron per application.

U.S. Borax Products for Cotton

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.

Learn more →

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.

Learn more →

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.

Learn more →

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.

Learn more →

10% Boron
Solubor Flow
For fertigation or hydroponic growing

First and only aqueous suspension of sodium borate microcrystals.

Learn more →

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.

Learn more →

Calculate Your ROI

Soil Application (Suggested rates of application)

  Granubor Fertibor
LBS/ACRE 6.25 - 12.5 6.25 - 12.5
KG/HA 7.0 - 14.0 7.0 - 14.0

Foliar Application (Suggested rates of application)

KG/HA 2.8
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.

Copyright © 2024 Rio Tinto. All Rights Reserved.