Cotton plants need Boron throughout their life cycle, but maintaining adequate availability of this important micronutrient is crucial to blooming cotton.  Even though small amounts are needed, Boron is essential for healthy growth during flowering and boll development, and aids in the efficient utilization of other nutrients, particularly nitrogen and potassium.

Because Boron is immobile in the plant, deficiency symptoms appear on new growth.  Boron deficiencies may show some of the following symptoms:¹

  • Abnormal uppermost leaves
  • Aborted flowers
  • Abnormal shedding of squares and young bolls
  • Abnormal fruit shed which can result in excessive vegetative growth and reduced yields
  • Dark green rings on leaf petioles
  • Petioles that are shorter and thicker than normal
  • Ruptures at the base of squares or blooms or on the stem that supports the squares
  • Death of the terminal bud and shortened internodes near the top of the plant, resulting in a stunted and many-branched plant
  • Mature bolls that are small, deformed and do not fluff normally

Boron is prone to leaching because it is mobile in the soil and very water soluble.  Factors that affect Boron availability include soil type, soil PH, lime application timing and organic matter content.  Boron deficiencies are more likely to be a problem in sandy soils, sandy loam and loam with neutral (6.0-7.0) to high (>7.0) soil pH, and in clay loam and clay with high soil pH (>7.0).  Dry weather can also decrease Boron uptake.

The use of tissue tests to monitor Boron levels is highly recommended as an aid to maintain correct levels for optimum plant growth and to avoid over-application which can be detrimental to the crop.

If your cotton needs Boron, Coastal’s Nutrisol 10% Boron should be included in your crop fertility program.  Nutrisol 10% Boron is a premium formulation designed for soil or foliar application.  In foliar applications, Nutrisol 10% Boron mixes readily with other fertilizers and crop protection applications (such as for stinkbugs or plant bugs), giving you several opportunities to include Boron in a tank mix.  Apply 1-2 quarts per acre in enough water to provide maximum coverage and use the recommended nonionic adjuvant to improve coverage and translocation.

Boron’s role in plant development:

  • Essential in formation of pollen grains and tubes
  • Essential for seed production and fruit development
  • Essential in cell wall formation
  • Regulates carbohydrate metabolism in plants
  • Essential for protein synthesis
  • Essential for translocation of sugars and starches
  • Regulates starch production
  • Helps in the use of nutrients and regulates other nutrients
  • Aids in terminal bud formation
  • Enhances quality
  • Aids in nodule formation
  • Enhances disease resistance

Information provided by Coastal AgroBusiness, Inc. Original post 7/21/2015.

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¹ Deficiency symptoms source,,