{Brassica napus var. oleifera}

Boron Deficiency in Canola

Canola (rape seed oil), like all its relatives in the Brassica family, has a very high boron requirement and is severely affected by boron deficiency. Canola seed production is critically dependent on boron—so much so that grain yields have been doubled when 2 lbs of boron per acre were applied to canola fields that showed no visual abnormalities.

Canola needs more boron through all growth stages—vegetative and flowering—than most other crops. Ensuring that canola has adequate boron will:

  • Stimulate root growth and early establishment
  • Enhance vegetative growth and speed maturity
  • Increase branching and flowering
  • Increase flower retention and pollen germination
  • Enhance nitrogen utilization to increase oil percentage
  • Increase the number of pods that set and fill

Although boron deficiency can markedly affect vegetative growth, it is more usual to find that yields are reduced by the deficiency even when the plants show no obvious symptoms. This is probably due to the fact that boron is required for pollination and because a slight deficiency can result in poor seed set, even though pods may be formed. Brown necrotic areas which form in the pith of the stem may be one of the earliest signs of boron deficiency.

When the deficiency is severe the new leaves will be very deformed; they may have cracked petioles and be bent back. Stem elongation will be restricted, the plants will be stunted, and ultimately the growing point may die. Branching may be excessive.

How much boron is enough?

  • Canola is grown in all types of soils and in all climates, from Alaska and Canada all the way to Florida. Consequently, boron fertilization needs and practices vary.
  • Many growers simply apply boron with their other preplant incorporated fertilizers. This practice may not be effective on fall-seeded fields with soils that are prone to leaching or fixing boron.
  • Research and experience show that multiple—or preferably, foliar—applications made up to flowering consistently result in the highest yields.
Rates of boron fertilization should be based on soil tests and/or plant analyses, along with field histories, yield goals, and application methods.

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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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.

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