{Arachis hypogaea}

Boron Deficiency in Peanuts

Boron is critical to peanut quality. While boron fertilization may only occasionally improve peanut yields, it almost always is necessary for the prevention of “hollow heart” and other concealed disorders that severely reduce crop value.

Peanuts need a constant supply of boron during all stages of growth, but especially from flowering to harvest. Fertilizing with boron will help peanuts:

  • Improve root nodule development for more nitrogen fixation and protein production
  • Produce and retain more flowers and pegs
  • Enhance calcium utilization
  • Move sugars and protein from leaves to nuts
  • Prevent “hollow heart”

Symptoms of boron deficiency are particularly evident in the nuts and are not frequently found on the foliage. While the effects on yield may be slight, a boron deficiency can markedly reduce the quality of the crop and the yield of marketable peanuts. The main symptom is a hollow darkening of an off-color area in the center of the cotyledon. Depending on the severity of boron deficiency, the depression may vary from being shallow and slightly colored to being deep and dark brown. Cracks may also develop on the pods.

The first sign of boron deficiency on the typically dark green leaves is the development of water-soaked areas, which give the leaves a mottled appearance. Prolific secondary branching occurs on short woody stems after dieback of terminal growing points.

When boron deficiency is less severe, flowers aren't followed by any fruit development, possibly as a result of pollen tubes failing to grow properly. When boron deficiency is extremely severe, flowers don't develop.

How much boron is enough?

Use these guidelines to reduce the chances of a boron deficiency:
  • Peanuts are typically grown in light, sandy, well-drained soils, which are inherently low in organic matter, including boron
  • Since boron is also readily leached from these soils, small annual boron applications are recommended to ensure an adequate crop supply during each growing season

Your boron fertilizer options

  • Granubor® is an ideal material for dry-blend fertilizers applied broadcast preplant or surface banded.
  • Fertibor® works best in fertilizer suspensions for preplant broadcast or band sprayed over the row.
  • Solubor® allows you the most flexibility for applying boron; it can be dissolved alone in water or in liquid fertilizers and/or pesticides, then applied to the soil or directly onto the foliage.*

Peanut fertilization

University research and field experience has led to the general peanut recommendation of 0.5 lb of actual boron per acre per year. Currently, the preferred practice is to split the fertilizer application by applying 0.25 lb of boron before the early bloom stage (tank mixed with leafspot fungicide or in the irrigation water) followed in two to four weeks at early bloom with another 0.25 lb. This ensures that boron is available to the peanut during flowering and fruiting, its time of maximum need.

As an alternative, 0.5 lb of actual boron per acre can be incorporated with other pre-plant, broadcast fertilizers or herbicides. Rates of boron fertilization should be based on soil tests and/or plant analyses, along with field histories, yield goals, varieties, and application methods.

Irrigated fields, or fields that have a history of serious "hollow heart," and/or fields planted to a high-yielding, large nut variety may benefit from split soil and foliar applications totaling up to 1.0 lb of actual boron per acre per year.

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

Soil Application (Suggested rates of application)

  Granubor Fertibor
LBS/ACRE 2-3 2-3
KG/HA 2.25 - 3.38 2.25 - 3.38

Foliar Application (Suggested rates of application)

KG/HA 1.125 - 2.25
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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