Vineyard Nutrient Management
Essential Plant Nutrients
Boron
Role and Deficiency Symptoms
Boron's key roles in the vine include its effects on pollen germination and growth, in addition to bud development, and root growth.
A classic symptom of boron deficiency is low bud break followed by slow shoot growth with short internodes and a “zigzag” growth pattern. Numerous lateral shoots will grow from the stunted shoots, giving the plant a bushy appearance.
Assesing the Need for Boron Fertilizer
As with most micronutrients, tissue sampling can be used to determine the vines’ boron status.
Time of Application
A foliar pre-bloom boron application is often recommended, 2 to 3 weeks before bloom, unless tissue results are unusually low in which case a second application is made at the start of bloom.
Application Methods
Direct Soil Surface Application: Boron is often applied in the fall to the soil by broadcasting or applied with banded herbicide sprays by merely adding the correct amount of soluble boron.
Fertigation: Fertigation is a relatively simple, cost-effective and efficient way to apply nutrients.
Foliar Application: Boron fertilization is most effectively achieved with a soluble boron foliar-applied fertilizer (e.g., Solubor).
Soil Factors Affecting Availability
Boron deficiency occurs mainly on alkaline soils (pH greater than 6.5), acid soils (pH 3.5 to 4.5), soils low in organic matter, or on sandy, gravelly soils.
Boron Toxicity
Boron is unique among the micronutrients due to the narrow range between deficiency and toxicity in soil and vine tissues. For grapevines, this range is 0.15 ppm to 1 ppm in saturated soil extracts, and 30 ppm to 80 ppm in leaf tissue (Peacock, 2005).
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