Boron Deficiency (AND TOXICITY)
Boron plays an important role in the structure of cell walls, fruit set and seed development. It is also a component of protein and carbohydrate metabolism.
Identification
Shoots
- Shoot tips and clusters wither and die
- Swellings with dark pith in younger internodes
- In the second season, short, bushy, branched, sterile shoots
Leaves
- Youngest leaves most affected
- Small and cupped
- Short thick petioles sometimes with lengthwise lesions
- Misshapen with interveinal chlorosis or necrosis
Berries
- Only a few seeded berries set
- Small, seedless berries develop
Often Confused with
Magnesium deficiency: leaf margins will curl and with severe deficiency the leaves may drop prematurely
Manganese deficiency: leaves maintain a normal size and shape
Iron deficiency: yellowing between the small leaf veins, eventually turning almost white
Zinc deficiency: interveinal areas turn light green to yellow in a mosaic pattern and can become reddish in black and red cultivars while leaf veins become clear with narrow borders of green; small, deformed leaves, poor fruit set
Scouting Notes
Boron deficiency may be observed on alkaline soils (high pH) or sandy knolls. Soil tests are recommended to establish base levels. Boron deficiency may be temporary and may be noticed during unusually dry springs. Boron levels in tissue fluctuate during the growing season.
Management Notes
Symptoms for deficiency and toxicity are similar. Tissue and soil tests are the only methods of confirming Boron levels. Foliar sprays may be used but should be confirmed with tissue analyses before use.
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