Cause Deficiency or unavailability of boron in the soil and subsequent deficiency in the plant. All vegetables require boron for growth, but the amount required varies considerably. Turnip, rutabaga, and cauliflower are sensitive to boron deficiency, which is common in soil that is alkaline or sandy and subject to excessive leaching. In any soil, boron also may become less available during long droughts.
Symptoms Leaves may or may not show abnormalities. They may turn reddish and stunted if deficiency is severe. Leaves may be twisted and curled and finally die. Roots develop a glassiness or water core of the root flesh followed by internal gray, punky flecks or spots that later change to brown or black areas.
- Use a fertilizer with an appropriate level of boron based on a soil test. The specific amount needed to avoid boron deficiency varies widely by area.
- If boron deficiency has been a problem, particularly in alkaline soils, apply soluble boron at 1 lb/100 gal water once or twice to foliage before deficiency symptoms appear.
- Maintain uniform soil moisture through irrigation.