California Agriculture

Boron deficiency of grapevines occurs occasionally on the east side of the San Joaquin Valley. Its symptoms include shot berries, shoot-tip dieback and leaves with yellowish mottling between veins. Boron must be applied carefully because the range between deficiency and toxicity is narrow. Our research evaluated the safety and efficacy of boron fertigation of grapevines using drip irrigation. Applying boron annually at 1/3 pound per acre to a moderately deficient vineyard elevated tissue levels into the adequate range within 2 years. However, the amount of boron used in a fertigation maintenance program will vary with leaching potential. Blade samples should be routinely monitored following fertigation and fertilizer amounts adjusted accordingly to avoid boron toxicity or deficiency.