Drip irrigation can effectively apply boron to San Joaquin Valley vineyards

Boron deficiency of grapevines occurs occasionally on the east side of the San Joaquin Valley. Its symp- toms include shot berries, shoot-tip dieback and leaves with yellowish mottling between veins. Boron must be applied carefully because the range between deficiency and toxic- ity 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 mainte- nance program will vary with leach- ing potential. Blade samples should be routinely monitored following fertigation and fertilizer amounts adjusted accordingly to avoid boron toxicity or deficiency.