Nutrient Management Research Database

This research evaluated the timing and rate of boron fertilization treatments of grapevines via fertigation and foliar sprays. The study was conducted on two separate vineyards. In fertigated vineyards, 1 lb of actual boron per acre can be safely applied to mature vines; however, yearly applications of 1 lb per acre of boron can result in excessive boron levels in the plant tissue. Recommended application rates to maintain boron levels is 1 lb per acre every 3 or 4 years or 1/4-1/3 lb per acre every year, applied three weeks prior to bloom. In vineyards suffering from severe boron deficiency, pre-bloom or bloom foliar sprays are partially effective in treating symptoms. Fall foliar sprays are more effective at increasing addressing boron deficiencies, as boron is stored in the dormant buds for the next season. Boron can be applied in a single application of 1 lb per acre via the fall foliar spray.

• This research evaluated the timing and rate of boron fertilization treatments of grapevines via fertigation and foliar sprays.
• The study was conducted on two separate vineyards.
• The fertigated vineyard received 5 different Boron treatments: 0, 1/3, 2/3, 1, 1/16, and 2 lbs per acre.
• Boron was applied three weeks prior to bloom in 1998 and 1999.
• The second vineyard received 5foliar spray treatments:
  • no spray
  • fall foliar (Oct. 19)
  • soil application as berm spray (Feb 8)
  • pre-bloom foliar (May 4th)
  • and bloom foliar (May 20), each at 1 lb per acre as 20.5 soluble boron product.

• Boron concentration of leaf tissue is elevated within three weeks of application;
• 1-pound actual B per acre (5 lbs. 20.5% B soluble product) can be safely applied to mature vines through drip, even in a single application;
• An annual drip application of 1-pound B per acre applied for three or four consecutive years can result in excessive levels in tissue;
• For maintenance, apply 1-pound through the drip system every three or four years or ¼ to 1/3 pound every year;
• In severely B deficient vineyards, pre-bloom and bloom sprays are only partially effective in preventing fruit symptom.
• Fall foliar sprays increase B content of dormant bud tissue and are more effective in eliminating cluster and berry symptoms the following year
• Leaves are more tolerant of B applied at fall, and B can be applied to foliage at 1-pound B per acre in a single application with no consequence.