The Effects of Hydrogen Cyanamide on Enhancing the Time and Amount of Budbreak in Young Grape Vineyards

Abstract

Dormant two-, three-, and four-year-old Thompson Seedless and Cabernet Sauvignon vines and two-year-old Grenache vines grown at the University of California, Davis, were treated with either 1% or 2% H₂CN₂ one day after pruning and compared to untreated control vines. The average number of days to initial budburst after treatment of dormant canes with H₂CN₂ was two to four days less (p < 0.05%) than untreated vines for two-year-old Thompson Seedless and four-year-old Cabernet Sauvignon vines. Hydrogen cyanamide at either 1% or 2% significantly increased the percentage budburst on the basal two-thirds portion of canes of all varieties and age groups. All portions of canes from four-year-old Cabernet Sauvignon vines treated with 2% H₂CN₂ had greater percentage budburst than control vines. Hydrogen cyanamide applied at a rate of 1% induced significantly (p < 0.05) greater percent budburst on two-year-old Grenache vines compared to a rate of 2%, whereas the latter treatment was most effective in inducing earlier budbreak on canes of Thompson Seedless and Cabernet Sauvignon vines.