Exogenously applied abscisic acid did not consistently delay budburst of deacclimating grapevines

Abstract

An experimental formulation of abscisic acid (ABA; Valent Biosciences VBC-30025) was evaluated for potential to delay budburst of Vitis vinifera L. winegrapes. Five experiments were conducted during 2004 and 2005 on dormant grapevine cuttings, container-grown vines, and field-grown vines to evaluate rates and/or timing of ABA applications. Two application methods were tested - spray application to buds or soil application. Spray application of ABA solutions to unopened buds increased the number of days to budburst by 3.5 days in one of four laboratory trials on single-bud cuttings, and delayed budburst by one day in established field-grown vines in one of two years. Further study to enhance the efficacy of ABA spray applications should examine materials or methods to improve penetration of ABA through bud scales. Soil applications of ABA to container-grown vines provided the greatest delay in budburst (up to 7 days) and gave the most consistent response. Soil application of ABA to established field-grown vines, however, produced no response and this may not be a practical or economical application method for commercial vineyards.