Spring frost damage to Four Pierce's disease resistant bunch grape cultivars in North Florida

Abstract

Two unseasonal spring frosts (daily low temperature below 0C) occurred in North Florida in March of 1996 and 1998, when the new shoots of the four studied bunch grape cultivars ('Blanc du Bois', MidSouth', 'Orlando Seedless', and 'Suwannee') were up to a few cm long. The freeze damage severity (number of collapsed young shoots / total young shoot number) of each vine was calculated. All four cultivars lost more than 70% of their new shoots. Results from Duncan's multiple range test (a = 0.01) indicated that damage to 'Orlando Seedless' (severity mean = 0.94) was significantly different
from 'Blanc du Bois', 'MidSouth', and 'Suwannee' with the severity means of 0.76, 0.74, and 0.82, respectively.