TY - JOUR T1 - Seasonal Changes in Low Temperature Resistance of Grape Buds JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 329 LP - 336 DO - 10.5344/ajev.1980.31.4.329 VL - 31 IS - 4 AU - E. L. Proebsting AU - M. Ahmedullah AU - V. P. Brummund Y1 - 1980/01/01 UR - http://www.ajevonline.org/content/31/4/329.abstract N2 - Fifty 5-bud samples were taken from selected Vitis labrusca L. cv Concord and Vitis vinifera L. cvs White Riesling (WR) and Cabernet Sauvignon (CS) vines weekly over a seven-year period to test cold acclimation of primary buds. Samples were placed in a cold box at 0°C programmed to lower the temperatures 3°C per hour to simulate winter temperature drop to determine the killing temperature of buds. Temperature required to kill half the buds (T50) was determined.A stable T50 value for primary buds during dormancy was -26°C for Concord and -23°C for WR and CS. Cold weather (maximum temperature below -1°C) preceding testing resulted in increased cold resistance. Primary buds reached an estimated T50 of -40°C for Concord, -37°C for WR, and -31°C for CS in January 1979. Concord retained its minimum hardiness level one to two weeks less than the two vinifera varieties. ER -