Unfortunately, following moderately warm mid-winter temperatures, the large temperature dip experienced at the end of January presented a visibly high risk of bud injury for several of the examined cultivars in the local conditions of the High Plains. Among the most susceptible (most cold tender) cultivars indicated by the collected data were Petite Sirah, Vermentino, Zinfandel, Tempranillo, and somewhat surprisingly, Cabernet Sauvignon.

The most protected (most cold hardy) cultivars included Albariño, Chardonnay, Sauvignon Blanc, and Merlot. For growers with acreage of the more susceptible cultivars, considering the incidence and severity of bud damage when making pruning decisions this year (how many buds to retain) has been advisable. As temperatures warm up heading into spring, buds undergo deacclimation, losing their hardiness and making them more susceptible to injury at much higher temperatures. As a general reference, at the woolly bud stage, damage to 50% of buds can be expected at roughly 26 °F. At budburst, damage can be expected at roughly 28 °F. During the cold event on March 16th, temperatures in Lubbock, Brownfield, and Plains reached as low as 24 °F, meaning that sadly, damage was widely reported across these areas. Fortunately however, the worst of the injury was limited to cultivars that had already begun to undergo budburst including Carignan, Chardonnay, Albariño, Tempranillo, Sangiovese, Viognier, Vermentino, Pinot Gris, and Zinfandel, among others.

A silver lining is that many growers had not yet completed pruning and in some cases were able to avoid damage to the most proximal primary buds. As of late March, damage has not been widely reported for late bursting cultivars. — By Dr. Patrick O’Brien, Assistant Professor & Viticulture Specialist, High Plains & West Texas, Texas A&M University