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78 W i n e s & V i n e s J U LY 2 0 1 4 WineEast WineEast Grapegrowing one vineyard that grew a range of varieties only showed significant amounts of injury in older Syrah and Tannat vines, and injury in the latter was only observed in those sections of rows that dipped into a low point of the vineyard topography (cold air ponding). Cabernet Sauvignon and Merlot were also affected in some vineyards, with both cane and trunk injury apparent. Riesling, which we consider to be a relatively cold-hardy vinifera variety, also showed significant trunk injury in one Fauquier County vineyard. In most cases, the injury was not observed until March of this year, even though some rough pruning had been done in January and February. Examination of split trunks in two separate vineyards revealed brown, desiccated wood. In other cases the injured trunks were hydrated and oozed moisture when shallow cuts were made into the trunk to examine the status of the phloem and cambial (regenerative) tissues immediately beneath the bark. In the former situation, the extent of browning and desiccation suggested that the trunk injury may well have occurred during the previous (2002-03) winter, but perhaps went unrecognized due to abundant moisture during the 2003 growing season. Canes on some of these vines were observed to be drying out in March of 2004, but the drying (and browning) appeared to radiate out from the cordon. Trunk splitting is thought to occur either from excess water freezing in the trunks, causing a physical strain, or from uneven drying of the wood. But more commonly, the drying and cracking of injured wood occurs in the winter following injury, when drier atmospheric conditions prevail. Some of the other cases of injury observed in Virginia (including splitting trunks) came from vineyards where the injury appeared to be localized in regions of the vineyard that experienced poor soil water drainage. It may be that in these cases the affected vines did not acclimate well to winter temperatures due to saturated soil conditions. T.W. (Continued from page 77.) Split trunk PHOTO: UNIVERSITY OF MISSOURI