Assessment of Vine Quality and Pruning Techniques in Oklahoma Vineyards

Pruning is one of the most important jobs for a viticulturist. Proper pruning can improve fruit quality and stabilize production over time. By consistently limiting the number of shoots and leaves via dormant pruning, one is also working to produce the maximum crop without delaying maturity year after year. Failure to prune can lead to improper ripening, reduced cane maturity, reduced productivity of buds the following season, and a decrease in root mass. Therefore, pruning needs to regulate the number and positions of shoots on a vine which in turn regulates cluster number and size. In April 2014, 26 vineyards throughout Oklahoma were surveyed for grapevine quality and pruning techniques. Measurements of spur diameter, internode length, and spurs retained per linear foot of row were taken. Data shows that among all cultivars observed, few spurs were within the desired range of 0.8 to 1.3 cm diameter. This indicates potential problems such as poor vigor (possibly due to own-rooted vines), poor nutrition, lack of adequate water, poor weed management, too much crop load in previous year, or leaving too many shoot/canes the previous years. Less of a problem was spur internode length. Although within the broad parameters of 2.5 to 10 cm, most cultivars in Oklahoma fell in the lower part of that range. The number of spurs per linear foot by cultivar was too many in most vineyards in Oklahoma. The desired range is ~2.5 spurs per linear foot of canopy; however, most observed were greater than 3 and most over 4.  Overall, there were deficiencies identified in vine quality and pruning techniques that could be improved to deliver better grape crops in the future.