University of Georgia Extension — We often think about pruning as a winter activity. However, this process starts much earlier in the year. Vines under stress are much more easily identified during the summer. Residual effects from cold damage or trunk disease issues, while they can appear early in the season, are often becoming more apparent as we move forward in the growing season. Renewing the trunks (or planning for their replacement) will help preserve or increase the vineyards long term productivity.
Action Item: Flag your vines! The most important thing you can do for this now and over the next several months before leaf fall, is the mark any vines to keep an eye on them while there is active growth happening. Vines that are not growing well and showing symptoms of issues with their trunk need to be marked. Addressing mildly symptomatic vines will increase the chance that you can retrain from your existing vine.
While most pruning occurs during the winter (and spring for delayed pruning), vine surgery can happen during the spring and summer as well. Planning the pruning for affected vines will then depend on several factors. Factors like labor availability, risk of disease spread, cause and extent of the damage should all be considered when making these pruning decisions. For instance, in theory, vines may be less susceptible to new trunk disease infection when the surgery occurs during the growing season and potentially be a little more resistant to frost damage in the spring, but they will also likely be more susceptible to future cold damage and, with our summer rains, at higher risk for renewed trunk disease infection. While the cause of the vine trunk issue can influence when the pruning may occur, the actions are generally the same. If you’re not sure about when, how, or where to work on symptomatic vines, let me or your county agent know and we can talk over your specific situation.
Action Item: Protect the vine at the pruning wounds! Pruning cuts, especially large ones, can leave your vine vulnerable to new infections. Consider using a pruning wound protectant like Topsin or Vitiseal (see below) to help reduce that infection risk. ALSO, the wood at the site of the pruning wound is likely to experience some natural dieback after the cut. Cut the would slightly further down from where new shoots are going to train out (leave a length of wood approximately twice as long as the diameter of the wood you cut). For example, if removing and renewing an entire cordon that is two inches in diameter, make sure to leave four inches of cordon left from the rest of the trunk to protect the rest of the permanent vine structure.
I’ve included a flyer on trunk renewal that my colleague, Dr. Kendra Baumgartner, from UC-Davis sent us on trunk disease (there’s also the poster available in Spanish). While CA certainly has different conditions than we do here in GA, this still makes a nice visual for vine surgery. — By Sarah Lowder, Assistant Professor & Extension Viticulturist, UGA Dept. of Horticulture
Additionally, keep an eye out for some of these other GA problems that will also make them candidates for renewal.