Here's this year's handout for pruning time disease considerations (this link opens Google Drive with this year's recommendation for trunk disease management). As I noted in this handout, the first line of defense against trunk diseases that may infect through pruning cut is a cultural control. Make sure to pick dates when you are expecting several days of dry weather.
In this handout, I refer to Topsin-M as a choice of trunk disease management, especially for Botryosphaeria canker, which is very common in our area. The product has been transferred to a new company in 2017, and there are changes in the label. [Note: The US distributor is still the same (UPI), thus, I do not think it will affect where you can purchase the product.]
If you are using Topsin-M for pruning wound protection, please update your label. You can download the new label by clicking this link (will open Google Drive).
If you are pruning, and wondering whether you can protect pruning wounds from infections by trunk diseases, there is a supplemental label of Rally for control of various trunk diseases (Botryosphaeria, ESCA, and Eutypa).
You can apply them with a sprayer or as a paint. It would be a very good idea to use them, especially when you are making a big cut. The timing of application would be soon after pruning and before a rain.
Also, double pruning (early winter rough cut followed by the final cut in early spring) showed to reduce 95% of trunk disease in a CA study.
Also, speaking of trunk diseases, I have been involved in a research effort to develop management strategies for various trunk diseases. Please check our project page which contains not only research reports, but also extension information, such as disease keys, management guides, and economic tools to estimate the benefit of trunk disease management over the life of a vineyard.