The best strategy is still to prune as late as possible and minimize wounds greater than 5/8“ diameter, or the size of a dime. When the wound diameter is doubled, susceptible surface area is increased 4X. Also, shoot-thin young vines during the early years to reduce as much as possible the number of wounds at pruning time. Coupled with late pruning is the tractor application of Rally and Topsin M within 24 hours of pruning. This is a rapid treatment that can he applied quickly if a storm is forecast after late pruning.

References

• Gu, S., Cochran, C., Du, G., Hakim, A., Fugelsang, K., Ledbetter, J., Ingels, C., Verdegaal, P. 2005. Effect of training-pruning regimes on Eutypa dieback and performance of 'Cabernet Sauvignon' grapevines. J. Hort. Sci. Biotech. 80(3): 313-318. http://www.lodiwine.com/Gu_et_al_Pruning_Training_and_Eutypa.pdf

• Gubler, W.D., Rolshausen, P.E., Trouillas, F.P., Urbez, J.R., Voegel, T., Leavitt, G.M., and Weber, E.A. 2005. Grapevine trunk diseases in California. Practical Winery & Vineyard, Jan./Feb. 2005. http://www.practicalwinery.com/janfeb05/janfeb05p6.htm

• Kotze, C. , Fourie, P. H., and Van Niekerk, J. M. 2008. Biological control of the grapevine trunk disease pathogens: Pruning wound protection. Master’ Thesis. https://scholar.sun.ac.za/handle/10019.1/2117

• Rolshausen, P. E., Urbez-Torres, J. R., Rooney-Latham, S., Eskalen, A., Smith, R. J., and Gubler, W. D. 2010. Evaluation of Pruning Wound Susceptibility and Protection Against Fungi Associated with Grapevine Trunk Diseases. Am. J. Enol. Vitic. 61:1, 113-119 (2010) http://www.cdfa.ca.gov/plant/ppd/PDF/RolshausenEtAl2010.pdf

• Weber, E. A.; Trouillas, F. P.; Gubler, W. D. 2007. Double pruning of grapevines: a cultural practice to reduce infections by Eutypa lata. Am. J. Enol. Vitic. 58:1, 61-66. http://www.ajevonline.org/cgi/content/abstract/58/1/61