Sonoma County wine grape growers with larger acreages finished mechanical pre-pruning activities earlier last month, says Nicky Frey, president of the Sonoma County Wine Grape Commission at Santa Rosa, Calif. Pre-pruning is done to reduce Eutypa dieback — caused when spores of the fungus infect fresh pruning wounds — by reducing the chance of rain spreading the spores. It is done more by machine than by hand in Sonoma County, speeding up the final selective pruning and allowing growers to prune large acreages in a very short time.