Issue link: http://winesandvines.uberflip.com/i/830382
June 2017 WINES&VINES 19 WINE INDUSTRY NEWS N apa, Calif.—Two recent news reports gave con- flicting information about a popular herbicide. "Glyphosate is a likely carcinogen!" exclaimed one. The other said the opposite. Yet other stories reported traces of the herbicide in some wines. It was timely, then, that the Napa County Agricultural Com- missioner's office and the Uni- versity of California Cooperative Extension already had a meet- ing scheduled about vineyard weed control using glyphosate and alternatives. "It's not my job to defend any product," Napa agricultural com- missioner Greg Clark told the large crowd. "But I do defend the right to use products approved in California." The first session featured Dr. Carl Winter, toxicologist at the University of California, Davis. He seemed almost exasperated as he said, "I'm amazed to be speak- ing to a large group about the risk of glyphosate. I've always re- garded it as one of our most be- nign chemicals." Glyphosate was first registered in 1974 under the trade name Roundup. The U.S. patent for glyphosate expired in 2000, and now glyphosate products are mar- keted by many companies. Winter said he suspected that mu ch o f t h e h y s t e ria ab o ut glyphosate was because it's used with genetically modified crops such as corn, cotton and soy- beans, which are engineered to be resistant to glyphosate while weeds are not. "It has very low mammalian toxicity," he stated, adding that the only known danger is eye contact. "Whether or not glyphosate is a risk, the dietary exposure is very low and of no health concern." Are other herbicides effective? Weed advisor John Roncoroni of UC Cooperative Extension dis- cussed reasons for weed control and glyphosate alternatives. Weeds are direct competition for young vines, and if you're trying to water-stress vines, w e e d s c o m p l i c a t e m e a s u r e - ment. Weeds also hamper frost protection by inhibiting heat rising from the soil. In addition, weeds can harbor pests like voles and gophers and provide increased moisture and disease pressure. They can inter- fere with harvest and can affect crop quality. One classic way to remove weeds is mechanical cultivation. However, mechanical cultivation uses fossil fuel and can cause ero- sion. A wet year like this may not be a good year for cultivation, he admitted. Roncoroni said he also likes sheep for weed control and noted that if you raise your trellises, they can be used year-round. —Paul Franson Is Glyphosate Dangerous? Weeds can harbor pests and provide vineyard disease pressure.