[Editor’s note: Steve Savage is a plant pathologist who has been working in agricultural technology for over 35 years.]
Grapes grown in a dry, Mediterranean climate like California are spared some of the most problematic diseases that occur in rainier places like France and Germany. However, the powdery mildew fungus can infect even without any rain.
Probably since ancient times, people have known that you can prevent powdery mildew damage on grapes by dusting them with the element, sulfur. Sulfur, which can be mined, is considered to be a “natural product” and thus it is approved for use in organic. Both conventional and organic farmers use a great deal of sulfur – it is by far the most widely used pesticide in California and particularly for grapes. Back in 1980 is was common for vineyards to be dusted with 6-10 pounds per acre of sulfur as frequently as every 7-10 days from the time the grapes start growing until they begin to ripen.
[It] turned out that with Bayleton, grapes growers could control mildew using a far lower dose than sulfur and do so only once every three weeks, not every week. When the product became available, it was enthusiastically adopted by the grape growers as a far better option than sulfur. … Sulfur is now playing a much smaller role in modern, “integrated pest management” programs in grapes that rotate different kinds of products through the season so that the fungus doesn’t become resistant to any of them.
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