Sulfur Damage on Grape Leaves

Problem

• Sulfur can cause phytotoxicity, or tissue damage. Phytotoxicity is more common when you apply sulfur on hot days, when the temperature is over 85 degrees Fahrenheit.

Solution

• Although there is no solution to the damage already done, using a bordeaux mix -- copper sulfate combined with hydrated lime -- is safer than sulfur alone. Apply this is at temperatures below 85 F, though it still may cause damage to sensitive varieties.

Considerations

• New microbial fungicides frequently come on the market, according to agriculture specialists with the National Center For Appropriate Technology. Contact your county cooperative extension office to learn what's new in organic fungicides.