Don't let the fungus and blackspot get to your tomatoes before you do this year. Use this product on other vegetables for more organic produce! The Concern® copper soap fungicide utilizes the powers of copper octanoate which is effective in controlling and preventing the spread of powdery mildew, blackspot, gray mold, leafspot and many other plant diseases. The nature of copper soap fungicide makes it one of the most economical and convenient solution to the wide array of garden annoyances on the market! OMRI Listed® and compliant for use in organic gardening. Begin treatment two weeks before plant diseases typically arrive. Continue using product at 7-10 day intervals. One quart will treat 10 yards.