The attached may make for good bedside reading, but I do think it is worthwhile information for you to review. I am including a research report as well as photos by replication (six reps of each treatment). We conducted a trial looking at low rates of captan, high rates of copper, and a biological control. All of these are purported to be good replacements for mancozeb, should the EPA follow through on removing this fungicide from the marketplace. Since we started the trial late and allowed untreated plants all around the treated plants, we had “tons” of exceptionally high disease pressure. However, this is what we need in order to separate out fungicides, so this was an excellent if “hot” trial. Numerically, the rate of mancozeb we tested, generally recommended in order to maximize the number of legal applications while also providing good efficacy, was better than captan or copper. However, the low rate of captan did come closer to providing equivalent efficacy than I would have predicted. Copper was clearly not as effective as mancozeb. We only looked at downy mildew and black rot, and we will need to look at other diseases like Phomopsis and ripe rot in the future. We will soon be conducting meetings in which we will query wine grape producers relative potential changes to current practices — changes that may allow some use of mancozeb in the future. We need your help in thinking this through — providing EPA with mitigation incentives that will allow continued use of mancozeb in the various types of wine and table grapes we grow in Georgia. Please make every effort to attend and participate in these meetings, as your ideas will be much better than ours.
A website from the College of Agricultural and Environmental Sciences
