My very mature 3 vines (common grape. I've called them Concord) in the back yard have been diagnosed having black rot. The most noticeable sign is spots on some of the green grapes. These turn into mummified grapes. The local agricultural agency made the diagnosis based on submitted photos. I've made wine from these in the past but now have been advised to destroy all fruit. The cure is to remove all of the fruit, clean up any fruit that has dropped & spray fungicide ( been advised to use "Mancozeb") in the spring. Wondering if anyone else has experienced this diagnosis and what their actions were and results? If I do nothing will my vines grow resistant to this fungi?