Yes, it is easy to miss posts. We were having a discussion on Osage Orange and I noticed that Susu’s post was two days old and I thought to myself, why shoot, everybody has overlooked her so I tried to help. Actually, I replied to her post twice.
Looking at my records, I use Immunox on my grapes about as much as I do Captan. Sometimes both together. Somehow I’ve got the impression that Captan was better for control of black rot. That may be an error on my part. Also, I must of read into Susu’s post that she had used Immunox previously without good results. Then I was looking at some documentation on grapes that indicated that mancozeb was much more recommended than Captan for very susceptible varieties or at critical stages of infection. I have never used mancozeb myself but years ago I used maneb which is comparable. Only use copper at the late stages of dormancy.