We planted 25 Marquette vines by our home in 2010 and then 75 more last year....
We planted 25 Marquette vines by our home in 2010 and then 75 more last year. We had a small harvest last year and a better one this year. In both years we see a few mummified grapes in the ripe clusters. We checked with the local extension and it was referred to Montana State University and two other states and they are puzzled. They said it doesn't appear to be black rot. Since the grapes came from Minnesota, Winterhaven Nursery, we'd like to ask you if you have any ideas. I've attached an image from last year below. Thank you Tom Eggensperger
Sanders County Montana
I'm Curious how it was determined that these were not black rot? Was it plated out in auger? I have to believe that this was fungal. Possibly a nutrition issue, but I would think that all the grapes would be affected.
Are there spots on the leaves? Everything that I have come up with points to black rot.
However, I don't have the grapes/plant in front of me, so I can't be definitive.
I would have someone plate out the affected grapes in auger and have a complete soil analysis performed to rule out the possibilities.