Black mold (?) on grape vines
I live in Talbot County and have table grapes that have grown on my yard fence in full sun for years. In the past the worst I've had to deal with are Jap beetles that I would spray with Sevin. Not my first chice because I'd rather use a less toxic chemical but it works and I don't know what else to use Ideas? But that's not really why I am contacting you today. I have a more urgent problem. This morning, I noticed some of the grape stems have this black mold-like infection. It also causes some of the grape leaves to curl up and die. See photo of healthy leaves at the tip and infected stem and leaves further up the stem. I am afraid it's going to spread. Can you please tell what to do to save my grapes? Thanks Jane
We can't make a final diagnosis based on the photo. Please look at the grape disease page from our website: http://extension.umd.edu/growit/disease-grapes
Do your grape symptoms line up with the photos for black rot?
Another possible disease is phomopsis, which is not as common as black rot. Look at images online. The stem cankers look very similar.
Either way, prune out diseased stems and leaves. Do not dispose of them near your grapes. Off-site would be best. Good garden sanitation will be important to get the amount of infectious material out of the area to prevent reinfection next year.
You may have to spray next year. There is more detail in the links at the bottom of the Grape Disease page.
You are also welcome to send us more photos of new or other symptoms which could help us be more precise in a diagnosis.
Thank you for your reply. But since the original photo I sent was not clear enough for a diagnosis, I took a couple more shots and are attaching them here : an unaffected leaf and stem, alongside one with the infection/mold/scale...?
Can you better see what the problem is?
It looks like anthracnose.
You should cut out all that you can, and in the future, begin a spray program detailed by following the links above.