Black Fungus on my bare Grape Vines! What now?

etherealsunshine(5b)April 26, 2013

My grape vines, planted last spring and summer, are just coming out of dormancy. I was checking the buds yesterday and noticed on the last 4-5 feet of one vine, there was a spotty black mildewy looking fungus concentrated around the knuckles of the buds. When I checked the rest of my vines, most had at least a few feet affected at the ends of last year's growth.

I looked online for a fungus that visually matched what I saw, but powdery mildew is whitish, and most pics of grape diseases were on bunches of fruit or leaves/growing vines, not on bare, dormant vines.
I didn't want the emerging buds to get infected, so I clipped off what appeared to have the mold/fungus and set it in the burn pile. I plan on getting some fungicide and spraying ASAP, but I wanted to know what I'm up against. Maybe I had powdery mildew last year and didn't see it...and it turns black when overwintered? I only sprayed for insects last summer and water via a soaker hose--the vines seemed fine...even had a growth spurt when we finally got some much needed rain in early August.

I'll try to post a pic or two before I burn the bad vines. I had to cut one lovely vine to about 3 feet tall :( I'm hoping I didn't jump the gun on pruning out the affected wood...the buds seemed to be a bit retarded in growth compared to the buds emerging on the unaffected portions of vine.

Any ideas?

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jean001a(Portland OR 7b)

The motto of these forums should be "Ask first, hack second, if at all."

Let us see pictures before you do anything further.

Also, please tell us where you live.

    Bookmark   April 26, 2013 at 11:04PM
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Did you spray the vines with dormant oil spray? I used horticulture oil and added to Monterrey fungi fighter and my grape vines are doing great. You can use some multi-purpose fungi fighter like Monterrey or spectracide. From my experience 90% of fruit tree destruction causedby fungus not insects.

    Bookmark   April 27, 2013 at 5:05AM
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calistoga_al ca 15 usda 9

My neighbor the grape grower, grows only organically and sprays nothing. Fungus is only a problem as the grapes ripen and is avoided by thinning the foliage to allow good sun penetration and air circulation. During dormancy last years growth is largely removed and burned. Here in the Napa valley wine country there is no summer rain to add moisture and contribute to fungus disease. Al

    Bookmark   April 27, 2013 at 9:57AM
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