11 replies to this topic

[DoItAll]

I have Vignoles that are kicking butt this year. Right next to them are a couple of my experimental Riesling vines. They are very vigerous, but I would say half of the crop has little rotten berries in the clusters. I've sprayed regularly and all my other grapes look great. Is this black rot already, or is it too early and something else?

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[chuckie68]

I have the exact same thing occurring on ALL of my grapes! Like you, I have sprayed regularly. I’m pretty sure it is not Black Rot… Starts with a light brown spot on the grape with a little flat area where the spot is – as can be seen in the center of the cluster in your 2^nd picture. I would say that every single vine in my vineyard has been affected. My Gewürztraminer vines seem to be the least affected. Chardonnay vines the most – and they are adjacent to one another… go figure.

[chuckie68]

anyone...

[aspuhala]

Hate to say it but looks like black rot to me.

[Haoleguy]

I'm thinking its not black rot but check the leaves for lesions. See Wilcox article for more info ...... http://www.nysipm.cornell.edu/factsheets/grapes/diseases/grape_br.pdf . It looks more like a problem at inflouresence/berry set which falls into a group of poorly described early grape necrosis/shrivel condition. I believe weather, nutrition, and vigor play a role in these conditions. I do recall a paper, I'll try to find it later, that there were differences in an early necrosis of chard to gewurz grapes. If you guys had weather like I did in CT then you probably had super warm April followed by a cool & wet May just when your grapevines were trying to inflouresce and set berries. I'll keep looking for more.....Gary

[chuckie68]

I'm thinking its not black rot but check the leaves for lesions. See Wilcox article for more info ...... http://www.nysipm.co...es/grape_br.pdf . It looks more like a problem at inflouresence/berry set which falls into a group of poorly described early grape necrosis/shrivel condition. I believe weather, nutrition, and vigor play a role in these conditions. I do recall a paper, I'll try to find it later, that there were differences in an early necrosis of chard to gewurz grapes. If you guys had weather like I did in CT then you probably had super warm April followed by a cool & wet May just when your grapevines were trying to inflouresce and set berries. I'll keep looking for more.....Gary

Gary, Thanks I almost sure its not BR. Was thinking maybe sunburned from the 106 heat we had two weeks ago...

[aspuhala]

Hey DoItAll, I was probably too quick to point to BR. Gary and Chuckie68 are probably right. THe totally shrivled grapes in the pic are not as dark colored as the black rot mummies.

[wxtrendsguy]

I got hit very hard last year with black rot. And I have bad news for you, the pictures look a lot like Black Rot to me. Get a spray on there immediately or you will lose em all. You need to use a post infection fungicide. Rally might be a good choice. I went through the vineyard and hand picked each bad berry off each cluster and made sure they went into the garbage.

Usually here in the east we will always fight black rot, powdery and downy mildew and some sort of bunch rot depending on the variety. Spraying every 7 days is about the only way to combat it and start early in the spring.

[DoItAll]

We had 80's in March, followed by a cool down and decent weather until early June. It has been hot ever since. I spray about every two weeks. It looks like I will have to pick off all of the bad berries or I will not have a crop of Riesling this year. The vine is crazy vigorous. Actually all of my vines are. I don't water, fertilize, or anything. I just don't understand why it's only the Riesling. I have a Pinot Noir vine maybe 10' away that looks beautiful. It started verasion the other day.

[HoCo Al]

We had 80's in March, followed by a cool down and decent weather until early June. It has been hot ever since. I spray about every two weeks. It looks like I will have to pick off all of the bad berries or I will not have a crop of Riesling this year. The vine is crazy vigorous. Actually all of my vines are. I don't water, fertilize, or anything. I just don't understand why it's only the Riesling. I have a Pinot Noir vine maybe 10' away that looks beautiful. It started verasion the other day.

“'Research in New York demonstrated berries of most varieties become resistant to black rot infection 3-4 weeks after bloom, therefore, sprays for black rot should not be needed at this time'.¹ Understanding times to limit application is important for good production practices. This shows that preventative chemical measures before the 3–4 weeks would be optimal." [From Wikipedia.]

Other research has shown that some vinifera and hybrid wine grapes don't become highly resistant or immune until 8 weeks after bloom. Also, leaves become resistant as they mature. So, while it does not hurt to remove the infected berries now, it is not really necessary. I would, however, remove all infected berries, mummies and all foliage at the end of the season for sure. Otherwise you will carry over a lot of inoculum into next season and the problem will probably be even worse next year.

The keys to black rot control are vigorous sanitation practices and well-timed, thorough sprays early in the season. I speak from experience, after having lost an entire crop from a couple of vines several years ago. After removing all prunings, leaves and mummies from the area that fall, and implementing a robust spray schedule the next season, I had almost no problem the following year.

[startnout]

Thanks for posting this information on black rot. I lost all my Concord and Niagra last year to it. Now I know what to do.

[HoCo Al]

Thanks for posting this information on black rot. I lost all my Concord and Niagra last year to it. Now I know what to do.

You're welcome. One other suggestion: it is often difficult to get all of the mummies and foliage fragments off the ground under the trellis. So one other thing you can do if you only have a small number of vines affected is to rake the ground under the trellis thoroughly in the early spring before bud break, and then apply a heavy layer of mulch - at least 2". The raking disturbs the fungus fruiting bodies and helps keep them from sporulating, and the mulch smothers any that are still viable. Don't, however, put any mulch up against the trunk of the vines - leave a circle of at least 8" - 1" in diameter bare around the trunk or you risk trunk rot diseases infecting the vine.