What's Going On With My Riesling?
Posted 07 July 2012 - 05:36 PM
Posted 09 July 2012 - 10:38 AM
Posted 13 July 2012 - 06:01 AM
Posted 13 July 2012 - 12:47 PM
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...
Posted 14 July 2012 - 07:56 PM
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.
Owner and Winemaker at Weathered Vineyards.
3 acres of Cab Franc, Merlot, Sauv Blanc, and Cayuga x Riesling.
Winery Opening Spring 2014 near Allentown, PA.
Posted 18 July 2012 - 06:14 AM
Posted 18 July 2012 - 09:07 AM
“'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.]
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.
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.
Posted 18 July 2012 - 10:08 AM
Posted 18 July 2012 - 10:18 AM
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.
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.
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