Help! Can't Get Rid Of Black Rot

[tshaljr]

I planted 6 Frontenac and 8 Vignole vines in 2008. Since then 6 of the Vignole died and I replaced them with 6 Melody. I cannot get rid of the disease. Last year I picked every mummy and used my yard vac to pick up all of the debris at the end of the season. This year I sprayed with captan but I think I was too late. I am considering ripping them all out and starting fresh. Is there anything I can do to get rid of this?

 

[bob1]

Well I hope to learn from this also but is black rot not caused by soil being to acidic?

 

[grapeman]

What you did was a good start for minimizing black rot. You will never get rid of it, but simply control it. No it is not true that it is caused by acidic soil. It is a fungus present everywhere in areas where it is located. Prune and clean the vineyard as you did (shop vac is optional- LOL). You need a dedicated spray program if you are in a wetter area. It should begin at least as soon as you get any growth. Captan will supress it, but mancozeb products do a better job early on (such as pencozeb, mancozeb or Manzate). The most critical period is between pre-bloom and bunch closure.

 

[Brew and Wine Supply]

You also need to spray every two weeks from bud break untill just before harvest.

 

[tshaljr]

Thanks for the responses. At this point the grapes that I do have are shriveling up daily. Should I just cut my losses this year, prune all of them off now and hope for better luck next year?

 

[grapeman]

If they are that bad, getting rid of them will lessen the source of innoculum for next year. Spray early and spray often until cluster closure.

 

[CARBOY]

I agree with Grapeman...my black rot experience caused me to loose two years of crop on three vines next to each other. I performed severe pruning and burned all the cuttings...do not compost it! I wanted to try and save the vines. A spray program with Mancozeb is the way to go...just keep in mind the 66 days before harvest no spray. Also you can alternate with Captan....but mancozeb is my primary. The severe pruning I spoke of was cutting everything off...basically I topped the trunk and allowed new cordons to grow along the wire (that was one season gone). The 2nd season after complete cut back was for cane growth. You must spray every inch of all vines, leaf and trunk surfaces from the top to the ground. Spray real good behind the peeling bark of the trunk. The amazing thing was that on the third year after the cut back I had an amazing crop on those three vines...now I am 5 years after the black rot first showed on those vines and I'm satified with the control....it will never be gone, just minimized in my case.

 

[Brew and Wine Supply]

I am fighting it with 35 vines of St. Vincent. My Frontenac does not seem to be affected by it. I may do what Carboy has done, just trim them way back and spray hard.

 

[tshaljr]

I've gotten a few hand fulls that actually taste pretty good. This year is gone but I'm excited for next year. I will spray early and often. However, I hate to sound like the rookie that I am but what are you talking about when you say "the 66 days before"?

 

[grapeman]

The 66 days refers to the Pre-Harvest Interval. That means that you need to stop using Mancozeb and related products a bit over 2 months before the anticipated harvest. Fortunately most grapes become immune to a nnew black rot infection by that point. You need to switch overe to another spray such as Captan at that point to offer protection against other diseases.

 

[WheeliePro]

I have 5 vines right now, (2) 3-year-old un-grafted merlot, (2) grafted Cab Franc planted this April, and (1) grafted Cab Sav planted this April. The 2 Merlot vines have large amounts of black rot. I sprayed twice this year with sulfur, not until early summer though, but then got busy with life and I haven't touched them since. Do I need to do a full cut-back like CARBOY in order to have a better chance of controlling this next year? Or can I just remove all of the rotted fruit? How about spotted leaves (most of them by now)? So far, nothing has spread to the new vines. If I do any full or partial pruning for this purpose, do I do it now or in the spring during regular pruning season?

 

[GibX]

Here's a great link to the effectiveness of sprays. Notice that captan is okay but not great http://winegrapes.tamu.edu/grow/fungicide.html

 

[WheeliePro]

Thanks for the link. I'll have to check what brand of sulfur spray I bought, but man do they advertise it as a cure-all product. According to that table, it's mainly just for powdery mildew. The source for that table has the full story of what to use and when: http://hort.agriculture.purdue.edu/pdfs/08SprayGuide.pdf

Sorry if this is well known on this forum. As I said, I'm in my first few years of growing and this was my first fruiting year for the Merlot's. I have a book, but it's not the most thorough. I'll be spending the winter reading and planning for next year. Thanks again.

 

[grapeman]

WheeliePro, see my response above. Mancozeb products are much more effective at controlling black rot.

 

[GibX]

Also...be cautious of organic sprays. I tried neem oil this year and lost half my crop. I was not thrilled. It is advertised for fungicide and pesticide.

 

[CARBOY]

Just an FYI....be careful of products containing sulfur. Some vines are NOT sulfur tolerant.