My very mature 3 vines (common grape. I've called them Concord) in the back yard have been diagnosed having black rot. The most noticeable sign is spots on some of the green grapes. These turn into mummified grapes. The local agricultural agency made the diagnosis based on submitted photos. I've made wine from these in the past but now have been advised to destroy all fruit. The cure is to remove all of the fruit, clean up any fruit that has dropped & spray fungicide ( been advised to use "Mancozeb") in the spring. Wondering if anyone else has experienced this diagnosis and what their actions were and results? If I do nothing will my vines grow resistant to this fungi?
Black Rot
- Thread starter Dewbie
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* native grapes are resistant to black rot. It is worse/ I can get no crop with hybrid vinifera grape genetics.
* two treatments of Mancozeb will help a lot. Ex after bud break with new shoots and at flowering. Black rot mainly attacks the new growth. You should not use Mancozeb closer than 60 days to your harvest period. It has residual toxicity.
* fungal spores are worse with high humidity. In a dry California climate less spraying is required and also not legal every two weeks. The midwest had drought conditions in May and June, I didn’t spray a lot this year. Yes diseased plant material carries the fungus. I burn canes.
* two treatments of Mancozeb will help a lot. Ex after bud break with new shoots and at flowering. Black rot mainly attacks the new growth. You should not use Mancozeb closer than 60 days to your harvest period. It has residual toxicity.
* fungal spores are worse with high humidity. In a dry California climate less spraying is required and also not legal every two weeks. The midwest had drought conditions in May and June, I didn’t spray a lot this year. Yes diseased plant material carries the fungus. I burn canes.
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I have three grape vines. Bought three years ago from a nursery in Georgia. Supposed to be all the same but one is seedless and the other two are not. Last year I picked about 60 or more pounds of purple grapes and made about 10 gallons of wine. This year the seedless vine shows signs of black rot but not the other two.
Should I spray the three vines and remove the bad grapes? I’m a newbie to this grape and wine business
Should I spray the three vines and remove the bad grapes? I’m a newbie to this grape and wine business
welcome @Gizmo x
* do you have access to Mancozeb? The positive is that a few spring/ early summer treatments will fix the issue. The negative is that it has a 60 day preharvest interval (PHI). For the grapes I have that gives me two weeks to put out a final treatment of the year.
* I have made wine from hybrids which showed infection. For this year, ,, It is work to remove the mummified berries but on a few plants can be done. The spores will not affect you/ other humans/ the flavor.
* Spraying, if you could keep the spray off the clean vines you have some flexibility on what to do with the crop. If they are together the PHI is involved and one should not use sprayed fruit. in my location I have raspberry 8’ from the last row of grape, because of drift I am not using that fruit this year.
* The spray is a preventative, it will not stop existing crop which is mummified, ie for this year you are late.
* do you have access to Mancozeb? The positive is that a few spring/ early summer treatments will fix the issue. The negative is that it has a 60 day preharvest interval (PHI). For the grapes I have that gives me two weeks to put out a final treatment of the year.
* I have made wine from hybrids which showed infection. For this year, ,, It is work to remove the mummified berries but on a few plants can be done. The spores will not affect you/ other humans/ the flavor.
* Spraying, if you could keep the spray off the clean vines you have some flexibility on what to do with the crop. If they are together the PHI is involved and one should not use sprayed fruit. in my location I have raspberry 8’ from the last row of grape, because of drift I am not using that fruit this year.
* The spray is a preventative, it will not stop existing crop which is mummified, ie for this year you are late.
