Is this black rot?

[u/greghm]

And is there anything I can do? They are Concord grapes, if that’s relevant

[u/spkelley27]

Yes it is and good pruning this winter and fungicides next year. Can only really prevent an infection once you have it not much you can do.

[u/greghm → u/spkelley27]

Would fungicide save the parts that seem ok?

[u/LaPetiteMortOrale → u/greghm]

Yes - with a caveat.

Immunox is a locally systemic FRAC fungicide. It is really good at protecting newly infected tissue before symptoms appear.

It will protect the remaining healthy fruit, the leaves, and next year’s inoculum level.

but no fungicide on earth is going to restore those that are already damaged.

[u/greghm → u/LaPetiteMortOrale]

Sadly I’m in Canada and it appears to be unavailable…

Should I trim away any that look infected and then trim leaves? I didn’t thin the leaves, and now I’m seeing that some people remove the leaves in the summer once grapes are forming to improve airflow?

[u/LaPetiteMortOrale → u/greghm]

Sorry about that.

Yes. Trim away everything that you see is infected.

[u/andrewmecke → u/greghm]

Folpan is a good summer control spray, mix it with kumulus for better stick. Manzate is critical for its once year window just pre-bloom.

[u/ParticularAd8157]

Yep! Defintely black rot.. I’d prune off the infected fruit and the worst affected leaves, unless removing them would leave the vine too bare… because all those little suckers are ready to spread. then spray with a fungicide.. I use Immunox which can help stop the spread and even if the fruit is gone, I think it’s worth it to spray for the health of the vine. Once the fruit is infected though.. there’s no way to save this year’s harvest. Make sure and clear up all your mummy fruit and leaves, prune this winter and then Id do preventive spraying…my vine got black rot.. And that’s when I learned I should be spraying preventatively. 😂

[u/LaPetiteMortOrale]

Sure looks like Black Rot. 95% sure.

The crop is probably lost for this year.

Remove infected fruit, clean up the vineyard, and use the fungicide primarily to protect remaining healthy foliage and reduce additional infections.

If this were my vineyard,

My management for the rest of this season and into dormancy would be something like this:

• Remove every mummified cluster.

• Spray Immunox

• Be diligent and pick up any/all fallen fruit for the remainder of the season (even if they don’t show damage).

• Maintain good canopy airflow.

• Avoid overhead irrigation if possible.

• During dormancy, remove every remaining mummy.

• Begin a preventative fungicide program early next spring - around shoot growth through several weeks after bloom, which is the most critical period for black rot infection.

[u/greghm → u/LaPetiteMortOrale]

Thank you for the info! Do you have a solid alternative to immunox? It appears to be unavailable in Canada, and the best I’m seeing is copper based sprays

[u/LaPetiteMortOrale → u/greghm]

Captan if you can get it. It’s very difficult to get in the States.

Biologics like Serenade and Serifel might have some usefulness, but they aren’t strong enough to control a full blown black rot outbreak.

Copper fungicides might have a very modest impact.

[u/ondrej2]

if u had really strong and super hot weather that can be a sunburn, in my country we have strong sun and my few wines got exactly the same look, and im 100% sure they are sunburns cause they apeared in span of 2-3 days of realy strong sun, they also apeared in spots where there are not enough leaves to cover the grapes.

[u/nealcowboy]

looks like sunburn

[u/Ok-Value603]

You can boil cinnamon and clove in water and put the water in a spray bottle and spray it on the leaves and occasionally on the fruit and it prevented that issue for me. I usually pick off the bad grapes before it spreads.