Spots on grape clusters

[justinb]

This is my 1st year of being able to harvest grapes, and I noticed dark spots on the grapes today. Im assuming its a fungus. I have been regularly spraying with Rally, and just recently switched to Captan.

Is there anything I can do to save this years crop of Marquette and Petite Pearl?

 

[wood1954]

This is my 1st year of being able to harvest grapes, and I noticed dark spots on the grapes today. Im assuming its a fungus. I have been regularly spraying with Rally, and just recently switched to Captan.

Is there anything I can do to save this years crop of Marquette and Petite Pearl?View attachment 63488

https://fruit.wisc.edu/wp-content/u...to-diseases-of-cold-climate-grapes-final3.pdf
try this site, it has good pictures of diseases

 

[Xnke]

That looks to be anthracnose. How many days til harvest?

 

[billybigcreek]

This is my 1st year of being able to harvest grapes, and I noticed dark spots on the grapes today. Im assuming its a fungus. I have been regularly spraying with Rally, and just recently switched to Captan.

Is there anything I can do to save this years crop of Marquette and Petite Pearl?View attachment 63488
It looks like you have let it go a little long but keep spraying and always spray 2 times with one and then the 3rd spray with another. You have to mix it up other wise your grapes will get use to the spray and stop fighting the funguses. Captan usually requires a mixture, like captan and nova. I use Abound 2 times and then switch to eagle 20 EW then back to abound. If it’s raining a lot spray every 7 days. If normal weather spray every 10 to 14 days.

 

[Rice_Guy]

The photos suggest black rot. I could show photos of my infection rate too
I am alternating sprays example spray for fungus Friday and then Saturday spray Japanese beetles with added sulphur. I would be more efficient if I upgraded to a fogging sprayer, efficiency is related to contact.

If you are showing this level in July it is established in this years crop. . One recommendation from the vinters group was remove and burn infected berries or clusters to try to save the rest. I am a home grower so I also sort at crush time.
I am debating removing Frontenac and itasca, (not petite pearl) ,,,,, Briana, concord and some self seeded are surviving better this year. @wood1954 really good variety comparison , wish I would have seen this when deciding what was worth planting.

 

[justinb]

Thanks all. Ill keep spraying and hope for the best. I did a lot of leaf pulling today to improve air circulation and for better spray penetration. Hopefully, I can salvage some of the clusters

 

[salcoco]

spraying for black rot must start in the spring once shoots are about 3 inches long. I believe manzibed(spelling?) is the preferred method. Google black rot should find information.

 

[user 36973]

It is definitely anthracnose. Black rot doesn't make those lesions; it starts from a small purple spot and spreads over the entire berry. I've attached a couple slides from Purdue's viticulturalist on anthracnose that should help.

 

[salcoco]

Black rot (grape disease) - Wikipedia here is discussion and pictures for black rot

 

[Xnke]

I am still in the anthracnose camp. The giveaway is the light spot in the middle of the dark area. Black rot never shows this. Just a darkening and shrivelling.

Keep in mind it is entirely possible you have both!

Check the green stems and canes for areas that look like cigarette burns. Black or dark areas with ashy grey centers. That's Anthracnose for sure. It affects both stems and fruit.

Black rot affects leaves and fruit, and starts out on leaves as tiny black pinhole spots.

 

[Cynewulf]

I’ve dealt with my share of black rot and my vote is with the others that it’s anthracnose. I haven’t experienced it myself but my understanding is it has to be prevented rather than treated. I’d get it out of the vineyard (grapes, leaves, shoots, etc) and make sure you’re spraying sulfur and mancozeb early next year.

 

[balatonwine]

Keep in mind it is entirely possible you have both!

I think he has both. Which is not unexpected if one did not spray and both diseases are local. One shold not assume that a singular disease is present without others.