# Spots on Marquette berries



## mattyc (Jul 7, 2016)

These black spots showed up about two weeks ago on my Marquette berries in my small vineyard in Central MN (near Twin Cities).

Anyone have any thoughts on what this might be? It doesn't seem to be getting any worse. 

I dealt with a little bit of black rot last year, but was better prepared this year. I've pretty much followed this Ohio State paper for my black rot treatment... Mancozeb once a week from the time the shoots were 3-5" to 3-4 weeks post-bloom.

I sprayed Sevin and I think one shot of Malathion for Japanese Beetles as well.

Also dealt with frost that killed probably 10% of shoots in mid-may.

Closest thing I can find is this picture of Pesticide Spray Injury partway down the page where it compares antracnose to pesticide spray injury.

Thanks!


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## GreginND (Jul 7, 2016)

It doesn't quite look like anthracnose. I would suspect black rot. Do you see any of the tell tale brown spots with dark edges on the leaves? Any black on stems?

I am seeing the same thing and haven't sprayed for black rot. So I was assuming it is black rot. Like you, they are not progressing. But we have been very very dry so I am hoping the disease pressure is low.


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## TonyR (Jul 7, 2016)

I agree, looks like early black rot.


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## mattyc (Jul 7, 2016)

Really? With weekly Mancozeb treatment?

When I had a small black rot infestation last year, it was very fast-moving, daily having more berries that looked like this even with picking the bad berries off dailiy. I don't have any like that this year.

Leaves/stems look good to me. Only damage is japanese beetle and some leftover frost damage only the first few leaves.


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## TonyR (Jul 7, 2016)

Maybe not black rot. Reread your post. And have not gotten any worse, if black rot it would be much worst. I remember reading somewhere that you do not youse Malathion if the temps are going to be in the 80's or higher. Has something to do with petroleum in the spray. Someone here should know for sure.


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## grapeman (Jul 7, 2016)

If you zoom in on the spots it is almost certainly anthracnose. You should be approaching the period where they will no longer be susceptible. If rot develops it will take on a birds eye appearance as the grapes get larger. The mancozeb should protect against it. It is possible you did not get good spray coverage during the period of rapid growth around bloom time. They will likely be useable if it doesn't get worse.


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## mattyc (Jul 10, 2016)

Thanks Rich. I'd be surprised if lack of coverage was the issue, but hey, I'm new at this. I'll definitely try to make sure COVERAGE is not an issue in the future!


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## mattyc (Jul 10, 2016)

Quick separate note... my wife and I had our first glass of 2015 Marquette this week - leftovers from bottling. It was amazing! And my wife liked it even better than I did - doesn't get much more rewarding than that! (We drank a blended french red a few nights later and she commented "It's good, but not nearly as good as the Marquette" )

Thank you to all here who helped me get to that point!


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## ILWIIA (Jul 12, 2016)

Feel free to share said 2015 Marquette


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## dorfie (Jul 13, 2016)

I agree, it looks like anthracnose. Mancozeb is only a protectant so if it isn't fully covered during one application and the spores can enter, you will get lesions. 
Jealous that you have fruit, my vines are still a few years out! 
Just keep in mind Mancozeb's 66 day pre-harvest interval!


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