Plant disease id

[justinb]

My 2 year old vines are struggling. Can anyone id the problem? Should I treat it or let it go until next year? I live in northern Illinois, so we should get a frost in 4-6 weeks

 

[BigH]

First picture looks like potassium deficiency to me, which can be brought on by periods of heavy rain.

H

 

[balatonwine]

One would need more information to really help beyond a WHAG. For example, early season fungus damage, can look like nutrient deficiency during late season senescence.

So a few questions:

- What variety of grape is this?
- What was your pest spray schedule, if any (fungicide and/or insecticide), and what products did you use?
- What was the weather like this year? Dry? Very wet? Etc.
- Is this issue affecting all plants, or just some?
- Is this issue recent or did you notice this or any other issues with these vine's growth during the spring or summer? (Nutrient deficiency is often first noticed as a spring and summer event, during plant growth, not really so much a late summer/autumn event).

 

[justinb]

-This is Itasca. I also have Marquette and Petite Pearl that seem to be unaffected.
-I did not spray anything except Sevin for the beetles
-Wet all year
-This started a month ago and is getting worse. Before this, everything has bee fine. A few cordons have shriveled and died off.

I can take a few more pics if it helps

 

[TOMMARIANI22]

Is there a white substance on the back of the leaves?

 

[justinb]

No white areas on the back of the leaves

 

[askins3097]

Did they start as yellow spots? I’ve been fighting Downey mildew on two of my six Niagara vines and it starts as yellow spots, then looks similar to this.

 

[Dennis Griffith]

If it's a potash deficiency, then you can get that at about any garden center (or Amazon). It would be best to get the soil tested so that you know where you stand,

 

[bstnh1]

https://learn.winecoolerdirect.com/common-grapevine-diseases/

 

[Dennis Griffith]

https://learn.winecoolerdirect.com/common-grapevine-diseases/

Good link..

 

[marquettematt]

Did you fertilize this year? with what?

Supposedly Itasca is resistant to mildews. At least that's what Double A and U of Minn claims. Was there any black rot this year?

How recent are those pics? For this time of year, the canes look way behind on hardening off.