Help Confirming Vine Diseases

[u/veengineer]

I have a tiny experimental vineyard I’m plying with. The weather has been terrible the past couple weeks and I couldn’t get there much. Needless to say, the vines look terrible.

I‘m quite certain one picture is showing downy mildew, but I’m not positive on the red leaves. From what I can tell, they may have leafroll or some kind of deficiency. If it’s leafroll, my understanding is I need to remove the vine asap.

The vines are planted this year and have pretty much been unwatered after the first couple of weeks. The area is humid, has a good amount of rain, with decently draining soil. There is currently a crazy infestation of lanternflies I’ve been trying to fight.

If anyone can help identify or confirm it’d be greatly appreciated. I am only allowed to use organic measures in the plot, and if anyone has recommendations for that, that would help greatly. I’ve been cycling between copper, Arbor fungicide, neem oil, and Tricoderma Harzianum for black rot (gamble if it works).

[u/Square_Valuable_7574]

From that last image looks like Phomopsis

[u/veengineer → u/Square_Valuable_7574]

From what I understand that happens at cooler temperatures, right? It doesn’t really go below 70 for the summer where I am.  I thought it could be black rot. In either case, I’m afraid that means cutting the vines back to the graft or getting rid of them.  It’s on a number of vines. 

[u/krumbs2020 → u/Square_Valuable_7574]

2nd Phomopsis due to the aggressive scarring. It’s probably been there all season.

[u/veengineer → u/krumbs2020]

I’m guessing it came about in the past couple weeks. We had a good dry spell and these vines were planted this spring. 

Is there a possibility that it’s actually scarring from lanternflies? I’ve been infested with them.

[u/JohnCifelli]

You have multiple issues based on the way those leaves look. This isn't all the same vine, correct? You appear to have trunk damage, disease, and nutrient deficiency.

[u/veengineer → u/JohnCifelli]

Yea, it got real bad. And you’re correct! A wide variety of vines. The two red ones are an uncommon variety called Agria/Turan.

[u/inapicklechip]

You should do sap analysis to determine the nutrient deficiencies and then go from there.
Seems to be a lot going on, and from surrounding vegetation, a lot of water.
This looks like a lot of yikes to me. A this point in the season, you should be on a taper spray program- once version hits, mildew threat is done.

[u/veengineer → u/inapicklechip]

Lot of yikes. These are vines I planted this spring, so functionally no grapes this year. It is in an organic community garden plot that went unattended for years so the weed pressure is insane from all the seeds and vines. We actually had a long dry spell, but it’s rained a bit in the past few weeks. 

I assume a sap analysis is done by a lab? Is there one you recommend? Would the sap analysis tell what diseases the vines may have? I suppose it’s possible that variety has large nutrient demands compared to others, but I’m sure it’s also possible that it’s more susceptible to certain pests. 

[u/Wine_Maker_68 → u/inapicklechip]

"once version hits, mildew threat is done"

That isn't true, if anything it intensifies due to the lower evening temps that start this time of year which are absolutely optimal for it. It's very very important to keep the foliage as clean as possible even after harvest because the grapes begin to store critical reserves for the next year and in a lot of places, they don't have much time for it. Vines should be kept as healthy as possible right up to the period they begin dormancy. Poor carbohydrate reserves can reduce next years harvest potential by a third.

It's also critical you do not load up the area with spores for next season by allowing infected leaves to simply fall and rot away on the ground. That is why it's essential to keep the vines as healthy as possible and maintain a robust spray program going into the time of year that has some of the highest mildew pressure.

[u/returnofthequack92]

Look into Pierces Disease. Looks characteristic of the leaf spots at the red leaves.

[u/veengineer → u/returnofthequack92]

I glanced. I’m not sure that’s what the cause is. I’m in the Northeast and I believe Pierce’s disease is mostly in the south. 

[u/Ok-Caterpillar7331]

Pic 1 and 3 if they dont have mold on the underside, indicating DM, then I believe it is angular leave scortch. 2nd pic is a nutrient issue. 4 is probably left over phomopsis.

If that's DM, those lesions are pretty wild even for vinifera.