Identify the Vine Issues

[koolmoto]

This grape vine came with the house and we have done very little to help it thrive. Now that I planted a backyard vineyard and am getting into grape growing, I am noticing that this vine may not be doing so well. It has black spots on the shoots, some leaves are curly and crumpled looking, and some leaves have leathery, yellowish splotches and dead edges. I am thinking it is a combination of poor nutrients and some mildew. What do you think? This picture was taken a few days after spraying Mancozeb and Neem oil.

 

[balatonwine]

Powdery mildew. The black spots on the stems are pretty typical of this disease.

Spraying now will not help these leaves much. They are too far infected. In fact, I would probably remove most of the very damaged leaves and stems, and all fruit (the vine is too infected to really produce a crop). Spaying will only protect new growth, which is to consider to help the vine survive the winter. And removing some leaves and stems will stimulate some new growth and open up the canopy.

 

[koolmoto]

Powdery mildew. The black spots on the stems are pretty typical of this disease.

Spraying now will not help these leaves much. They are too far infected. In fact, I would probably remove most of the very damaged leaves and stems, and all fruit (the vine is too infected to really produce a crop). Spaying will only protect new growth, which is to consider to help the vine survive the winter. And removing some leaves and stems will stimulate some new growth and open up the canopy.

Thanks so much! I will remove the damaged leaves/stems+all fruit as you suggested. Thankfully this vine is on the complete other side of the property so I don't think it will infect the rest of my newly planted vines unless I accidentally bring material over there. I'll spray it earlier next season.

 

[Neb Farmer]

It may depend on your climate where you are, but to keep powdery mildew under control is primarily a preventive action. I spray with an organic wettable sulphur spray at least once every two weeks just to keep powdery mildew from taking over my winegrapes. I adhere to this spraying schedule from the time right before buds break open and right up through veraison, then stopping somewhere 4 or 5 weeks before harvest. If there are any hot periods during my spray time, I will try maybe to spray a little earlier within the two-week period. Spraying in the heat ( 85F or higher) is not a good thing to do , due to chemical burning of the plant.
There are chemicals you can spray with that will 'kill' the powdery mildew on your vines, but by the time you have to resort to that course of action the damage is already done. It will retard the growth and development of the grape berries themselves and you will end up with grapes that are hard, juiceless, and only good for slingshot ammo.

 

[koolmoto]

It may depend on your climate where you are, but to keep powdery mildew under control is primarily a preventive action. I spray with an organic wettable sulphur spray at least once every two weeks just to keep powdery mildew from taking over my winegrapes. I adhere to this spraying schedule from the time right before buds break open and right up through veraison, then stopping somewhere 4 or 5 weeks before harvest. If there are any hot periods during my spray time, I will try maybe to spray a little earlier within the two-week period. Spraying in the heat ( 85F or higher) is not a good thing to do , due to chemical burning of the plant.
There are chemicals you can spray with that will 'kill' the powdery mildew on your vines, but by the time you have to resort to that course of action the damage is already done. It will retard the growth and development of the grape berries themselves and you will end up with grapes that are hard, juiceless, and only good for slingshot ammo.

Good to know. It sure requires more often spraying than I expected, so I'm glad I asked. I have some sulfer too. Should I mix mancozeb, neem oil, and sulfur, rotate them, or choose one over the others?

 

[Cynewulf]

Good to know. It sure requires more often spraying than I expected, so I'm glad I asked. I have some sulfer too. Should I mix mancozeb, neem oil, and sulfur, rotate them, or choose one over the others?

Definitely do not mix the sulfur and oil. In fact, I think you’re supposed to wait 30 days between applying one before the other. Mancozeb is not effective against powdery mildew so you will need one of the other treatments. I personally mix mancozeb with sulfur for my first six sprays, then rotate mancozeb out for Captan, Immunox, and sulfur. You need to start when shoots are about 1/2-1 inch.

 

[koolmoto]

Definitely do not mix the sulfur and oil. In fact, I think you’re supposed to wait 30 days between applying one before the other. Mancozeb is not effective against powdery mildew so you will need one of the other treatments. I personally mix mancozeb with sulfur for my first six sprays, then rotate mancozeb out for Captan, Immunox, and sulfur. You need to start when shoots are about 1/2-1 inch.

OK, good info here. Thanks! I'll have to pick up some Captan/Immunox. I have a half sprayer tank full of Mancozeb+Neem Oil, but I feel like just dumping it so I can mix Mancozeb and Sulfur. How would you dispose of it?

 

[user 36973]

Should I mix mancozeb

And don't lose track of the 66 day PHI for mancozeb. It's great for early season disease prevention, but you'll need to move on to other, shorter PHI sprays later such as Captan and Ziram.

 

[Cynewulf]

OK, good info here. Thanks! I'll have to pick up some Captan/Immunox. I have a half sprayer tank full of Mancozeb+Neem Oil, but I feel like just dumping it so I can mix Mancozeb and Sulfur. How would you dispose of it?

You don’t want to be keeping your leftover fungicide (a mistake I made myself when I first got started). The half life of mancozeb after being mixed in water is only about 24 hours so it degrades quickly and will become ineffective. Captan will also degrade fairly quickly once mixed. I now try to mix only what I need. I understand you can dump out whatever is left into the soil.

 

[koolmoto]

You don’t want to be keeping your leftover fungicide (a mistake I made myself when I first got started). The half life of mancozeb after being mixed in water is only about 24 hours so it degrades quickly and will become ineffective. Captan will also degrade fairly quickly once mixed. I now try to mix only what I need. I understand you can dump out whatever is left into the soil.

Learning so much today! Thank you! I love this forum.

 

[Cynewulf]

Btw, based on one of your other posts, I just realized that you’re in California. I spray with mancozeb, et al because I’m on the East coast and deal with heavy disease pressure, including black rot and downy mildew, which I don’t think are significant issues out West. You should check with others in your area, but you may be able to get away with only spraying sulfur from time to time for powdery mildew. I’m in favor of spraying as little as possible and wish I could get away with just a bit of sulfur but it’s not to be out here.

 

[koolmoto]

Btw, based on one of your other posts, I just realized that you’re in California. I spray with mancozeb, et al because I’m on the East coast and deal with heavy disease pressure, including black rot and downy mildew, which I don’t think are significant issues out West. You should check with others in your area, but you may be able to get away with only spraying sulfur from time to time for powdery mildew. I’m in favor of spraying as little as possible and wish I could get away with just a bit of sulfur but it’s not to be out here.

Thanks. Now that I care about grape growing, I am noticing that both grape vines I have (came with my house) have powdery mildew on some shoots, but I don't necessarily see any black rot or downy mildew. I'll try getting away with sulfur only and just check them vigilantly. I also would like to spray as little as possible.

 

[Neb Farmer]

Thanks. Now that I care about grape growing, I am noticing that both grape vines I have (came with my house) have powdery mildew on some shoots, but I don't necessarily see any black rot or downy mildew. I'll try getting away with sulfur only and just check them vigilantly. I also would like to spray as little as possible.

When I first began my small vineyard I wanted to be as organic as possible. I had grown food grapes for years before this, and thought it would not be an issue. Well, winegrapes are an entirely different thing, and I found out that I would HAVE to spray sulphur, and on a schedule of once every two weeks, or else face crop failure.
The interesting part is that I thought maybe being in the Western side of Washington ( moderate and humid, sometimes downright damp) was the reason I had powdery mildew. But after discussing this topic with a winery owner on the dry side of the state, he mentioned it was the same for him ,too. So...dry...wet...hot...moderate...powdery mildew loves vinifera.
Organic wettable sulphur isn't what I consider to be nasty stuff, and it will also take care of a few insects like mites. I don't have the insect problem, though. Just powdery mildew. It only takes about 2 gallons of spray/mix for my small 45 vine vineyard, which I use a ryobi battery powered sprayer to spray it with. I like the battery powered sprayer a lot because the spray/mix is not under pressure. This allows me to open the tank and add or dump the liquid without waiting for the tank to de-pressurize. This is much faster and easier than dealing with a pump-up sprayer/tank.
Have fun farming and making wine!