Problems?

[Mark64]

This is what I had last yr. Can anyone please advise on what spray and when to use it? Thanks

 

[grapeman]

That is a mildew - either downy or powdery mildew. The spray would be determined by which one it is. Hard to tell without being able to have a larger picture. When I get more time I will zoom it in a photo editor and let you know. Right now I am prparing for a pruning workshop here later today.

 

[Mark64]

Thanks for quick response.

 

[Mark64]

Bump up one time!

 

[djrockinsteve]

You will need to start a spraying program and before you see signs of this. I had same problem last year. Grapeman and Rob are more knowledgable than me.

 

[grapeman]

I can't blow it up on this computer, but it surely looks like downy mildew to me and a very bad case of it. The leaf blotches are indicative of it and the fuzzy grapes are almost a sure sign of it from what I can make out. You will need a preventative spray program to keep it in check. There are spray chemicals you can use or you can use less toxic sprays such as Prophyt which is basically a liquid fertilizer. Alternate spray chemicals listed to control it to reduce chances of resistance buildup. Keep the foliage open through proper canopy management and get rid of diseased foliage when you can do so safely.

Refer to the NY Penn State IPM Guide for a description of the disease and ways to control it.

http://ipmguidelines.org/grapes/

 

[Mark64]

The more I read the less I understand. Some say use Captan. Others tell me to use Copper Fungicide???????????
Maybe I should just try some ROUNDUP.. LOL

 

[grapeman]

Both Captan and Copper Fungicides work with downy mildew so what don't you understand? LOL Captan has certain problems with it but has been used for a lot of time. Copper products when repeatedly used over time tend to pollute the soil with heavy metals. That is where using different products helps somewhat. I use mancozeb products early as that helps with black rot also and controls downy, so you are protecting against multiple problems. You need to switch to Captan or something else as you can't spray that closer than 66 days to harvest.

Then powdery mildew requires something else to control it. Learn your diseases, what can be used to control them along with their precautions. Then scout for problems and act when a certain threshhold is reached. Most diseases you wan't to act proactively with a protective plan as it is harder to kill some of them than protect against them.

 

[Mark64]

Both Captan and Copper Fungicides work with downy mildew so what don't you understand? LOL Captan has certain problems with it but has been used for a lot of time. Copper products when repeatedly used over time tend to pollute the soil with heavy metals. That is where using different products helps somewhat. I use mancozeb products early as that helps with black rot also and controls downy, so you are protecting against multiple problems. You need to switch to Captan or something else as you can't spray that closer than 66 days to harvest.

Then powdery mildew requires something else to control it. Learn your diseases, what can be used to control them along with their precautions. Then scout for problems and act when a certain threshhold is reached. Most diseases you wan't to act proactively with a protective plan as it is harder to kill some of them than protect against them.

Thanks;

I am beginning to think it's powdery mildew. Why? My garden is close to my grapes and last yr I had cucumbers and zucchini loaded with powdery mildew to the point that plants died in the middle of producing season. This spring (if it ever gets here) I will pay close attention and see what happens. Is it safe to spray some Copper fungicide now before leaves pop out? All I see is some buds for now. Last yr my first sign was that some leaves were starting to yellow.