Grape leaves turning brown!

Phoenix, AZ

My grape leaves are turning brown! This was a severely neglected vine. I pruned it back in the beginning of February and it seemed to be growing ok. Until all of a sudden the leaves started looking terrible. Any ideas on what this is and how to combat it?
Thanks in advance!

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Contra Costa County, CA(Zone 9b)

I think it is a disease, perhaps a fungus, but to be sure, I would take some samples (well sealed, zip-lock bags) to an extension office or department of agriculture, if there are any local to you.

Phoenix, AZ

Thank you very much! I was afraid of that :(. I already lost an apricot tree due to what I believe is fire blight. This is the one aspect of gardening that I had no idea about, or how difficult it can be to deal with.

Do you know how much something like that may cost?

Contra Costa County, CA(Zone 9b)

Consulting with either of the places I suggested, or even a reputable nursery are free.

They can suggest possible treatments, and these will cost something.
Often the treatment may include improving the health of the plant with fertilizer (small cost, big benefit), deep soaking irrigation (costs some time, and some water) and pruning specific to the plant (no cost, unless you hire a specialist, but anyone can learn the timing and technique to prune various plants), and timing these things to minimize disease or insect problems.

There may also be some sprays that can be used at the right time to prevent this from happening next year. The spray might be expensive or cheap, or there might be simple home remedies that could work. Depends on what the actual problem is.

Hummelstown, PA(Zone 6b)

Did you ever figure out what this was?

To me it doesn't look like disease. The two most common foliar diseases in grapes are downy mildew in cool moist climates and powdery mildew in hot dry climates but neither disases looks like that.

Have you applied anything oil based to the leaves on a hot sunny day? or even splashed water?

How about applied any herbicides in close proximity or to the soil around the grapes? Arizona gets very hot at times...could be a sunburn?



This message was edited Jul 19, 2013 7:38 AM

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