What's wrong with my grape vine?

August 12, 2012 12:42 PM

UnhealthyGrapeVineFilter: Can anyone help me identify what's causing this leaf discolouration on my grape vine? Is it anything to worry about? I'm not sure if it's natural colour change, disease, mineral deficiency or more than one of these things happening at once. The vine is two years old, fruiting quite heavily, on a very sunny south aspect on a poor mix of clay and various stones. I don't know the variety but it's a standard garden centre dessert grape. The photos are in a what I think is a chronological sequence: http://imgur.com/a/2uITk
posted by cromagnon to home & garden (4 answers total)

Could be severe phosphorus deficiency, could be grape leafroll.

The vine is two years old, fruiting quite heavily,

Generally you don't let grapes fruit the first two years because you want resources going to the roots and foliage. Is that two year figure counting the fact that the vine was probably one year old when you bought it?
posted by jedicus at 12:58 PM on August 12, 2012

Sorry, yes it would have had at least a years growth in the pot before I bought it. This will be its third summer and the first it has borne fruit.
posted by cromagnon at 2:30 PM on August 12, 2012

Seems more like a deficiency- your leaf doesn't seem disfigured. If discoloration occurs primarily on the older leaves that's a good indication it is not leaf-roll, which would occur indiscriminately on the plant. I agree that it looks most like phosphorous- the red-violet is characteristic. Phosphorus deficiency is kind of rare in clay soils, though. Usually it occurs when pH is too low (<5>
You probably need to add organic matter as well. Grapes like about 2-3% organic material in the soil.
posted by oneirodynia at 7:10 PM on August 12, 2012

Well, with a few months development it's definitely leaf-roll. Very sad, but it's for the chop. I'll put in another one in a different location, and get it from a specialist nursery. Thanks!
posted by cromagnon at 3:10 PM on October 1, 2012