Vine blight - can you identify this problem?
Posted 08 October 2003 - 10:53 AM
I've looked around on the net and haven't found anything useful about this problem, so I wonder if anyone has had this happen to their vines and could diagnose the problem. I planted these vines this year, and some of the older leaves are developing these spots. The vines seem healthy other than that, and are growing well. I can't figure it out. Here's a picture:
Any ideas or references would be appreciated. Could it be from underwatering?
Thanks a lot,
Posted 08 October 2003 - 10:56 AM
Only 3-4 leaves have this problem.
Posted 08 October 2003 - 12:32 PM
The top vines looks like it may have a little downy mildew. Or maybe a chome type virus.
The bottom vine looks like it has suffered insect damage quite some time ago. But the damage looks like nothing that I have seen around here so I cannot diagnose which insect/worm. If I had to guess I would say slugs or catapillars.
Also the burning on the lower edge of the bottom leaf looks like drought stess . 'could also be a potassium deficiant.
Posted 08 October 2003 - 07:02 PM
Yeah, the bottom one is surely insect damage. We have a crushed Habenero pepper/water spray that's supposed to keep them off. We'll use that next year. It's a very small problem - just a few leaves on that one plant.
As for the top one being powdery mildew, here's the descriprion I found in 'vines to wines' - "P.M. attacks leaves...where it appears as whitish patches of cobweblike growth ont he upper surface...later, the whiticsh patches turn gray...the leaves eventually turn brown then black".
These leaves just start with the brown spots, which slowly cover the leaf. there's no white growth or mildewey smell, and only older leaves are effected. I've really scoured available material and haven't found much.
Posted 08 October 2003 - 07:20 PM
If you have not sprayed, you probly have a little bit of everything.
Copper is a good slug, worm deterant. I figured that out myself.
Posted 08 October 2003 - 07:37 PM
The Downy mildew description looks a little more like my situation, though it does describe whitish growth on the undersides of the leaves. It's possible I missed that. Fortunately, it's treatable. I'll try out the 'Bordeaux mixture' recommended in 'vines to wines' which includes copper sulphate and may take care of both problems.
Really appreciate the advice. I'll read a little more closely in the future.
Posted 08 October 2003 - 07:39 PM
Posted 08 October 2003 - 07:45 PM
Glat to hear that Betty - confirms the diagnosis. I only have it on the bottom leaves of 2 plants, so it was confusing me. I was hoping I could get by without spraying, but it looks like I'll need to.
I planted these 4 plants this year as a sort of trial run and will be putting in 8-12 (still undecided) more next spring. I'll know a lot more by then and hopefully will not have ruined these poor souls in the meantime.
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