For the last 6 of 8 years my grapes have been attacked by what I was told is "red vein disease" which seems to be caused by some sap-sucking parasite that appears in mid-summer just as the baby grapes are getting bigger. It curls the leaves, turns them red then halts the growth of the grapes, making them split and turn bad. I have treated them with a "captan ultra" (ethanethiol methyl mercaptan) and water solution which I was told spraying on when the flowers grow, would save them. It didn't. Last year I cut the 3 vines all the way back to their stock (which I don't usually do as their main function is to provide shade). and hoped for the best. But already, some of the first leaves growing back are curled and a few show the beautiful but deadly sign of the dreaded red vein disease. I've include a pic from past years and acouple from this. I would appreciate any help in treating this problem. TIA
Since I know of no insect vector for fungi it make no sense to use a fungicide. Bacterial and viral diseases are spread by insects the most notable being Xylella fastidiosa spread by Glassy-Winged Sharpshooter and other leaf hoppers. The disease if it's bacterial or viral is incurable and the vines should be destroyed. http://www.scielo.br/pdf/tpp/v33n6/v33n6a07.pdf
Well, saltcedar, that sounds a bit drastic. You refer to it as a fungus which it certainly looks like on the grapes, but I took a magnifying glass to the leaves a few years back and I saw little sap-suckers sucking sap from the veins of the leaves. Any other ideas, or opinion on the use of ""captan ultra" (ethanethiol methyl mercaptan) and water solution"? TIA
My point wasn't that you have a fungus, my point is that you have a virus or bacterial infection which is commonly spread via insects. My other point is that whomever sold you the fungicide didn't have a clue since insects don't spread fungi. Fungicide can't cure or treat a viral or bacterial infection. http://en.wikipedia.org/wiki/Xylella_fastidiosa This link explains the most common major Grape disease in North America. Your plants appear to have a phloem inhabiting pathogen not a fungal infection
Hi saltcedar, Are you SURE that destroying my 3 vines is the only answer? And if so, will it hurt any of my other plants (mostly cactus) if I do it at the end of the Summer? You see, I planted the vines about 10 years ago mostly to bring much needed shade to my patio. The grapes (Thompson Seedless) were just an added bonus. If possible I'd like to enjoy that shade for just a little longer, even if it means doing so midst a faux-Fall. TIA
The only concern is that other grapes may be infected by your vines. If you're confident no other uninfected grapes are within two miles of your location they can stay indefinitely. The prudent thing to do is take a sample of the vine to be tested and verify what pathogen it is.
I will look into a testing option in the nearby wine area of Valle Guadalupe, Ensenada and see what comes out of it. I appreciate your involvement, despite the harsh advice.
