I'm noticing the oldest, lower leaves of my cab franc vines are showing a bit of reddening--like premature fall coloring. And the leaves are beginning to--ever so slightly--curl under. I believe this is leaf roll virus. I thought it might be a potassium deficiency, but there is no symptom on newer leaves or the upper canopy.
Is there a rememedy for leaf roll virus? Can it be controlled this year? What preventative maintenance will stop it from coming back next year? Is it fatal to vines? (i've been told no, but need to confirm it)
Jeff