On some of my largest, older cab franc leaves (basal), I am noticing what
appears to be a slight burning on the tips of the leaves. Otherwise the
leaves look good. Good color. Good size, etc.

Any ideas to suggest what might cause this? A deficiency of some sort?
"General Viticulture" has a paragraph that suggests high sodium, but I'm not
sure how that would happen.

Regards
Jeff Chorniak