Thanks for this
"David Rance" wrote in message
I have a 3y.o. outdoor grape vine, Chardonnay on a 3309 american
rootstock.

[snip]

Are the leaves a uniform yellow or are they blotchy and beginning to
look as though they are scorched?

They seem to go a uniform yellow, sometimes starting from one side of the
leaf. There's what looks like a few rust spots on some.

If the former then it could be lack of water (though this isn't normally
a problem with an established vine) and/or lack of trace elements. Three
years old is barely established.
If the latter then you have a mildew problem.

I've looked up the Oxford Encyclopaedia on Wine and I don't see any traces
of powdery or downy mildew as described there. There has been a lot of rain
this summer but the vine is against a garage wall and down through gravel
where there won't be much moisture. I'm hoping it's actually lacking trace
elements.

thanks for your help.