I found the question, and the RHS link, most useful. I have a 5 or 6
year-old chasselas white vine growing outdoors here (W Brittany) which I am
maybe guilty of having overcropped. Whatever, this year the central section
(i.e. the section of oldest wood, and closest to the stem) has many dark and
shrivelled grapes, and is losing its leaves pretty quickly at present. The
other sections, which flowered a little later, and fairly normal. I have
suspected cold damage to the earliest fruit, but now wonder whether I
haven't been pruning and cropping too much, compounding the problem.
David

"billtheburglar" wrote in message
m...
my grapes are turning themselves into raisins, as you can see here
http://myweb.tiscali.co.uk/rleigh/index.html. It is a 4 year old black
hamburgh and produced four good bunches last year. The vine grows
along the ridge of an unheated greenhouse. It may be too close to the
glass and I might be overcropping it a bit. help please!