Grow Your Own Magazine

can someone tell me why some of the leaves on my grapevine are turning yellow and dying there are about a dozen on both plants doing this
they are planted together about one and a half feet apart.
i do not know old they are but are about 3 foot tall and have grapes on them but i did cut some off as there was alot.
please help!!!!

I have problems with mine too, yellow leaves withered and then falling off. I checked over the vine and found scale. I have been picking the scale off and have sprayed the vine but it looks like its dying.

i stopped watering mine as much and they seem to be ok now,the grapes are ripening but are small and sour.but i only got them this year so they may need a hard pruning,