Hi

I'm very new to grape vines and have always wanted to grow my own. I now have 5 young vines growing in the south of France and most of them have developed the kind of staining on the leaves shown in the picture . They are young and have not yet started to produce fruit but are actively growing.

They are all in very large pots with plenty of room for root growth

I was hoping that someone can identify the staining , explain what it is and what to do about it ?

Best Regards

Mike