1. 
   Rougeau
   Leaf reddening, caused by any of several viruses in grapevines. The virus infection seals off the leaf petiole (stem) so that the sugars produced by the leaf through photosynthesis cannot be transported back into the vine. The sugar accumulates there until the leaf, in an effort to get rid of a prob...
   Found op http://www.edenwines.co.uk/Glossary_r.html
   
   

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