Paul Jackson, who owns Colinas Farming, has several tracts of vineyards effected by the leafroll virus near Rutherford, Calif. He says there is no cure yet. The leafroll virus that is affecting California vineyards is most noticeable at harvest time when the leaves of red grape vines turn red and white grape vines curl and turn brownish.

Photo: Brant Ward, The Chronicle

Read more: http://www.sfgate.com/wine/article/Leafroll-A-quiet-threat-in-the-vineyard-3258673.php#ixzz2J2RZbA8M