A Comparison Between Healthy and Leafroll-Affected Grapevine Planting Stocks

¹ Department of Viticulture and Enology University of California, Davis, California 95616.
² Department of Plant Pathology University of California, Davis, California 95616.
³ Department of Viticulture and Enology; University of California, Davis, California 95616.

A vineyard trial set in 1968 at Davis, California, to compare performance of commercial, non-certified Burger scions and Dogridge rootstocks from Lodi, California with certified Burger scions and Dogridge rootstocks from the Foundation Vineyard at Davis in a factorial experiment became a comparative study between healthy and leafroll-affected grapevines. Indexing showed that the non-certified Burger scion wood was infected with leafroll virus; the Burger scion wood from Davis and both sources of Dogridge were free of virus. Vines developing from noncertified Burger scions on either rootstock source were leafroll-affected. Those developing from healthy scions on either rootstock source were leafroll-free. With full crops, the healthy vines were superior to leafroll-affected ones in growth, yield and sugar content of the fruit. With approximately 50 percent crop reduction, the rate of sugar accumulation in the leafroll affected vines was equal to that in the fully-cropped, healthy vines. Regardless of crop or sugar level, the acidity of the fruit of leafroll-affected vines was higher than that of healthy vines at any given date during the ripening period.