Graft Transmission of Lettuce Big Vein

Abstract

LETTUCE big vein disease, first described by Jagger and Chandler¹, causes a pale yellow vein banding on the leaves, sometimes accompanied by leaf puckering. The disease is soil borne and healthy lettuces planted into contaminated soil develop leaf symptoms, usually in 4–6 weeks. Fry² and Yarwood³ isolated tobacco necrosis virus from the roots of affected plants, but plant or soil inoculation with the virus failed to reproduce the disease. Grogan et al.⁴ showed that the roots of affected plants were invariably invaded by a fungus which they identified as Olpidium brassicae (Wor.) Dang., and they reproduced the leaf symptoms by adding zoospores of this fungus to the soil in which lettuce plants were growing.