Lettuce big-vein disease

Lettuce big-vein disease causes leaf distortion and ruffling in affected lettuce plants.

This disease was first associated in 1983 with a rod-shaped virus Lettuce big-vein associated virus, which is transmitted by the obligately parasitic soil-inhabiting fungus, Olpidium brassicae. However, in 2000 a second virus Mirafiori lettuce virus was found in lettuce showing big-vein symptoms. Furthermore, since the lettuce infected with this virus alone developed big-vein symptoms, it is considered to be a main agent of the big-vein disease.