Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson

Abstract

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves.

The incidence of disease varied from about 10% up to practically complete destruction of some plantings.

A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.