Association of Xanthomonas sesami with Two Types of Leaf Spots affecting Sesame

Abstract

SESAME (Sesamum orientale L.) grown under rain-cultivation in the Sudan is severely affected by two types of leaf spotting. In one (Fig. 1) the spots are usually small, 2–4 mm in diameter, dark red-brown to black in colour, somewhat translucent, often angular with sharply defined margins, and may coalesce to form irregular lesions. The dead tissue of the spot later dries up and becomes brittle. In the other type (Fig. 2) the spots are large, 4–14 mm in diameter or more, greyish or light brown, usually opaque with somewhat diffuse margins, often irregular and frequently coalescing. Affected tissues become wrinkled before they dry. The first type is more often found towards the top of the plant while the second type is more frequently encountered towards the base.