Main symptoms
 

Microdochium panattonianum can attack young plants which are particularly susceptible. In severe attacks, when covered with wet spots, the seedlings become chlorotic and their growth remains blocked.

This fungus is mainly responsible for spots on all parts of the leaves close to the ground (figure 1). On the leaf blade, these are initially small and moist (figure 2). Subsequently, they expand and become rather circular. Their delimitation by the ribs can give them an angular appearance. Damaged tissue turns orange to brown in color. It does not take long for them to thin out as they dry out, split and fall off (Figure 3). The leaves are thus sifted (figure 4).

The spots are more elongated on the veins (Figure 5), slightly depressed and more often confluent. They also have a more or less dark orange tint.

At the periphery of the spots, discrete whitish to pink spore masses form; it is the acervuli (or sporodochia, figure 6) of Microdochium panattonianum which ensure its asexual (anamorphic) reproduction.

When late contamination occurs, lesions only appear during storage and transport, degrading the quality of salads ready to be marketed.