Anthracnose of Lettuce

Marssonina panattoniana (Microdochium panattonianum)

This disease mainly attacks the young plants. Large numbers of tiny round to angular yellow spots (3 - 5 mm diameter) occur on the outer leaves, then become necrotic and dark.
The necrotic spots may fall off and leave holes in the leaf.
The whole crop can die when contamination is high.