Ascochyta blight (Black spot)
Mycosphaerella pinodes (Ascochyta pisi)

Description

Ascochyta blight, sometimes called black spot, causes a purplish-black discolouration and streaking of the lower stem.  Severe stem infections may also cause stem or foot-rot which kills the plant.

Conspicuous spotting of the leaves and pods also occurs. The leaf spots may be either small, irregular, dark-brown and scattered over the leaf, or a few large, circular brown spots.  Spots on the pods may coalesce to form large, sunken, purplish-black areas.

Infected seeds may be discoloured and appear purplish-brown. Discolouration is usually more pronounced on those areas of the seed coat next to diseased areas on the surface of the pod. Lightly infected seed may appear healthy.