Symptoms start with a brown speckling of the lower leaves, eventually spreading upwards to the newer leaves and pods. These lesions are often dotted with small fruiting bodies called pycnidia. Cool, wet conditions favour disease development. These organisms may be found on seed, on crop residue and in the soil. Mycosphaerella blight may be found on the leaves and stems as purple spots.
Foot rot symptoms usually appear on the stem near the soil surface as bluish black discolorations.
Both fungi thrive in wet environments. Powdery mildew is probably the most commonly observed disease in field peas in Alberta because the fungus, Erysiphe polygoni, develops just before or at harvest. As the name implies, a white powdery coating covers the leaves. Eventually, the speckles turn into spots and the plant turns purple, bluish-green and, lastly, brown. Warm, dry days and cool nights are critical to this organism's development.