Bacterial Blight (Pseudomonas syringae)
Bacterial blight in peas first appears as dark-green, water-soaked lesions on the leaves, stipules, pods and stems. These lesions are angular in shape, follow the leaf veins and may eventually coalesce and turn necrotic. Lesions on the pods are sunken and become olive-brown. This disease favours high humidity or leaf moisture and warm temperatures.
Bacterial blight in peas is best controlled by crop rotation, planting disease-free seed, using resistant varieties and keeping equipment clean.
Powdery Mildew (Ersiphe pisi)
Powdery mildew appears as white, powdery tufts of fungal growth that can be rubbed off during early infection. This fungal growth will eventually expand and become chlorotic on the upper leaf surface. Black fungal structures may appear later in the season. Pod infection causes grey-brown discoloration of the seeds. This disease favours heavy dew and moderate to warm temperatures. It can be soil-borne, seed-borne or wind-dispersed.
The best way to manage powdery mildew is through resistant cultivars, crop rotation and in more severe cases, foliar fungicide.
Mycosphaerella (Ascochyta) Blight (Mycosphaerella pinodes)
Visit ‘Foliar Fungicide Decision Making in Peas‘.
Additional Resources
Field Pea Disease Diagnostic Series – North Dakota State University
Diseases of Field Pea – Alberta Agriculture
Field Pea Disease Management – Saskatchewan Pulse Growers