Ascochyta blight of pea

Symptoms

Small purple-brown lesions on stems near soil line in seedlings, brown leaf spots with dark concentric rings as plant matures, dark sunken lesions on pods + flower clusters, infected seeds show brown discoloration + may carry pathogen to next planting.

Easily confused with

• powdery mildew of pea

  How to tell them apart: Ascochyta pisi (Ascochyta blight) and Erysiphe pisi (pea powdery mildew) both attack pea leaves but differ in the lesion itself. Ascochyta pisi makes discrete, sunken, tan-to-brown spots with a darker reddish-brown rim, often with tiny black dots (pycnidia) in the centre, and the same lesions appear on stems and pods. Erysiphe pisi instead produces a superficial powdery white-to-grey coating that wipes off with a finger, starting as faint pale patches on the upper leaf surface and spreading to cover whole leaves, stems and pods in a dusty film, and it is favoured by warm dry days with cool humid nights rather than the wet conditions Ascochyta needs.