Symptoms

• Symptoms on foliage

Attacks on growing crops often go unnoticed.

Black pycnidia may appear at the base of the stems at the end of the growing season or even later, after haulm destruction.

• Symptoms on tubers

Dark depressed areas may be observed on tubers, characterised by thumb mark spots (photo 1) which are frequently found around the wounds, the eyes, the lenticels or at the heel-end.

When the tuber is cut across the lesion, the flesh is shown to be infected by a dark-brown dry rot (photo 2), and pycnidia develop in the lining of the cavities (photo 3).