Loss of the basal rosette and infection of the crown causes plant death. Excellent control of all stages of the weed under a wide range of environmental conditions is obtained by applying the spores. Under field conditions, typical anthracnose lesions are usually confined to the base of seedling stems or stems of the basal rosette, although lesions can also be found on flowers, peduncles and foliage.
Lesions expand or coalesce to girdle the stems.
Plant tissue above the lesion generally withers and loses its leaves. Leaf lesions have brown centres and alternating light and dark zones. The pathogen is deposited in the national mycological collection in Ottawa as DAOM 195231. In NS, the development of lesions on healthy stems is first observed in early May with the progression of symptoms and first mortality by late May which continues until late fall through a series of secondary infections. Conidia may also originate from infected overwintered plants or from seedlings arising from infected seed.