Seed Borne Anthracnose in Lupins

Anthracnose is a highly destructive disease of lupins. The disease can cause complete crop losses in susceptible varieties. Anthracnose lesions can form on all above-ground parts of the lupin plant. The most distinctive symptom is the bending and twisting of stems with a lesion in the crook of the bend. This is particularly noticeable when the crop is flowering. Stem lesions are usually dark brown and elongated up to about two centimetres in length. A pale pinkish (sometimes orange) spore mass develops within lesions. The stem is often completely girdled by these lesions or weakened so that it breaks. Both the main stem and lateral branches can be affected and close inspection will often show similar symptoms on leaf petioles. Leaf lesions are not numerous but may be seen as beige spots with a dark brown border. Pods develop lesions similar to stems and are often twisted and distorted. Pod infections can result in complete loss of pods or production of infected seed. Infected seeds can be malformed, have brown lesions, fungal mycelium on the seed surface, or have an occasional pink spore mass. Seeds can also be anthracnose infected without any visible symptoms.