Fungal Genomics & Biology
Open Access

Bean Anthracnose

Bean anthracnose, caused by the fungus Colletotrichum lindemuthianum, is a major disease of beans (Phaseolus vulgaris L.), causing serious crop loss in many parts of the world. In 1921, M. F. Barrus of Cornell University demonstrated that bean anthracnose is seedborne. 

The seeds infected from the seedlings often show cotyledons and stems on black lesions to sunken dark brown. Cotyledons are severely infected prematurely and plant growth is slowed down. Sick areas can girdle the stem and kill seedlings. In wet conditions, spores of small pink masses are produced in lesions. Spores produced on the cotyledon and stem lesions can spread to the leaves. Symptoms usually appear on the underside of the leaves, as in the linear, dark brick-red to black lesions that are often not obvious and may be examining when overlooked. The pods on developing the most striking symptoms. Small reddish-brown to black blemishes and distinct reddish-brown circular lesions are typical symptoms. Mature lesions are surrounded by a grayish-black interior with a circular reddish-brown to black border. During wet periods, spores of the exotic pink masses of the interior. Severely infected pods can shrink and the seeds they carry are usually infected. Infected seeds have brown to black spots and sunken lesions. Severely infected pods can shrink and the seeds they carry are usually infected. Infected seeds have brown to black spots and sunken lesions.

The fungus survives winter mainly in bean seeds. Survival in soil or plant residues varies considerably depending on environmental conditions. Research in Canada has shown that the fungus can survive in the field and come into contact. with water. Laboratory tests have shown that alternating wet-dry cycles in the soil reduces the survival of the fungus.