Chocolate Spot Disease of Faba Bean

Faba bean is also known as broad bean, is one of the earliest domesticated food legumes in the world, probably in the late Neolithic period. Cultivated faba bean is mainly used as human food in developing countries and animal feed in industrialized countries.

          Chocolate spot is the most important disease of faba beans. This disease can be managed through an integrated approach including careful paddock selection, the use of resistant varieties and strategic use of foliar fungicides. Symptoms are varied and range from small spots on the leaves to complete blackening of the entire plant. Leaves are the main part of the plant affected but under favorable conditions for the disease, it also spreads to stems, flowers and pods.

          Chocolate spot, caused by Botrytis fabae and Botrytis cinerea, can survive either as sclerotic in the soil or on crop debris, in infected seed, or plants. Previously unaffected areas the disease developed by the sowing of infected seed. Initially infection usually occurs when spores formed on old bean trash are carried by wind into new crops. These spores may move long distances. Once the disease becomes established it rapidly spreads within a crop, and within 4-5 days, the infection spores can be formed on infected tissue and spread the disease throughout the plant.

The fungus is most aggressive it occurs mainly under cool, humid conditions, particularly at flowering time. Environmental conditions mainly determine the severity of a chocolate spot disease. The optimum conditions are temperatures between 15 and 22°C with at least 90 per cent relative humidity. 

The above Article originally got published at SciFed Journal of Mycology in 2017,To have a glance please visit: Click Here