Alternaria spp.

Early blight or brown spots

• Causal agents and transmission

Early blight is caused by a group of species of the fungal genus Alternaria. At least two species are responsible for early blight symptoms on potatoes, A. solani and A. alternata. These fungi overwinter in the soil, on crop debris and infected tubers. They are pathogenic to Solanaceous plants, potatoes and tomatoes, but can also be considered as saprophytes. The spores are spread by the wind and rain splashing.

 
• Significance

Early blight occurs in most of the continents where potatoes are grown. Its real severity is probably disguised by efficient chemical control against late blight. In view of predicted climate change, the reduction of mancozeb- based chemicals and the use of susceptible cultivars, severe early blight epidemics may become problematic in the future.