Pathogen. The fungus persists in plant refuse in the soil, on weeds and on other susceptible hosts.

Disease development. Infection occurs when windblown spores germinate on the foliage. Temperatures above 18°C favour disease development.

Initial symptoms of brown spot are tiny brown
circles or pepper spots on leaves
Older lesions of brown spot are round with concentric rings that are not as noticeable as
the rings of early blight lesions Brown spot lesions may coalesce to form larger necrotic
areas with dark brown margins These necrotic areas usually form near the edges of leaflets
Brown spot lesions develop on stems when disease
pressure is very high
Stem lesions
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T.G. Lynn
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