Worldwide distribution. On peanuts, and other plants belonging to the genus Arachis. Important diseases.
There are two types: early and late, but difficult to tell these fungi apart on symptoms – there is need of a microscope.
Reduction of yields of 50% are possible.
Spots, first on older leaves, produce spores that spread in wind and rain; the fungi survive in crop debris.
Cultural control: avoid planting near old crops; 1-year crop rotation; remove “volunteers”; check crop once a week; tolerant varieties; collect and burn trash after harvest.
Chemical control: begin to spray as soon as spots are seen and no later than 30-35 days; use chlorothalonil (also effective against rust) at 10-14 days until 14 days before harvest. More often if rainfall high.