Fungi responsible for this condition may be introduced on cuttings or be present in soil. Use sterilized soil. Fungicides may be used as a drench. Use cuttings from healthy plants only. This fungus is most severe when temperatures are cool and moisture levels are high.
Affected plants decline rapidly with stems and leaves developing brown, water-soaked lesions.
In advanced stages all tissues may be penetrated by the fungus. This disease is especially severe under greenhouse conditions where begonias are propagated. Growers should be sure to start with disease-free cuttings, use a sterilized medium and keep the growing area free of any type of weak or decaying plant material that might serve as a food source for the fungus. Brown spots appear on foliage and reduce plant vigor. Most leaf spotting fungi thrive under high moisture conditions.