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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Bean charcoal rot (315)

Photo 1. Brown to grey area of infection covering the entire lower stem and girdling the plant caused by charcoal rot, Macrophomina phaselina. Tiny black dots are the sclerotia.

Photo 2. Sclerotia of charcoal rot, Macrophomina phaselina on maize stem.

Photo 3. Close-up of the sclerotia of charcoal rot, Macrophomina phaselina

Summary

Worldwide distribution. On beans, capsicum, cocoa, curcubits, Caribbean pine. Minor fungal disease.
Watery rot at ground level, spreading up the stem and into roots, causing wilts. On older plants, spots have ash-grey centres with dark margins. Black spots on seedling may girdle stems.
Forms "sclerotia" - balls of the fungus with black protective skin - giving stems sooty or charcoal look.
Spread with movement of soil or plant debris containing sclerotia, and by seed. Sclerotia live up to 3 years.
Cultural control: site nursery far from production areas; use pasteurised soil or soilless mixes; nursery hygiene; check seedlings for spots; in field, sterilise soil under tarps (30 days); 3-year rotation (maize, sorghum); avoid planting next to diseased beans; ensure rapid plant growth ( good tillage, nutrition, weed); collect and destroy trash after harvest.
Chemical control: treat seed with thiram.

Common Name

Bean charcoal rot, ashy stem blight, damping-off, bean blight

Scientific Name

Macrophomina phaseolina. Previosuly known as Macrophoma phaseoli, Macrophoma phaseolina, Macrophomina phaseoli, Rhizoctonia bataticola, Sclerotium bataticola.

AUTHORS Grahame Jackson & Eric McKenzie
Information from Charcoal rot of bean/tobacco (Macrophomina phaseolina). Plantwise Knowledge Bank. (http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsID=32134); and from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, Tony Cooke, Susan House. CSIRO Publishing. Photo 1 David B. Langston, University of Georgia, Bugwood.org. Photo 2 Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org. Photo 3 Paul Bachi, University of Kentucky research and Education Center, Bugwood.org.

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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