- Worldwide distribution. On beans, capsicum, cocoa, cucurbits, 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.
Pacific Pests, Pathogens, Weeds & Pesticides
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.
Bean charcoal rot, ashy stem blight, damping-off, bean blight
Macrophomina phaseolina. Previously known as Macrophoma phaseoli, Macrophoma phaseolina, Macropshomina phaseoli, Rhizoctonia bataticola, Sclerotium bataticola.
AUTHORS Grahame Jackson & Eric McKenzie
Information from Charcoal rot of bean/tobacco (Macrophomina phaseolina). Plantwise Knowledge Bank. (https://www.plantwise.org/knowledgebank/datasheet/32134); and Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al. CSIRO Publishing; and from Macrophomina phaseolina (2021). Wikipedia. (https://en.wikipedia.org/wiki/Macrophomina_phaseolina). 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.