Charcoal rot (Macrophomina phaseolina) is a widespread soil-borne fungus but a weak pathogen. It attacks plants that are moisture-stressed late in the season when soil temperatures are warm.
What to look for
Paddock
Plants mature prematurely as individual plants or in small groups.
Plant
The stem and taproot interior have an ash-grey discolouration, partly caused by masses of tiny black microsclerotia embedded in the tissue.
Where did it come from?
Contaminated soil
M. phaseolina survives as microsclerotia in the soil and on infected plant debris. The microsclerotia serve as the primary source of inoculum and may persist within the soil up to three years.
It has a wide host range, although cereal species are not normally infected.
Management strategies
None. Charcoal rot does not usually reduce yields because infection takes place after the plant has completed pod set and the crop is approaching maturity.
