Saprophytic Behaviour of Some Cereal Root-Rot Fungi

The ability of four cereal root-rot fungi, Helminthosporium sativum, Curvularia ramosa, Ophiobolus graminis and Fusarium culmorum , to colonize wheat straw as saprophytes has been investigated. Test pieces of straw were buried in a graded dilution series of maizemeal-sand culture of the test fungus with unsterilized soil. For assessing percentage straws colonized, three methods were compared: (1) isolation on agar plates, (2) Garrett's (1938 b ) wheat-seedling test and (3) incubation on moist sand, to promote sporulation (the 'sand-plate' test). Curvularia ramosa and Fusarium culmorum were found to behave as vigorous competitive saprophytes of the soil-inhabiting type, whereas Helminthosporium sativum and Ophiobolus graminis proved to be weak saprophytic colonizers of the specialized root-inhabiting type.