Inoculum potential of Macrophomina phaseolina
Short, G.E.; Wyllie, T.D.
Phytopathology 68(5): 742-746
Sodium hypochlorite was used to dissolve the melanin-like cementing agent that engulfs sclerotial cells of Macrophomina phaseolina. Then sclerotia were 'squashed' to enable enumeration of cells of the propagules. The number of cells per sclerotium was directly related to size of sclerotia; and sclerotium size appeared to depend on the available nutrients of the substrate on which the propagules were produced. Large sclerotia produced considerably more germ tubes than did small sclerotia when germinated on culture media. Sclerotia of M. phaseolina were sensitive to soil fungistasis; but in the spermosphere of soybean, sclerotia germinated within 2-3 mm of the seed surface and produced one to seven germ tubes per germinated sclerotium.