Interaction of biocontrol fungi with sublethal rates of metham sodium for control of Verticillium dahliae

Two methods were used to expose microsclerotia of V. dahliae to various rates of metham sodium ranging up to 935 1 ha(-1). When microsclerotia were entrapped in a single layer of nylon mesh, buried in nonsterile soil and exposed to metham sodium, radial growth from the microsclerotia was reduced by rates as low as 93.5 1 ha(-1) of metham sodium. When microsclerotia were enclosed inside a nylon mesh envelope, buried in soil and exposed to metham sodium, growth rate was not affected by 1871 1 ha(-1). The biocontrol fungi Gliocladium roseum and Talaromyces flavus were incorporated into alginate prill, buried in soil and exposed to metham sodium. Growth rate of G. roseum from prill was reduced by 187 and 935 1 ha(-1) metham sodium while growth rate of T. flavus was not affected by either rate of the fumigant. In a greenhouse test in field soil, infection of eggplant by V. dahliae was not reduced by 187 1 ha(-1) of metham sodium, but was reduced with (187) 1 ha(-1) plus either biocontrol fungus. The combined effect of the sublethal rate of the fumigant with either biocontrol fungus was additive for reduction of disease incidence as was the sublethal rate of the fumigant with both biocontrol fungi together.