INTERACTION OF BIOCONTROL FUNGI WITH SUBLETHAL RATES OF METHAM SODIUMFOR CONTROL OF VERTICILLIUM-DAHLIAE

Two methods were used to expose microsclerotia of V. dahliae to variou s rates of metham sodium ranging up to 935 1 ha(-1). When microsclerot ia were entrapped in a single layer of nylon mesh, buried in nonsteril e soil and exposed to metham sodium, radial growth from the microscler otia was reduced by rates as low as 93.5 1 ha(-1) of metham sodium. Wh en microsclerotia were enclosed inside a nylon mesh envelope, buried i n soil and exposed to metham sodium, growth rate was not affected by 1 871 1 ha(-1). The biocontrol fungi Gliocladium roseum and Talaromyces flavus were incorporated into alginate prill, buried in soil and expos ed to metham sodium. Growth rate of G. roseum from prill was reduced b y 187 and 935 1 ha(-1) metham sodium while growth rate of T. flavus wa s 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 18 7 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 b oth biocontrol fungi together.