EFFECTIVENESS OF THE ENTOMOPATHOGENIC FUNGUS BEAUVERIA-BASSIANA (BALS) VUILL FOR CONTROL OF THE STEM BORER CHILO-PARTELLUS (SWINHOE) IN MAIZE IN KENYA

The fungus Beauveria bassiana (Bals.) Vuill. and insecticide trichlorf on were compared for the control of stem borer, Chilo partellus (Swinh oe) in field experiments at different times of infestation. Egg masses of C. partellus at the blackhead stage were pinned to the undersurfac e of the maize leaves. Two fungal formulations, conidial aqueous suspe nsions and a granular formulation, were applied. Compared with the unt reated checks, the numbers of surviving C. partellus larvae were signi ficantly reduced in treatments where B. bassiana was applied at a conc entration of 10(13) conidia ha-1 as granules and as two aqueous spray formulations. No significant difference in numbers of stem borer larva e was found between trichlorfon and the untreated check. Fungus granul es persisted longer in the field than did one spray of the fungus inoc ulum at the same concentration, or trichlorfon. A major increase in gr ain yield was obtained with two fungal sprays and with fungus granules both applied at a concentration of 10(13) conidia ha-1. A granular fo rmulation of B. bassiana should be considered for the control of the s tem borer C. partellus.