Therefore, the specific objectives of this research were: (1) to evaluate the biocontrol effcacy of a wide range of structurally different invert and/or oilemulsion formulations against waterhyacinth in the field; (2) to determine the inoculum threshold of the bio-herbicide; (3) to study the effect of Ae5 culture age on itsinfectivity; and (4) to attempt to reduce the oil content in the Ae5 formulation as much as possible without reducing its effcacy against waterhyacinth.