Research into biocontrol of cotton diseases at the ACRI began in 1991. Since thennumerous microorganisms have been tested. Several of these have controlled seedling diseases, Verticillium wilt and Fusarium wilt effectively in the glasshouse. Recently their usefulness in controlling seedling diseases was demonstrated in a field trial at the ACRI. Biological control agents increased seedling emergence, protected the seedlings from damping-off and increased seed cotton yield. Their performance was better than, or on par with the standard fungicide treatment. In previous years, plant growth promotion effects (regardless of disease control) were also observed under field conditions.