MYCOHERBICIDE FORMULATION AND THE POTENTIAL FOR BRACKEN CONTROL

The imperfect fungus Ascochtya pteridis, causal agent of curl-tip dise ase, is considered as the potential active ingredient of a mycoherbici de for the control of bracken (Pteridium aquilinum (L.) Kuhn). Results of experimental attempts to improve pathogenicity by the addition to the spore inoculum of one or more adjuvants are reviewed. The importan ce of protecting spores and germ tubes from desiccation in the pre-pen etration phase is emphasised and results of experiments demonstrating the potential for water retention by invert (water-in-oil) emulsions d iscussed. Provisional results of field trials using an invert emulsion of water in soybean oil are summarised. Infection was achieved, but i t is thought that the low level of mycoherbicidal activity was due to application when the host was beyond its most susceptible stage.