Method and compositions for controlling round-leaved mallow using

Abstract

Commercial mycoherbicide compositions for the control of round-leaved mallow weeds (Malva pusilla Sm.), the active ingredient being the spores of the fungus Colletotrichum gloeosporioides f.sp. malvae, ATCC 20767, these spores having been produced by a two-phase multi-staged liquid fermentation process, then separated from the mycelial biomass and concentrated into a spore slurry. The active ingredient of the mycoherbicide compositions, i.e., spores, can be packaged as a concentrated spore slurry or alternatively, dried and then packaged. Both the liquid and dry forms of the myco-herbicide are packaged in gas- and water-impermeable containers. The spores are stabilized prior to packaging or drying by the addition of a stabilizing agent or alternatively, stabilized after drying by adjusting their final water content. The initial, i.e., primary, fermentation phase may be made up of multiple stages and is performed under conditions which are optimized for production of mycelial biomass while restricting spore production. The final-phase fermentation is performed under conditions which limit mycelial biomass production but are optimized for production of the active ingredient, i.e spores. These mycoherbicide compositions are applied by suspending the spore slurries in water or alternatively, suspending the dried spores in water, and followed by spraying of the resulting suspension onto round-leaved mallow weeds. The active ingredient of these mycoherbicidal compositions, i.e., fungal spores, will control only round-leaved mallow weeds, and does not affect other weed species or non-target crop plants.