Wounding of <i>Cirsium arvense</i> enhances the efficacy of <i>Sclerotinia sclerotiorum</i> as a mycoherbicide

Abstract

Two experiments were conducted in which mycelial fragments of the plantpathogenic fungus Sclerotinia sclerotiorum were applied with an organic food source to Cirsium arvense shoots with and without prior wounding In the first experiment more shoots developed disease when the fungus was applied to crush wounds on stems (100 of stems diseased) than when applied to the wound of decapitated stems (38) or to the uppermost leaf axil of decapitated stems (13) In the second experiment reduction in the autumnal shoot dry mass of C arvense due to the mycoherbicide (broadcast in early December at 60 kg/ha) was greater when the shoots were wounded with a spade before applying the mycoherbicide (49 reduction) than when not wounded (26) These results imply a greater susceptibility of wounded C arvense tissues to S sclerotiorum that could be exploited to enhance the efficacy of this fungus as a mycoherbicide