A methodology for risk analysis of plurivorous fungi in biological weed control: Sclerotinia sclerotiorum as a model

Abstract

In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete Sclerotinia sclerotiorum, as a biocontrol agent for Cirsium arvense in pasture. As a consequence of the wide host range of this fungus, the proposed biocontrol may pose a risk to non-target arable plants. Crop disease risk is primarily due to the formation of sclerotia. These perennating bodies may directly infect susceptible crops sown at the biocontrol site in years after the biocontrol event. Additionally they may cause infection in neighbouring crops through the formation of apothecia from which airborne ascospores are dispersed. A methodology for a risk analysis is proposed, embodying both temporal and spatial processes, where the relative disease risk from biocontrol is defined as the ratio of added to naturally occurring inoculum.