Characterisation of biotic factors affecting the pathogenicity of a <i>Sclerotinia sclerotiorum</i>based mycoherbicide

Abstract

Giant buttercup (Ranunculus acris L.) is a serious weed of dairy pastures in many regions of New Zealand and at its peak can occupy over 50% of the pasture area. It is unpalatable to cattle and is avoided to the extent whereby pasture plants in the immediate vicinity are also avoided. The national revenue loss incurred by New Zealand dairy farmers from current infestations of giant buttercup is estimated to be $118 million annually. The emergence of resistance to the herbicides historically used to control this weed has led to the need for alternative options for control. Previous work investigated the potential of the fungus Sclerotinia sclerotiorum as a mycoherbicide against giant buttercup. This poster reports on a continuation of this developmental work in which we compare the pathogenicity of three different formulations of S. sclerotiorum. The standard formulation (WH1) and two novel biopolymer formulations (T425 and T425N) were tested in bioassays on excised giant buttercup leaves and the resulting lesions measured after 24, 48 and 72 hours. After 72 hours both T425 and T425N had produced significantly (P<0.05) larger lesions than WH1, indicating that the two novel biopolymer formulations were more pathogenic towards giant buttercup than their rudimentary counterpart.

Evaluation of <i>Sclerotinia sclerotiorum</i> for giant buttercup control in dairy pastures

“…1). It is possible that these chemicals prevented the disease from developing further since it is known from detached leaf studies that some fertilizers can substantially interfere with the growth of this pathogen (Pottinger et al 2004).…”