|Jones, Suzanne -|
|Pethybridge, Sarah -|
|Hay, Frank -|
Submitted to: New Zealand Journal of Crop and Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2011
Publication Date: June 2, 2011
Citation: Jones, S.J., Pethybridge, S.J., Gent, D.H., Hay, F.S. 2011. Sensitivity of Australian Sclerotinia sclerotiorum isolates from bean fields to boscalid. New Zealand Journal of Crop and Horticultural Science. 1:1-5. Interpretive Summary: White mould is one of the most economically damaging diseases of bean. The disease causes losses through reductions in marketable pods, and high levels of the disease can result in complete crop rejection. Management of white mould depends largely on the use of a single fungicide. In this study, the level of pathogen sensitivity to the fungicide was quantified to determine if there were indications of fungicide resistance in the population. No evidence was found to suggest reduced sensitivity from pathogen isolates from Australian bean fields. This study provides valuable baseline data for monitoring changes in sensitivity to this fungicide.
Technical Abstract: White mould caused by Sclerotinia sclerotiorum is one of the most economically damaging diseases of bean in Australia. The disease causes losses through reductions in marketable pods resulting from flower infections by ascospores. High incidence of white mould can lead to complete crop loss through rejection by processors. In Australia, white mould is managed by the prophylactic application of the fungicide, boscalid over the flowering period. Boscalid was introduced into bean production in 2004. The sensitivity of S. sclerotiorum isolates collected in 2008 (n = 102) and 2009 (n = 48) was tested using a mycelial growth assay. The effective concentration of boscalid required to reduce mycelial growth by 50% (EC50) was calculated using probit analysis. The frequency distribution of EC50 values was unimodal, and similar to that of 11 isolates nonexposed to boscalid sourced from pyrethrum and culture collections. No evidence was hence found of reduced sensitivity within the S. sclerotiorum population from Australian bean fields. This study provides valuable baseline data for monitoring changes in sensitivity to this fungicide.