Suppression of carpogenic germination and viability of Sclerotinia sclerotiorum sclerotia by biofumigation, biological control and Perlka

Abstract

Sclerotia play an important role in the disease cycle of Sclerotinia sclerotiorum. Traditional control measures do not effectively suppress germination and viability of sclerotia. This study performed a series of in-vivo bioassays to investigate the effect of biofumigants produced by Brassica juncea ‘Caliente 199’, biological control by Coniothyrium minitans, and Perlkaâ on carpogenic germination and sclerotial viability. Coniothyrium minitans alone or in combination with Perlkaâ resulted in complete inhibition of carpogenic germination and high sclerotial mortality. Perlkaâ treatment in quantities equivalent to field rates of 400 and 300 kg ha-1 resulted in 100% and 77% reduction in sclerotial germination, respectively compared with the untreated control, but viability remained high (³97.5%). Treating the potting mix with plant tissue of ‘Caliente 199’ in quantities equivalent to the field rate of 100 and 75 t ha-1 reduced carpogenic germination by about 46% compared to unamended control but did not result in significant reduction in sclerotial viability. Coniothyrium minitans and Perlkaâ were effective in suppressing carpogenic germination but the suppression achieved with biofumigation was much lower. Coniothyrium minitans with Perlkaâ resulted in high sclerotial mortality, which was not achieved with the Perlkaâ only treatment. These results showed that of the treatments tested, C. minitans able to reduce the carpogenic germination and the viable inoculum. Further studies are needed to assess the effectiveness and potential of integrating with non-pesticide methods to achieve better control of S. sclerotiorum in the field.