Morphological characterization, cross infectivity and chemo-sensitivity of Sclerotinia sclerotiorum isolates towards bio-agent and new molecules of fungicides

Abstract

Six different isolates of Sclerotinia sclerotiorum were isolated from vegetable host crops namely brinjal, cauliflower, French bean, and pea on potato dextrose agar. These isolates were subjected for morphological characterization, cross infectivity/pathogenicity test and
chemo-sensitivity towards bioagent and new molecules of fungicides. On the basis of morphological characteristics viz., colony colour and texture, the tested isolates were categorized into two groups. Cross infectivity / pathogenicity test were performed on French bean, dolichos bean and pea using leaf detachment technique. Results on cross infectivity revealed non-host specificity of tested isolates of the pathogen. As regards to chemo- sensitivity of these isolates with tebuconazole 250 EC, azoxystrobin 23 SC, fluopyram 17.7+ tebuconazole 17.7 SC, Fluopicolide 6.25 %+Propamocarb Hydrochloride 62.5% SC at concentration of 250, 500, 1000 and 1500 ppm, the combination fungicide fluopyram 17.7+ tebuconazole 17.7 SC was found most effective at concentration of 250 ppm against tested isolates of S. sclerotiorum. In case of in vitro evaluation of bioagent, Trichoderma asperellum against these isolates, the highest
mycelial growth inhibition (50.46%) against pea isolate (PSS- 1) and the lowest inhibition (26.15%) in case of French bean isolate (BSS-1) was observed. Cross infectivity and chemo sensitivity of the pathogen clearly indicate the emergence of this pathogen as broad spectrum covering wide host range.