In vitro screening of fungicides and antagonists against Sclerotium rolfsii
A study was conducted in the microbiology laboratory of Plant Pathology Department, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, during 2010 to 2011 to control Sclerotium rolfsii with fungicides and Trichoderma harzianum. Six fungicides namely Provax-200, Bavistin, Ridomil, Dithane M-45, Rovral 50 WP and Tilt were screened at 100, 200 and 400 ppm concentration for their efficacy against the radial colony growth of S. rolfsii. The complete inhibition was obtained with Provax-200 at all the selected concentrations. Complete inhibition also obtained at the highest concentration of Tilt. The highest concentration of Rovral 50WP inhibits 93.88% radial growth and significantly superior to Dithane M-45 at the highest concentration. Bavistin and Ridomil were found to be significantly lower when used against the test pathogen. A total of 20 T. harzianum isolates collected from rhizosphere and rhizoplane of different crops were screened against S. rolfsii following dual plate culture technique. The screened isolates of Trichoderma showed significantly variable antagonism ranging from 65.01 to 83.06% reduction of radial growth of S. rolfsii. Among the screened antagonists, the isolate TH-18 of T. harzianum showed the highest (83.06%) inhibition of radial growth of S. rolfsii.
Key words: Sclerotium rolfsii, Trichoderma harzianum, fungicides, antagonist.