Effect of chemicals and antagonists on the growth of Rhizoctonia solani (Kuhn) causing black scurf of potato (Solanum tuberosum L.)

Abstract

Rhizoctonia solani is the cause of potato black scurf disease, which has become a serious hazard in the majority of India's potato-growing regions. The effectiveness of fungicides was verified in vitro for the per cent mycelial growth inhibition of Rhizoctonia solani. Monceren entirely inhibited the mycelial growth at 100 ppm as compared to MEMC and boric acid, which inhibited mycelial growth up to 81 per cent and 76 per cent, respectively at 100 ppm concentration. Among tested fungicides, mancozeb was least effective which checked 45.00 to 74.33 per cent of fungal growth, followed by hexaconazole (70.00 to 99.33%) and propiconazole (72.33 to 99.66%) relatively at 100 to 1000 ppm concentrations. Amongst the four bioagents, Trichoderma harzianum showed superior results, inhibiting mycelial growth by 71.11 percent, followed by T. viride (64.44%). Bacillus subtilis and Pseudomonas fluorescens, the bacterial bio-agents, showed the least effectiveness, inhibiting mycelial growth by 55.27 and 47.22 percent, respectively.