Evaluation of Streptomyces spp. for Pathogenic Fungal Inhibition of Rice

Abstract

Rice is often suffered from plant diseases and pest insects, especially, fungal diseases including dirty panicle disease caused by Curvulania lunata, Cercospora oryzae, and Fusarium semitectum and brown spot disease is caused by Bipoloris oryzae. Most rice farmers always used synthetic chemicals to control these plant diseases but those fungicides often provide a negative effect by regular and continued application leading to fungal resistance to fungicides, chemical contamination on agricultural products and environment. The objective of this study was to evaluate the isolates of Streptomyces spp. that could inhibit the growth of Pyricularria oryzae causing rice blast disease. The seven isolates of Streptomyces spp. including 2USVRA408, 2USVRA105, 2USVRB204, 2USVRA202, 2USVRA108, 2USVRA104 and 2USVRA101 were investigated on the growth of three plant pathogenic fungi causing agents of dirty panicle disease (C. lunata, C. oryzae, and F. semitectum) and the pathogen of brown spot disease of rice (Bipoloris oryzae). The result showed that Streptomyces spp. could inhibit the dirty panicle pathogens by 43.56-55.44% of C. lunata, 46.56-56.78% of C. oryzae and 52.22-65.56% of F. semitectum, whereas the pathogen of brown spot disease, B. oryzae, could be inhibited by 50.11-56.33%. From this study indicated that almost all isolates of Streptomyces spp. had the potential to control the rice disease pathogen at low to moderate in vitro antagonistic activity excepted isolate 2USVRA108 against of F. semitectum showed a high level of in vitro antagonistic activity.