สูตรสำเร็จของ Streptomyces philanthi RL-1-178 ในการควบคุมโรคทางใบที่เกิดจากเชื้อราของถั่วฝักยาว (Vigna sesquipedalis (L.) Fruw.) โดยชีววิธี

Abstract

The objectives of this study were to prepare and test Streptomyces philanthi RL-1-178 formulations for biological control of yard long bean (Vigna sesquipedalis Fruw.) fungal leaf diseases. Culture filtrate of S. philanthi RL-1-178 inhibited spore germination of leaf fungal pathogens of yard long bean (Uromyces vignae, Oidium sp. and Cercospora cruenta) at the rate of 100% in vitro. Two granule formulas and two powder formulas of S. philanthi RL-1-178 exhibited good formulations whith high invariability and mild acidic pH. After formulations, the products were made and kept at 4, 28 and 40°C for 6 months. Formula 1 (kaolin 5%; lactose monohydrate 85%; cell and spores 10%) contained highest viability of S. philanthi RL-1-178 (6.2x10 cfu/g) after storage at 4°C for 6 months, and inhibited spore germination of fungal pathogens at the rate of 87.00 -91.20%. The tests under field conditions showed that formulation of S. philanthi RL-1-178 reduced the incidence of all leaf diseases but its efficacy was less than the fungicide carbendazim. Spraying with carbendazim reduced the incidences of rust, powdery mildew and leaf spot by1.22, 0.63 and 0.96, respectively. The reduced rust diseases when spraying with the granule formula 1 (1.67) and powder formula 1 (1.78). The reduced powdery mildew diseases when spraying with granule formula 1 (0.85) and powder formula 1 (1.04), and reduced leaf spot diseases when spraying with the granule formula 1 (1.07) and powder formula 1 (1.37). The yield of yard long beans in each experimental treatment was higher than the control (distilled water).