|Control efficacy of an extract of cultured Xylogone ganodermophthora on powdery mildew caused by Podosphaera xanthii on watermelon in Korea|
H. J. KANG (1), Y. Kim (1), T. Kim (1), C. U. Han (1), T. k. Jeong (1), S. Y. Nam (2). (1) Watermelon Research Institute CBARES, Eumseong-gun Chungcheongbuk-do, Korea; (2) Watermelon Research Institute CBARES, Eumseong-gun Chungcheongbuk-do, South Korea
<i>Xylogone ganodermophthora</i> (Xg) is an ascomycetous fungus that causes yellow rot on cultivated <i>Ganoderma lucidum</i>. Previously, we reported the <i>in vitro</i> antifungal activities of an Xg culture extract against several watermelon pathogens, including <i>Phytophthora capsici</i>, <i>Fusarium oxysporum</i>, <i>Sclerotium rolfsii</i>, and <i>Podosphaera xanthii </i>(Px). In 2014, we carried out greenhouse experiments to evaluate the control efficacy of a water extract of cultured Xg on watermelon powdery mildew (WPM). The test material (stock solution) was prepared by autoclaving an Xg culture in water at a ratio 800 g of culture per 6 L of water and then filtering it through filter paper. In the first trial, application of the solution (diluted 100- and 1,000-fold) at 7-day intervals suppressed the formation of conidiophores and conidia significantly. In the second trial, the 100-fold diluted solution was applied to watermelon plants 14 times before harvest (no fungicide was used). Near harvest time, more than 90% leaves of the plants were infected with Px. However, the farmer harvested 93.5% marketable fruits. These results suggest that a water extract of cultured Xg could be used as an environmentally friendly agent for the control of WPM in greenhouses.