水田雑草に対するイネごま葉枯病菌の病原性

Susceptible lesions of Helminthosporiose inoculated by Cochliobolus miyabeanus were observed on Oryza sativa L., Leersia sayanuka Ohwi., Beckmannia syzigachne Fernald, Setaria viridis Beaw. and hypersensitiye flecks were recognized on Polygonum thumbergii Sieb. et Zucc. and Polygonum perfoliatum L. The penetration of the pathogen was observed on Polygonum hydropiper L., Ranunculus sceleratus L., Oenothera javanica D. C., Bidens fondosa L., Kalimeris yomena Kitamura, Houttuynia cordata Thumb., although the lesion formation was not recognized on these plants without the help of microscope. When the boiled juice of Oryza sativa and Polygonum thumbergii was supplied on these plants through their roots and leaves, number of leaf spots increased in compa rison with the control. In case of the pressed juice of Polygonum thumbergii, the number of spots decreased just a few compared with the control.