PROBLEM TO BE SOLVED: To impart various favorable characters to agriculturally useful plants by biological means.SOLUTION: The present invention relates to a method and a microbiologic agent in which Escherichia bacteria are made to artificially infect agriculturally useful plants such as Leguminosae plants, Poaceae plants, and Liliaceae plants so that the disease and insect damage to these plants are inhibited, their growth is promoted, or their yield is increased.【課題】本発明は、生物学的な手段によって農業上有用な植物に種々の好ましい性質を付与することを目的とする。【解決手段】本発明は、エシェリヒア（Escherichia）属細菌をマメ科植物、イネ科植物、ユリ科植物等の農業上有用な植物に人為的に感染させることにより、これらの植物の病虫害を抑制し、生長を促進し、或いは収量を増加させるための方法、並びに、微生物製剤。【選択図】なし
