pathogenen.病原体(病菌)pathogenn.病原体Pathogenetic deficiency mutant致病力减弱突变体pathogen of pear blossom blast梨花枯病原pathogens causing wilt disease萎蔫病原微生物Pathogen bacteria distribution病原菌分布pathogen smaller than bacteria小于细菌的病原体Pathogen of wilt of watermelon西瓜枯萎病pathogens causing downy mildews霜霉病菌类pathogenieities differentiation遗传多样性Pathogens of wheat sharp eyespot小麦纹枯病菌pathogenetic condition evaluation病情评估