Identification of a pathogen causing soft rot on Amorphophallus albus and laboratory screening for bactericide

【Objective】In order to provide reference for field bactericide control,this paper identified the pathogen species of Amorphophallus albus soft rot in Anlong County,Xingyi City,Guizhou Province,and explored the indoor inhibitory activity of several bactericides against the pathogenic strain.【Method】The pathogen were isolated and purified from diseased stalk of A. albus by streak plate method sampled from planting base in Anlong County,Guizhou Province,the pathogenicity of the isolates were detected by Koch's postulate,the pathogen was identified by morphological characteristics,16S rDNA sequence analysis and phylogenetic tree analysis. The indoor toxicity of thirteen common agents to pathogen were measured by bacteriostatic circle method.【Result】It was confirmed that Pectobacterium aroidearum was the causal agent of the A. albus soft rot,which was found in Anlong County,Guizhou Province,and the strain was named as XYmy-A1. The results of indoor toxicity measurement indicated that there were seven bactericides of experimental pesticides had inhibitory effect on the growth of XYmy-A1,80% ethylicin EC,5% oligosaccharins ·20% ethylicin ME,25% brothermothingonil ME,3% zhongshengmycin SL,0.3% tetramycin AS had inhibitory effects on the growth of pathogen at the tested concentration,while 1.5% benziothiazolinone EW and 1.8% xinjunan acetate AS had inhibitory effects on strain only at high concentration. Among them,0.3% tetramycin had the strongest inhibitory effect to XYmyA1,the median inhibition concentration(EC₅₀) was 0.1980 mg/L,and followed by 25% bromothalonil,whose EC₅₀ was 9.1359 mg/L.【Conclusion】The pathogen is P. aroidearum which causing soft rot on A. albus in Anlong County,Guizhou Province. 0.3% ehydroxide AS and 25% bromothalonil ME can be selected for the first choice for field trials,1.5% benziothiazolinone EW,3% zhongshengmycin SL,80% ethylicin and 5% oligosaccharins·20% ethylicin can be used as alternative agents.