Determination of Pathogenic Forms of Sweetpotato Blast by Computer and lts Utilization

During 1984 1993, 403 strains of sweetpotato bacterial wilt(Pseudomonas solanacearumm Smith).which were collected from 42 counties of Fujian and 11 counties from Guangdong,Guangxi, Zhejiang and JiangXi provinces were tested for their pathogenicity。 According to the vilu-lence.these strains were divided into three groups(Ⅰ-Ⅱ).The most widely distributed groupwas the first one),which made up 45.66 percent of the total strains tested.The third group(Ⅲ)was the strongest in virulence, account for 21.34 percent of the total strains。 All the strainstested showed quantitative difference in the virulence.No distinct specificity was found.The distribution of the strains was that, the strains stronger in virulence tended to be in old diseased areaswhere the resistant variety was cultivated, and the strains weaker in virulence existed in new dis-eased areas where the susceptible varieties were cultivated.The blast resistant variety was culti-vated 181 thousand ha.based on the distribution of the strains groups tested in Quanzhou, Ningdeand Fuzhou during 1988 1993.The calculated food increased was 1.5 hundred million kg.The so-cial and economic income increaed was 1.45 hundred million yuan.