Pathogen Identification And Control Techonolgy Of Water Soft Disease On Chinese Angelica In Gansu Province

1.Water soft disease on Chinese angelica in Gansu was a new bacterium disease, which caused many seedlings died and seriously impacted on Chinese angelica yield and quality. The disease occured from mid-may in the field,then development.The incidence of disease in the field reached peak at the early August.This is the first report about the disease.2.Three bacteria strains were isolated from the typical symptoms of the sample,they were gray、white and yellow,pathogenic test on the Min angelical,the results showed that:gray strain was water soft disease pathogen.Inoculated on tobacco were carried out, the results showed:gray and yellow strains produced necrotic lesions, the white strain did not react.3. Three angelica varieties were evaluated resistance for Pseudomonas fluorescens.Take, seedling plate and pot experiment,the seedling plate results showed that:’Korean angelica’ resistance was the best in three varieties,’Min angelical’ take the second place.’Korean angelica’incidence was13%,’Min angelical’ incidence was40%,’Min angelica2’ incidence as high as86.7%.Pot experiment results showed the same as the seedling plate.4.According to morphology、physiological、biochemical and、16S rDNA sequenceo of the colony and the result of pathogenicty test,the pathogen identified as Pseudomonas fluorescens.The physiological and biochemical characteristics of the pathogen was studied:The optimum growth temperature was25～30℃, under UV light irradiation on KB medium could produce yellow-green fluorescent pigment, it did not resistant to salt, strict aerobic.16S rDNA sequence, getted the length of1445bp DNA fragment, by comparison with the GenBank, Pseudomonas fluorescens similarity reached99%.5.Toxicity tests in laboratory showed that:chlorobromoisocyanaria acid antibacterial、copper hydroxide、amber plastic fatty acid copperand trichloroisocyanuric acid could be effectively protected the pathogen.The cyanuric acid bacteriostasis was the most effective intested pestcides. 6.Field chemical control exprement results showed that:the effective of copper hydroxide was the best in four pestcides.The incidence of disease was processing copper hydroxide30g was less than1%,the relative control effect was88%.Yield results showed that:penethamate2.0g producted up to20307g, the production was2times as the CK as increase rate of97.9%.