First report of leaf blight on Saposhnikovia divaricata by Pseudomonas viridiflava in Gansu, China.
During disease surveys on medicinal plants in August 2010, a bacterial leaf blight was discovered with a general incidence of 40 to 60% on S. divaricata farms in Longxi, Weiyuan County in Gansu, China. In young plants, tiny yellow-white points were visible on the backs of the leaves. They then expanded to 2- to 3-mm oil-soaked lesions; leaves appeared crimped and deformed. Later the leaves shriveled; black-brown oil-soaked lesions appeared on the vein and the tissue around it; and black streaks appeared on the stems. Based on the symptoms, colony morphology, biochemical tests, 16S rDNA sequence identity and pathogenicity tests, the pathogen was identified as P. viridiflava. This is thought to be the first report of leaf blight of S. divaricata by P. viridiflava in Gansu province. In Jilin province, the same disease was reported in 2008. The impact of P. viridiflava on S. divaricata production is not yet known.