Identification of causal agent for sunflower Verticillium wilt.

More than 200 diseased plants having shown typical Verticillium wilt symptoms were collected from Heilongjiang, Inner Mongolia Autonomous Region, Hebei, Shanxi, Shaanxi, Ningxia Hui Autonomous Region and the Xinjiang Uygur Autonomous Region. 120 strains obtained by tissue isolation technics were identified. On PDA, the colonies showed black, white or gray white. The vegetative mycelium was hyaline and septate. Conidia were o-void or ellipsoid and single - celled. They were borne on phialides, which were produced in a whorl around each conidiophore. Most of these isolates produced black microsclerotia. Genomic DNA was extracted and used as a template for amplification of the internal transcribed spacer (ITS) region of rDNA with primer pair ITS1/ITS4. All of the 120 strains were identified as Verticiilium dahliae Kleb. [ABSTRACT FROM AUTHOR]