Analysis on the Biological Characteristics and Pathogenicity Correlation of Ustilaginoidea virens in Fujian

To clarify the biological characteristics and pathogenicity of Ustilaginoidea virens in Fujian, the colony color, mycelial growth rate, sporulation ability and pathogenicity of 74 strains collected from 6 regions of Fujian province were determined by conventional biological culture and artificial injection inoculation. The results showed that four phenotypes, namely white, yellowish green, green and dark green, appeared on the back of the colonies of the tested strains, with frequencies of 37.84%, 35.14%, 17.57% and 11.45% respectively. The occurrence frequencies of strains with a fast mycelial growth rate（greater than 2 mm·d⁻¹）and strong sporulation ability（sporulation quantity greater than 3×10⁶ cells·mL⁻¹）were 66.21% and 64.86%, respectively. The occurrence frequencies of strains with disease index ranged from 25 to 50 and greater than 50 were 56.76% and 20.27% respectively. The mycelial growth rate of Ustilaginoidea virens was negatively correlated with pathogenicity at a low degree（R=−0.305）, and the sporulation ability was positively correlated with pathogenicity at a moderate degree（R=0.509）. In Fujian region, there was obvious differentiation in the biological characteristics of Ustilaginoidea virens, among which strains with fast mycelial growth rate, strong sporulation ability and moderate pathogenicity were dominant.