7Watanabe T, Ozawa M, Sakai R. Anew disease of Chinese cabbage caused by veticillium alboatrum and some factors related to the incidence of the disease [ J]. Ann Phytopath Soc Japan, 1973, 39:344-350.
8Dixon G R. Theoccurrence and economic impact of Plasmodiopho- ra brassicae and clubroot disease [ J ]. J Plant Growth Regul, 2009,28 : 194-202.