The strains of BYDV were more complicated in Baxia, the lower land of Zhangjiakou and Chengde Perfecture.A complex infection of PAGV and PAV was detected besides that of GAV strain.

• 为此，应进一步加强对该地区病毒株系分布及流行的研究，并培育适于各生态区栽培的抗耐病品种。