1. College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, P.R. China
2. National-Local Joint Engineering Research Center for Development and Utilization of Small Fruits in Cold Regions, Northeast Agricultural University, Harbin 150030, P.R. China
3. College of Agriculture, Northeast Agricultural University, Harbin 150030, P.R. China
4. Department of Plant Pathology, University of Georgia, Tifton, GA 31794, U.S.A.