1. First and second authors: Fujian Key Lab of Plant Virology, Institute of Plant Virology; Fujian Agriculture and Forestry University, Fuzhou, China; first, third, and fifth authors: CSIRO Agriculture, PO Box 1600, Canberra, A.C.T. 2601, Australia; and fourth author: INRA Biostatistics and Spatial Processes, Domaine Saint-Paul AgroParc, 84914 Avignon, France.