Determination of specificity and compatibility of six primer pairs used for the uniplex and multiplex PCR using different primer combinations to assay for PRSV, PLDMV, and PapMV. The amplified products were sizes of 953 bp, 613 bp, and 515 bp for PRSV; 476 bp and 205 bp for PapMV; and 355 bp for PLDMV. Lanes 1-6 indicate the uniplex PCR using primer pairs of PRSV953-F/R, PRSV613-F/R, PRSV515-F/R, PapMV476-F/R, PapMV205-F/R, and PLDMV355-F/R. Lanes 7–12 indicate the multiplex PCR using different primer combinations of three primer pairs specific for PRSV, PapMV, and PLDMV: (7) PRSV953-F/R, PapMV476-F/R, and PLDMV355-F/R; (8) PRSV953-F/R, PapMV205-F/R, and PLDMV355-F/R; (9) PRSV613-F/R, PapMV476-F/R, and PLDMV355-F/R; (10) PRSV613-F/R, PapMV205-F/R, and PLDMV355-F/R; (11) PRSV515-F/R, PapMV476-F/R, and PLDMV355-F/R; (12) PRSV515-F/R, PapMV205-F/R, and PLDMV355-F/R. Lane 13, negative control. Lane M, 2000 bp DNA marker.