Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV) were isolated from naturally infected squash plants in northern Egypt. The two viral isolates were maintained on squash plants cv. Eskandrani. Serological and molecular methods, including enzyme-linked immunosorbent assay (ELISA), dot-blot immunoassay (DBIA), tissue-blot immunoassay (TBIA), and reverse-transcription polymerase chain reaction (RT-PCR) were compared to evaluate their usefulness for detection of Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV). Each method was tested with primary leaves and true leaves at different times after inoculation squash plants. Results showed that Indirect ELISA and TBIA were more sensitive than DBIA, with all samples tested. WMV and ZYMV were detectable in squash primary leaves and true leaves after 2-day post inoculation. DBIA was less sensitive than either indirect ELISA or TBIA. DBIA could not detect WMV on day 2 or after inoculation started to give results on day 3. ZYMV was detected by DBIA at 2 day after inoculation in primary leaves and 3 day in true leaves. The most sensitive method was RT-PCR, which could detect WMV after 12 hours on primary leaves and true leaves post inoculation, while in case ZYMV, RT-PCR method could detect the virus as early as 6hour post inoculation with all leaves tested.
Key words: Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV), indirect ELISA, DBIA, TBIA and RT-PCR