Detection of Zucchini yellow mosaic virus Infecting Wax Gourd in Guangdong Province and Genetic Variation of Its Coat Protein Gene Development of a Multiplex RT-PCR Protocol for the Detection of Three Viruses on Benincasa hispida. var. chieh-qua Development of a Multiplex RT-PCR Protocol for the Detection of Three Viruses on Benincasa hispida. var. chieh-qua