Survey of virus diseases affecting cucurbits in Taiwan
Yuan-li Chan - World Vegetable Center. Lawrence Kenyon- World Vegetable Center, Su-Ling Shih- World Vegetable Center, Li-Mei Lee- World Vegetable Center, Fu-hsun Kuo- World Vegetable Center
Cucurbits, including cucumber, chayote and bottle gourd, are some of the important vegetables in Taiwan. However, virus disease is a major constraint to the production. To identify predominant and emerging virus diseases of cucurbits in Taiwan, a field survey was conducted in 2016 and 2017. Samples from different cucurbit plants with virus-like symptom were collected from different areas of Taiwan and the virus(es) present in each were diagnosed by ELISA, RT-PCR and PCR. In cucumber samples, CCYV was predominant in southern Taiwan with approximately 76% of samples testing positive. About two thirds of CCYV positive samples also tested positive for presence of one or more other viruses. CCYV was not detected in the samples from eastern and central Taiwan. The major virus in eastern Taiwan was SLCuPV while MYSV was prevalent in central and northern Taiwan. It suggests that cucumber production in central and northern Taiwan is greatly affected by thrips-transmitted Tospovirus while whitefly-transmitted viruses are the major threat in eastern and southern Taiwan. Similarly, whitefly-transmitted SLCuPV was predominant in the samples of bottle gourd and chayote. Approximately 88% of chayote samples and 38% of bottle gourd samples tested positive for SLCuPV by PCR. The second important virus in bottle gourd was from the genus Potyvirus, including PRSV-W and ZYMV; approximately 32% of samples were infected with potyvirus. These results suggest that whitefly- transmitted viruses are the most important factor to limit production of cucumber, bottle gourd and chayote in Taiwan.