Progress and Challenges in Managing Watermelon Vine Decline caused by whitefly transmitted Squash Vein Yellowing Virus (SqVYV)

Authors: Kousik, Chandrasekar - Shaker; Adkins, Scott; Turechek, William; WEBB, S - University Of Florida; BAKER, C - Florida Department Of Agriculture And Consumer Services; STANSLY, P - University Of Florida; ROBERTS, P - University Of Florida

Submitted to: Israel Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2012
Publication Date: 5/31/2013
Citation: Kousik, C.S., Adkins, S.T., Turechek, W., Webster, C.G., Webb, S.E., Baker, C.A., Stansly, P.A., Roberts, P.D. 2013. Progress and Challenges in Managing Watermelon Vine Decline caused by whitefly transmitted Squash Vein Yellowing Virus (SqVYV). Israel Journal of Plant Science. 60(4):435-445.

Interpretive Summary: Watermelon is an important crop grown in 44 states in the U.S. About 47% of the watermelon in the U.S. is grown in four southeastern states (FL, GA, SC and NC). Many different pests and diseases attack watermelon plants causing extensive damage. In recent years, an emerging disease called watermelon vine decline (WVD) that is incited by a virus, has caused havoc in watermelon production in the southern parts of Florida. The newly described virus causing this damaging problem has been named the Squash Vein Yellowing Virus (SqVYV), and studies have shown it is transmitted from plant to plant by a small insect called whitefly. This viral disease has already caused over $60 million in losses to watermelon growers in Southwest Florida. Various strategies have been developed to manage this disease by managing the insect that transmits it from one watermelon plant to another. Weeds that can serve as reservoir hosts for the virus have also been identified, and growers are advised to destroy such weeds. Sources of resistance to this disease have been identified, and resistant germplasm is being developed from a few wild watermelon accessions maintained by the USDA, ARS. The knowledge and information gained from this research will be useful to the seed industry and watermelon growers for managing this devastating disease.

Technical Abstract: Watermelon vine decline (WVD) is an emerging threat to watermelon production in south-west and west-central Florida. Losses in 2004-2005 due to WVD were estimated to be more than 60 million U.S. dollars. The disease is caused by Squash vein yellowing virus (SqVYV), family: Potyviridae, genus: Ipomovirus)) which is transmitted in a semi-persistent manner by whitefly (Bemisia tabaci). SqVYV is a close relative, but distinct from another cucurbit-infecting ipomovirus; cucumber vein yellowing virus (CVYV) that has been reported from most countries in the Mediterranean basin, since it was first described in Israel in the 1960s. Symptoms of WVD typically include a sudden decline and death of vines at or just prior to harvest. Fruit symptoms include internal flesh degradation and necrosis of the fruit rind. So far, only cucurbits have been confirmed as hosts for SqVYV, and striking symptoms of vine decline in agricultural production have been observed only on watermelon. Balsam-apple (Momordica charantia), a cucurbit weed that is widely distributed in Florida, was found to be a common reservoir host for SqVYV near affected watermelon fields. Management of whitefly populations using insecticides was shown to reduce WVD development and incidence of fruit symptoms. Sources of resistance to SqVYV in the USDA germplasm collection have been identified and resistant germplasm resources are being developed. Present recommendations for managing WVD include management of whitefly populations, removal of SqVYV reservoir hosts, and crop destruction soon after harvest. This manuscript will review the progress and challenges in dealing with WVD since it first appeared in Florida in 2003 and compare and contrast it with CVYV.