IDENTIFICATION, ELUCIDATION, AND DEVELOPMENT OF DISEASE AND NEMATODE RESISTANCES IN VEGETABLE CROPS
Location: Vegetable Research
Title: Review of Viral Watermelon Vine Decline: a New and Emerging Threat to Watermelon Production in Florida
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: September 23, 2009
Publication Date: August 31, 2010
Citation: Kousik, C.S., Adkins, S.T., Turechek, W., Webb, S.E., Stansly, P.A., Roberts, P.D., Baker, C.A. 2010. Review of Viral Watermelon Vine Decline: a New and Emerging Threat to Watermelon Production in Florida. Acta Horticulturae. (ISHS) 871.
Watermelon vine decline (WVD) is a new and emerging threat to watermelon production in southeast and west-central Florida and has caused more than $60 million in losses since 2004. The disease is caused by Squash vein yellowing virus (SqVYV, family: Potyviridae, genus: Ipomovirus) which is transmitted in a semi-persistent manner by whiteflies (Bemisia tabaci, B strain). Symptoms of WVD typically include a sudden decline of vines at harvest time, or one to two weeks before harvest and internal necrosis of the fruit rind. So far only cucurbits have been determined to be hosts for SqVYV and symptoms of vine decline have been observed only on watermelons. In surveys conducted in Florida, greater than 40% of balsam-apple (Momordica charantia) plants collected from watermelon growing areas with previously reported cases of vine decline were found to be infected with SqVYV. A combination of reflective plastic mulch with insecticidal treatments of a neonicotinoid at transplanting followed by two foliar sprays of spiromesifen to manage whitefly populations significantly reduced WVD and incidence of fruit symptoms compared to un-treated plants that were grown on non reflective mulch. We have identified several sources of resistance to SqVYV in the USDA germplasm collection. PI 500354 (Citrullus lanatus var. citroides), PI 386024 (C. colocynthis), and PI 459074 and PI 392291 (C. lanatus var. lanatus) had significantly lower levels of WVD in the field studies compared with the highly susceptible commercial cultivars. Variability in the resistant reaction to SqVYV within these and other accessions was observed. Present recommendations for managing WVD include management of whitefly populations, removal of SqVYV reservoir hosts, and crop destruction soon after harvest.