Influence of Insecticides and Reflective Mulch on Watermelon Vine Decline Caused by Squash vein yellowing virus (SqVYV)

Abstract

Watermelon vine decline (WVD) caused by the whitefly-transmitted Squash vein yellowing virus (SqVYV) has been a serious limiting factor in watermelon production in southwest and west-central Florida over the past few years. Symptoms of WVD typically appear as sudden decline of vines a few weeks before harvest or just after the first harvest. Fruit symptoms include rind necrosis and flesh discoloration that affects fruit quality and marketability. The combination of insecticide treatments consisting of an imidacloprid drench (Admire Pro, 560 ml/ha) at transplanting followed by two foliar applications of spiromesifen (Oberon, 2SC, 490 ml/ha) and reflective plastic mulch was evaluated for management of WVD during fall growing seasons of 2006, 2007, and 2009. Virus inoculum source was introduced by planting SqVYV-infected squash plants at the ends of each plot. In all three experiments, the insecticide-treated plots had significantly lower levels of WVD on foliage and fruit compared to non-treated plots. In 2007, the reflective plastic mulch was effective in reducing foliar WVD compared to non-reflective mulch, but not in 2006 and 2009. No significant interaction between plastic mulch and chemical treatments was observed on WVD development on foliage or fruit. Our results suggest that application of insecticides for managing whiteflies can help manage SqVYV-caused WVD. Accepted for publication 13 January 2015. Published 25 March 2015.