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Title: Influence of insecticides and reflective mulch on watermelon vine decline caused by squash vein yellowing virus (SqVYV)

item Kousik, Chandrasekar - Shaker
item Adkins, Scott
item Turechek, William
item Webster, Craig
item STANSLY, P - University Of Florida
item ROBERTS, P - University Of Florida

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2015
Publication Date: 3/25/2015
Publication URL: http://doi:10.1094/PHP-RS-14-0040.
Citation: Kousik, C.S., Adkins, S.T., Turechek, W., Webster, C.G., Stansly, P.A., Roberts, P.D. 2015. Influence of insecticides and reflective mulch on watermelon vine decline caused by squash vein yellowing virus (SqVYV). Plant Health Progress. 16:43-48.

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. Watermelon vine decline is a serious disease that has plagued watermelon growers for the past several years and has resulted in losses of over $60 million in southwest and west central Florida. The watermelon vines decline and die off a few weeks before harvest or just after first harvest. Fruit on diseased vines look normal from outside but show necrosis and rotting inside. The disease is incited in watermelon plants by a virus called Squash Vein Yellowing Virus (SqVYV). The virus (SqVYV) is transmitted from plant to plant by a small insect called whitefly. Reducing the whitefly populations in watermelon using insecticides was shown to reduce the occurrence of watermelon vine decline on the foliage and fruit. The knowledge and information developed by this research will be useful to University researchers, extension agents, and commercial watermelon growers for managing this devastating disease.

Technical Abstract: Watermelon vine decline (WVD) caused by the whitefly-transmitted Squash vein yellowing virus (SqVYV) has been a major limiting factor in watermelon production in southwest and west-central Florida for the past several years. Symptoms of WVD typically manifest 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 sprays 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 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.