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Physiological Effects of Squash vein yellowing virus Infection on Watermelon

September 2013 , Volume 97 , Number  9
Pages  1,137 - 1,148

Scott Adkins, T. Greg McCollum, and Joseph P. Albano, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), U.S. Horticultural Research Laboratory, Fort Pierce, FL 34945; Chandrasekar S. Kousik, USDA-ARS, U.S. Vegetable Laboratory, Charleston, SC 29414; Carlye A. Baker, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL 32945; Craig G. Webster, USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, FL 34945; Pamela D. Roberts, University of Florida, Department of Plant Pathology, Southwest Florida Research and Education Center, Immokalee, FL 34142; Susan E. Webb, University of Florida, Department of Entomology and Nematology, Gainesville, FL 32611; and William W. Turechek, USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, FL 34945

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Accepted for publication 9 March 2013.

Squash vein yellowing virus (SqVYV) is the cause of viral watermelon vine decline. The virus is whitefly-transmitted, induces a systemic wilt of watermelon plants, and causes necrosis and discoloration of the fruit rind. In the field, SqVYV is often detected in watermelon in mixed infections with other viruses including the aphid-transmitted Papaya ringspot virus type W (PRSV-W). In this study, watermelon plants of different ages were inoculated with SqVYV or SqVYV+PRSV-W in the greenhouse or SqVYV in the field to characterize the physiological response to infection. Symptoms of vine decline appeared about 12 to 16 days after inoculation with SqVYV regardless of plant age at time of inoculation, plant growth habit (trellised or nontrellised), and location (greenhouse or field). However, the presence of PRSV-W delayed the appearance of vine decline symptoms by 2 to 4 days, and vine decline did not develop on plants with no fruit. For all inoculation treatments, more severe symptoms were observed in younger watermelon plants. Physiological responses to SqVYV infection included reduction in plant and fruit weights, alterations in fruit rind and flesh color, reduction in fruit sucrose content, increase in fruit acid content, and changes in plant nutrient composition, particularly increases in Ca, Mg, B, Mn, and Zn and decreases in K and N. These results demonstrate wide-ranging physiological effects of SqVYV infection and provide new insights into watermelon vine decline.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2013.