In 1988, a new vine decline of cucurbits was observed in Oklahoma. Early-planted watermelon and cantaloupe can be severely affected by the disease, whereas crops planted after 15 June may have little or no incidence. This disease has never been observed in cucumber.
Leaves change from green to lime-yellow, and then to bright yellow.
Affected plants gradually decline and exhibit a blighted appearance within 7 to 10 days. In some cases, immature plants may not turn yellow, but wilt and collapse in 1 day. Fruit and flowers on affected plants are not distorted, but watermelon fruit lose their chlorophyll very quickly. Although foliar symptoms of YV are similar to vine decline symptoms caused by soilborne pathogens, root degeneration occurs only in the later stages of YV development. Recent research has shown the consistent association of a walled bacterium with the disease.