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Yellow vine decline (Serratia marcescens) affects muskmelon, pumpkin, squash, and watermelon. Symptoms begin to appear approximately two weeks before fruit matures. The disease may appear initially as stunting of plants and/or intense yellowing of foliage followed by a slow decline in plant health. In some cases, a sudden collapse of vines may occur with no other symptoms. Vascular tissue from crowns of affected plants is often discolored (light brown). The pathogen is transmitted through feeding by the squash bug, and the presence of these insects, along with symptoms of the disease, can help in the initial diagnosis.

Yellow vine decline.

(Photo: Ric Bessin, University of Kentucky)

Management:

• Effective control of yellow vine decline is completely dependent on early management of squash bugs, beginning at emergence or transplanting.
• Refer also to the section on squash bug.

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