Pumpkin Viruses

I am highlighting three viral diseases of pumpkins: Cucumber mosaic virus (CMV), Watermelon mosaic virus (WMV), and Squash mosaic virus (SqMV). These viruses can also infect other members of the cucurbit family including squash, zucchini, gourds, melons, and cucumbers.

Cucumber Mosaic Virus

Cucumber mosaic virus (CMV) can infect over 1,200 plant species and results in a wide range of symptoms depending on host type and at what age the plant was infected. Plants that are infected from a young age will have more severe symptoms. CMV can be spread though infected seed, aphid vectors, and mechanical damage. As CMV has a wide host range an important source of virus inoculum can come from weedy plant species growing outside of a field of pumpkins.

CMV infected cucurbits will experience stunting, malformed leaves, bumps on fruits, and a mosaic yellow and green pattern on the leaves. CMV symptoms in other plant families vary.

Close up view of a symptomatic malformed bush zucchini leaf showing rugosity (roughening). The plant was inoculated 38 days previously.

CMV can be managed by using resistant varieties of cucumber, squash, and melons. If resistant varieties are not available floating row covers can be applied to susceptible crops, which will prevent aphids from infecting young plants.[1]

Watermelon Mosaic Virus

Watermelon mosaic virus (WMV) can infect all cucurbits and several weedy plant species. Typical early symptoms include vein clearing. Vein clearing is when the veins of plant leaves become translucent or clear. Mosaic patterns, mottling, and stunting of leaves will also occur later in an infection.

WMV can be spread by aphids so early detection and roguing (pulling out) infected plants is necessary. Protective systemic insecticides can also be used to reduce aphid populations limiting virus spread, however this will not completely eliminate virus spread as the aphids only need to probe a leaf once to infect a new plant.[2]

Close up view of a stunted zucchini leaf infected with WMV showing a mottled light/dark green pattern.

Squash Mosaic Virus

Squash mosaic virus (SqMV) infects various members of the cucurbit family, several beans (Leguminosae), several members of the carrot family (Umbelliferae), and several weedy plant species.

Symptoms of SqMV infection include a dark green mosaic, vein clearing, and malformed leaves and fruit.

SqMV can be spread by seeds and though beetle spit transferred while feeding. Infected beetles can transmit the virus for up to 20 days. SqMV however is not spread by aphids. To avoid a SqMV infection plant only certified virus-free seed and limit beetle populations.[3]

Close up view of zucchini leaves infected with SqMV showing mosaic and rugosity. Yellowish tint is from artificial lighting.

All photos were taken by Sara Bratsch. For non commercial use only.

Please contact regarding all other uses.

Cite this article:

Bratsch, Sara. "Pumpkin Viruses! Happy Halloween!" 31 October 2015. http://plantpathlesstraveled.com/pumpkin-viruses-happy-halloween/


Zitter, Thomas A., and J. F. Murphy. "Cucumber mosaic virus." The Plant Health Instructor 10 (2009): 1094. http://www.apsnet.org/edcenter/intropp/lessons/viruses/Pages/Cucumbermosaic.aspx[1]