Mosaic Virus on Squash

Viruses represent some of the toughest diseases to manage in cucumber, squash, pumpkin, and melon plants.  Often the disease doesn’t kill but does reduce the size and number of leaves, which in turn decreases fruit production. Cucumber mosaic, cucumber green mottle mosaic, watermelon mosaic, zucchini yellow mosaic, and squash mosaic are some of the viruses that infect plants in the Cucurbit family. The viruses are spread from infected seeds, by aphid feeding, and by mechanical means, such as using a gardening tool on an infected plant and then using the same unclean tool on a healthy one.

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When gardeners notice mottled leaves, raised dark green blisters on fruits, and stems that dry out rapidly, a mosaic virus is the likely cause. There is no product to spray that will eradicate the virus from plants. Instead, use certified virus-free seeds, choose varieties that are resistant to mosaic, clean gardening tools with a 10% bleach solution between uses, and remove weeds from inside and outside the garden to reduce the amount of pathogen spread by insects. If you don’t already, clean up the garden this fall to remove vines that can harbor the virus.

Are squash and melons affected by mosaic virus safe to eat?  “Yes,” says Nebraska Food Safety Educator Carol Larvick, citing information from Minnesota Extension. “These viruses are specific to plants and do not harm humans. The presence of mosaic won’t cause fruits to rot prematurely but severely distorted fruit will have a different texture, so use your own judgement.”

For more information on mosaic virus, check out this website: https://blog-yard-garden-news.extension.umn.edu/2018/09/can-i-eat-that-strange-looking-squash.html .

Kathleen Cue
Horticulture Educator at Nebraska Extension
Kathleen serves as the Horticulture Educator for Nebraska Extension in Dodge County. She educates people on making smart plant choices to reduce use of fertilizers and pesticides in their landscape which has a positive impact on air, water, soil and environmental quality, property values and people’s pocketbooks.

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