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Squash in wooden baskets at a market.

AUBURN UNIVERSITY, Ala. – Squash is a vegetable commonly seen on many tables during the summer. With many varieties to choose from, there are a lot of ways to prepare this southern favorite. One common problem that growers deal with are viruses. There are several common viruses that can disfigure the squash, potentially making them undesirable for eating.

Squash Virus

Image by Melissa Muncher

Common Viruses

In Alabama, there are four common viruses that affect squash plants.

  • papaya ringspot virus (PRVS)
  • zucchini yellow mosaic virus (ZYMV)
  • cucumber mosaic virus (CMV)
  • watermelon mosaic virus (WMV)

Bethany O’Rear, an Alabama Extension regional agent of home grounds, gardens and home pests, said that infected plants can show several symptoms.

“Infections result in stunted, discolored plants. Leaves may have a mottled appearance or fade to a light-green color,” O’Rear said. “The fruits may be spotted, warty and have an irregular shape. While extremely unattractive, the fruit is perfectly safe to eat.”

In many cases, the discoloration on the fruit is only skin deep. However, O’Rear said if the fruit has a severely distorted appearance, the texture may not be suitable for eating.

Control

Squash Virus

Image by Melissa Muncher

Ed Sikora, an Alabama Extension plant pathologist, said these viruses are transmitted by various insects, the main one being aphids.

“Insecticides will not control the spread of these viruses because the aphids are very efficient vectors,” Sikora said.

Insects infect plants immediately after they feed. As an insect moves from plant to plant, so does the virus. Once infected, there are no chemical options available to control or kill the virus.

According to O’Rear, if a plant is showing symptoms, pull up the entire plant and discard away from the garden. To help prevent future infections, never leave a diseased plant on the perimeter of the garden or in the compost pile. After discarding, clean any gardening tools and gloves used before handling healthy plants.

Prevention

The best way to control any of these viruses is by prevention. O’Rear said there are several steps gardeners can take to help prevent infection.

“Always plant resistant varieties,” O’Rear said. “There are several varieties of cucurbits that are resistant (not immune) to these viruses.”

When planting, be sure to rotate crops. This is great way to control many common garden diseases. Growers should never plant members of the same plant family in the same area season after season.

Another step to prevent diseases is making sure plants are healthy. Stressed plants are always more susceptible to insect and disease pressure.

O’Rear said that growers should always be on the lookout for changes in a plant.

“If you notice a plant or fruit that looks odd, try to determine the cause sooner rather than later,” O’Rear said. “Early detection is critical to success in controlling the issue and preventing further infection.”

More Information

For more information on these viruses or other gardening topics, visit Alabama Extension online, or contact your county Extension home grounds agent.

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