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Garden Help Desk: How can I get squash without these bumps?

By USU Extension - | May 7, 2022

Courtesy Meredith Seaver

Very tender plants like basil can be damaged when temperatures drop below the mid 50s, especially in the spring when the plants are young.

Is there anything that can be done to reduce the chance of getting squash fruit that is distorted with bumps all over the place?

If your squash fruits looked like some of today’s photos, the problem is probably one of the mosaic viruses that affect cucumbers, squash, melons, and pumpkins. The growth of infected plants can be stunted. You may see a mosaic pattern or splotching and yellow streaks on leaves, and fruits can be distorted and usually develop raised bumps or spots and lines. The fruits may also have a different texture and flavor.

These viruses spend the winter in weeds and are spread to other plants by aphids that feed on the weeds in the spring and then carry the viruses into gardens during the early growing season.

Insect feeding can spread mosaic viruses from infected to healthy plants during the gardening season, but you can also move the virus from plant to plant with tools or on your hands or gardening gloves.

Herbicide exposure, heat stress and nutrient deficiencies can worsen the symptoms on infected plants.

Courtesy Photo

Chilling (cold) injury can affect many different plants.

To reduce the risk of losing your cucumbers, squash, and melons to mosaic viruses, take steps to prevent the problem.

  • Practice good weed control, especially in the fall to reduce overwintering hosts for viruses and insect vectors. Remove any weeds that you find around your garden again in the spring.
  • Control aphid populations. Scout for aphids frequently and apply insecticidal soap or horticultural oil at the first sign of them. Repeat the applications as needed and as recommended on the product label.
  • Exclude insects early in the season by covering your plants completely with floating row cover or very fine-meshed tulle fabric. Remove the covering once your plants begin bloom.
  • If you find virus symptoms on any plants in the garden, remove them to protect your healthy plants. Leaving infected plants in the garden gives aphids more time to pick up and transfer the virus to other plants. Infected plants won’t “get better,” so there’s no reason to keep them in the garden.
  • Sanitize any tools you use with susceptible plants, including any tools used to remove infected plants. It’s a good idea to keep your gardening tools clean whether or not you are having disease problems.
  • Look for certified virus-free seeds if you start your plants by seed in the garden.
  • Choose resistant varieties when purchasing seeds or transplants.

I keep waiting for good planting weather, but it just isn’t happening. Is there something I can plant now that won’t die if the weather stays bad for a while?

The hardier veggies in the garden- spinach, peas, lettuce, onions, broccoli, and cabbage-, etc. are loving the weather. They need to be planted while the days are still cold and the nights are a little frosty. Some gardens in the county are still having frosty nights but many others are staying a few degrees above freezing each night. Plants that are more tender- tomatoes, peppers, squash, beans, etc.-won’t freeze, but they probably won’t thrive either. You’ll need a little patience if you want to get great performance from a salsa garden, pumpkin patch, or other tender vegetables.

When tender plants are put out into the garden when soils and night temperatures are still cold, they may survive, but if they do, they’ll pause their growth and wait for better conditions. Those vegetable plants may also suffer from cold (chilling )injury and need some recovery time even though they haven’t been exposed to frost.

Seeds of tender plants like squash, cucumbers and beans won’t germinate if the soil is too cold. Tender seeds that are planted in cold, wet soil may even decay instead of germinating.

Courtesy Meredith Seaver

Mosaic viruses can cause squash fruits to develop a splotchy color and very bumpy skin.

You can still plant some of those hardier veggies if you want to, but don’t be in a rush to get your tender plants out in the garden, unless you can give them good frost protection. Wait another week or two for better conditions before you plant seeds or set out transplants and your garden will do just as well or better than gardens that were started while conditions were still wet and chilly.


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