Why is My Yellow Squash Bumpy?


It can be understandably worrying for beginners if they notice prominent bumps on the skin of their yellow squash. Usually, the young skin of the yellow squash is smooth. For a newbie, this is the trigger for questions such as: ‘Why is my yellow squash bumpy?’ ‘Is the bumpy skin on my yellow squash sign that they have gone bad?’

The yellow squash, closely related to zucchini, are cucurbits and belong to the same family as pumpkins, melons, and cucumbers. The versatile plants are very easy to grow making them perfect for newbie gardeners aching to cut their vegetable-growing teeth.

But how bad is the situation and what solutions are available if this is indeed a budding disaster for the yellow squash? These are more are the questions we would be discussing in this article.

Why is My Yellow Squash Bumpy?

When it comes to yellow squash, there is bumpy that is normal, and then there is bumpy that is a sign that something isn’t right. The yellow squash, notable for its crooked neck is usually smooth-skinned. There are two varieties: summer squash and winter squash with the summer variety having smoother skin.

Both varieties can develop bumps on the skin. The bumps can appear on the summer varieties when the ripe squash is left for too long on the vine.

While the development of bumpy skin is the natural result of late harvest, other reasons are also responsible for this issue. This is when it becomes a real problem and not just an issue of late harvest.

Major Reasons for Bumpy Yellow Squash

The primary culprit behind this yellow squash ‘deformity’ is the mosaic virus. There are many strains of the virus with the cucumber mosaic virus (CMV) squash mosaic virus (SqMV) the major strains when it comes to distorting the skin of yellow squash.

Occurring worldwide, they are transmitted by various types of beetles including the leaf beetle, spotted cucumber beetle, and spotted ladybird beetle. The beetles’ saliva is the primary means of transmission while feeding on the leaves of the plant.

The symptoms of CMV and SqMV infestation, before the fruits develop bumpy skin, include yellowing of leaves, blistering, hardening, loss of regular green coloration of the veins, distortion of leaves, poor fruit production, and misshapen fruits.

The symptoms can also be different depending on the squash variety. Green overgrowths might also appear on the exterior of the summer variety and in winter squash, you’d notice lumps that stick out to make the surface uneven.

If an infected yellow squash is harvested and used to make pickles, for instance, the pickles would often be mushy. The bitter taste of the fruit is also one of the signs of mosaic virus infection.

Other factors are also implicated in the production of bumpy yellow squash, these include:

  • Too much calcium in the soil
  • Boring insects
  • Excessive and rapid plant growth

How To Prevent Bumpy Yellow Squash

Get disease-resistant seeds

The best way of ensuring avoiding this problem is to purchase and plant only disease-resistant seeds. If you are getting the starters instead of seeds, also ensure they are disease-resistant.

The disease-resistant starters or seeds can be purchased in garden stores. To be sure, inquire from experienced farmers for information on where and how to get some.

And when it comes to planting the seeds, the best time is before aphid and beetle season to prevent these vectors from transmitting diseases to the young plants.

Taking good care of your yellow squash

If you want the plant to grow healthy and strong to be able to withstand disease and other problems, proper care cannot be over-emphasized.

Below are tips on how to properly care for yellow squash:

Light – 6 – 8 hours of sunlight daily is the optimal light requirement for a healthy, strong yellow squash. If you are growing it indoors, place the container near a window that allows bright, sunny light.

Each container or planter must be large, have drainage holes, and have high quality potting soil that drains well.

Soil – Yellow squash love soil that is slightly acidic. Before planting and throughout the planting season, never allow the soil pH to exceed the 5.8 – 6.8 range. You could ensure this using a soil pH tester. Found in most stores, they are inexpensive and easy to use.

In terms of the soil texture, the plants like rich, organic soil that is not too compact to ensure proper drainage. You can improve your garden soil by spreading about 4 inches of compost and working it into the soil.

Adding leaf mulch and other organic matter would also help improve the soil quality.

Water – Like most veggies, yellow squash thrive best in moist soil as opposed to soggy soil.

During dry spells, water the soil deeply with about 1-2 inches of water weekly in the mornings. Early morning watering helps the roots absorb as much water as possible.

Keep in mind that if the plants are grown in containers, you might need to water them more frequently.

Finally, try as much as possible to avoid watering the foliage to prevent disease transmission.

Temperature and humidity requirements – The best temperature range for growing yellow squash is between 65 – 75°F. Though they can tolerate high humidity, fungal diseases can become a problem in wet heat.

Yellow squash grown in containers should be moved indoors when the prevailing temperature and humidity are excessively high. No matter what happens though, they’ll still need at least six hours of sunlight or bright light daily.

Fertilizer – Before applying fertilizer, it is best to carry out a soil test to determine its nutrient properties. The objective is to have an idea of the vital nutrient or nutrients the soil is deficient in.

Generally, yellow squash plants are heavy feeders so fertilizer application is necessary and should be frequent. For best results, use a balanced fertilizer formula (10-10-10 should be written on the label).

Tip: Avoid adding extra nitrogen or using fertilizer with too much nitrogen. This promotes excessive foliage growth at the expense of fruits.

Proper use of gardening tools

You can prevent the spread of the disease by ensuring that gardening tools are not washed near or around the squash patch.

Harvest early and frequently

Yellow squash, apart from being very thirsty plants, are fast-growing veggies. A small squash can easily become ready for harvest 24 hours later

So it’s important to inspect the plants daily to check their growth progress. Pick the yellow squash as soon as they look ripe. This is because the older and matured they get, the more bumps are likely to appear on the skin. Also, harvesting often promotes production.

When the fruits at about 4 – 6 inches long, they should be ready for harvest. Use a sharp knife to cut through the stem rather than the main vine.

Inspect the yellow squash daily

Since they are susceptible to pests and diseases, it is smart to maintain a daily inspection routine so that you can nip budding problems before they get out of control.

Things you can do include:

  • Inspect leaves’ underside for bugs and their eggs. You can remove the bugs you discover by hand
  • Leaves severely affected by powdery mildew should be cut off and disposed
  • To prevent the recurrence of powdery mildew, spray the leaves with a sulfur solution. Milk or baking soda solution can also be sprayed on the leaves to prevent powdery mildew.
  • Diluted neem oil also works perfectly when sprayed on the leaves weekly until the powdery mildew is eliminated.
  • For aphids and beetles infestations, spray the leaves with an insecticidal soap solution. Then rinse the leaves by spraying them with water as the soap solution might promote leave burn when exposed to sunlight.
  • Cut and dispose of leaves that are heavily infested.

Wrapping up

Matured yellow squash fruits have a smooth skin texture. At the best of times, bumps on yellow squash making the skin slightly rough is normal. Excessive yellow squash skin bumps could be the result of pest infection, nutrient deficiency, or when the ripe fruits are allowed to remain for too long on the vine.

Bumps due to viral infestations can easily damage the fruits making them useless as food.  Most of the time, sticking to the correct yellow squash care routine is all that is needed to prevent diseases and bumps from appearing.