Why Your Squash Leaves Are Turning Yellow & How to Save

For me, a summer garden isn't complete unless I'm growing some sort of squash. There is always a squash plant growing, whether it is spaghetti, butternut, or zucchini. Like all vegetables, squash have particular requirements that must be met in order to avoid illness and death. The right nutrients, sunlight, and water are necessary for squash to grow. Your squash leaves are probably going to be the first to show any issues.

Yellowing leaves are one of the most frequent issues with squash. Your squash has started to grow in the middle of the summer, but the leaves are now dying and starting to turn brown and yellow. This article will explain what's going on, explain why your squash plants' leaves are turning yellow, and suggest remedies to help them recover.

If every leaf is turning yellow, there may be a nutrient or water shortage. On a squash plant, disease or pests are most likely to blame if only some of the leaves are turning yellow. Let's see what causes squash leaves to turn yellow.

Why Your Squash Leaves Are Turning Yellow

A Nutrient Problem

Your squash leaves may be turning yellow for a variety of reasons, not just improper watering methods. An imbalanced diet may be the cause.

Like all plants, squash requires specific nutrients in order to develop and yield edible squash for human consumption. NPK, also referred to as nitrogen, phosphorus, and potassium, are essential for growing squash. You can try adding bone meal if your phosphorus level is particularly low.

By combining 10 pounds of bone meal, 10 pounds of feather meal, and 2 pounds of potash sulfate, you can create your own natural, all-organic NPK fertilizer.

Healthy squash depends on your soil being fertilized both at planting time and throughout the summer.

Viruses

Squash is vulnerable to a variety of viruses, including potyviruses and the squash mosaic virus. These viruses are spread to the squash plant by aphids, beetles, and other feeding insects like whiteflies. The squash plant's vascular system picks up the virus from the insects as they feed, which spreads it throughout the entire plant. Loss of vigor in the infected squash is accompanied by thickened, yellowed, and distorted foliage that is also mottled.

Root Rot

Another symptom of root rot infections is yellowed and wilted squash foliage. Although these infections can be brought on by overwatering, phytophthora root rot, verticillium wilt, and fusarium wilt are the most common causes of root rot infections in squash. Before squash is planted, the soil will typically already contain these soil-borne infections. Through the squash's root system, these rotting infections infect it, rupturing the vascular system. As a result of this collapse, the plant is unable to supply the rest of the plant with water and essential nutrients.

Pests

Feeding pests can be a direct cause of the squash's yellowing foliage in addition to spreading diseases to the squash. Most often, whiteflies and squash bugs are to blame for yellowing foliage. Squash bugs leave behind tiny, whitish bite marks or specks as they consume the foliage. The yellow specks change to brown shortly after feeding as the bitten area decomposes and dies. Similar to how bites from whiteflies turn the foliage yellow. Whiteflies leave behind sticky honeydew after feeding, which frequently accompanies these bites. In addition to causing decay and wilt, these yellowed areas cause the foliage to turn brown just before it dies.

Treatment for Squash Yellow Leaves

Infestations and the squash virus should be treated concurrently to lower the risk of recurrence. Use a fungicidal spray with neem oil as a base to treat the squash, which will also eliminate any viral infections and pest infestations. Spray the chemical evenly across the squash plant until it is nearly saturated. To find any pests that are hiding, thoroughly wet the undersides of the squash foliage as well. If there are serious infections and infestations, apply the chemical again after seven days. By removing and discarding the squash plants from the area, you can treat infections with root rot. Fungal root rot infections cannot be cured with chemicals. Additionally, even after plants have been removed from the soil, the contagious spores may continue to be active for several years. Replanting squash there is not advised. Plant vegetation that is resistant to infections of root rot in its place.

Yellowing Leaves on Squash Due to Lack of Sun

Squash's yellowing leaves are a result of lack of sunlight. For squash to grow, sunlight is necessary.

Sunlight is essential for the healthy growth and development of squash. You should place squash in a place where they receive at least six hours of direct sunlight, ideally eight hours.

To avoid having yellow leaves on squash plants due to lack of sunlight, you should choose the right place to plant your squash to make sure it gets enough sunlight.

If the squash was already planted but did not produce much growth, you could move it to a location with more sunlight.

You can also plant the squash in a large pot and then move it to the best spot with plenty of sunlight. If the squash gets enough sunlight, squash will not have problems with yellow leaves.

Yellowing Leaves on Squash Due to Watering

Due to watering, squash leaves have become yellow. Because squash plants have a high demand for water, the soil must be able to supply it. Using irrigation, rainwater, or—more frequently—a combination of the two. On squash plants, excessive watering results in yellow leaves.

Depending on the type of soil in question, it will be necessary to act in one way or another to ensure that constant humidity is maintained near the squash plant.

In general, it is advisable to make frequent irrigations of low intensity – a few liters/gallons at a time. Although, as we previously stated, this will depend on the soil type and climate.

In soils rich in organic matter or clay, watering should be less frequent because this type of soil retains more water.

On the other hand, in soils that retain almost no water (sandy), watering should be very frequent and of very low intensity. Whatever we overwater will be lost in the deeper layers because they can hold so little water.

That is why we must water the squash plant correctly, as overwatering will rot the roots and insufficient watering will dry it out due to lack of water. Inadequate watering will produce yellow leaves on squash.

Yellowing Leaves on Squash Due to Nutrient Deficiencies

Squash's yellowing leaves are a result of nutrient deficiencies. Squash needs a certain amount of nutrients to develop properly. Yellow leaves on squash plants are an indication that there are not enough nutrients present.

We recommend always checking the quality of the soil before planting squash.

Squash plants adapt quite well to soils with pH values between 5 and 7, but prefer slightly acidic soils, with average values between 5.6-6.8.

Deficit symptoms may manifest with a basic pH, but they can be resolved with macro- and micro-elements. First, measure the soil pH and see if needed to be corrected.

Without the right nutrients, squash plants cannot grow properly and are more vulnerable to pests and diseases.

Lack of nutrients results in yellow leaves on squash plants. Iron and calcium deficiency are the most common nutrient deficiency in plants that cause yellow leaves on squash plants. The presence of yellow leaves is not a problem for the squash plant if it has the necessary nutrients.

 

With a 4-4-4 or 4-6-4 fertilizer, squash plants will have the necessary nutritional supply for correct growth. A 4-4-4 fertilizer means Nitrogen-Phosphorus-Potassium or NPK is 4-4-4. In this article about types of fertilizers, we explain more about this terminology and how to choose correctly.

In their two-year life cycle, squash plants require fertilization. The first fertilization is before planting or sowing the squash seeds while preparing the soil to place the seeds. The second fertilization needed is when the squash plant is blooming.

Yellowing leaves on squash due to lack of nutrients is easy to fix by adding a suitable fertilizer for the squash plant. I recommend removing yellow leaves on the squash plant and verify the soil pH is suitable for the plant.

Yellowing Leaves on Squash Due to Pests and Diseases

The presence of pests and diseases is one of the most common causes of yellow leaves on squash plants, as in any type of plant.

In the case of squash plants, the leaves are susceptible to infection by bacteria, fungi, and viruses and can also attract certain non-beneficial insects to our gardens such as aphids and spider mites.

 

In the next paragraphs, we will review what causes yellow leaves on squash plants related to pests and diseases and how to fix yellowing leaves and prevent them.

The first sign of the infection with Pseudomonas syringae is yellow spots on squash leaves.

On squash leaves, yellow spots start to appear and eventually the entire leaf turns yellow. Cucurbitaceae (pumpkin, squash, melon, watermelon, and zucchini) are affected. The yellow spots on squash leaves spread until they are delimited by the nerves of the leaves.

What to Do Next?

It's important to keep in mind that after you find the solution, your plant's leaves won't turn green again. Don't assume that you fixed the problem because the leaves remain yellow after turning yellow; they will remain yellow. You most definitely did!

Your plant will probably continue to grow and thrive, and you might even continue to get fruits depending on what was ailing it. In order to maintain the health of your plant, remove the yellow leaves.

Although no one wants to notice their cucumber or zucchini plants' leaves turning yellow, this is a common occurrence. Most gardeners will run into this problem, but as long as you work to fix it, your plant ought to be able to survive.

Frequently Asked Questions

Here are some of the most typical queries regarding how to handle squash plants with yellowing leaves, stems, or vines.

Why My Squash Leaves Turning Brown

Insufficient Water. Drought conditions often make winter squash leaves turn brown. The plant cannot transport moisture to the ends of the leaves when there is insufficient water available to the roots, which results in those areas drying out and dying. It might not be sufficient to water a squash plant a little bit every day to maintain its health.

Why Are My Squash Leaves Turning White

Powdery mildew fungus can also cause the appearance of white coloration on the leaves of squash and many other plants. In this case, the white coloration due to the "fruiting structures" of the fungus as they produce spores will look more like a dusting of flour on the leaf.

Why My Squash Leaves Turning Yellow With White Spots

The reason why there are white spots on your Squash leaves is due to powdery mildew. When leaves have powdery mildew, you will notice circular white spots on them. Applying a bicarbonate solution as a spray will get them off of your plant.

Should You Remove Yellow Leaves from a Squash Plant

The short answer to the question of whether or not you should remove the leaves from your squash plant is no. You should never take leaves off your squash plant because of a number of factors.

First off, removing leaves makes it much easier for bacteria, viruses, parasites, and other unwanted visitors to enter the interior of your plant. It is best to avoid leaving your squash that exposed as this will only lead to more issues for both you and your plant.

Second, if you remove the plant's leaves, the sun may harm the squash fruit. As the photosynthesis process that the leaves go through is essential for the plant's nutrition, it is now well known that light is great for the squash plant.

While the leaves are partially intended to shield the fruit from direct sunlight because the sun can harm the fruit, this is not always the case. It might be detrimental to the squash itself to remove them.

And finally, the leaves act as a strong deterrent to weeds that could further harm your squash and the nearby plants. Avoid cutting your leaves to prevent weeds from spreading and entangling or otherwise hurting your squash plant.

Are Yellow Squash Leaves Common?

Yes, but don't be alarmed; yellow squash leaves are a very common issue. The majority of the causes of yellow squash leaves listed here are not only fairly common, but they can also be easily avoided and/or fixed. Therefore, not only did you not make a mistake that was that serious, but it can also be fixed and resolved going forward!

For any issues you may encounter, just adhere to the procedures described above. By doing this, you can identify the issue that is plaguing your squash plant and causing some of its components to turn yellow, then fix the issue to stop it from happening again in the future.

Conclusion

The leaves, vines, and stems of your squash plant could be yellowing for a variety of reasons. Most frequently, it is most likely the result of pest problems, nutrient deficiencies, overwatering, or underwatering. These issues can all be resolved, avoided, and they are all not very serious.

Additionally, it might be a more harmful condition like bacterial wilt or a vine borer. Take care of these as soon as you can and stop them if they haven't already happened because they can easily kill your squash.

The simplest way to maintain your squash plants' safety, health, and prosperity is to keep them on a regular watering schedule, ensure that they receive enough light on the leaves (but not on the fruit itself), and take preventative measures against pests like using natural fungicides and pesticides based on neem oil. The use of glass or plastic to cover your plant can also be beneficial, but it can be costly and time-consuming.