Squash plants will grow in abundance if they don’t become prey to powdery mildew.
This fungal disease grows slowly and appears as white spots on leaves, stems, and fruits.
In this article, you will learn what causes white spots on squash leaves and what you can do about it.
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White Spots on Squash Leaves
White spots on Squash leaves are most likely due to powdery mildew. You will see circular white spots on leaves infected by powdery mildew. Remove them from your plant using a bicarbonate solution as a spray.
How White Spots Spread on Squash Leaves
Since these white spots are caused by powdery mildew, they spread mostly by strong winds. However, if you have previously seen white spots on your Squash leaves, then it can spread again.
The powdery mildew will also spread from a new outbreak that can occur on surrounding vegetative materials or even nearby weeds.
Powdery mildew is a bit different than other fungal diseases. This fungus loves to live in a warm to dry climate of 60 to 80 degrees Fahrenheit (15-27 degrees Celsius).
However, powdery mildew requires high humidity levels around the plant to actually spread. Powdery mildew is less likely to spread if you keep your plant in a cooler or hotter area.
This is because temperatures higher than 90 degrees Fahrenheit (32 degrees Celsius) are not ideal conditions for it.
Thus, it will stop the spread, and keeping your plant under more sunlight can also prevent powdery mildew.
Identifying Damages Done by White Spots
Plants that have white spots on them will have powdery mildew, which looks like dusted flour. These spots will start off as circular white spots and will be seen on leaves, stems, as well as fruits.
This dusty flour will cover the upper parts of your Squash leaves and grow on the bottom sides as well. The younger Squash leaves are more likely to get damaged, turn yellow, or dry out.
These white spots are identified as a fungus that will break, twist, or even become disfigured over time. The spots will cover the majority of the leaves surrounding the plant if not caught early.
The damage caused by these white spots will disfigure the tips of the leaves and buds. However, it’s vital to know that most of these signs are seen late into the growing season.
Preventing White Spots on Squash Leaves
With any pest or disease, the best thing to do is take action to prevent the fungus from forming first. Having your Squash plants surrounded by plants that are resistant to powdery mildew is a good start.
Some Cucurbits plants are now even resistant to powdery mildew, such as melons and cucumbers. You can also keep your plant in a sunny area since powdery mildew grows mostly in shaded areas.
Prune over-crowded areas of your plant so that there is better air circulation around your plant. This will greatly aid in reducing the humidity surrounding it.
Watering your plant from overhead will also help wash off the spores from leaves. However, it is important to note that wet leaves can cause other diseases, so this method should not be used often.
You can also use wettable sulfur as a prevention method for powdery mildew. However, wettable sulfur will not be able to remove the white spots.
But it can prevent them from occurring on your plant if it has also been infected. Simply dust your plant with sulfur powder.
Repeat this step every ten days, and make sure even the new leaves are coated. Use the sulfur only two weeks before or two weeks after you have used other oil treatments.
Controlling the Spread of White Spots on Squash Plants
You can try spraying your plant with protective fungicides. Some effective organic fungicides are available in the market that can help get rid of white spots, such as neem oil and potassium bicarbonate.
These organic fungicides are most effective when applied before you see white spots on your Squash leaves. You can even use them when you see the first signs of powdery mildew on your plant.
Make sure that when you apply neem oil on your plant’s leaves, the temperature is not above ninety degrees Fahrenheit (32 degrees Celsius).
Apply the oil in intervals, so after the first application, make sure ten days have passed before you apply again.
Suppose chemical fungicides are not something you wish to invest your money in. Then you can make a bicarbonate solution to remove the white spots.
The solutions can be made by creating a 1-quart teaspoon solution of water and baking soda. Spray the whole plant thoroughly since the solution will only kill the fungus it touches.
If your plant becomes heavily infected, getting rid of the white spots can be extremely difficult. Thus, it is always better to focus on prevention rather than just controlling how much it spreads.
To ensure your plant survives, remove all the infected foliage, stems, and fruits and burn them or even throw them in the trash.
Never compost any of the infected parts of your plant. This is because the disease will then spread through wind or remain alive in the compost material, thus infecting your plants in the future.
Frequently Asked Questions about White Spots on Squash Leaves
Which species cause white spots on Squash leaves?
White spots on squash leaves are caused by powdery mildew.
Can vinegar help get rid of white spots on Squash leaves?
Vinegar can be used as a temporary solution to control the spread of the white spots. Just take a gallon of water and add two to three tablespoons of 5% acetic vinegar acid.
Daniel has been a plant enthusiast for over 20 years. He owns hundreds of houseplants and prepares for the chili growing seasons yearly with great anticipation. His favorite plants are plant species in the Araceae family, such as Monstera, Philodendron, and Anthurium. He also loves gardening and is growing hot peppers, tomatoes, and many more vegetables.