Powdery Mildew Disease on Squash Plants


Squash, which belongs to the genus Cucurbita, is an annual plant that thrives in warm climates and is often cultivated in home gardens for the production of edible fruit, seeds, and flowers. Because it is a member of the cucurbit family, it is related to cucumbers, pumpkins, and melons, among other things. The fungus known as powdery mildew may easily infect squash, much like its close cousins. In addition to making the leaves seem unpleasant due to the spread of fungi, the illness has the potential to completely destroy your crop. You are in luck since there are many methods at your disposal for warding off powdery mildew on squash and treating it in the event that it does get infected.

About Powdery Mildew

When squash plants are infected with powdery mildew, the plant’s leaves and stems will first acquire a number of tiny, light yellow spots. According to the research published by the University of California Statewide Integrated Pest Management, these spots evolve into big patches of white, powdery fungal growth very quickly, covering the whole of surfaces. When days are warm and humid and are followed by nights that are chilly and humid, the fungal pathogens proliferate.

Powdery mildew fungus, in contrast to other fungal diseases, do not need standing surface water in order to germinate and infect their hosts. In point of fact, free water may eradicate the viruses by washing them off the leaves in the appropriate manner. The infections that cause cucurbit powdery mildew develop unique spores that enable the fungus to survive the winter and then spread to fresh squash plants in the spring thereafter.

Effects of Infection

It is common for the leaves of a squash plant that is infected with powdery mildew to seem as if it has been sprinkled with confectioner’s sugar. Particularly during the hotter parts of the day, infected leaves take on a dull yellow colour and wilt. The inability of the damaged leaves to conduct photosynthesis results in the leaves changing colour, becoming brittle, and falling off the squash plant earlier than normal. The fruit may get scorched as a consequence of the lack of leaves. Plants that are affected with mildew often yield fewer or smaller squash, and plants that are severely infected with mildew may even perish.

Cultural Control of Powdery Mildew

The fungus that cause powdery mildew like cool, gloomy environments; hence, growing your squash in a spot that gets full light is the best way to combat the illness. The Master Gardeners of Santa Clara County recommend leaving sufficient space between individual squash plants in order to ensure adequate circulation of air. Shade and air humidity levels are both increased when there is dense planting. It is possible to remove fungal pathogens from the foliage of plants by watering them with an overhead sprinkler or by squirting them with a strong stream of water from a garden hose. However, you should water the plants first thing in the morning so that the foliage can dry off as quickly as possible in the sun.

Neem Oil Fungicide

The disease known as cucurbit powdery mildew normally does not call for the use of fungicidal treatments; nevertheless, particularly vulnerable squash plants may benefit from some kind of intervention. Neem oils are the most effective fungicide for powdery mildew because they are able to completely remove mildew infections that are mild to moderate in severity while also providing extra protective characteristics. In accordance with the directions provided on the product’s packaging, combine about 2 teaspoons of neem oil with 1 gallon of water.

Because neem oil is only effective when it comes into direct touch with the plant, it is important to spray all of the foliage, including the stems and the undersides of the leaves. Spray the diseased squash plants with the solution containing neem oil once every seven days until there are no more indications of illness; after that, continue treating the plants once every 14 days to prevent the disease known as powdery mildew from returning.

A Few Considerations

Neem oil should be sprayed on squash plants first thing in the morning or last thing at night to lessen the likelihood of leaf burn. Neem oil solutions should not be used if the temperature is forecasted to get over 90 degrees Fahrenheit, if there is a high chance of wind, or if rain is predicted within the next 24 hours. The spray is not hazardous to humans or animals, although it may irritate the eyes if it gets in them. Put on protective eyeglasses, long sleeves, trousers, shoes with socks, and gloves made of waterproof material to shield yourself from the effects of exposure.