Don’t panic if you spot pumpkin leaves turning white – it happens to us all, here are the best ways to combat the problem

I have grown pumpkins for many years, and on numerous occasions my pumpkins had leaves that turned white. Was it concerning? Yes. Did it mean ultimate doom for the plants? No, as the problem can be controlled.

As a professional kitchen gardener, I commonly had large sections in the walled gardens I worked in turned over to pumpkin patches, full of different types, plus I have always grown pumpkins on my plots at home. When my pumpkins had white leaves, it was due to powdery mildew, a common fungal disease that coats foliage with a white powdery substance.

If you are new to growing pumpkins and see foliage changing color like this, you may understandably feel disheartened about pumpkin leaves turning white. So I am here to reveal what the issue is and how to get rid of powdery mildew.

Are your pumpkin leaves turning white? Let’s unmask the culprit

Powdery mildew is a common fungal disease that affects many plants, including pumpkins, which are highly susceptible. It is an airborne ailment that spreads rapidly via spores. It can stunt growth and affect photosynthesis, but it is avoidable and treatable when it does strike.

Powdery mildew is caused by various species of fungi. Affected plants will have white, powdery fungal growth on the upper surface of leaves. It can start as white spots on the top that spread to cover the entire leaf surface, and affected leaves can also yellow, shrivel, and ultimately die back.

The issue thrives in warm, humid conditions, and the spores can spread from plant to plant by rainfall, poor watering techniques, insects, or via a gardener’s tools or clothes.

It is so common that it is beneficial to inspect plants regularly and take preventative measures. The spores can even overwinter in plant debris and fallen leaves, ready to strike again the following year.

How to prevent pumpkin leaves turning white

Pumpkin leaves turning white due to powdery mildew is very common, but there are steps you can take to reduce the chance of your plants being affected. While I cannot guarantee that the following will absolutely avoid pumpkin leaves turning white, they are recommended control measures:

• Grow resistant varieties – when scanning through seed catalogues or websites to plan your vegetable plot for the season, look for varieties that are resistant to powdery mildew. If you plant pumpkins bred to provide resistance to the disease, it will reduce the risk of infection. An example of one such variety is the Mammoth Gold Pumpkin, with seeds available at True Leaf Market, which has a very good resistance to powdery mildew.
• Space plants properly – powdery mildew thrives in overcrowded pumpkin patches, where it can spread. Properly spacing pumpkins at least six feet apart allows for proper air circulation. You can go even further and grow vines vertically on a vegetable garden trellis, or prune pumpkin vines to limit the spread of the plant.
• Keep plants well-watered – pumpkin plants stressed due to a lack of moisture are more susceptible to powdery mildew. Check plants regularly and water them deeply, especially during hot periods. Mulching around pumpkins will help keep moisture in the soil.
• Avoid overhead watering – when you water plants, avoid the watering mistake of simply soaking the foliage from above. Wet foliage increases the risk of fungal diseases; instead, soak the soil around the plant or use drip irrigation or soaker hoses to seep water into the soil slowly down to the root zone.

How to treat pumpkin leaves turning white

When you spot pumpkin leaves turning white, there are steps you can take to control the spread. You may not be able to eradicate it, but in my experience, you can easily control it enough to guarantee you a good pumpkin harvest.

• Remove infected leaves promptly – if you see the first signs of pumpkin leaves turning white, remove them from the plant immediately to prevent the issue from spreading. However, never use the foliage to make compost, as the spores can survive on plant material and be added to the garden again when you spread the compost.
• Spray plants with a fungicide – you can get fungicides to treat powdery mildew and get rid of white mold on plants. Ensure that any product is suitable for edible plants, such as this fungicide spray for organic gardening, available at Amazon. Spray the top and bottom of the foliage, and repeat the applications as needed, including after rain.
• Use homemade sprays – if a more natural solution appeals to you, there are a few options for DIY treatments you can try when you see pumpkin leaves turning white. One is a milk solution, where you simply mix a solution of 10% milk and 90% water in a spray bottle and apply it to plants. Another is to mix four tablespoons of vinegar with 4 liters of water and spray it over the leaves. Both solutions can be sprayed every 3-5 days until the powdery mildew starts to clear.

FAQs

Can I use baking soda on pumpkins with powdery mildew?

You can make a spray by mixing a couple of teaspoons of baking soda with a few drops of liquid soap and 500ml of water to apply to plants to combat powdery mildew. It is not a fully effective measure, but this spray can limit the disease from spreading or be applied as a preventative measure.

It is not just against diseases that you can successfully use DIY sprays, rather than reaching for bottles of chemicals off the store shelves. To combat pest problems, you can make homemade bug sprays out of the likes of garlic, vinegar, liquid soap, or essential oils to deal with many common bugs that may trouble your plants, indoors or outdoors.