Sasha CampbellPowdery mildew can spread quickly through a garden. Once it appears, it can weaken plants, slow their growth, and reduce harvests if left untreated [1].
Thankfully, several homemade sprays can help fight this common plant disease.
Not only are these sprays affordable to make, but they’re also better for the environment than many store-bought fungicides.
Identification
Powdery mildew is a group of fungal diseases characterized by white to gray, powdery spots or blotches on plants [2, 3].
It grows best in warm, humid conditions with poor air circulation. Unlike many other plant diseases, powdery mildew does not need wet leaves to spread.
Left unchecked, this plant disease can significantly reduce your crop’s quality and yield.
Moreover, powdery mildew can affect a wide range of plants. Vegetables like cucumbers, squash, tomatoes, zucchini, and beans are commonly affected.
It may also affect fruit crops such as apples, grapes, pears, and strawberries. Peppers can also be affected.
Even ornamental plants, such as roses, zinnias, bee balm, peonies, and succulents, can be affected by this fungal disease.
The Best Homemade Sprays for Powdery Mildew
If you’re wondering how to get rid of powdery mildew naturally, these homemade sprays can help control the disease without relying on synthetic fungicides.
However, always test homemade sprays on a small section of the plant first and wait 24 hours before treating the entire plant.
Also, before spraying your plants, remove any severely infected leaves and throw them in the trash rather than the compost pile. This helps reduce the number of fungal spores that can spread to healthy leaves.
1. Baking Soda Spray
One of the most popular home remedies for powdery mildew is a baking soda spray. It can help slow the spread of powdery mildew, especially when used as soon as the first white spots appear.
It is also used to help suppress other fungal diseases on plants.
To make a baking soda spray, combine one tablespoon of baking soda with a gallon of water. Next, add a teaspoon of liquid soap and pour the solution into a spray bottle.
Finally, spray your plants, focusing on all infected areas.
2. Milk Spray
Milk spray might sound unusual, but it is one of the best-studied homemade remedies for powdery mildew [4].
To make a milk spray for powdery mildew, mix one part full-cream milk with ten parts water.
Next, shake it up and spray it onto the affected plants, coating both sides of the leaves. Reapply this DIY powdery mildew treatment every 10 to 14 days.
Milk sprays are gentle on plants when appropriately diluted.
3. Soapy Water
Soapy water is not a strong treatment for powdery mildew on its own. Instead, it is often added to homemade sprays to help them spread evenly and stick to plant leaves.
If you use a soap spray on its own, mix 1 to 2 teaspoons of mild liquid soap with a gallon of water. Spray only a small area first, as some plants can be sensitive to soap.
4. Apple Cider Vinegar
Apple cider vinegar contains acetic acid, which may help suppress powdery mildew.
Mix 2 to 3 tablespoons of apple cider vinegar with a gallon of water, then spray it on the affected leaves.
While this spray can help control white powdery mildew, it’s best to use it sparingly, as excessive vinegar can burn your plants.
Reapply every 7 to 10 days if needed.
5. Neem Oil
Neem oil has natural fungicidal and insecticidal properties, making it a versatile solution for the garden. It is widely used as an organic pest and disease control agent in organic agriculture.
Therefore, mix 1 to 2 tablespoons of neem oil with a gallon of water and 1 to 2 teaspoons of liquid soap. Spray the neem oil solution onto your plants, covering all the leaves.
Neem oil works best when used early or as a preventive spray before the disease becomes severe. So, you can keep using it even after the mildew disappears to prevent it from returning.
Moreover, you can use it as an organic fungicide for both indoor and outdoor plants.
6. Potassium Bicarbonate
This remedy is more effective at treating powdery mildew than many of the other remedies on this list.
Potassium bicarbonate can kill powdery mildew spores on contact and makes it harder for the fungus to keep growing. It is often considered one of the more effective organic treatments.
Mix one tablespoon of potassium bicarbonate with a gallon of water and half a teaspoon of liquid soap to create the spray.
7. Sulfur Spray
Sulfur has been used as a natural fungicide for centuries and remains effective against powdery mildew [5].
Spray on a dry, cool day. Avoid using it during hot weather, especially when temperatures exceed 85°F, as sulfur can damage plants in high heat. Also, do not apply sulfur within 2 weeks of using neem oil, as combining the two may damage plants.
Mix sulfur powder with water according to the label instructions to make a sulfur fungicide spray.
Spray on a dry, cool day. However, avoid using it during hot weather, especially when temperatures exceed 85°F, as sulfur can damage plants in high heat.
8. Compost Tea
Some gardeners use compost tea to help reduce powdery mildew, but research shows mixed results.
Steep 2 cups of well-aged compost in a gallon of water for 24 to 48 hours, then strain it before use. Strain and dilute the tea with equal parts of water, then spray it onto the plant leaves.
You can also apply compost tea to the soil to support overall plant health.
9. Garlic Spray
Garlic contains natural sulfur compounds that may help slow the growth of some fungi.
Follow our recipe to make a basic garlic spray for your plants. Spray it on affected plants.
Test this homemade fungicide spray on a small section of the plant first. Concentrated sprays may damage the leaves of sensitive plants.
10. Hydrogen Peroxide
Hydrogen peroxide may help reduce powdery mildew when used correctly.
Mix 4 to 8 tablespoons of 3% hydrogen peroxide with a gallon of water. Next, spray the solution on the plant leaves.
However, test the solution on a small portion of the plant before applying it broadly.
Arber Bio Fungicide
Arber Bio Fungicide is a commercial yet organic option for gardeners looking for a ready-made solution for powdery mildew.
Follow the label directions and spray the affected plants thoroughly.
How to Prevent Powdery Mildew
- Space plants properly to improve airflow.
- Water at the base of plants rather than overhead.
- Remove heavily infected leaves.
- Avoid excessive nitrogen fertilizer [6].
- Grow resistant varieties when possible.
- Water plants early in the morning so they dry quickly.
- Clean up infected plant debris at the end of the season.
- Avoid crowding plants so air can move freely between them.
Takeaway
These homemade sprays can help control powdery mildew and slow its spread. They usually work best when you begin treating plants as soon as you notice the first white spots.
Different remedies work better for different plants and growing conditions. If one spray doesn’t help after a few treatments, try another option. Check your plants often so you can stop powdery mildew before it spreads.
Thank you. Very helpful and informative article