What is the Best Treatment for Powdery Mildew?
Let's be honest. when you work hard on your garden, bringing your vision to life, there’s nothing worse than finding a serious problem like powdery mildew on your plants. While it may seem to cause few to no issues at first, if left untreated, this fungus can destroy all your efforts and seriously dampen your enthusiasm for gardening in the first place?
But what is it, and why is it such a problem?
Powdery mildew is a fungus that appears in white, fluffy circles on plants. Over time, it will sap the plants of their nutrients, causing altered growth. Ultimately, the fungus will kill your plants if it is not handled effectively.
This article will explain exactly what powdery mildew is, how to identify it, and the best ways to treat it. We’ll also discuss whether you can actually cure a plant once it’s developed powdery mildew. Read on for everything you need to know about this frustrating fungus.
**J&R Pierce Family Farm is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to allow sites to earn advertising fees by linking to products on Amazon. I often link to Amazon when recommending certain products, and if you choose to purchase, I may earn a small percentage of the sale. It costs you nothing extra, and all recommended products are ones that I personally vouch for.**
What is the Best Treatment for Powdery Mildew?
What is Powdery Mildew?
Powdery mildew is a prevalent fungal disease that affects many types of plants. It is characterized by circular spots of white powder or gray spots on the plants, especially the leaves. When it is severe, it will spread to the fruits, flowers, and buds.
While any plant is susceptible to powdery mildew, you’ll find that the younger ones are more likely to be affected. The following plants, regardless of age, are also highly susceptible to this fungus:
Generally, powdery mildew is not fatal… unless left untreated. However, it causes an unsightly appearance on your plants, diminishing their natural beauty.
When left to spread uncontrollably, it ultimately blocks the plant’s ability to perform photosynthesis, resulting in stress and overall weakness. Eventually, the plant will lose nutrients to the powdery mildew, leading to widespread leaf loss.
In addition to the leaves, the fruit can be affected as it is exposed to excessive sunlight, causing burns. The number of blooms can be reduced. You’ll also likely experience negative impacts on the fruit’s flavor.
Powdery mildew is easily spread throughout the garden from plant to plant, making it essential to treat when first recognized. It generally occurs during the late spring and early summer seasons.
One thing to note about powdery mildew is its difference from other fungi. This fungus enjoys an environment with moderate temperatures, high humidity, and dry foliage.
What Are Powdery Mildew Symptoms?
When powdery mildew forms on a plant, it produces structures that become inserted into the cells of the plant. These structures allow the fungus to extract the nutrients it needs to develop and produce more spores.
Overall, you’ll see a general loss in health, growth, and development in any affected plants. The symptoms that occur are quite noticeable, including abnormal growth and white patches of fungus.
The abnormal growth that can occur may be seen as yellowing, twisting, and curling of the leaves. These can all happen before the first signs of the fungus’s tell-tale trademark signs of white patches. When the fungus appears, you’ll see circular, white powdery spots.
As the mildew continues to spread across the leaves, the plant’s ability to perform photosynthesis will be diminished. This can result in premature leaf loss.
In the case of edible plants, this also impacts the flavor. Because of the reduction in photosynthesis, fewer sugars are produced, resulting in your favorite fruits and vegetables not tasting how you’d expect or lasting as long in storage.
This is why it's so important to plan ahead to prevent this frustrating scourge! More on this below.
What Causes Powdery Mildew?
Powdery mildew is typically transported from one location to the next by the wind. These spores can travel for hundreds of miles before settling in your garden. The spores will land on a host plant, germinate, and infect the host and any surrounding plants.
However, if you’ve had previous problems with powdery mildew, it can lead to more problems at any time. Spores can lie dormant within dead vegetation or weeds before becoming a nuisance once more.
While powdery mildew requires high humidity in the area directly surrounding the plants, it thrives in environments that are mostly dry and warm, which is different from most fungal varieties.
It will not spread well in cold, rainy environments. When the temperature exceeds 90℉, its spread slows down. This fungus prefers temperatures between 60 and 80℉ and plants that are shaded.
Which Types of Plants Can Develop Powdery Mildew?
Powdery mildew comes in several forms, and not every variety attacks every type of plant. However, there are quite a few plants that are highly susceptible to this fungus. These plants include the following:
California poppy
Hydrangea
Pansy
Rhododendron
Snapdragon
Dahlia
Delphinium
Calendula
Azalea
Aster
Chrysanthemum
Cosmos
Zinnia
Verbena
Sweet pea
In addition to these shrubs, trees, and ornamentals, several vegetables can also be impacted by powdery mildew. These plants include the following:
Lettuce
Potato
Pumpkin
Squash
Turnip
Brussels sprouts
Carrot
Parsnip
Artichoke
Beet
Black-eyed pea
Okra
Eggplant
It is important to note that powdery mildew species are host-specific. Not every type of this fungus will affect every plant.
For example, if your parsnips become infected, it doesn’t necessarily mean that every plant in the garden will be affected - probably just the parsnips.
What is the Best Home Treatment for Powdery Mildew?
While you can use a fungicide purchased from the store to treat powdery mildew, you can also create at-home treatments. These options range from common pantry items to self-care items that you likely already have on hand.
Baking Soda
Baking soda is a great home treatment option for powdery mildew. However, you can’t just sprinkle it on the affected areas and call it a day. It works best when made into a spray with water and soap.
To make the spray, combine one tablespoon of baking soda with one-half teaspoon of non-detergent soap in one gallon of water. You’ll need to thoroughly spray all affected parts of the plant, paying particular attention to the leaves, top and bottom.
Milk
One home treatment option for powdery mildew that may come as a surprise is using milk. You can create a milk spray using two parts milk to three parts water. When applying this spray, it’s essential to do it when the sun will effectively target all affected parts of the plant.
Thoroughly spray all areas impacted by the powdery mildew, including the bottoms of the leaves. You want to soak them well. When the sun shines on your plants, it will activate the milk, making the environment no longer hospitable for the fungus.
Milk is efficient and can produce results in as little as 24 hours. You can use whole or skim, as long as it’s milk.
Mouthwash
An alternative to milk is using the mouthwash you have on the bathroom counter. In this case, you need to mix one part mouthwash with three parts water to create your powdery mildew spray.
You’ll need to thoroughly spray the tops and bottoms of the leaves. Ensure you soak them down to cover all affected areas.
Vinegar
Because it is much stronger than milk or mouthwash, you’ll need to heavily dilute vinegar before using it on powdery mildew. Combine two to three tablespoons of white vinegar with one gallon of water.
Once again, you’ll need to thoroughly soak the leaves, top and bottom. This will target the powdery mildew, eliminating the threat from your plants.
Hydrogen Peroxide
When it comes to hydrogen peroxide, you should purchase the 3% variety. Combine one-half to three-quarters cup of hydrogen peroxide in one gallon of water. Thoroughly spray all exposed parts of the affected plants with the mixture.
What is the Best Fungicide for Powdery Mildew?
You can choose from several options for fungicides, but it’s important to note that they will not fix the damage caused by powdery mildew. Most fungicides stop the spores from germinating, which will also prevent the powdery mildew from spreading.
The application of fungicides will also prevent the fungus spores from penetrating the plant’s tissues so they cannot leech the nutrients they need for survival. One of the primary considerations you’ll need to make is whether you want an organic solution.
Organic fungicides are often preferred, as they allow a gardener to maintain their plants without chemical interference. However, when you make your selection, you’ll need to consider how the fungicide works.
Several organic options are better as preventative measures. A great example of this type of treatment is sulfur. In this case, if you know you have a plant that is likely to develop a problem, you can take a proactive approach with sulfur to prevent it from occurring.
Once powdery mildew has already appeared, you’ll need an organic fungicide that works to stop its spread and germination. In this case, you should choose a horticultural or plant-based oil like neem oil.
Can You Cure a Plant of Powdery Mildew?
Truly the best way to handle a powdery mildew outbreak is to remove and completely destroy all infected plants. However, this is hardly the answer most gardeners want to hear. After all, you’ve put your time, money, and effort into your garden.
Instead of this, you can start by using sterilized clippers to remove visibly affected portions of your plants. Wherever you can see the powdery mildew, remove the leaves.
Do NOT compost the parts you remove. This can allow the spread of the fungus to your other plants, as the compost pile will likely not get hot enough to destroy the powdery mildew.
When you’ve finished removing the affected parts of your plants, thoroughly wash your hands and sterilize your clippers. This ensures you will not accidentally spread the powdery mildew to any other plants in your garden.
Next, you’ll need to apply your chosen remedy, whether you want to make an at-home treatment or use a fungicide. Again, these remedies will not reverse the damage caused by the fungus. They will, however, prevent the spread to other plants.
It is important to note that fungicides will also not cure a plant of powdery mildew. They work to stop the spores from germinating, which, in turn, prevents them from spreading to other plants.
For the best results, you’ll need to continually reapply the fungicide approximately every 14 days. This will act as a preventative measure that stops the powdery mildew from taking hold again and spreading throughout the garden.
Other Steps to Take
You can take additional steps to protect your plants. First, you’ll want to ensure they have enough air circulation between them. This allows them to have room to breathe while preventing the spread of fungi.
Powdery mildew favors young plant growth. Because of this, it is essential not to fertilize your plants while you have an active outbreak. Doing so would increase the spread, making the problem worse than what you were originally dealing with.
Finally, you should always try to water your plants at the roots. Avoid wetting the leaves, as this can promote mold and mildew growth. Some varieties of powdery mildew love wet leaves, while others prefer dry, so it’s best to water with care.
Final Thoughts
Powdery mildew starts off as an unsightly problem that detracts from the beauty of your plants. At first, it will do little to harm your affected plants. When left untreated, your plants will show signs of diminished growth and ultimately die.
That said, as you now know, there are plenty of treatment options available if you want to rid your garden from powdery mildew for good. You don't have to suffer in silence - consider these tips, and enjoy a healthy, happy, and safe gardening season!
Want to learn more about gardening? Check out these featured articles!
Subscribe to our email newsletter for regular tips and tricks on homesteading and farming – wherever you are. You can also follow us on Instagram (@jrpiercefamilyfarm) and Pinterest (J&R Pierce Family Farm) for frequent updates. Happy farming!
