If, like me, you’ve ever grown your own vegetables, herbs, or flowers, you’ll know the challenge of dealing with powdery mildew. This common disease, which affects many plants, will slow growth and prevent fruiting or flowering if left untreated. Luckily, this affliction is also easily treatable with a few simple remedes. Read on to learn all about how to make your own effective powdery mildew treatment.
What is Powdery Mildew?
Before we discuss how to make an effective powdery mildew treatment, we’ll first explore what powdery mildew is, exactly.
Powdery mildew is a general term that can be applied to a number of fungus-related plant diseases. Many ornamental and edible plants can suffer from this affliction, though different fungal strains attack different plants. For example, the powdery mildew that attacks your peas is different from the strain that targets roses. Most forms of this fungus developed from the Eryspihe cichoracearum fungus.
Powdery mildew can strike in most climates and conditions, but it thrives in warm climates. Additionally, it’s more likely to spread in humid conditions. It’s slower—or unlikely to spread—in cool, rainy climates.
If you catch it early enough, this disease is easily treated. However, if it’s allowed to spread, the fungus will eventually kill your plant and even spread throughout your entire garden.
Identifying Powdery Mildew
The most obvious sign of infection is the appearance of a powdery, white dust on plant leaves. This may only be a small patch to begin with, but it will grow steadily.
Powdery mildew is sometimes confused with the similar downy mildew. However, downy mildew appears only on the bottom (or underside) of the leaf. In contrast, powdery mildew will appear anywhere on the leaf. Take note that downy mildew isn’t as powdery in appearance, either.
If untreated, the small white spots will grow, forming a root-like structure. This saps the plants leaves of nutrition and also prevents photosynthesis. As the fungus takes hold, the plant’s leaves will turn yellow and fall off.
Leaf loss in this manner will cause the plant stress, meaning that it will fail to flower or fruit. The plant will also stop growing, so you’ll have to remove it from your garden.
Additionally, the fungal spores are spread on the wind or by visiting pollinators. Needless to say, this can be a particular problem if you grow lots of pollinator-friendly flowers. Without prompt action, powdery mildew can wreak havoc in your yard.
Luckily, powdery mildew is not only easy to prevent, but there are also a number of effective powdery mildew treatments. If applied quickly, they’ll rid the plant of fungus and keep the rest of your garden safe.
How to Prevent Powdery Mildew
It’s virtually impossible to completely prevent powdery mildew. This is largely because spores are carried on the wind, and can therefore fall on any surface. If the conditions are right, they will then begin to reproduce.
If you’re concerned about powdery mildew, many plants such as melons, squash, and cucumbers have commonly available mildew-resistant varieties. In addition, adopting basic good gardening practices will also help to reduce the chances of powdery mildew—or any other disease—from striking.
Deadheading, and removing any diseased or dried leaves as soon as you notice them, also deters a host of plant diseases. Pruning overcrowded areas, or just planting sparsely, will help to increase air circulation. This lowers the humidity level around the plant.
Promptly dealing with any aphid problems will also decrease the risk of your plants developing the fungus. Aphids carry powdery mildew spores from plant to plant. A simple, chemical-free way of controlling aphid infections is to introduce baby ladybugs to your garden.
These beneficial little insects won’t merely help keep aphids at a minimum, but they’re also helpful pollinators. Similarly, companion planting, and planting pollinator attracting flowers, can encourage beneficial insects and improve the general health of your garden.
Growing vulnerable varieties in light areas, away from too much shade, can help to deter powdery mildew. So can watering just the base of the plant, instead of watering from overhead. Damp leaves can increase humidity and encourage fungal infections.
Making your own Powdery Mildew Treatment
If powdery mildew does take hold on your plants, there are a number of chemical treatments available. While these fungicides are effective, many people dislike using the potentially harmful chemicals. Organic treatments are also widely available. That said, making your own chemical-free powdery mildew treatment is quick and cost-effective.
This may sound like a surprising solution, but milk is an extremely effective powdery mildew treatment. A 2009 study by the University of Connecticut concluded that milk is just as effective than chemical applications (if not moreso) when it comes to treating powdery mildew. Apparently, milk’s fungal-killing potential comes from the way it reacts to the sun, producing free radicals that are toxic to the fungus.
To make up a milk treatment, mix a solution 60 parts water with 40 parts milk (or whey). Spray this solution onto the affected plants biweekly. If the infection is particularly strong try applying undiluted milk. This will be more potent and should clear up any stubborn infections.
Alternatively dilute 1oz of powdered milk into 2 liters of water. This should be sprayed onto the affected plants once every two weeks until the infection has gone.
2. Bicarbonate Soda Sprays
One of the most effective treatments is spraying affected plants with a bicarbonate solution. To make your own solution, mix 1 teaspoon of baking soda (potassium bicarbonate), with 1 quart of water. Stir the solution, making sure that it is thoroughly mixed. The solution can then be sprayed all over the plant. No need to worry: it’ll only kill the fungus, and won’t harm the plant in any way.
An alternative method is to mix up a solution of 3 tbsp of potassium bicarbonate, 3 tbsp of vegetable oil, and half a teaspoon of castile soap (like fragrance-free Dr. Bronner’s) into a gallon of water. Spray this solution over the affected plant.
Potassium bicarbonate is a safe, effective fungicide that can kill all spores on contact. You can also apply it as a preventative treatment. It works by slightly raising the pH level to above 8.3. This creates a slightly alkaline environment that fungal diseases dislike. You can also use baking powder solutions as a preventative application because they work in a similar way.
Garlic is naturally high in sulfur, and is an effective powdery mildew treatment. To make a fungus-killing solution, crush 6 cloves of garlic and mix with 1 ounce of an organic oil, and one ounce of rubbing alcohol. Allow this mixture to set for 2 days.
Once set, strain the mixture, retaining both the liquid and the crushed garlic. Soak the crushed garlic in a cup of water.
Strain the water and dispose of the crushed garlic. Measure out one gallon of water and add to it the oil and alcohol mixture. Add the garlic water and mix thoroughly. Spray this solution onto the leaves of your plant.
To save time, you can purchase garlic oil and mix it with water to create a solution.
4. Neem Oil
Neem oil is an extremely potent fungal treatment that’s capable of killing an infection within 24 hours. It originates in the seeds of the neem tree, and disrupts the plant’s metabolism, preventing the spores from reproducing. This oil is also an effective insecticide. You can apply it as a treatment, or as a preventative measure to keep your plants healthy.
To make up a neem oil solution, mix 3tbsp of oil in one gallon of water. Spray this solution onto your affected plants once a week until the infection has gone. Be careful not to overly spray the leaves, as this can lead to sunburn. As a result, apply the solution in the evening or as the sun is fading to prevent any burning. Don’t apply neem oil to a plant’s buds or the flowers.
Another effective powdery mildew treatment is acetic acid, which is present in vinegar. In fact, acetic acid has been used to treat fungal infections in human since the time of the ancient Egyptians. Needless to say, it’s also an extremely effective treatment for plants.
Mix 4 tbsp of vinegar with one gallon of water. This creates a 5% solution that you can apply to diseased plants every 3 days. This may seem weak, but a mix that’s overly acidic can burn leaves, doing more harm than good.
Since it’s formulated to kill germs, ethanol-based mouthwash can also eliminate powdery mildew spores. Mix a solution of one part mouthwash to three parts water and spray over affected leaves.
7. Compost Tea
Many organic gardeners like to brew their own compost tea. This solution is prized for its anti-fungal properties, and is growing in popularity amongst many growers.
This mildew can be a frustrating, and often stubborn, problem to deal with. Fortunately, by adopting good gardening practices and using the ideas in this article, you’ll be able to protect your plants from its harmful effects.