There are a lot of things that can go wrong with your plant’s health. Powdery mildew is a common plant disease attacking plants during the cooler months.
One of the most common plant diseases that often attacks plants during the cooler months is called powdery mildew.
Powdery mildew is a broad term for several fungal species. These fungi create powdery white dust on the leaf plant surfaces resembling talc.
Some powdery mildew species are harmless. Others affect a specific type of plant. Others can devastate a wide selection of susceptible plants and crops.
Even worse, mildew often appears due to scale, mealybug, or aphid honeydew.
Before you panic and get rid of your ornamental plants or prized petunia, catch up with an old friend, neem oil – a natural insecticide for plants.
This all-natural jack-of-all-trades is more than just an insecticide. Neem can save you time, money, and tears when powdery mildew rears its ugly head.
Powdery mildew fungus needs favorable conditions to spread. High humidity and stagnant air all contribute to powdery mildew spores spreading.
Can You Use Neem Oil For Powdery Mildew Control?
Believe it or not, neem oil is an effective fungicide that works wonders against downy mildew and other infections.
The oil contains unique active ingredients, which give it inherent insecticidal, fungicidal, and pesticide properties.
As a preventative, apply this product on a 7 to 14-day schedule until the potential for disease development is no longer present.
Remember that success will depend on how bad the infection is and the neem remedy you’ll use.
To Soak or Spray Neem Oil For Powdery Mildew
Powdery mildew is a surface fungus that won’t infect below your plant’s surface outside of a massive infection.
As a result, you may wish to skip a soil soak – unless there are scale, bugs, spider mites, aphids, whiteflies, Japanese beetles, or other pests also affecting the plant.
In such cases, the neem oil soil drench will act as a systemic insecticide, poisoning these pests when they break through the plant’s surface and hindering or outright stopping their growth and reproductive cycles.
Don’t use neem oil in the middle of the day because the direct sunlight and neem oil together can burn the plants.
Neem oil works all through the growing season because it can kill pests at every stage of their life cycle, including when they are eggs, larvae (grubs), pupas, and adults.
Sprays containing clarified hydrophobic neem oil extract are also used as fungicides against rust, black spots, mildew, leaf spot, scab, anthracnose, blight, and botrytis.
However, your main weapon will be a foliar spray, which acts as a contact poison that leaves behind no harmful residue.
The foliar spray suffocates soft-shelled insects that produce honeydew while also killing the fungus with which it comes into direct contact.
Be warned that completely eliminating a fungal infection takes time, and the worse the infection, the more applications will be necessary.
Neem Oil Recipe for Powdery Mildew Infections
You can pick up commercial oil sprays such as the Safer Brand BioNEEM product, but it’s just as easy to make your own foliar spray at home. Follow the label instructions for mixing neem into a spray.
Depending on the amount of disease pressure, you may need more or less frequent spraying.
Gently blend 2 tablespoons of Dawn dish detergent (liquid soap) or pure castile soap for plants into a gallon of water to serve as an emulsifier.
Related: More on How To Use Castile Soap For Aphids here.
Next, add four teaspoons of 1% percent clarified hydrophobic neem oil.
Test the mix on a small portion of the infected plant to ensure no adverse reactions.
If the treated area is fine after 24 hours, you must soak the entire plant with your foliar spray, taking care to get the undersides of each leaf and any crevasses or joint areas.
Repeat this treatment every other day for 14 days. Planting resistant varieties will eliminate the need to treat at all.
The infection may be gone at the end of this period, or you might need to upgrade to a stronger clarified oil.
Clarified neem oil is available commercially in concentrations between .5 and 3% percent. Although the latter can be hard to find, it is an efficient way to destroy powdery mildew spores on your houseplant or in the garden.
NOTE: Always read and follow the product labels when using commercial products.
Prevention Is The Best Medicine
Once you have eliminated a fungal infection, giving your plant a monthly neem soil drench treatment or a bath in the foliar spray every two weeks is a good idea to prevent future problems.
To protect them, avoid spraying near known hives and only spray at dusk or early morning, or late evening before the pollinators are active.
Always remember to use fungicides like neem oil sprays at dawn or dusk if the plant is accessible to pollinators. It takes an hour after treatment before the plant will be safe for them to land on.
While this product functions to kill the powdery mildew organism and is nontoxic to people, pets, and beneficial insects, it has not proven to be as effective as oils or sulfur in controlling this disease.
However, these compounds can burn delicate plant tissue, so use them only as directed and space applications a sufficient amount of time apart to avoid harming the plants.
Remember that fungal and pest issues can be highly contagious. Therefore, be sure to treat any plants close to an infected or infested plant to ensure no traces of the problem are left alive.