Does Neem Oil Kill Powdery Mildew?

There are a lot of things that can go wrong with your plant’s health. One of the most common plant diseases that often attacks plants during the cooler months called powdery mildew.

Powdery mildew is a broad term used to describe a number of fungal species that create powdery white dust on the leaf plant surfaces resembling talc.

Close up of powdery mildew, plant diseasePin
Powdery mildew up close, plant disease | Tunatura-DepositPhotos

Some species of powdery mildew are relatively harmless or affect a specific type of plant. Others can devastate a wide selection of susceptible plants and crops.

Even worse, mildew often appears as a result of scale, mealybug, or aphid honeydew.

Before you panic and get rid of your ornamental plants or prized petunia, you might want to 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 and could save a lot of time, money, and tears when powdery mildews 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 and can work wonders against powdery mildew and other infections.

Keep in mind 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, meaning it won’t infect below your plant’s surface outside of a massive infection.

As a result, you may wish to skip on a soil soak – unless there are scale, aphids, 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.

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 it comes into direct contact with.

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.

Gently blend 2 tablespoons of Dawn dish detergent or pure castile soap for plants into a gallon of water to serve as an emulsifier.

More on How To Use Castile Soap For Aphids here.

Next, add in four teaspoons of 1% percent clarified hydrophobic neem oil.

Test the mix on a small portion of the infected plant to ensure there are no adverse reactions.

In the event the treated area is fine after 24 hours, you will need to 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.

At the end of this period, the infection may be gone, 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.

NOTE: When using commercial products always read and follow the product labels.

Prevention is the Best Medicine

Once you have eliminated a fungal infection, it’s a good idea to give your plant a monthly neem soil drench treatment or a bath in the foliar spray every two weeks to prevent future problems.

Always remember to use 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.

Remember that fungal and pest issues can be highly contagious. Be sure to treat any plants that were in close proximity to an infected or infested plant to ensure no traces of the problem are left alive.

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