How Do You Treat Powdery Mildew On Ninebark

Helen Skeates
Helen Skeates
10 min read

Those that have wondered, “How do you treat powdery mildew on ninebark?” are not alone.

The devastating effects of powdery mildew can reduce the allure of ninebark in a hurry. Incorporating ninebark, in any of its many cultivars, into your landscape is a surefire way to add a splash of color there.

If you see white fungi growing in your space, it’s time to get rid of the infestation as quickly as possible. Powdery mildew is the common name for that unfriendly fungus.

What Is Powdery Mildew?

Powdery mildew is a fungus that can infect many different types of vegetation. Powdery mildew is a common fungal disease that affects a wide variety of plants. Many types of garden plants are susceptible to this disease, including nightshades (tomatoes, eggplants, and peppers), cucurbits (squash, pumpkins, cucumbers, and melons), roses, and legumes (beans, peas).

If a fungus is invading your plant, you’ll notice a mildewy film on the leaves. This film is actually made up of many spores. The spores are spread to other plants via the wind. Powdery mildew is a fungal disease that can stunt your plant’s development and, in extreme cases, lower your harvest and ruin the quality of your fruit.

Controlling Powdery Mildew

How Does Powdery Mildew Spread?

Although powdery mildew spores often enter your garden on the wind, dormant spores in dead plant material or surrounding weeds can also cause new outbreaks if you’ve had powdery mildew before.

Although it requires rather high relative humidity (i.e. humidity around the plant), powdery mildew thrives in warm (60-80°F / 15-27°C) and dry regions. In addition to being hindered by temperatures above 90°F (32°C), its spread is also impeded in locations where it is cooler and rainier. More so than plants in full sun, it tends to impact those in partial shade.

How to Identify Powdery Mildew

  • Plants with powdery mildew infection have a flour-like appearance.
  • To begin with, powdery mildew manifests as white spots, either round or irregular in shape, on the surface of your plant’s leaves, stems, and even its fruit.
  • Powdery mildew typically appears on the upper surfaces of the leaves, though it can also develop on the undersides.
  • Most damage occurs to young plants as they are just starting to establish themselves. Yellowing and desiccation of the leaves are signs of autumn’s end.
  • Some leaves may twist, shatter, or become deformed as a result of the fungus.
  • The powdery mildew spots will grow and eventually cover the entire leaf or affected area.
  • Disfigurement extends to the plant’s foliage, bud structure, and emerging growth points. These symptoms typically manifest themselves late in the growth season.

Tips in Treating Powdery Mildew

Powdery mildew is typically eliminated by gardeners for cosmetic reasons. After all, you shouldn’t automatically consider them hazardous, especially if you get them addressed. Because of their parasitic nature, they will prevent your ninebarks from flowering.

Tip #1: Location and temperature matters

Powdery mildew typically appears between the months of May and June. Humid, temperate, or cool climates are perfect for it. Ninebarks are susceptible to mildew and will likely become ill if kept in dark, damp conditions.

Therefore, it is recommended that you provide your plants with adequate light and avoid planting them in shaded areas. Keep some distance between them for ventilation, too. Remember that water drainage is an important consideration as well.

Tip #2: Ensure that they get the nutrients they need

An increase in powdery mildew growth has been linked to high humidity, as has been mentioned before. So remember to water your Ninebarks and watch the soil instead of the leaves. Make sure you don’t drown them in water, though.

Composts, not fertilizers, are what you want to use to increase the soil’s nutrient content. It’s best to stay away from them, as their nitrogen content is likely to be quite high. It’s important to take care not to over-fertilize, as newly established plants are more susceptible to disease.

Tip #3: Make use of environmentally friendly treatments

Fungicide treatments can be used whether powdery mildew is just in its early stages or has spread extensively. Pick organic varieties and apply them on your ninebarks every 10-14 days.

One effective solution for preventing powdery mildew is baking soda. All you have to do is combine one tablespoon with one-half teaspoon of liquid soap and a gallon of water.

Does Greenhouse Gardening Make Perfect Sense?

A greenhouse not only shields your plants from the outdoors, pests, and other variables that can easily ruin your gardening efforts, but it also gives you limitless options for cultivating any plant and achieving your ideal harvest. If you’re interested in learning more about the advantages of owning a greenhouse, whether it’s a little hobby greenhouse or a larger semi-professional greenhouse, here you go:

It protects your plants from pests and critters

If you have berries, melons, and peas in your garden, the last thing you want to see is a deer or raccoon gleefully munching away at them. If you have a greenhouse to protect your plants from the elements and potential predators, you may rest easy knowing that your plants are protected.

To add to this, you can rest easy knowing that your greenhouse effectively separates your botanical haven from the devastating bugs that plague typical outdoor gardeners on a daily basis.

What you can do to get rid of mildew on your plants | CBC News

It keeps your plants safe from bad weather conditions

When your plants are housed in a greenhouse, you can rest assured that they will be protected from any adverse weather. This saves you the trouble of having to think of elaborate contingency plans for unexpected events. Nothing beats a greenhouse for protecting your plants from the elements, whether it’s a blizzard or a thunderstorm.

You can grow any type of plant

In a greenhouse, you can easily cultivate exotic species that aren’t normally found in your region. Because it is an enclosed space, the temperature and humidity levels in a greenhouse may be readily controlled. The time has come to get the exotic plants you’ve always wanted into your own backyard.

How to Prevent Powdery Mildew

The greatest method for combating powdery mildew, like any other pest or illness, is to take preventative measures.

  • If you want your garden to thrive, you should select plants that can withstand powdery mildew. Melons, cucumbers, squash, and other cucurbits have all been bred to be resistant to mildew, and these strains are now widely available from most seed companies.
  • Powdery mildew is more common in shaded regions, so plant where the sun can reach them.
  • Reduce relative humidity by increasing airflow to your plants through strategic removal of overgrowth.
  • Overhead watering can help remove spores from leaves. Wet foliage, however, can often contribute to the development of other prevalent diseases, so this shouldn’t be relied upon as a prevention tactic alone.

Homemade Prevention

Sulfur, lime-sulfur, neem oil, and potassium bicarbonate are all effective organic fungicides for treating powdery mildew. To maximize their efficacy, they should be used either before infection or as soon as the first symptoms appear.

  • Numerous gardeners have attested to baking soda’s efficacy against powdery mildew. In a quart of water, dissolve 1 teaspoon of baking soda. The solution will only be effective against the fungus it comes into touch with, so be sure to spray plants thoroughly.
  • Another useful home cure is milk spray. Spray the milk/water mixture on roses at the first indication of infection or as a prophylactic precaution, diluted at a 1:10 ratio.


Particularly for rose bushes, there is a wide variety of fungicides available that are highly effective while also being low-toxic, residue-free, and long-lasting. As an illustration, consider the case of Triadimefon. A wettable powder solution of between 1000 and 1200 WP, at a concentration of 15%, can be sprayed on the area twice or three times at 10-day intervals. However, you should verify the fungicides’ legality in your region with a nearby nursery.

Powdery Mildew – Deciduous Woody Ornamentals | Plant Disease Diagnostics  Clinic


The correct response is to take measures to limit the extent of the damage. If the fungi persist despite these countermeasures, the affected ninebarks must be removed.

As a precaution against spreading their disease to neighboring vegetation, their extermination is a must. Don’t forget to seal them up in a plastic bag to prevent the spores from spreading. Once you have removed the affected plants, clean up the area surrounding them and reapply mulch to prevent further spread of the disease.

Remember, if you want to know the answer to the question of how do you treat powdery mildew on ninebark, then keep the other ninebarks maintained by removing the infected parts and tending to their needs.

Helen Skeates

Helen Skeates

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