How To Treat Powdery Mildew On Roses (DIY Tips)

Powdery mildew on roses is a common fungal disease that can strike even the most meticulously cared roses.

There are few things in the world more beautiful than roses and as plant owners, we pride ourselves on how we take care of our beloved plants.

We’re here for you with this complete guide to powdery mildew on roses. We’ll cover what rose powdery mildew is, as well as how to treat powdery mildew and which rose varieties are resistant to this disease.

What Is Rose Powdery Mildew

Powdery mildew is a type of mildew that affect a roses’ leaves and flower buds.

It is caused by the fungus Sphaerotheca pannosa var. rosae.

Rose Powdery Mildew Symptoms

Rose powdery mildew symptoms are entirely physical and the disease can be diagnosed by visually inspecting the plant.

True to its name, powdery mildew has the appearance of light gray powder sprinkled on the foliage of the rose plant.

These powdery spots can appear on both the outside and underside of the leaves, so it is important to inspect your plant carefully.

In addition, new growth can come in deformed and covered in the same gray-white mildew substance that covers the leaves and buds.

Prolonged exposure to powdery mildew can cause rose leaves turning yellow and become crinkled-looking.

If left untreated, severe cases of powdery mildew can completely wipe out all the leaves on your rose plant.

What Causes Powdery Mildew On Roses

Powdery mildew is primarily caused by fungal spores spreading to the foliage of the rose plant.

This disease spreads very easily via the wind. It takes one infected plant to rapidly cause an entire garden of roses to contract powdery mildew.

Dry growing seasons increase the likelihood of powdery mildew.

Warm and dry days contrasted with wet and cool nights particularly promote the growth of powdery mildew.

Powdery Mildew On Rose Disease Cycle

The fungus causes powdery mildew overwinters in the rosebuds and dormant leaves.

When spring comes around and these buds break open, the spores that have been collecting in the buds cause these shoots to become infected.

Then, the resulting infection can develop spores that are quickly carried through the wind, further spreading the disease.

The spread spores infect healthy areas of the plant, and the cycle continues as the mildew migrates to the upper and lower leaves.

These formerly healthy parts of the plant now have fungus on them that will turn into powdery mildew.

How To Prevent Powdery Mildew On Roses

The best way to stop powdery mildew is by preventing it from ever occurring in the first place.

There are several rose varieties on the market that have been bred to resist common rose diseases, such as powdery mildew.

Whether you are a new or experienced rose gardener, we highly suggest considering a disease-resistant species of rose.

Simple changes you make to your roses’ care routine plays a big role in the likelihood of your plant developing powdery mildew.

Healthy roses are less likely to succumb to the effects of mildew.

Maintaining a strong plant will ensure its longevity against diseases such as powdery mildew.

For most roses varieties, it is strongly suggested to plant your roses in full sunlight.

If possible, plant your roses in an area of the garden where they will receive at least 6 hours of light per day.

Maintaining a pruning schedule is also essential to prevent powdery mildew.

Pruning will help increase air circulation between the rose plant, which in turn lowers the odds of powdery mildew developing.

How To Treat Powdery Mildew On Roses

Small cases of powdery mildew can be treated by removing the affected areas and disposing of them entirely.

Do not add infected foliage to your mulch pile, instead burn the plant trimmings or wrap them in plastic and throw them away.

If the case has gotten too large to prune, then you can opt to use either a fungicide or a homemade remedy in order to control the cases of powdery mildew.

Will Powdery Mildew Go Away On Its Own?

In mild cases, powdery mildew has the potential to go away on its own, but it is not a certainty.

Oftentimes, weather changes are the main cause of powdery mildew disappearing.

However, there is always a chance that powdery mildew won’t go away, and intervention is necessary.

Prolonged exposure to powdery mildew can weaken your plant and deplete it of both water and nutrients.

Of course, we all want your roses to be unblemished from any danger.

Controlling powdery mildew is so easy, it takes very little effort to ensure that your roses live their lives disease-free.

5 Powdery Mildew Home Remedies

Powdery mildew can often be treated using home remedies with simple ingredients you can find around your home.

Keep in mind none of these home remedies is a “one-and-done” control method.

You will need to apply this in several rounds in order to completely eradicate the mildew.

1. Powdery Mildew Milk Treatment

Combine 1 part milk with 10 parts water.

Unlike the other remedies in this list, this is a perishable mixture and should be used in one sitting.

2. Powdery Mildew Baking Soda Treatment

Mix 1 tablespoon of baking soda with 1 tablespoon of vegetable oil and 1 teaspoon of dish soap in 1 gallon of water.

Preferably, you’ll want to find a dish soap that is scent-free.

3. Mouthwash

Combine 1 cup of mouthwash with 3 cups of water.

Some gardeners swear by using mouthwash as an effective treatment for powdery mildew.

However, it is worth noting that this method is not organic.

If you are strict with using organic-only methods, this is not suggested.

4. Vinegar

Mix 2 to 3 tablespoons of white vinegar with 1 gallon of water.

Vinegar has the potential to burn your plants.

We recommend doing a patch test first on a small section of the rose plant before applying this to your entire plant.

5. Water

Some less severe cases of powdery mildew can be remedied by dousing your rose plants with water, which washes the mildew away.

This should be done in the afternoon.

The Best Fungicides For Powdery Mildew On Roses

Aside from homemade remedies, there are a multitude of fungicides available for purchase online or at your local plant nursery.

Perhaps the most popular fungicide used for powdery mildew is neem oil.

Neem oil is a natural substance made with seeds from the neem tree.

It is a natural fungicide (as well as an insecticide).

You can buy pure neem oil and dilute it in a spray bottle, or there are many ready-to-use neem oil sprays on the market.

Other fungicides that are very effective for powdery mildew include those that contain the active ingredients triforine, sulfur, myclobutanil, or copper.

Just like homemade remedies, you should apply these fungicides in several rounds for powdery mildew to be totally eradicated.

If you are purchasing a fungicide from a garden retailer, we suggest reading the instructions carefully to prevent any additional damage.

Roses Resistant To Powdery Mildew

1. Leverkusen Rose

Leverkusen roses are medium- size climbing roses.

This repeat-flowering rose variety is very hard against powdery mildew as well as other rose diseases.

To grow it best, plant it on a tall fence or trellis, providing it with plenty of space and good airflow.

The plant itself grows dense, bushy leaves. Yearly pruning will be a necessity.

2. William Baffin Rose

Another medium-sized climbing rose, the William Baffin rose is a hardy rose plant that is tolerant of light shade.

If your garden cannot sustain 6 hours of full sunlight a day, then the William Baffin rose is a compatible choice for you.

Avoid frequently wetting the leaves of this plant.

Instead, we recommend watering your rose plant as close to the base as possible; this prevents wet foliage, which can be a catalyst for other rose diseases.

3. Champlain Rose

Champlain roses are a small, shrub rose variety that has many advantages beyond being mildew-resistant.

Being small you can grow these roses in a container, which allows you to move them around if any surrounding plants catch a disease.

Additionally, Champlain roses can withstand full sun to partial shade.

4. Charles Albanel Rose

Charles Albanel roses belong to the Hybrid rugosa cultivar group of roses.

Native to Canada, this rose variety is about as hardy as it gets.

Not only are they very resistant to disease, but they are capable of withstanding zones as low as 2b.

You can enjoy these clusters of roses with the assurance that they are safe from powdery mildew.

Conclusion

Although powdery mildew is treatable, it’s never desirable to find it in your garden.

The good news is that there are many ways to effectively control and prevent powdery mildew.

With these easy methods, we can all enjoy beautiful, healthy rose plants.