5 Common Rose Plant Diseases  – And How to Treat Them

While roses are hardy plants that can withstand tremendous adversity, they’re also susceptible to disease. It’s almost inevitable that one of these common fungal diseases will make an appearance in your rose garden at one point or another, but don’t panic – there are ways to identify and treat them before they get out of control. 

Although we can’t promise you’ll never see one of these diseases crop up in your garden, a variety of disease-resistant roses are available. You’ll just want to be sure the one you choose is suited to your hardiness zone. Check out our Guide to Rose Hardiness Zones & What They Mean to ensure the rose you choose thrives under the conditions of your climate.

Black Spot:

Black spot in roses is mainly an appearance issue and usually doesn’t cause any major damage. This fungal infection mostly affects the lower leaves of the rose, but can spread to the upper leaves if left untreated.

Symptoms of Black Spot:

• Black splotches on the foliage of the rose

• Yellowing of the leaves as the disease progresses

• Premature falling of the leaves 

How to Treat Black Spot:

• Remove the infected tissue on your rose. Find an abscission point and pull back and downwards on the stem to cleanly remove it. 

• Excessive moisture is a common cause of black spot. Leave room for proper air circulation by lightly pruning and removing the branches that are growing inward. This will give your rose a chance to dry out a little. 

• At the base of your rose, thoroughly clean up any fallen or infected leaves to prevent reinfection. 

• Apply a coarse, organic mulch – such as wood chips – at the base of your rose. This helps to suppress the fungus from spreading back upwards.

Powdery Mildew:

Noticing white, fuzzy patches on the leaves of your rose? That’s powdery mildew – another common fungal infection you’ll probably see in your rose garden. It could reduce the flowering of your rose, but won’t be devastating to its health.

Symptoms of Powdery Mildew:

• Small, circular, sometimes fuzzy white spots that appear on the upper surface of the leaves. 

• Leaf discoloration - may turn yellow, reddish, or brown.

• Premature falling of leaves

• Reduced flowering

How to Treat Powdery Mildew:

Prevention is the best protection when it comes to powdery mildew. Here are a few tips to decrease the likelihood of your rose becoming infected:

• Avoid overhead watering – Excessive moisture on the leaves is a major cause of powdery mildew.

• Prune outward and give sufficient space between plants to allow for proper air circulation.

• Remove and dispose of any parts of the rose that are affected to prevent the disease from spreading further.

• If you choose to use a fungicide, neem oil is an organic & effective commercial product that can suppress the disease from spreading.

Rust:

This common disease looks just how it sounds – an orange-y dust appears on the foliage of the rose. As with other fungal infections, the main culprit is excessive moisture. While it isn’t likely to kill your rose, it damages the foliage – leading to stunted growth.

Symptoms of Rust:

• Brown spots with orange, yellow, or tan centers on the leaves of the rose

• Yellowing of the leaves

• Powdery orange clusters 

• Leaves may become distorted, curl up, and eventually die

How to Treat Rust:

Complete eradication of rust is unlikely, but you can easily mitigate the symptoms and reduce the spread. The key is to be proactive and treat early. 

• Remove and dispose of all infected leaves 

• Spray with an organic fungicide – such as neem oil. Sulfur and copper-based products are also effective treatments. Make sure to protect yourself when spraying and use your mask and gloves!

Botrytis Blight:

Roses often develop this fungal disease under wet conditions. It causes premature balling of the petals, failure to produce blooms, and can even lead to rot.

Symptoms of Botrytis Blight:

• Browning & balling of the petals

• Grayish brown, fuzzy mold on the petals

• Failure of the buds to open

How to Treat Botrytis Blight:

• Deadhead your roses - cut off the spent flowers and prevent the infection from spreading.

• Prune your roses to create an open structure and improve air circulation.

• Routinely examine the petals and remove any infected parts.

• Always clean any tools you’ve used to care for your roses to avoid spreading the disease.

Rose Mosaic Virus (RMV):

During your roses’ first flush in the spring, you may see a yellow mottling – a pattern of irregular spots – on the foliage. Rose mosaic virus is a common fungal disease that makes its way into your roses through budding, grafting, or rooting cuttings from infected plants.

Symptoms of Rose Mosaic Virus:

• Yellow veins on the leaves

• Yellow zigzag patterns or ringspots

• Very faint swirls or squiggles

How to Treat Rose Mosaic Virus:

There is no cure or treatment for RMV, but you can still enjoy your infected roses for a period of time. Some gardeners choose to simply leave it until it starts to decline. The only thing to do after that is remove and dispose of it.

Remember – if your roses become infected with one of these diseases, it’s not the end of the world! With a few measures of prevention and early treatment, you can control the symptoms and still enjoy their blooms for years to come.

Looking for a new rose to add to your garden this season? Head over to April and Ashley to browse our selection of premium rose bushes and bouquets – straight from our farm to your doorstep.

Happy gardening!

April & Ashley