Rose diseases are a nightmare for any gardener.
All your hard work and dedication to your plant can flash before your eyes.
That’s why we’re here to help you!
We’ve compiled this list of the five most common diseases that affect roses.
We’ll go over how to identify these diseases as well as helpful information on how to treat and prevent these diseases.
1. Black Spot
As its name suggests, black spots are identifiable by the black splotches that cover the rose plant.
These black spots can be found primarily on the leaves and stems of the plant.
The edges of the spots are rough and the surrounding area can turn yellow.
In more severe cases of black spots, it is not uncommon for leaves to start dropping from the plant.
Preventing and Treating Rose Black Spot Diseases
When tackling black spots in your garden, keep in mind that this is a water-borne disease that thrives on heat and humidity.
We recommend steering away from any rose varieties that are susceptible to black spots if you live in a humid, warm environment (such as the southeast United States, for example, which is prone to heat, humidity, and frequent summer rains).
Instead, opt for one of the many disease-resistant varieties on the market.
In order to prevent black spots, the key is to reduce excess water and increase air circulation between the foliage.
When watering your plant, avoid overheat watering, which unnecessarily leaves the foliage wet.
This wet foliage can cause trapped moisture to fester and develop black spots.
In addition, pruning your rose plant at least once a year can help clear away excess branches and increase airflow, which aids in evaporation.
2. Downy Mildew
Downy Mildew is one of the more serious cases of mildew compared to powdery mildew and black spot.
When downy mildew takes, it has the ability to completely shed a plant of its leaves within 24 hours.
Downy mildew manifests itself as round purple spots with a yellow border around them.
These spots commonly show up near the leaves’ veins, but can also be found on the branches as well.
Occasionally, you may find grayish fuzz developing on the underside of the leaves.
Preventing and Treating Rose Downy Mildew Diseases
Downy mildew thrives in wet conditions, so eliminating any unnecessary moisture is key to preventing it from making an appearance at all.
Just like with black spots, it is advised to water your plants as close to the base of the soil as possible and avoid watering overhead and splashing the foliage with water.
In addition, it is also helpful to water your plants in the morning so the plants have time to dry out during the day.
3. Powdery Mildew
Powdery mildew manifests itself as light gray spots on your roses’ leaves.
These spots have an appearance reminiscent of powder, hence their name.
Powdery mildew can affect both new leaves and flower buds.
Unlike most fungal diseases which spread via moisture, powdery mildew spreads on dry foliage via the wind or physical contact.
Preventing and Treating Rose Powdery Mildew Diseases
If you spot powdery mildew in the early stages of infection, it is advised to give your affected plants a good spray of water in the afternoon.
This will aid in washing off the spores before they have the chance to establish and spread.
You can prevent powdery mildew from ever happening by planting roses that are resistant to this disease.
In addition, try to plant your roses in locations that receive full sunlight (at least 6 hours per day) and prune your plants regularly in order to increase the air circulation between plants.
Anti-fungal sprays can be applied as well to curb an existing infection or to prevent one from ever happening.
You may choose to purchase an anti-fungal spray or mix your own solution using common household ingredients.
A popular spray consists of 1 tablespoon of baking soda, 1 tablespoon of vegetable oil, 1 teaspoon of dish soap, and 1 gallon of water.
4. Rust
Rose rust is identifiable by its signature rusty-orange pustules and yellow spots.
The small orange lesions form on the underside of the roses’ leaves, while the yellow spots litter the top of the leaves.
In severe cases, rust can completely strip a plant of all its leaves.
Rust is most likely to occur in situations where the climate is warm during the day, but cool at night.
Rust is least likely to appear in climates that are consistently hot and dry.
Preventing and Treating Rose Rust Diseases
Preventing rust is very similar to preventing blackspot.
Reducing excess moisture and increasing air circulation is necessary for preventing rust from occurring.
Make sure to frequently prune your rose plants in order to rid your plant of diseased foliage and to promote better airflow.
This increased airflow is essential to preventing residual moisture from harboring fungus that can develop into rust.
When trimming your roses of diseased foliage, make sure to completely dispose of them to prevent the possibility of reinfection.
Either burn your diseased trimmings or place them in a plastic bag in the garbage.
5. Rose Mosaic Virus
Rose mosaic virus can be identifiable by yellow mottling that appears on its leaves, it can also cause new growth to become deformed.
This virus can cause plants to grow poorly if left untreated in some severe cases.
However, sometimes rose mosaic virus can affect a few leaves and cause very little harm to the overall plant.
While the rose mosaic virus cannot spread from plant to plant, you should not propagate your rose plant with an infected branch as the virus is able to spread from parent to offspring.
Rose mosaic virus is fairly rare, as most commercial nurseries’ roses are 95% virus-free.
Older plants are more likely to carry the virus.
Preventing and Treating Rose Mosaic Virus Diseases
In mild, benign cases, you can prune your rose bush of the infected foliage.
All accredited rose nurseries will replace a rose bush that has been infected as well.
If your rose plant has a severe case of the mosaic virus, then it should be removed and destroyed.
Conclusion
It is never fun to find a disease on your beloved rose plants; it can be scary, especially when you are unfamiliar with the disease or how to care for it.
Hopefully, with this comprehensive guide to 5 of the most common rose diseases, you’ll be able to more accurately identify rose diseases and how to treat them.
