Rose Bush Diseases

Rose bush diseases are most often diseases of the leaves on the rose bush, not the flowers themselves. There are some rose bush diseases that show symptoms on the flowers, such as black spots on blossoms, but diseases like powdery mildew and other fungus diseases are the most common problems for rose bushes.

In my experience, there’s nothing more frustrating for a rose gardener than a rose bush disease. Most rose varieties are fairly delicate, and we spend so much time tending to them, caring for them, and planning and organizing their maintenance that a diseased rose bush feels like a diseased part of our body. Our rose bushes are like members of our families. 

Besides diseases, there are lots of pests that attack rose blossoms and bushes. Even in the face of attack by pests and disease, rose bushes are worth growing and caring for. They add the perfect element to any landscape or garden, and the positive aspects of rose ownership far outweigh the potential headaches caused by rose bush diseases and pests.

Disease Resistant Roses

If you’re worried about rose bush diseases and pests, you should consider planting some of these varieties of rose known to be disease-resistant and sometimes even pest-resistant.

New Dawn climbing roses are large-flowered climbers, some of the most popular roses in the world. These climbing roses need a strong support for the twenty-five foot canes that grow. The flowers are a soft pink with a fruity fragrance that grow in clusters. Zones 5-10 only.

Blaze climbing roses produce a large blanket of two to three inch scarlet-red double rose blossoms. Plant these roses in a sunny area with good drainage and you’ll have beautiful red disease-resistant blossoms throughout summer and fall. These roses climb eight to ten feet tall.

Rugosa roses are naturally disease and pest-resistant and come in many different colors and varieties. They are weather-hardy and bloom a very long time, sometimes across three seasons.

Hybrid Rugosa roses are great disease and pest-resistant choices if you live in a zone too cold for standard Rugosa roses. They can also flourish in poor soil and in soil that isn’t very well-drained.

Knockout roses are the most disease-resistant roses on the market. There are seven different varieties of Knockout rose, some with double blossoms. They bloom from spring until the first frost and require very little maintenance.

Preventing Common Rose Bush Diseases

Taking control of your roses and protecting them from black spots and other rose bush diseases is a combination of choosing good rose varieties that are well-suited for your growing zone,  getting advice from your local nursery about which roses to grow, doing proper care and maintenance year-round on your roses, and knowing what treatments work for what diseases and pests.

Powdery Mildew Rose Bush Disease

Powdery mildew is actually a fungus that grows on rose bushes that experience humid nights and hot days. The most obvious symptom of this fungus is a powdery white colored residue on rose bush leaves. This fungus causes the leaves to crinkle and grow into all sorts of odd shapes.

The best treatment for powdery mildew rose bush disease is a simple and non-toxic baking soda solution. Mix two tablespoons of horticultural oil with one tablespoon of mild dish soap (I prefer Dawn) and a heaping tablespoon of baking soda. Mix this oily paste into one gallon of water and stir until the ingredients are combined.

Now water the rose bushes that are to be treated very well, making sure to wet down all the foliage. Spray the baking soda mixture as soon as the bush is in full shade, such as the early morning or evening, otherwise the mixture could burn the blossoms and leaves.

You can also use this treatment as a preventative–spray your rose bushes once a week with the baking soda mixture as soon as the leaves first appear, then twice a month after the first treatment.

Black Spot Rose Bush Diseases

Humidity doesn’t cause black spots on roses, no matter what your rose gardening friends say. The actual cause of black spots is rain and overhead watering. When you use overhead watering instead of deep root watering, the leaves stay wet for so long that fungus grows on them. Rain can also cause black spots.

To treat black spots, use the same baking soda mixture you would use for powdery mildew, and pre-treat your rose bushes with baking soda to prevent black spots as well. The best way to prevent black spots is to water at the base of the bushes and not from above.

Rusty Rose Bush Diseases

Another fungus that loves rose bushes is what gardeners call “rust.”  Rust most frequently attacks hybrid tea rose bushes and other rose bushes that have large leaves. Rust on roses is most common on the coast of the Pacific Ocean, though it can happen anywhere.

The symptoms? Rusty looking spots on the underside of the leaves and yellowish rusty spots on top of the leaves. The only way to control rust on your rose bushes is to remove the leaves showing symptoms and totally destroy them.

To prevent rust on your roses, prune the bushes before buds break in the early spring to reduce the number of fungus spores on your bushes and pray for the best.

Common Rose Bush Pests and Insects

Insects love your rose bushes as much as you do, maybe more because they use them for food and shelter. Every rose garden is going to have some insect and pest presence, but there are things you can do to cut back on the pests and their effects on the bushes.

Aphids are the most common rose pest. You won’t find a rose in any garden without some aphids present. These nasty pests create a sticky sweet juice-like substance that attracts mold. The best non-toxic way to deal with aphids on your rose bushes is to blast your bushes with a hose and knock the nasty creatures off. You should also spray your bushes with a non-toxic insecticidal soap bought from your nursery. A terrific organic way to get rid of aphids is using a spray made from rhubarbs. Find this spray at your local garden supply store.

Japanese Beetles are most common east of the Mississippi River, though they thrive pretty much all over the country these days, except for the desert. Japanese beetles swarm in groups. You’ll never find just one Japanese Beetle on your rose bushes. To get rid of Japanese Beetles, just pull them off your roses and drop them in a bucket of soapy water.

Spider mites respond to blasts of water from the hose like aphids. Hit your rose bushes daily with the hose (after the hottest part of the day) to knock them off the underside of leaves.

I believe an ounce of prevention is worth a pound of cure, and this is especially true for roses and other garden plants. The more diligant you are in preventing rose bush diseases, the less problems with rose diseases you will have over the life of your rose garden.