Love My Roses, But Not Rose Diseases!

Do you love your roses, but hate seeing the diseases that can hurt them? I love making flower arrangements for myself and my friends throughout the summer and fall. I love all the different colors and varieties. But I hate diseases that threaten my lovely rose bushes! I hope the following information about Idaho’s 3 most common fungal rose diseases will help you to better understand how to keep your roses healthy. 

Rust

The symptoms of this fungal disease are small orange blisters on the underside of leaves. A small amount will not cause a lot of damage to the rose, but the spores can blow to other roses and infect those roses. This disease can survive the winter, so it's best to control it so it doesn't carry from one year to the next.

Black Spot
This fungal disease fungus looks like spots on the surface of the leaves and causes the leaves to drop off early. It can survive the winter and in the spring the rain will splash on to the rest of the plant and spread it. It is recommended to prune off the disease for winter, allowing plenty of air flow between the major branches. Additionally, water the bottom of the plant to avoid getting water on the leaves.

Powdery Mildew
This fungus looks like grey and white powder. It will show up anywhere on the plant. This does not need water to spread and can survive the summer. Remove any infected leaves that you see on the plant and prune for winter. Water to avoid leaves, as with Black Spot. Once into the summer weather you can give your rose a wash with the hose to remove mildew and aphids. 

The following fungicides and natural pesticides can be helpful in keeping your rose bushes healthy:

Potassium bicarbonate is a chemical relative of baking soda. We also see it as antacid in over-the-counter medications.  It will control Black Spot and Powdery Mildew.  A few of the names you can find it under in the garden center are: Bi-Carb Old Fashioned Fungicide, Kaligreen, and Bonide Remedy. 

Bacillus subtilis is a microbial pesticide. It is a bacteria found in air, water and soil.  According to the product label, it is effective in controlling all three important rose diseases. It is sold as “Serenade Garden Disease Control”.

Neem Oil is a naturally-occurring pesticide found in seeds from the neem tree. It kills a variety of insects, including aphids.

Along with the tips above, it is important to keep the ground area under roses clean, of leaves, rose buds, and debris. I hope this helps you to keep your roses looking beautiful and healthy all season!

Pictured above:
My 5 year old rose bush