Roses – Diseases
Raising roses can be fun yet challenging. Roses – Diseases can hinder your work and keep you from having the beautiful rose bushes you have always wanted. Fungi, mildew, bacteria, and viruses can attack your roses just the same as they can you. These things are in the air around us. Take care of your plants regularly and watch for blackspot, stem cankers, powder mildew, botrytis blight, mosaic, and crown gall.
When you are watching for blackspot, stem cankers and powder mildew, you will be looking for similar signs. Each has different signatures but they are all a fungal roses diseases. Be careful of which fungus you think you have in your roses because of the several different causes of fungi and their effects. Blackspot causes nearly full defoliation by the early fall. This weakens the bush, causing cankers on the cane, which are severe with circular black spots on the upper surface of the leaves that start at the base of the plant and move upward. It also causes infected leaves to turn yellow and fall off prematurely. Stem cankers are brown, oval-shaped areas on the cane which are sunken and shriveled; canker is a disease of stress.
Keep plants healthy and actively growing; they stand a better chance of not having cankers. Be sure to prune well below the affected area to prevent spreading the roses diseases. Powdery mildew is a fungus that affects the young leaves. They turn purple, twist and curl. Mildew is spread by wind. It develops quickly with warm, humid days followed by cool nights. Progression leaves a white powdery fuzz that starts at the top of the plant.
Botrytis blight is also a fungal disease. However, it likes to attack the dying tissues around plants and flowers. It can sometimes attack healthy tissues, too. Be sure to clean away any pruned droppings, and prune the dying leaves and stems from your roses often. This is the best way to keep this ugly disease away. It can be gray in color, so it is sometimes known as gray mold.
Some more serious of roses – diseases are mosaic and crown gall. Rose mosaicis is one caused by a virus that is deadly to plants. This is easily spread between plants. It is identified by stunted growth or bright yellow patterns on the leaves. It cannot be cured. If you have a diseased bush, do not prune healthy plants after pruning it unless you sanitize the tools by soaking them in a bleach solution for 10-25 seconds. A severely infected plant should be removed and destroyed. The same is to be done with a severely infected plant with crown gall. Since it is a bacterial disease that can live in the soil for 15-20 years, no plants should be planted in affected soil for at least five years. There are also no controls for this. It can be identified by the irregularly shaped, dark-colored, rough galls on the stems near the soil. Keep the vigor of your rose plants with fertilization and watering.