Identifying and Treating Rose Problems and Diseases

Next to planting disease resistant roses, good housekeeping is the best measure of prevention and control of rose diseases. Take care when watering roses. Most rose problems are caused by different kinds of fungi, all of which are attracted to moisture and grow in wet, damp and stagnant conditions.

It is best to avoid splashing water on your roses - water the ground - not the foliage. Always water in the morning to allow time for foliage to dry before the afternoon heat. A good 2 to 3 inch layer of mulch will help protect your rosebushes from soil born diseases and also regulates the soil temperature and moisture.

Here is a list of the most common fungus diseases that attack roses:

Black Spot:
Black spot is caused by the fungus diplocarpon rosae and is one of the most common fungal diseases of roses. Early symptoms are small small black spots on the leaves which are outlined by a yellow margin. If left untreated, black spot will spread over the entire leaf and go on to the rest of the plant, eventually causing complete defoliation. The disease is spread from plant to plant through splashing water and damp, wet conditions.

Botrytis:
Botrytis blight is a fungus that attacks the flower buds causing malformation and decay. The fungus takes the form of a grayish-black lesion and usually develops below the blossom head. In order to prevent spread of this fungus, cut off and remove any affected decaying or dead blossoms.

Brown Canker
Another fungus that can attack both leaves and stems of roses. Brown canker first appears as red or purple areas on new canes or grayish white lesions on older stems. Left untreated, this disease can kill the entire stem in a very short time.

Powdery Mildew:
This is another common and devastating fungus. Powdery mildew is easily identified by the visible presence of a white coating on any or all parts of the plant, causing new growth to curl and die off. Humid conditions will spread the disease.

Rust:
Rust generally first appears on the underside of the leaves. If left untreated, it will spread to the top side of the leaves as ugly orange and brown spots.

Check your roses regularly and remove any dead parts, fallen leaves and debris from around the base of the bushes. Cut off any blossoms, leaves or canes that look like they might be infected and dispose by burning or throwing them in the trash (not your compost pile).

Roses are sensitive to chemical pesticides and fungicides and these should be used as a last resort. A good all-around home made prevention and treatment against fungus is a solution of 2 tablespoons of baking soda and one tablespoon of Murphey's oil soap or one teaspoon of dishwashing liquid in a gallon of water. Use as a spray and drench plants every two weeks. This will also take care of aphids.