Rose Bush Leaves Dying

Spraying roses regularly with fungicide helps prevent foliar diseases.

Various fungal diseases are the most common causes of discolored or dying roses leaves. Understanding the types of diseases found in rose gardens and developing a preventive treatment plan helps gardeners keep roses disease free.

Common Diseases

The most common disease afflicting the leaves of roses include downey mildew, rust, spot anthracnose, powdery mildew and black spot. These diseases are caused by fungi, and influenced by garden care and weather conditions, according to the Olympia Rose Society.

Symptoms

Though each disease causes defoliation, their specific symptoms vary. Downey mildew fungi cause black spots on the upper surfaces of leaves that then spread over the plant. Rust disease causes an orange, powder-like coating to develop on the underside of the rose leaf. Spot anthracnose is characterized by small spots ranging in color from red to brown to purple. Black spot, like downey mildew, also causes black spots on leaves. Spots generally are more circular than those associated with downey mildew and surrounded by a yellow halo.

Prevention/Solution

Since most fungal diseases do not respond to "cures," it is best to begin a preventive cycle of fungicide application before symptoms develop. Apply foliar fungicide sprays throughout the growing season, according to the recommendations of your local agricultural extension office. Avoid overwatering plants and always apply water to soil, as fungi prefer moist conditions.

Home Remedy

For organic control methods, Rose Magazine recommends making an holistic garden spray. The ingredients include 1 medium onion, 4 cloves of garlic, 1/2 of a Jalapeno pepper, 1 1/2 tsp of baking soda and 2 drops of dishwashing detergent. Steep chopped vegetables in hot water and then strain through cheesecloth. Mix remaining ingredients with vegetable juice in a spray bottle.

Resistant Varieities

For gardens in which fungal diseases regularly become problematic, consider purchasing diseases-resistant roses. Contact local nurseries for more information about the disease-resistant varieties available in your area.

References

• The Olympia Rose Society: Pests and Diseases
• Rose Magazine: Rose Diseases