Natural Spray for Powdery Mildew on Roses

Powdery mildew affects roses in warm, dry climates.

Powdery mildew attacks roses by producing a white or gray substance that infects leaves, stems and flowers. Gardeners can minimize its effects by choosing disease-resistant rose varieties and giving them plenty of space for good air circulation.

Solution

A mixture of 4 tsp. of baking soda, 2 tbsp. os horticultural oil and 1 gallon of water combined in a spray bottle or hose-end sprayer is effective at controlling powdery mildew on roses, according to Good Earth Organic Rose Care. This formula is based on research conducted by Dr. Kenneth Horst at Cornell University.

Application

For effective treatment, gardeners should spray the roses at least once a week. Soak the leaves, including the undersides thoroughly, first thing in the morning so they dry completely before nightfall.

Preventative Treatment

Powdery mildew thrives in dry, warm climates and attacks new lush growth. Frequently dousing rose leaves and stems with water increases humidity, thwarting powdery mildew. Gardeners should wash roses in the morning so leaves can dry during the day. Sometimes over-fertilizing can promote powdery mildew growth. Good Earth Organic Rose Care advises waiting until after new growth emerges to fertilize, if powdery mildew is a problem.

References

• Good Earth Rose Care: Mildew and Blackspot Control Options
• Good Earth Rose Care: Mildew in Your Garden?

Resources

• American Rose Society: Grow Beautiful Roses