Rid Your Roses of Black Spot / PBS-TV’s Garden Rx starring Loren Nancarrow reveals the secrets to treat black spot on rose leaves.
Signs – black spots on the leaves and sometimes yellowish edges.
It’s a fungus that only attacks roses. It lives on the canes and on fallen dead leaves in the winter and then spreads to the leaves when the weather is moist or wet. Problem in areas where the summers are warm and humid.
Buy resistant varieties
Rake up dead leaves, good sanitation.
Be aggressive as soon as you see it. Apply a baking soda spray (2 tablespoons baking soda, 1 gallon of water and optional sticker/spreader of 1 teaspoon liquid car wax or vegetable oil.)
Prune for good air circulation.
Water roses in the early morning.
Never work on wet roses.
Clean tools after working with roses with alcohol or bleach.