Answer: I've not heard of using vinegar on roses, but I have heard of using baking soda mixed with water. The recipe is 2Tbps. baking soda to one gallon of water. The baking soda mixture changes the pH of the water on the surface of the leaf and keeps the black spot from attacking. Try to keep your plants well pruned to increase good air circulation, pick off the affected leaves as soon as you notice the black spots, make sure your rose bushes get full sunshine, try not to splash water on the leaves, and youmay be able to avoid black spot in the first place.
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