Q: I have some old rose bushes. They start out great each spring, but most summers, black spots develop on all my plants. By mid to late summer, most of the leaves are off the rose bushes, and they really look sad. I don’t want to start over with new varieties as these smell nice when I bring them indoors.
A: Black spot is a fungus that causes black spots up to 3/4-inch in diameter on rose leaves and sometimes on the stems. The infected leaves then turn yellow around the spots and fall from the plant. If the plant is not resistant, black spot can cause all the leaves to fall off. The environmental conditions that promote black spot are wet leaves and warm temperatures. Plants that lose their leaves produce less food and have a harder time surviving the winter.
