It attacks primarily the lower leaves, producing dark brown, circular spots up to one-fourth inch in diameter, the centers of which are light gray, almost white. Infected leaves dry up and die prematurely. For control, spray periodically with recommended fungicides and burn infected leaves. White or grayish moldy growth on upper side of older leaves.
Leaves gradually die, beginning on the lower part of the plant.
For control, spray with recommended fungicides as soon as the mildew appears. Neither rust is important enough to warrant control. Both rusts appear on leaves as raised blisters or pustules covered with a brown coating that ruptures releasing the brown spores. They cause a rotting of the plant at the soil line. Sterilizing potting soil is the best control.