Leaves eventually turn yellow and fall from the plant. Spot anthracnose, a fungus disease. The fungus spreads in water. When symptoms appear, begin spraying with a fungicide once every seven days until all signs of the disease are eliminated. Do not water plants from above, since the fungus spreads in splashing water.
Rosebuds fail to open and are covered with a grayish brown, fuzzy mold.
Open flowers are flecked with yellow or brown and lower petals are wilted and brown. The stems below infected flowers become discolored. Botrytis blight, also called gray mold, a fungus disease that spreads in moist air and cool temperatures. There are no chemical cures for blight once it occurs. If symptoms appear, cut off and destroy all infected plant parts.