Diseased plants usually wilt, turn brown, become stunted, and produce poor flowers. If the plants do not wilt, areas between veins of the leaves turn yellow. Stunting Chrysanthemums stunt, aster yellows, and leaf nematode infection prevent normal growth. They cannot be controlled. Pull up severely stunted plants and burn them immediately.
Chrysanthemum stunt is caused by a virus.
Leaves fade to light green or turn a reddish color. The virus may be carried to un-infected plants on a knife used to take cuttings or on your hands when you pinch plants. Prevent spread by thoroughly washing your hands and the cutting knife after touching any stunted plant. Aster yellow is caused by a virus that is carried to chrysanthemums by leafhoppers. Diseases plants develop distorted flowers and many small, weak shoots.