These diseases occur mainly under cool, moist weather conditions and in soggy soils. Remove and discard infected plant material. Bacterial rot, or soft rot, may begin as a slow yellowing of the leaves often beginning at the leaf tips. Leaves may wilt, collapse and die. Bulbs and the base of the leaves decay and often have a foul-smelling odor.
Soft rot is most serious in wet, heavy soils.
Provide adequate drainage, and remove infected plants. Viruses can infect plants, causing leaves or flowers to be mottled or discolored and growth to be distorted. Control aphids and other sucking insects, which can spread viruses. Dig up and destroy infected plants.