Erwinia carotovora causes bacterial rot at the base of the flowers and in the rhizomes. The bacteria that cause rot are normal soil inhabitants. Disease development is favored by high temp- eratures, poor air circulation, poor soil drainage and improper fertilization. Discard all infected plant material. Flower thrips and various other thrips species are serious pests of daylilies.
Thrips are slender, dark-colored insects, with fringed wings.
To see these fast-moving pests, you need a magnifying lens. Thrips are typically found on leaves and between flower petals. When they feed on flower buds, the flower may die without opening. With a light infestation, their feeding causes leaves to have silvery speckles or streaks. With severe infestations, leaves and flowers are stunted and distorted and may turn brown and die.