Impatiens (Impatiens walleriana), or busy Lizzies, are annual flowering plants that produce clusters of colourful blossoms. If the pointed green leaves on impatiens start to turn yellow, there may be a problem.
Impatiens Downy Mildew
Impatiens downy mildew is a fungal disease that causes speedy foliage yellowing and loss. There is no fungicide that kills downy mildew. Infected plants must be destroyed to prevent the spread of infected spores to healthy plants.
Impatiens Necrotic Spot Virus
Impatiens necrotic spot virus, or INSV, is a virus that eventually kills impatiens after infection. INSV is carried from plant to plant by pest western flower thrips. Symptoms include yellowing leaves, dark ringspots, wilting and death. While insecticides can be used to control thrip infestations, no chemical treatment exists for plants infected with INSV.
Verticillium wilt is a fungal disease that causes impatiens leaves to yellow. The disease attacks from the roots and causes serious damage. One way to avoid verticillium wilt is to plant impatiens in pasteurised soil.