Why Are My Impatiens' Leaves Turning Yellow?

Downy mildew begins with wilted flowers, pale leaves and a white, purple or beige film on the underside of the leaf. As the disease progresses, the leaves turn yellow and fall off. Leaf spot disease first appears as brown spots on the leaves. Left untreated, more spots appear, and the leaves turn yellow and shed. Wilted plants that have partially decayed root systems along with yellow leaves are most likely infested with nematodes, which are unsegmented roundworms that feed on impatiens.