US: Mildew affecting variety of impatiens plants

While it is too early to transplant most annuals outside, greenhouse operators are offering alternatives to garden impatiens walleriana, which are dying from a worldwide epidemic of Impatiens Downy Mold.

The popular shade-loving annual flower variety was infected with the fungus-like pathogen last year and it is still prevalent this year. Only the garden impatiens walleriana plants are affected by the fungus, according to the Michigan State University Department of Horticulture.

The downy mildew can overwinter in the soil, so landscapers and gardeners are advised not to replant in the same area, or to pick other varieties that are resistant, such as the New Guinea Impatiens, which have larger flowers and leaves, or the Japanese hybrid SunPatiens. Other flower species which grow well in the shade include Begonias, Caladiums, Lobelia and Salvia.

The fungus causes leaf yellowing, followed by the leaf curling and falling off. It is characterized by a white fuzzy coating on the underside of leaves. It is not the same downy mildew that affects vegetables or other ornamental plants, according to the Michigan State University Department of Horticulture.

For more information, visit flor.hrt.msu.edu/IDM/index.htm.