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April 2013
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Downy mildew on bedding impatiens

Downy mildew on impatiens leaf. Photo courtesy Purdue University Plant & Pest Diagnostic Laboratory.

Gardeners and growers throughout the country are battling a fungus called impatiens downy mildew, which turns the underside of the plant’s leaves white or gray.

If you noticed this last year, do not plant bedding impatiens (I. walleriana) in the same place this year. This disease only affects bedding impatiens. New Guinea and SunPatiens are not bothered by the disease.

Besides a white mildew on the undersides of leaves, other symptoms include collapsed centers on the impatiens or all of the flowers will be on the tips of the plants. Avoid planting impatiens where there was disease for at least five years. Don’t compost any diseased impatiens.

Trade off with begonia, torenia, coleus or another annuals that tolerates the same low-light condition that impatiens loves. Many tropicals, including some gingers, also make good shade plants.

Early symptoms of downy mildew on bedding impatiens. Photo courtesy Purdue Plant & Pest Diagnostic Lab

 

Severe symptoms of downy mildew on bedding impatiens. Photo courtesy Purdue Plant & Pest Diagnostic Lab