“In the last seven to ten days there have been several reports of impatiens downy mildew’s appearance in the Midwest; as of this time we have two reports from Ohio,” according to an article on the Ohio State University Extension website written by Francesca Peduto Hand and Nancy Taylor. “The pathogen that causes the disease, Plasmopara obducens, is extremely aggressive on bedding plant impatiens and Ohio’s impatiens producers should be aware of and scouting for this disease.”
The article cites the early symptoms of impatiens downy mildew as a slight curling or mottling of the foliage, which may be subtle. High humidity, however, can result in a heavy coating of white sporulation on the underside of the leaves.
“One grower described white dust floating above the plants when they were disturbed,” the article states.
Researchers at Ohio State are interested in collecting diseased plant samples and will perform tests at no charge. Growers are asked to send samples to:
C. Wayne Ellett Plant & Pest Diagnostic Clinic
Ohio State University
8995 E. Main St., Bldg. 23
Reynoldsburg, OH 43068
Phone: (614) 292-5006
Pictures of diseased plants and information regarding location and the extent of the problem can also be eMailed to to firstname.lastname@example.org.
For more information on symptoms and treatment, visit Greenhouse Grower’s Downy Mildew On Impatiens: Resources And Advice page.