New Plant Disease Attacks Annual Impatiens ...Production manager, horticulturist and plant pathologist Kurt Bartel of David J. Frank has identified our first case of the much publicized plant disease called Downy Mildew on some bedding impatiens (Impatiens walleriana) at a location near a job site. Impatiens are the nation's most popular annual bedding plant so there is a lot of concern about this new (to impatiens) disease that has caused problems in the United States, Europe and South Africa. Our crews have been alerted so they can take necessary steps to control its spread when possible, but here's what you can look for too:
Symptoms of the disease include leaves are chlorotic or stippled and become completely yellow over time. There may be subtle gray markings on the upper leaf surfaces and white, downy growth (fruiting bodies) on the underside of the leaves. Plants affected by Downy Mildew will not produce an acceptable floral display. As the disease progresses, leaf drop occurs and stems become bare. The stems may then become soft and the plants simply collapse.
If the disease is found, remove the plants and the leaf debris and dispose of the material offsite. Debris should be put in plastic garbage bags and disposed of in a dumpster, NOT a compost pile! Impatiens walleriana should not be planted back into the same location for at least one year. Spores overwinter in the soil – making sanitation and crop rotation very important. Chemical treatments cannot be relied upon for control for a variety of reasons, but we can help you with control and other options for beautiful displays for upcoming seasons.