Controlling downy mildew on impatiens in greenhouses in 2015

Recommendations for the control of downy mildew on impatiens were modified for 2015 based on recent Michigan State University research results.

Downy mildew on impatiens leaf. Photo credit: Mary Hausbeck, MSU

Downy mildew on impatiens leaf. Photo credit: Mary Hausbeck, MSU

Downy mildew is still a major concern for greenhouse growers who produce bedding impatiens for either the retail or wholesale marketplace. Outbreaks of the downy mildew disease on impatiens in greenhouses can quickly escalate into epidemics if not controlled according to Mary Hausbeck from Michigan State University’s Department of Plant, Soil and Microbial Sciences.

However, recent MSU research studies conducted in 2013 and 2014 by Hausbeck’s lab showed clearly that if impatiens are treated in the greenhouse with the fungicides listed in her recommendations, the risk for a downy mildew outbreak in the landscape are reduced. Recent data has also shown that impatiens can be successfully grown in landscape beds even when the planting bed has a history of impatiens infected with downy mildew. The critical factor to success is that impatiens plants must be treated with the most effective products just prior to shipping and sale. This last application prior to planting will ensure protection for an extended period once the plants are transplanted into the landscape.

View the 2015 greenhouse impatiens downy mildew recommendations.

Please contact your local Michigan State University Extension floriculture educator for more information on this subject.

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