Impatiens downy mildew has been found in Michigan, according to a brief from Michigan State University Extension.
“In the last two weeks, downy mildew on impatiens has been confirmed in Michigan greenhouses spanning four counties,” the report states. “In each case, the disease was widespread within the greenhouse and the losses were nearly 100 percent.”
The report recommends some newer fungicides, such as Adorn, Segway, Micora, Orvego and FenStop, for downy mildew control.
“It has been our experience through fungicide trials that the most effective fungicides must be used in an intensive application program to protect impatiens from this pathogen when the environmental conditions are favorable for disease development,” the report says.