Impatiens Downy Mildew
Gardeners in the US may not be able to purchase the common garden impatiens (impatiens walleriana) for their shade gardens this year. That is because a destructive fungus has attacked them in nurseries and landscapes in 33 states. The fungus is commonly called downymildew which is different from other kinds of plant mildews. Downy mildew causes complete defoliation or plant collapse, especially in landscape plantings under moist conditions and cool nights. (see here)