Ornamental insects, Pests & Diseases
Powdery mildew occurs on many herbaceous and woody ornamentals in Tennessee. Mildew diseases may appear in greenhouses, nurseries or landscape settings. Woody ornamentals like Chinese photinia (Photinia serrulata), flowering dogwood (Cornus florida) crepe myrtle (Lagerstroemia indica), common lilac (Syringa vulgaris), Persian lilac (Syringa X persica), euonymus (Euonymus spp.), rose (Rosa spp.) and many crab apple cultivars are highly susceptible and may be seriously damaged by powdery mildew infections. Herbaceous ornamentals that are frequently infected with powdery mildew include pot plants such as African violet (Saintpaulia ionantha), begonia (Begonia sp.), chrysanthemum and kalanchoe (Kalanchoe blossfeldiana). Bedding plants that are infected by mildew include zinnia (Zinnia elegans) and snapdragon (Antirrhinum majus).
"SP370-B-Powdery Mildew of Ornamentals," The University of Tennessee Agricultural Extension Service, SP370B-2M-3/98(Rev) E12-2015-00-056-98, http://trace.tennessee.edu/utk_agexdise/37