Black spot on roses. Photo by: Brian Kunkel, Ornamentals IPM specialist, University of Delaware.

Powdery Mildew on common lilac. Photo by: Whitney Cranshaw, Colorado State University, Bugwood.org.

Fire blight on pear. Photo by: Nancy Gregory, Plant Diagnostician, University of Delaware.

Elm pouch gall (caused by aphids).

Elm pouch gall (caused by aphids). Photos of elm pouch galls by: Brian Kunkel, Ornamentals IPM Specialist, University of Delaware.

Rose slug sawfly feeding damage. Photo by: Tracy Wooten, Sussex County Extension Agent – Horticulture, University of Delaware.

Rose slug sawfly. Photo by: John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org.