4 tips to keep your roses free of diseases and pests (Oregonian)

4 tips to keep your roses free of diseases and pests (Oregonian)
When it comes to one of the county’s most popular perennial plants, the “big four” vexations are powdery mildew, black spot, rust and aphids, according to Jay W. Pscheidt, a plant pathology specialist with Oregon State University’s Extension Service.