Rose black spot is a fungal disease that causes black spots on rose bush leaves and stems. It makes leaves turn yellow and fall off the rose bush. Severely infected plants often look bare with few leaves and flowers.

Powdery mildew is a fungus that causes white powdery growth on rose bush leaves and flower buds.
Infected leaves may die and drop from the plant earlier than healthy leaves.
Powdery mildew causes distorted leaf growth.
It develops during warm (not hot), dry weather. Look for it in summer in the western parts of the Pacific Northwest, and during cool, wet springs east of the mountains.

Downy mildew is a fungus that causes purplish to dark-brown, irregular spots on leaves, stems & flowers.
Infected leaves turn yellow and drop from the plant earlier than healthy leaves.
It may cause dieback of canes.
Downy mildew develops in warm and humid conditions. In the Pacific Northwest, look for it in the spring, summer & fall when rose leaves are wet.

Rose rust fungus causes orange, bumpy growth on rose bush leaves, flower buds, and stems.
Rose rust stresses the infected plant. It weakens and distorts plant growth.
Rust develops in warm and humid conditions. Look for it in late spring and early summer in the Pacific Northwest.

Rose gray mold (Botrytis) is a fungus that infects rose flowers and stems. Flowers may develop spots. Infected buds may fail to open. Canes may develop large, sunken, dead cankers. Dead or decaying tissue develops a fuzzy, gray-brown growth. A severe infection causes many dead, disfigured flowers and stems.

Gray mold infection is worst during cool, wet weather. Watch for it during the late fall through early spring rainy season.

Rose aphid feeding causes distortion of leaves, flowers, and shoots. Aphids rarely kill plants. They produce honeydew: a sweet, sticky substance that promotes sooty mold growth.

Azalea lace bugs suck sap, which damages leaf tissue of azalea and rhododendron plants. This causes white or yellow stippling damage on the upper leaf surface. Nymphs and fecal spots are visible on the underside of leaves.

Slugs and snails are mollusks. Non-native slugs and snails damage plants in gardens and landscapes in the Pacific Northwest. Native slugs (such as banana slug) and snails are not considered garden pests and may be left alone.