Causes leaves to turn yellow and fall off. The black spots have diffuse edges.

Look for black spots forming on the leaves and stems in the spring.

Spots may be unevenly distributed. They may follow the veins of the leaf.

Black spot defoliates rose bushes. This bush has few leaves to create energy the bush needs to live now and in winter.

Look for white spots forming on young leaves, buds, & stems in the spring.

Leaves and shoots are twisted or distorted. New growth is often impacted.

Look for irregular, purplish spots that may stop at leaf veins. Leaves may turn yellow.

Purplish blotches caused by rose downy mildew on rose cane.

Pale, felty spore masses form on the underside of leaves. They don’t form on the upper side of leaves.

Look for orange spots (pustules) on the lower leaf surface.

Orange pustules form on buds and stems.

Black fungal structures develop on the undersides of rust infected leaves during the winter. These structures make spores that spread rust the following spring.

On rose petals, gray mold may appear as small, light-colored spots surrounded by reddish halos.

Young, green canes may develop large, sunken, dead areas.

A fuzzy, gray-brown growth develops on decaying tissues.

Severe aphid infestations damage rose flowers.

Rose aphids range in color from green to deep pink or red-brown.

Aphids congregate on the underside of leaves.

Severe aphid infestations cause distortion of leaves.

Scab first appears as tiny yellow, or chlorotic, spots on leaves. They enlarge and turn dark olive-green, then black. Leaves may become distorted, puckered, and mottled. Severely affected leaves often turn yellow and drop early. This defoliates and weakens the tree.

Scab spots on fruits begin as small, raised, brown or black circular areas. As fruit develops, scab spots enlarge. The central areas become brown and corky. Deep cracks may develop. Severely infected fruit becomes misshapen and usually drops from the tree.

Late-season infections may not show on fruit until they are in storage. There they develop small black "pinpoint" scab spots. This may be tolerated in backyard trees. Peeling the fruit will remove the pinpoint-sized scab lesions.

The infection may over-winter in a bud. Young leaves may show symptoms as soon as they begin to grow. They may show gray-white powdery growth, often on the underside. Leaves become curled and distorted.

Flowers infected with powdery mildew develop white powdery coating. They are deformed, then turn brownish and shrivel up.

Infected apples show a net-like pattern of lines, known as russeting (left). The fruit on the right shows the normal, healthy appearance for this variety. Russeting may also be caused by cool wet weather, frost, pesticides and viruses.

The white fungus leaves a russeted patch by summer. The russeted area expands as the fruits enlarge.

Shoots may wilt, forming a “shepherd’s crook” shape.

Infected tissues quickly turn brown to black and die. They stay on the tree and appear scorched.

Infected fruits show sunken black spots up to 1" in diameter and 1/4" deep. There may be bacterial ooze exuding from the diseased areas.

Azalea lace bugs suck sap, which damages leaf tissue. This causes white or yellow stippling damage on the upper leaf surface.

Nymphs and fecal spots are visible on the underside of a rhododendron leaf.

Severe damage turns rhododendron leaves yellow.

Severe damage turns azalea leaves white.

Azalea lace bug nymphs and adults feed on leaves.