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Plant NameTypeDescription 
Armillaria root rotOrnamental CherryDiseaseArmillaria root rot is a fungal disease transmitted between plants by root contact. Armillaria is often found in newly cleared soils or ones which have been flooded. Symptoms typically include sudden or gradual slowing of growth, yellowish or undersized leaves, leaf drop, dieback of branches, or gumming (sticky, oozing sap). White thread-like masses of the fungus may be found beneath the bark near the crown of infected trees, and/or as shoestring-like rhizomorphs, which are dark strands of the fungus growing on or just beneath the soil surface. Honey-colored mushrooms often grow near the base of infected trees in the fall. Infected trees may also exhibit a dark black line in the infected area encircling the base of the plant. Young, stressed trees are most susceptible to infection. Armillaria-infected trees have damaged root systems and are more likely to fall in high winds. It may also make trees more susceptible to insect attack.
Bacterial cankerOrnamental CherryDiseaseBacterial canker can be found on any part of the tree. The disease causes cankers and dieback of twigs and branches. A typical branch canker is elongate and enlarges during the dormant season from around the base of an infected twig. It may leak sap (gumming) at the edges of the canker and may show brown or black streaking in the wood when cuts are made at the top or bottom of the canker. Cankers can girdle limbs or trunks. Bacterial canker can kill buds in winter and blossoms in the spring, and can also cause dead spots on leaves. In combination with frost the disease can cause serious damage to trees.
Brown rotOrnamental CherryDiseaseBrown rot is a fungal disease which initially infects the flowers. The petals turn light brown, develop water-soaked spots and may have tan or grayish areas of fungal spores. Infected flowers often remain attached to the plant, spreading the disease to small twigs and branches. Infected twigs and branches are often observed in the summer as flagged, dead leaves and twigs. Infected branches develop cankers which may produce gumming (leaking sap) or may girdle and kill the branch. Most brown rot cankers develop with a dead twig at the center where the initial branch infection occurred. Fruit can also be infected, dry out, and hang in the tree. Tan or gray fungal spores may be found on infected blossoms, fruit, or twig cankers. Ornamental and fruiting stone fruit trees are affected.
Coryneum blight (Shothole)Ornamental CherryDiseaseShothole is a fungal disease typically attacking the leaves of ornamental (flowering) cherries. Lesions are initially dark brown, reddish, or purplish spots and may be surrounded by a light green to yellowish halo. They are oval to round and expand into brown spots with light centers. The lesions are typically up to 1/4" in diameter. The centers of infected spots often die and drop out in warm weather, giving leaves the characteristic "shothole" appearance of the disease. Occasionally, twig cankers may be observed. The fungus probably overwinters on the bark and in infected buds. Spores are primarily spread by water. Coryneum can also attack stone fruits including peach, apricot, and fruiting cherries.
Leaf spotOrnamental CherryDiseaseLeaf spot on cherry first appears as small circular, purple spots on the leaves about the time they reach full size. Infections begin in the spring and continue through late summer. The spots turn brown, and enlarge. The centers may drop out, giving a "shothole" appearance to the affected leaves, or the leaves may turn yellow and drop, sometimes resulting in severe defoliation. This fungal disease overwinters on fallen leaf debris and attacks new leaves in the spring. Mild, wet summer weather promotes infection, which can only occur on wet foliage.
Virus diseasesOrnamental CherryDiseaseMottle leaf is one virus disease of cherries. Symptoms are seen mainly on the leaves, which are puckered and mottled with light green to yellow blotches between the veins. The mottling is less noticeable later in the growing season. Leaves may be smaller than normal and some shothole symptoms may occur. Shoots are rather stunted. The cherry mottle leaf virus can be transmitted by budding or grafting, and occasionally by eriophyid mites. Bitter cherry (Prunus emarginata) is a common host of both virus and mites in the wild. Necrotic rusty mottle is also a disease believed to be caused by a virus. Affected trees are slower to leaf out and bloom in the spring. Terminal buds may be killed and the leaf and flower buds open irregularly. About a month after bloom, leaves begin to show angular purplish to brown spots. The spots may dry and drop out, giving leaves a tattered appearance. They can also coalesce and affect most of the leaf. Severely affected leaves develop a yellowish mottling along the veins and often drop. Defoliation can be severe. In the fall, remaining leaves turn mottled yellow and green, dropping prematurely. Decayed areas with gumming may be present on the bark. Twigs, larger branches, and whole trees may die. The necrotic rusty mottle virus is probably spread primarily by grafting with infected wood.
AphidsOrnamental CherryInsectSeveral aphids attack flowering cherries, including the black cherry aphid. Black cherry aphids are small black insects which typically feed on the new growth, causing the expanding leaves to curl and distort and tip growth to be reduced. These and other aphids produce large amounts of honeydew, a sweet, sticky material excreted by the insects during feeding. The honeydew may attract ants or become covered with a dark growth of sooty mold.
Apple-and-thorn skeletonizerOrnamental CherryInsectThe apple-and-thorn skeletonizer is a yellow-green caterpillar with small black spots. As a young caterpillar it feeds on the underside of leaves. More mature caterpillars move to the upper surface of the leaf, use silk to tie the edges of the leaf together near the base, and feed inside the tent-like structure. Leaves are skeletonized, with all tissues eaten away except veins and the lower leaf surface. Skeletonized leaves turn brown and drop. The feeding caterpillars produce large quantities of webbing and frass (excrement). The adult apple-and-thorn skeletonizer is a small dark-brown moth. Apple, birch, hawthorn, mountain ash, and willow may also be attacked.
Cherry bark tortrixOrnamental CherryInsectThe cherry bark tortrix (CBT) is a pest of most woody ornamental trees and shrubs in the family Rosaceae. CBT attacks Prunus (cherry, plum and peach), Malus (apple, crabapple), Pyrus (pear), Crataegus (hawthorn), Sorbus (mountain ash), Cydonia (quince), Pyracantha (firethorn) and Photinia. CBT has one generation per year and a prolonged flight period from April until September. All life stages occur within the host tree except for the eggs and adults. Eggs are laid singly on the bark surface. Hatching larvae penetrate the bark through openings (natural and mechanical wounds) and feed on the living tissue of the tree's bark. Graft unions of ornamental trees are preferred sites for attack. Larvae do not penetrate the hard wood of the tree. During feeding, CBT larvae construct a frass tube consisting of fecal pellets and webbing. The frass tube is the location for pupation once CBT has completed the larval stage. Frass tubes are an excellent indication of CBT infestations and susceptible trees should be regularly monitored for frass tubes.
Pear slugOrnamental CherryInsectPear slugs, or pear sawflies, are insect larvae which resemble a small greenish or black slug. They are typically 1/4" to 1/2" long, tadpole-shaped, and produce large amounts of slime. The adult sawfly is a small, dark, wasp-like insect which is usually about 1/4" long. The larvae feed on the leaves of cherry, plum, and pear trees. Leaves are typically skeletonized (the upper layers of the leaf are eaten away, leaving only the veins and the lower leaf surface). Heavily damaged leaves often drop from the tree. The pear slug has two generations per season and can be found from mid- to late spring and again in late summer.
Redhumped caterpillarOrnamental CherryInsectThe redhumped caterpillar is the larvae of a 1" gray-brown moth. The mature larvae are yellow with a red head and hump, and have orange, black, and white lengthwise stripes. The body of the caterpillar also has dark "spikes" on it. Young redhumped caterpillars are found in clustered colonies which disperse as caterpillars mature. They eat entire leaves (except the major veins) and can cause considerable defoliation.
ScalesOrnamental CherryInsectVarious species of scales can attack flowering cherry trees, among them the San Jose scale, a serious pest of fruit trees. Depending on species, scales may be found on the upper or lower surfaces of leaves, or on twigs and branches. Symptoms of scale infestations may include yellowing and/or wilting of leaves on affected plant parts as well as the presence of honeydew, a sweet, sticky material produced by some species of scales. Honeydew, if present, may become covered with a dark growth of sooty mold. Scale insects are generally yellowish to dark brown or gray in color and rounded or oval in shape. They are generally 1/8" long or less.
Shothole borerOrnamental CherryInsectShothole borer larvae feed between the bark and the wood on the limbs and trunks of cherry trees. The white larvae (bark beetles) are about 1/8" long and feed in galleries made beneath the bark parallel to the grain of the wood. The adults emerge from the trees, leaving numerous small holes about the diameter of a pencil lead in the bark. Adult beetles are black with cinnamon-colored antennae and legs. They are about 1/8" long or less. Shothole borers may bore into the buds of healthy trees, but are primarily attracted to unhealthy trees. Sunscald damage to trunks during winter serves as a common entry point for these beetles.
Spider mitesOrnamental CherryInsectSpider mites are tiny, eight-legged, and yellowish to brown in color. Their feeding causes mild to severe stippling (little specks or dots) on leaves. Usually yellowish or bronzish, stippling can, in severe cases, cause leaves to drop. Fine webbing is often present, especially on the underside of leaves. Mites may be found on either leaf surface and can be more damaging during dry, dusty conditions. Spider mites overwinter as fertilized females in litter and duff, usually away from the tree.
Tent caterpillarsOrnamental CherryInsectTwo species of tent caterpillar are common in Washington. The forest tent caterpillar is about 2" long at maturity and has a bluish body with black and white markings. This species makes silk mats on branches and trunks. The western tent caterpillar is the most common species in western Washington. It is dark with orange and black markings. Characteristic tents are made on the tips of branches. Young caterpillars typically feed in large groups in the protection of the nests. Older caterpillars feed in small groups or as individuals. Tent caterpillars are present in spring and early summer. They can partially or completely defoliate trees, causing some loss of vigor. Badly weakened trees may be killed, but damage is rarely this severe.