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Problem
(factsheet)
Plant NameTypeDescription 
Bacterial cankerApricotDiseaseBacterial canker is favored by cool, wet weather and is common in western Washington. The bacteria overwinter in cankers, buds and other host tissues. Dark, cankered areas on trunks and branches may develop and expand in early spring. The infected tissues may produce gum, although gumming can also be caused by other factors. The cankers often girdle twigs and branches, causing dieback above the lesion. Leaves on girdled twigs often yellow and fall by late summer. Infected buds may be killed or leaf infections may occur as the new growth emerges resulting in collapse of leaves. Infection can be spread by wind, rain, insects, pruning tools, or by planting or grafting with infected stock. The disease may spread throughout the entire tree (systemic infection) with or without visible symptoms.
Brown rotApricotDiseaseBrown rot is a blossom-infecting fungal disease. Infected flowers wilt and die. The brown blossoms remain attached to the twigs, becoming covered with a grayish-brown fungal growth during wet weather. Blossom or fruit infections may spread to twigs. Infected twigs develop sunken, elongate cankers with gumming at the margins. Leaves on girdled shoots turn brown and remain attached. Infected fruit initially show a small brown spot which rapidly enlarges. The fruit remains fairly firm and often becomes covered with gray-brown fungus. Fruit may dry and harden into mummies, which serve as a source of infection in the spring.
Cytospora cankerApricotDiseaseThe fungi which cause Cytospora canker attack through wounds on twigs and branches. Initial cankers are small, but enlarge quickly and may streak up and down the stems without girdling. The cankers may also girdle twigs, resulting in dieback above the infection site and causing "flags" of dead material to appear in the canopy. The leaves on the dead twigs turn color and droop, but often remain attached. The canker itself appears as a dark, sunken area of dead bark and wood. Later, callus forms at the margin of the canker. Amber gumming is often present. Pinhead-sized black fruiting structures of the fungi often erupt through the bark and produce orange tendrils or droplets of spores in wet weather. Spores are easily spread by wind, rain, and insects. The cankers may enlarge over several seasons.
Shothole (Coryneum blight)ApricotDiseaseShothole is a fungal disease which attacks leaves, buds, blossoms, fruits, and twigs. Twig cankers are rare on apricot. On apricot, the fungus often infects and kills buds, which may be covered with a shiny, gummy material. Lesions on leaves and fruit are initially small purplish areas which expand into brown spots with light centers. The lesions are seldom larger than 1/4" in diameter. The infected spots on leaves often die and drop out in warm weather, giving leaves a "shothole" appearance. The fungus probably overwinters on the bark and in infected buds. Spores are easily spread by water.
Silver leafApricotDiseaseSilver leaf is a fungal disease affecting cherry, apricot, plum, and other stone fruits. The fungus typically grows on dead wood, but it can infect living tissues through wounds and become systemic (established throughout the plant). The leaves of affected branches turn silvery to ashy in color and the margins may curl slightly upwards. The branch may either die quickly or show symptoms for several seasons before dying. Affected branches have a dark staining in the heartwood. The fungus can produce fruiting bodies only on dead wood. The shelf-like fruiting bodies push through the bark and are light brown to purple on the upper surface and pinkish to purple beneath. Trees are least susceptible to infection summer through fall in dry weather.
Brown marmorated stink bugApricotInsectThe brown marmorated stink bug (BMSB) is an introduced pest species from Asia that is spreading quickly across the United States. Nymphs and adults feed on a wide variety of plant hosts. BMSB prefers to feed on fruit, seeds, and seed pods, but will also feed on stems and leaves of some hosts. Both adults and nymphs have piercing-sucking mouthparts and inject digestive enzymes into plant tissues to aid in feeding. Sunken areas and deformities (catfacing) on the surface of the fruit are typical symptoms. Damaged areas are discolored beneath the fruit’s skin and become hard and pithy or corky in texture. Stone fruits such as cherry, peach, plum, and apricot may show gumming at the injury site and from the corky areas beneath the surface. Other known tree fruit/nut hosts of BMSB include apple, pear, filbert, and other stone fruits including cherry, peach, and plum. One or two generations of BMSB per year are expected in the Pacific Northwest. Adults overwinter in sheltered locations (including houses, where they can become a significant nuisance pest). In the spring, light green to white eggs are laid in groups of about 20 to 30 on the underside of leaves. Young stink bugs, or nymphs, are black with a red-and-black striped abdomen. Nymphs often feed in groups when young. Older nymphs are dark with white bands on body, legs, and antennae. They may feed in groups or singly. Adults are a little over 1/2 inch long, with a shield-shaped body. Body color on adults is mottled gray and brown, while the legs and antennae have alternating dark and light bands. The abdomen also has dark and light bands which are visible at the edge of the wings. NOTE: BMSB adults closely resemble other stink bugs found in WA and OR. For more information on BMSB identification, see FS079E, Pest Watch: Brown Marmorated Stink Bug, available at https://pubs.wsu.edu/.
Peach twig borerApricotInsectThe peach twig borer is an important pest of apricots, particularly in eastern Washington. In the spring, overwintering larvae bore down the center of shoots, causing the tip to wilt or "flag". Each caterpillar can damage several shoots. Later generations of larvae feed on both shoots and fruit. They often burrow into the stem end of young fruit. Pits of infested fruit are often split. They may also feed on the fruit surface. The caterpillars are reddish-brown with black heads and yellowish rings on the body. Mature caterpillars are up to 1/2" long. The adult moth is dark gray and about 1/3" long. Peach, nectarine, plum, and prune may also be attacked.
Peachtree borerApricotInsectThe peachtree borer adult is a dark, bluish, clear-winged moth which somewhat resembles a wasp or hornet. The female, which has dark forewings and a red-orange band on the abdomen, lays eggs on the tree. Emerging larvae move to ground level or just below ground, where they burrow beneath the bark on the trunk and feed in the crown region. Signs of larval feeding include the presence near ground level of jelly-like gum mixed with dirt and pellets of excrement. Heavy infestations can weaken older trees, and foliage may be yellowed as if nitrogen-deficient. Young trees may be girdled and killed.