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Problem
(factsheet)
Plant NameTypeDescription 
Botrytis blightBlueberryDiseaseBotrytis is a fungus that survives on dead twigs of bushes and prunings. It also overwinters on dead organic matter or on the soil surface. During wet periods of the spring, the organism produces vast numbers of spores, which spread by wind and splashing water. Blossoms take on a brown, water-soaked appearance and die, later exhibiting dense grayish powdery masses of Botrytis spores. Infections can move through the blossoms rapidly and often destroy the whole floral structure. Also, the disease can move from blossoms back into fruit-producing wood. Young leaves may show pale brown lesions. Fruit may shrivel and be covered with the typical gray sporulating structures after harvest. Cultivars that tend to retain floral structures for longer periods are more susceptible.
MummyberryBlueberryDiseaseMummyberry is a fungal disease affecting blueberry flowers, leaves, twigs, and fruit. In the spring, flower and shoot buds are infected. The affected tissues turn brown and withered. A grayish to brown growth of fungal spores may appear on the infected tissues. These spores are easily spread to the blossoms by wind, rain, and pollinating insects, causing infection of the fruit. Diseased fruit appear normal until nearly full-sized, although infected green berries may show a white fungal growth around the seeds when sliced open. Infected berries may be somewhat pumpkin-shaped and turn white, tan, or pinkish as they approach maturity. They often drop from the plant before healthy fruit matures. The fallen berries harden and "mummify". The fungus overwinters in the fallen mummies.
VirusesBlueberryDiseaseThree major viruses continue to significantly impact blueberry plantings in the Pacific Northwest: Blueberry scorch virus, Blueberry shock virus, and Tomato ringspot virus. Blueberry scorch virus is spread by an aphid vector, and causes vegetative shoot tip dieback in the spring. Flowers blight just as the earliest ones begin to open. The entire bush may be blighted, but usually only a portion of the branches will show dieback. Scorch virus symptoms may resemble those of mummyberry or bacterial canker, and infected plants repeat this symptom cycle each spring. 'Atlantic', 'Berkeley', 'Collins', 'Herbert', and 'Pemberton' are particularly susceptible; several other cultivars are symptomless and considered tolerant. Blueberry shock virus symptoms resemble those of scorch virus, but may not reappear in spring growth in years following the initial infection. Shock virus is spread by pollen moved by wind or bees. 'Berkeley', 'Bluegold', and 'Bluetta' are highly susceptible, while a few cultivars are symptomless and considered tolerant. Tomato ringspot virus causes distortion, circular chlorotic lesions on leaves, and necrotic stem lesions. Shoot dieback, stunting, and plant death may eventually occur, while fruit yield and quality are severely depressed. The virus is spread in the soil by the dagger nematode. 'Atlantic', 'Dixie', 'Earliblue', 'Olympia', and 'Pemberton' cultivars are the most susceptible to tomato ringspot infection; 'Bluecrop' appears to be resistant. Other viruses that may affect blueberry plantings in the Northwest include Blueberry mosaic virus, Blueberry red ringspot virus, Blueberry shoestring virus, and Tobacco ringspot virus.
AphidsBlueberryInsectAphids are small, soft-bodied, pear-shaped insects. They may vary in color from yellow to green to pinkish. Aphids typically feed in colonies on leaves and shoots, often preferring the newer growth. Severe infestations may cause leaves to turn yellow and wilt or show other signs of water stress. Repeated severe aphid infestations can weaken plants. Feeding aphids often produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold. Honeydew and sooty mold can reduce the quality of fruit.
Brown marmorated stink bugBlueberryInsectThe 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. BMSB feeding causes a sunken area at the puncture site on the surface of the berry. The flesh beneath is discolored and killed, resulting in distorted and misshapen fruit. Secondary damage from rot may also occur at the feeding site. Other known fruit/nut hosts of BMSB include caneberries, apple, pear, filbert, and stone fruits including apricot, cherry, and peach. 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/.
LeafrollersBlueberryInsectLarvae of the orange tortrix and other leafrolling caterpillar species may be found on blueberries. The caterpillars are typically light to dark green with light or dark heads, and are about 3/4" long at maturity. Typical symptoms of leafroller feeding include damaged buds and leaves that are rolled and tied with webbing. Damage to fruit occurs occasionally. Leafroller caterpillars are often active when disturbed, wiggling vigorously or dropping to the ground on a thread. The adult moths are 1/2" to 3/4" long and are brown or mottled tan and rusty brown. Adults of some species, including the orange tortrix, have darker bands across the wings. The orange tortrix overwinters in dead leaves on the plant or on the soil surface.
Lecanium scaleBlueberryInsectLecanium scales are shiny brown insects found on twigs. Adults are 1/8"-1/4" in diameter and roughly turtle-shaped. They may have light markings or appear somewhat waxy. Crawlers (immature scales) are flatter. Heavily infested branches may be wilted, yellowish, or show other signs of stress. New growth may be stunted or lacking. Twigs and small branches may be killed. Lecanium scale is a common pest in the landscape and garden, infesting many plants including ornamentals and fruit trees. Feeding scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Honeydew and sooty mold can reduce fruit quality. Lecanium scale overwinters as immature scales on the twigs and branches of the host plants.
Spotted wing Drosophila (SWD)BlueberryInsectSpotted wing Drosophila (SWD) resembles other Drosophila species (fruit flies or vinegar flies) in appearance, but unlike other members of the family which attack only overripe, damaged or decaying fruit, SWD attacks healthy fruit as it ripens on the plant. Adult SWD flies are about 1/8 inch long, with red eyes and a yellow-brown body. Darker bands may be visible on the abdomen. Male flies have a distinctive dark spot on the leading edge of the wing near the tip. SWD is the only fruit fly species in our area with this spotted wing, making identification of males relatively simple. Females lack the spotted wing, but have a large, sawlike egg-laying organ called an ovipositor at the tip of their abdomen. It is used to deposit eggs in fruit (oviposition). The eggs are laid beneath the surface of ripening fruit as it begins to soften and show color (from first blush of color in blueberries), continuing through to harvest. Scars left by oviposition may appear as indented, soft spots on the fruit surface. Small white- or cream-colored larvae hatch within a few days and feed in the fruit, causing the fruit to soften and collapse around the feeding site. Further damage may be caused by secondary pathogens (fungi and bacteria) which attack the damaged fruit. At maturity, the larvae may be up to 1/8 inch long. They may pupate inside or outside the fruit. The length of the life cycle depends on temperature, with adults most active at cool temperatures (around 68 degrees F). Most soft-skinned fruits are vulnerable to attack by SWD, including peach, plum, cherry, grapes (table and wine), strawberry, blueberry, and cane fruits. It has also been found in Asian pear, fig, and hardy kiwi. See SWD under Common Insects for an additional image of the larval stage.