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Plant NameTypeDescription 
Common leaf spotStrawberryDiseaseCommon leaf spot is caused by a fungus that overwinters on old infected leaves. It produces abundant spores in lesions of infected leaves, and rain splashes them onto healthy tissue. Only young leaf tissue is susceptible to infecting, and long wet periods and warm temperatures encourage spread of the disease. Foliage symptoms start as dark purplish red spots, and eventually become grayish white. Developed spots are about a 1/10 inch in diameter, with a white center and reddish outline, and become scattered all over the leaf surface. Sometimes the whitish centers of spots fall out, leaving a hole in the leaf. Infections occur in moist weather and are most severe in spring and fall. "Olympus" and "Shuksan" cultivars are the most susceptible.
Gray moldStrawberryDiseaseFruit rot is caused by a fungus which attacks many plants. Strawberry leaves, stems, flowers, and buds may be attacked, but the worst damage is to the fruit. The rot typically begins as a brownish, water-soaked spot on any portion of the fruit. Infection may occur at the stem end of the fruit, or where the fruit contacts diseased plant parts or the ground. The infection spreads quickly throughout the fruit. Infected berries often develop a powdery coating of brownish-gray fungal growth. Berries infected in the field may not show symptoms until they are in storage, where they quickly rot. Cool temperatures and moist conditions favor disease development. Spores are spread by wind and splashing water. The fungus overwinters in diseased plant debris.
Red steleStrawberryDiseaseRed stele is caused by a soil-infesting fungus. It is active in cool, wet weather. It attacks roots soon after fall rains begin and remains active through winter, spreading most rapidly where drainage is poor or in heavier soils. The core or stele of diseased roots has a reddish-pink tinge which gradually turns cinnamon-brown and finally black. The root's outer cortex stays white. Lateral roots are quickly destroyed, giving main roots a "rat tail" appearance. Slightly diseased plants show few above-ground symptoms. Severely diseases plants are stunted, foliage may turn bluish-green and eventually plants wilt and die.
VirusesStrawberryDiseaseCrinkle virus, mottle virus, mild yellow-edge virus, and vein-banding virus commonly infect Pacific Northwest strawberry plants. They are transmitted by the common strawberry aphid, and can decrease vigor and yield. Usually, the only distinctive symptoms are dwarfing, leaf cupping, and yellowing. The "Hood" cultivar is the most sensitive. The Tomato ringspot virus, spread by the dagger nematode, can cause stunting and sometimes death. The Tobacco streak virus, which spreads naturally by unknown means, can also reduce vigor and yield.
AphidsStrawberryInsectAphids are small, soft-bodied, pear-shaped insects. They vary in color from yellow to green to brownish. Aphids on strawberries are typically found on the underside of leaves along veins and on new shoots and buds in the crown of the plant. Infested plants may be stunted, and leaves may be crinkled and deformed. Feeding aphids produce large amounts of honeydew, a sweet, sticky material which may attract honeydew-feeding ants or become covered with a dark growth of sooty mold. Honeydew and sooty mold can reduce the quality of fruit. Aphids can also transmit several virus diseases of strawberry.
Brown marmorated stink bugStrawberryInsectThe 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 damage may appear either as a sunken area or as a pinprick surrounded by a light discolored spot. Secondary damage from rot may occur at the feeding site. Other known fruit/nut hosts of BMSB include caneberries, blueberry, 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
Cutworms and armywormsStrawberryInsectCutworms and armyworms are the larvae of noctuid moths. These common moths are medium-sized with fairly dull coloration. The greenish, grayish, or tan caterpillars are hairless, nocturnal, and generally spotted, striped, or otherwise marked. They may be 1/4" to 1" in length and tend to curl up when disturbed. They may climb into the plant and feed on foliage, buds, flowers, or fruit. Armyworm behavior is similar to that of cutworms, but armyworms feed in large groups instead of individually. They tend to be voracious feeders. The caterpillars typically spend the day just beneath the soil surface or under debris near the host. Weeds are a primary food source for both cutworms and armyworms.
LeafrollersStrawberryInsectSeveral species of leafrollers can occur on strawberry. 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. Some species may also cause damage to fruit by tunneling into berries. The larvae typically produce large amounts of webbing on the plants. Leafroller caterpillars are often active when disturbed, wiggling vigorously or dropping to the ground on a thread. The larvae of many species overwinter in webbed leaves on the plants. The adult moths are 1/2" to 3/4" long and are brown or mottled tan and rusty brown. Some species have darker bands across the wings. Plants easily tolerate some damage from leafrollers, which are seldom serious pests on strawberry.
MitesStrawberryInsectCyclamen mites and two-spotted spider mites can be pests on strawberries. Cyclamen mites are microscopic, amber, oval mites typically found in the crown of the plant on the new growth. Young leaves on infested plants are stunted and deformed, often appearing crinkled or blistered. Severe infestations cause the new growth to become brownish-green in color. Flower buds and runners are also damaged, and the fruits are small, dry, and misshapen. Adult female cyclamen mites overwinter on or near the host plant. Two-spotted spider mites feed on the underside of leaves. Characteristic symptoms of infestation include brownish speckling or stippling of leaves and webbing beneath infested leaves. Damaged leaves often turn reddish or brown, dry up, and drop from the plant. Adults overwinter in buds or in leaf debris. Hot, dry, dusty conditions favor spider mites.
Root weevilsStrawberryInsectSeveral species of root weevils are common pests of strawberries. Adults are typically brown to black in color and may have lighter markings on the back. They range in size from 1/5" to 1/3" in length. These beetles cannot fly. Adults cause minor damage to plants by chewing ragged notches in the leaf margins. However, the most serious damage is done by the larvae. They are curved, legless, and white or pinkish with darker heads. They are found in the soil, where they feed on the roots. Severe root damage can occur, resulting in wilting and death of plants. Root weevils generally overwinter in the soil as larvae, with adults emerging in spring to early summer. Root weevil adults typically feed at night and spend the day at ground level.
SlugsStrawberryInsectSlugs are common garden pests in western Washington. They resemble snails, but lack shells. They may vary from as little as 1/4" up to several inches in length, depending on age and species. Slugs typically feed on strawberry fruit, making deep holes in ripening berries. The damage commonly occurs under the cap. Slugs may also feed on the leaves. They leave behind a characteristic slime trail, which appears silvery when it dries. Slugs typically feed at night and do more damage during cool, moist weather.
SpittlebugsStrawberryInsectSpittlebugs feed on many plants. On strawberry, the nymphs feed on the leaves and leaf stems, preferring the tender new growth. Infested plants are stunted, and leaves may be distorted or killed. They may also feed on buds, blossoms, and fruit, which can be distorted. Spittlebug nymphs are pale to green in color and are typically covered with a distinctive white, foamy mass of protective spittle. The nymphs and spittle are present for 1-2 months on the plants beginning around April or May. The adult spittlebugs are mottled gray or brown. They are about 1/4" long. Spittlebugs overwinter as eggs laid in the fall.
Spotted wing Drosophila (SWD)StrawberryInsectSpotted 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 (pink-white to red-pink in strawberries), 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.