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Plant NameTypeDescription 
Angular leaf spotCucumber, Pumpkin, SquashDiseaseAngular leaf spot is a bacterial disease which can affect cucumber and many related species. Leaves initially develop small, water-soaked spots which enlarge until limited by the larger veins. The lesions are typically angular in shape rather than round. The spot may exude clear or milky droplets of bacterial ooze on the underside of the leaf. The droplets dry to a whitish, crusty layer. Leaf lesions often turn tan and tear away from the leaf, leaving ragged, irregular holes. Spots also appear on stems, vines, and fruit. Lesions on fruits are typically small, circular, water-soaked spots. These spots may be associated with an internal fruit rot. The bacteria are spread by splashing water, insects, and mechanical means including hands and tools.
Cucumber mosaic virusCucumber, Pumpkin, SquashDiseaseCucumber mosaic is a viral disease of cucumbers, melons, squash, and other plants. It is spread primarily by aphids, but can also be transmitted by mechanical means, infected seed, and by cucumber beetles. The early symptoms may be limited to downward leaf curling, yellow and green mosaic patterns on leaves, and reduced leaf size. Other typical symptoms include plant stunting, leaves that are yellow, mottled, and wrinkled, and deformed plant parts. Fruit produced by affected plants may have warty bumps and blotchy coloration. These fruit are usually bitter in flavor. This virus has a very wide host range, including many vegetables, ornamental flowers, woody plants, and weeds. Other viruses, such as Zucchini Yellows Mosaic Virus and Watermelon Mosaic Virus, can also cause mosaic symptoms in squash.
Curly top (Beet curly top virus)Cucumber, Pumpkin, SquashDiseaseCurly top is caused by a virus transmitted by the beet leafhopper. Many crops are affected, including tomato, bean, squash, cucumber, and pepper. In cucumbers, growth is slow and older leaves are yellowed. The terminal leaves may be unusually dark, and the plant is stunted. Yield is low, and fruits are small and of poor quality. Young squash plants may be killed without showing symptoms. Older plants show yellowing of older leaves, dwarfed new growth, overall stunting, and upward rolling of leaves. Runners often bend upward at the tip. Diseased plants may fail to set fruit. The virus is also found in annual flowers and weeds. Curly top is not a problem in western Washington.
Damping-offCucumber, Pumpkin, SquashDiseaseDamping-off of seeds and seedlings is caused by fungi that remain in the soil for long periods of time. Infected seeds decay without germinating. Seedlings may be infected and fail to emerge from the soil. Emerged seedlings are also attacked, causing them to wilt and topple over. Water-soaked to brownish lesions are often visible on the stem at the soil line. Plants become more resistant to attack as they mature. Damping-off fungi are more of a problem in cold soils with poor drainage, and in conjunction with overwatering.
Pollination failureCucumber, Pumpkin, SquashDiseaseFruits may begin to develop without pollination, but must be pollinated to continue normal growth. The unpollinated fruit remain small and may show a rot beginning at the blossom end. These fruits usually turn yellow and drop from the plant fairly quickly. Incomplete pollination may also be a problem, resulting in misshapen fruit (curved, bell-shaped, or nubbins). Portions of the fruit may have abnormal seed development. Both male and female flowers are necessary for pollination to occur (except in some cucumbers). Since female flowers typically appear on the vines before male flowers, the earliest female flowers are not usually pollinated.
Powdery mildewCucumber, Pumpkin, SquashDiseasePowdery mildew is a common fungal disease of squash. Upper and lower leaf surfaces and stems are typically affected. Small, white spots quickly enlarge into patches of characteristic powdery-white fungal growth. Older leaves, shaded leaves, and leaf undersides are favored locations for powdery mildew development, although it can quickly spread to involve large portions of the plant. Tiny, speck-like, black fungal structures may be present in the white mats. Severely affected leaves may yellow and die prematurely. Occasional fruit infections occur on cucumber, although most commercially-grown varieties are resistant. Disease development is favored by humid weather, cool nights, and cloudy days. Dense plantings are more likely to be affected.
Root rotCucumber, Pumpkin, SquashDiseaseSeveral species of fungi can cause a wilting and root rot of squash and related plants. Above-ground symptoms may not be noticed until vines wilt and collapse during hot weather. Typical symptoms include rot of the root system, with a soft, dark brown, mushy rot affecting the base of the stem. Affected plants generally have abnormally small root systems and may break off easily near the soil line. The fungi can survive for several years in the soil.
Verticillium wiltCucumber, Pumpkin, SquashDiseaseVerticillium wilt is caused by a fungus which can persist in the soil for many years. It has a broad host range, including many vegetables (potato and tomato are favored hosts), woody and herbaceous ornamentals, fruit trees, and weeds. Typically, the fungus attacks the roots and moves throughout the plant via the vascular system. Symptoms may not be noticed until plants are stressed. Leaves wilt and develop yellow, V-shaped areas along the margins. Affected leaves die. The wilt progresses upward through the plant and may kill entire vines. Discoloration of the vascular system is noticeable when cuts are made into stems near the base of the plant. Cool soil temperatures favor disease development.
White moldCucumber, Pumpkin, SquashDiseaseWhite mold is a fungal disease which affects stems and fruit of cucumbers and squash. Initial infections commonly occur through dead tendrils, withered flowers on fruit, and dead leaves which are still attached to the plant. After infection, the fungus can spread into living tissues, where it causes a stem blight or fruit rot. White, cottony fungal growth develops on the stems, which later become dry and withered. Small black structures of the fungus may be present in the cottony mats or inside the stem. Affected cucumber fruits develop a soft, watery rot. Disease development is favored by long periods of cool, wet weather. Although widespread, the disease is not a serious concern on squash or cucumber.
Brown marmorated stink bugCucumber, Pumpkin, SquashInsectThe 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 appears initially as a pinprick surrounded by a discolored spot on the surface of the fruit. These injured areas may turn yellow or decay as the fruit matures, or entire fruits may become distorted or catfaced. The surface spots often appear slightly sunken as whitish corky or spongy areas develop under the skin. Secondary damage from rot may occur at the feeding site and severely damaged fruits may rot on the vine. Other known vegetable hosts of BMSB include peppers, corn, beans, and tomatoes. 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
SlugsCucumber, Pumpkin, SquashInsectSlugs are common garden pests in western Washington. They resemble snails, but lack shells. They may vary in size from as little as 1/4" up to several inches in length, depending on age and species. Foliage of older plants is raggedly chewed, while younger plants may be totally consumed. Slugs 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.
Spider mitesCucumber, Pumpkin, SquashInsectSpider mites are tiny, eight-legged mites which range in color from yellowish to green or red. They typically feed on the underside of leaves, causing a yellowish to bronze stippling or speckling of leaves. Severe infestations can cause entire leaves to turn yellow and may reduce yields. Spider mite feeding is usually accompanied by webbing on the underside of leaves. The mites may be visible as "moving dust" in the webbing. Mite infestations are worse in hot, dry, dusty conditions.
Squash bugCucumber, Pumpkin, SquashInsectThe squash bug attacks squash, pumpkin, melons, and related crops. Adults are typically dark brown, but may have gray or light brown markings. They are about 3/4" long at maturity. Brown to reddish eggs are laid along the veins of new leaves. The newly hatched nymphs (immature bugs) are greenish to gray. Squash bug nymphs and adults feed on the leaves, causing small yellow specks which later turn brown. Squash bugs also inject a toxin into vines which causes a wilt from the point of attack to the end of the vine. Affected runners wilt and turn black and crisp. Small plants may be killed, while larger plants may lose several runners. Squash bugs may also attack young fruit. Adult squash bugs overwinter in debris and sheltered places in the garden.
Western spotted cucumber beetleCucumber, Pumpkin, SquashInsectThe western spotted cucumber beetle is a pest of many ornamentals and vegetables. About 1/4" long, the adult beetles have yellow wing covers with black spots. The rest of the body is black. Adults feed on leaves of plants, while the larvae feed on the roots of some plants.