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Plant NameTypeDescription 
Armillaria root rotPineDiseaseArmillaria root rot is a fungal disease transmitted between plants by root contact or through infected soil. Armillaria is often found in newly cleared soils or soils which have been flooded. Symptoms typically include sudden or gradual slowing of growth, yellowish or undersized needles, needle loss, or dieback of branches. 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. Pines may develop a resin flow at the base of the trunk and then yellowish foliage. Infected trees are more susceptible to attack by bark beetles. Young, stressed trees are most susceptible. Armillaria-infected trees have damaged root systems and are more likely to fall in high winds.
Dwarf mistletoePineDiseaseDwarf mistletoe is a parasitic plant that grows on the branches of a host tree. It is yellow-green, olive-green, or somewhat orange in color and grows in clusters to about four inches high. The tree's branches may be swollen and spindle-shaped at the infection site (some pines show little or no swelling), and develop into witches' brooms. Severe infestations can greatly reduce growth of the host tree, sometimes causing dieback or death. Dwarf mistletoe spreads by seeds.
Elytroderma needle castPineDiseaseTrees infected with Elytroderma needle cast often display clusters or flags of red-brown needles in the spring. The diseased twigs turn up at the tip. The bases of affected needles often remain green. In summer, infected needles develop dark lines (fungal structures) which open along a lengthwise slit. Infected needles usually drop in fall and winter, but may turn gray and remain on the tree. Trees may be stunted, since several years of infection can cause nearly complete defoliation. Knobcone and ponderosa pines are most severely affected. Ponderosas may develop pitchy lesions on twigs. The lesions are streaked reddish when cut open. Infected trees are more susceptible to attack by root rots and bark beetles.
Lophodermella needle castPineDiseaseThis fungal disease infects current-season needles, but symptoms are not found until the following spring. Infected needles turn reddish-brown, and later become yellow or straw-colored. Shallow dimples or depressions can be found on all needle surfaces. Infected needles are killed and cast (dropped from the tree) the following summer. Fungal fruiting bodies which open with a longitudinal slit may be found in dead two-year-old needles. Severely infected trees often develop a "lion-tailed" appearance, as only current-season needles remain on the tree. This disease may be confused with Lophodermium needle cast.
Lophodermium needle castPineDiseaseLophodermium needle cast is a fungal disease infecting the needles of pines. There are 19 Lophodermium species in the Pacific Northwest. One species of concern, L. seditiosum, infects current-season needles, which are killed by the next growing season. Yellow spots appear from late fall to spring. These later turn brownish, then whole needles turn reddish or yellow and drop by the following midsummer. Infected needles typically display black, football-shaped fungal structures with a slit in the center. Some species of pine also develop characteristic black lines across infected needles. Repeatedly infected trees may be stunted. Low branches are more severely affected. This disease may be confused with Lophodermella needle cast, which lacks the distinctive black, football-shaped structures.
Phytophthora root rotPineDiseasePhytophthora root rot is usually a problem only in areas with poor drainage or where flooding occurs. The fungus attacks the roots, which rot and die. The infection moves up into the crown, where the cambium (soft inner bark) turns reddish-brown instead of the normal greenish-white. Older trees may develop cankers on the trunk, possibly accompanied by split bark and oozing pitch. Lower branches wilt, turn brown, and die back. Younger trees are often killed outright, while infected mature trees may show wilting, branch dieback, or other signs of inhibited water and nutrient uptake. Phytophthora root rot on pines is mainly a problem in nurseries or other irrigated plantings.
Western gall rustPineDiseaseWestern gall rust affects primarily two- and three-needle pines, including shore, lodgepole, mugo, Scotch, Austrian, and ponderosa pines. This fungal disease causes small to large round or pear-shaped galls on infected twigs, branches, or trunks. The galls persist and enlarge each year. Branch tips beyond the galls become stunted and bushy and may die. In the spring, two-year-old and older galls are covered with orange or yellow-orange spores, which cause new infections on young shoots of susceptible trees. Large galls can weaken the trunk or major limbs, making them highly susceptible to breakage.
White pine blister rustPineDiseaseWhite pine blister rust is a fungal disease which attacks all five-needle or white pines. Elongate cankers are formed on trunks and branches. The cankers may ooze resin. In the spring, fungal spores are formed in orange- or rust-colored pustules or blisters on the bark of the cankers. Branches usually die back (flagging) above the canker, which may also have severe pitching associated with it. The alternate hosts for white pine blister rust are currants and gooseberries, which display brown, hairlike structures and tiny yellow blisters on the underside of infected leaves. The upper surface of currant leaves is often discolored. Infection of pines typically occurs in late summer.
ConewormsPineInsectConeworms attack trees by boring into green cones. They also may bore into shoot tips or stems, especially around wounds. Tip dieback may result from coneworm feeding. Injured twigs often can be distinguished by the presence of pitch and sawdust-like frass produced by the coneworms. These larvae are small (about 1/2" long) and light brown with a darker head. The adult coneworm is a mottled gray moth. Coneworms also attack true firs, hemlocks, Douglas fir, and spruces.
Eriophyid mitesPineInsectEriophyid mites are tiny, wormlike, whitish or tan mites which feed under bud scales or in the needle sheaths, often between the needle bases. Symptoms of eriophyid mite infestations include yellowing, distortion, and stunting of new needles, and development of numerous buds where a bud has been infested (rosetting). Severe infestations may kill needles and cause needle drop, leaving naked branch tips. Rosettes may develop into witches' broom growths. Two-needle pines, particularly lodgepole or shore pine, are affected.
European pine shoot mothPineInsectThe larvae of the European pine shoot moth feed on tips of branches, boring first into needles or bud bases, then into the shoots. Infested tips are covered with pitch-covered webbing, often develop a characteristic "shepherd's crook" shape, and may die back. Infested needles are yellowed near the twig tips and eventually turn brown and die. The mature larvae are about 5/8" long and reddish-brown with black heads. Adult moths are reddish-orange with silver markings on the wings. All pines are susceptible, especially two- and three-needle species.
Mountain pine beetlePineInsectThe mountain pine beetle attacks pine trees (trunks and branches) four or five inches in diameter or larger. The adults and larvae mine the bark, weakening and girdling trees. Heavily infested trees may decline or die. Red sawdust on the bark and ground and pitching on the trunk or large branches may indicate the presence of these bark beetles. Adults are black and about 1/4" long. Larvae are white and found under the bark in straight galleries. Bark beetles typically attack weakened trees. Lodgepole pine is the preferred host, but other pines are also attacked.
Pandora mothPineInsectPandora moth larvae are brownish- to yellowish-green, spiny, and about one inch long at maturity. The larvae feed on the needles of pines, especially ponderosa, Jeffrey, and lodgepole. The stubs of eaten needles remain on the twigs and the crowns of infested trees are often thinned. The larvae may cause severe defoliation when there are large outbreaks. They travel in single file when moving to new feeding areas. The adult is a brown-gray moth with black markings on the wings. This is a sporadic pest of forest and landscape trees.
Pine aphidPineInsectPine aphids are long-legged dark green or brown aphids covered with a white, woolly material. They are found in colonies on the needles. The aphids produce large amounts of honeydew (a sweet, sticky material) which is often covered by a black growth of sooty mold. Heavy aphid infestations may cause trees to turn yellowish, but otherwise cause only minor damage.
Pine bark adelgidPineInsectPine bark adelgids form woolly or cottony white masses on the trunk, branches, or twigs. Heavy infestations can look like snow on the trunks of trees. Seedling and young trees may have adelgids at the base of the needles or on shoots instead of on the trunks. Needles often become somewhat yellowish (chlorotic). The adelgids are black and short-legged under the white material. Severe adelgid infestations can result in stunting or death of trees.
Pine butterflyPineInsectThe larva of the pine butterfly is a dark green caterpillar with white stripes on the sides and a black head. The caterpillars feed on the needles, hatching out when new needles begin to appear. Young larvae feed in clusters on the older needles, while older larvae feed singly. They cause relatively little damage except in years of severe outbreaks. Adult pine butterflies are white with black markings and closely resemble the cabbage butterfly. The preferred host tree is ponderosa pine.
Pine needle scalePineInsectPine needle scales are elongate, pure white scales which feed on the needles. Heavily infested trees may appear "flocked". Infested needles turn yellow, then brown. Twigs and branches may be killed. Repeated infestations may eventually kill trees. Pine needle scales are often found with the black pineleaf scale, which is gray to black instead of white. Pine needle scale is a serious pest of ornamental pines and may also infest spruces and Douglas fir.
Pine needle sheathminer (Pine sheath miner)PineInsectPine needle sheathminers are orange to tan larvae that feed on the needles. Young larvae mine inside needles, while older larvae feed at the base of needles inside the needle sheath. Damaged needles often droop or stick out from the stem at a sharp angle. Adults are silvery moths about 1/2" across. They lay eggs on the needles in early to mid-summer. Pine needle sheathminers attack species and hybrids of two- and three-needle pines and seem to prefer smaller trees.
Sequoia pitch mothPineInsectThe larvae of the sequoia pitch moth feed by boring into branches or trunks. At the point where the larva enters the wood, small to large masses of white to pinkish pitch accumulate. The larva feeds locally underneath the pitch mass. Although healthy trees are occasionally attacked, stressed trees are most vulnerable. Branch crotches are also sometimes infested. Adults are black and yellow clear-winged moths that somewhat resemble yellowjackets. This pest causes mainly aesthetic damage (the pitch masses). Incidentally this pest does not attack Sequoia.
Spider mitesPineInsectSpruce spider mites feed on older needles, causing yellowish to gray stippling (tiny spots) and needle chlorosis or yellowing. Fine webbing is usually present on infested needles and twigs. The mites are tiny and greenish or yellowish in color. They overwinter as eggs on the host and can hatch as early as April or May.
White pine weevilPineInsectWhite pine weevils are brown beetles with light blotches on the highly curved back. Adults grow to about 1/4" long and feed on shoots and needles of pines and spruces. The larvae feed on needles and also mine shoot tips, often distorting or killing back the terminals and causing trees to appear deformed. Infested terminals often develop a "shepherd's crook" appearance. Adult beetles emerge in late summer (around mid-August into fall) and overwinter in organic debris on the ground. Damage is mainly aesthetic, however, the infested terminal usually dies.