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Plant NameTypeDescription 
2,4-D damageLawn and TurfDiseaseBentgrasses are commonly used for lawns in western Washington and found as weeds in eastern and western Washington. Both weedy species and cultivated varieties are susceptible to damage by 2,4-D, an ingredient often found in turfgrass fertilizer-herbicide ("weed and feed") products and in broadleaf weed killers used in lawns. Well-established, healthy grasses may tolerate some damage, but young plants and those stressed by environmental conditions are very susceptible to damage. 2,4-D is translocated within the plant tissues and also damages the root system of affected grasses, affecting nutrient and water uptake. Early symptoms may resemble those caused by root disease or drought injury and include yellowing and dieback of leaves followed in severe cases by death of the plants. Other factors which may affect the amount of damage occurring include temperature (higher temperatures often result in more damage) and the particular 2,4-D formulation used (esters are more damaging than amines).
AlgaeLawn and TurfDiseaseAlgae are tiny, single-celled plants commonly found in lakes and wet areas. Algal growth on lawns is common in the coastal regions of the Pacific Northwest, particularly on grass planted in wet, low-lying, or shaded areas. Also at risk are lawns with compacted soils that prevent proper drainage. Algae form a slick greenish to black scum on the surface of the soil, particularly over thin turfgrass. It can look like an oil spot. The grass is usually not killed, but growth is reduced because of shading and reduced air and light penetration. The algal scum becomes a black, water-repellent crust in dry conditions.
Anthracnose/Basal crown rotLawn and TurfDiseaseAnthracnose of turfgrass is a fungal disease with two phases. Phase I affects the leaves and is active in the summer. Typical symptoms include yellow to tan or brown lesions on the blades of older leaves and sheaths, followed by small black fungal fruiting bodies on killed tissues. The fruiting bodies are covered with black hairs. The diseased grass appears as blighted or thinned areas a few inches to a foot or more in diameter. Warm, humid summer weather favors spread of the disease, especially on stressed lawns. Phase II occurs in fall and winter on basal portions of the stems. Leaves on affected stems turn yellow to orange-red beginning at the tip. Blighted areas of grass in this instance are typically small, seldom exceeding an inch in diameter. Grass wounded by aeration or other treatment is more susceptible to fall infection. The disease is more severe on bentgrass, annual bluegrass, and red fescues.
Brown blightLawn and TurfDiseaseBrown blight is a fungal disease affecting the leaves of perennial ryegrass and some fine fescues. Infection commonly occurs during cool, wet periods. The disease is typically worse during the first fall after planting and on grass with insufficient nitrogen. Affected leaves develop small, oval, chocolate brown spots or larger brown streaks up to 3/8" long. The leaves may be girdled and turn yellow, dying back from the tip. Overall, the affected areas of grass look brown and thin and may appear drought-stressed. The disease is spread by infected grass clippings, contaminated equipment, wind, or splashing rain. The fungus can survive in infected plant debris and infected plants. This disease rarely does enough damage to kill grass.
Brown patchLawn and TurfDiseaseBrown patch is a fungal disease typically affecting bentgrasses and annual bluegrasses. Infected grass appears as patches a few inches to several feet in diameter. The patches are generally circular and light brown in color. Shorter grasses (1/4") may show a "smoke ring" symptom, which is a band of grayish-brown grass about 2" across surrounding the brown patch. A cobweb-like growth of fungus may be associated with the smoke ring in humid weather. Brown patch damage is typically limited to the leaves. Lush turf that is overfertilized and overwatered is more susceptible to infection. Disease development is favored by hot (>82 degrees F), humid weather. Brown patch is relatively rare west of the Cascades and is not common east of the Cascades. The fungus can survive in infected tissues and plant debris of many plant species.
Curvularia blight (Fading out)Lawn and TurfDiseaseCurvularia blight of turfgrass can be caused by eight species of fungi. Infected areas of lawn develop yellow or dappled yellow-green patches 2 to 3 inches in diameter. These patches later turn reddish-brown. The patches may expand to form dead areas a foot or more in diameter. The fungi cause root and crown rots, which in turn cause the above-ground symptoms. Leaves of affected grass plants may show yellow dappling from the tip downward and tan, brown, or gray lesions may occur on the leaves. Some grass species may also show a reddish-brown band separating diseased and healthy tissues. The fungi survive on plant debris and diseased tissues at ground level. They are most destructive during warm, wet weather from May to October. The disease is most common on bluegrass and fescue.
Dog injuryLawn and TurfDiseaseDog injury typically appears on lawns as brown, circular patches a few inches in diameter. These patches may be surrounded in a few days by a ring of darker green, more vigorous grass, resulting from the nitrogen in the urine. Samples of the dead grass placed in a plastic bag will release ammonia, which can be detected by smell. Animal urine does more damage on dry soils, where the salts cannot be easily dispersed. Urine damage can be mistaken for symptoms of several patch-type diseases. Other chemical injury such as fertilizer spills or salt spills can cause similar symptoms, but do not release an odor of ammonia.
Dollar spotLawn and TurfDiseaseDollar spot is a fungal disease that affects most turfgrass species under low fertility. Leaves develop watersoaked, dark lesions which become light tan with a reddish-brown margin as they dry. Lesions are often hourglass-shaped and may involve the whole leaf blade. Leaf blades may be girdled, and crowns and roots may be decayed when the disease is severe. The affected areas appear as small (3" or less), circular, somewhat sunken patches in the lawn. The patches are yellow-brown to gray in color, often with reddish-brown margins. The fungus may be present as a cobweb-like mass of whitish mycelia at the edge of the patches. The fungus survives in the soil or in infected plant tissues and debris. Warm, humid weather and cool nights favor disease development, which is more severe on drought-stressed grasses. The fungus can be spread by infected clippings. This is not a major disease in western Washington.
Fairy ring and mushroomsLawn and TurfDiseaseSeveral species of fungi can cause fairy rings in lawns. The common symptoms may include a ring of dead grass with darker green grass and mushrooms on the inside and/or the outside of the ring, circular patches of darker green grass, or rings of mushrooms or puffballs appearing with or without other symptoms. Mushroom rings most commonly appear in the spring or fall when adequate moisture is present. The type of fairy ring which causes dead rings is the most damaging. The fungus feeds on decomposing organic matter such as dead tree roots and undecomposed bark mulch in the soil and makes water penetration difficult. Fairy rings are more severe on sandy soil with low fertility. Grass inside the rings may be weakened or killed and replaced with weeds and weedy grasses. Fairy rings may disappear suddenly.
Leaf spotLawn and TurfDiseaseFungal diseases of turf caused by Drechslera sp. include leaf spot and melting-out, root, crown, and rhizome rots, and net blotch. Leaf spots first appear as small, water-soaked areas that soon become uniformly dark (reddish-brown to purplish-black). In severe cases, this results in severe thinning of the lawn and is termed "melting-out". Root, rhizome, and crown rots caused by Drechslera sp. cause plants to display symptoms of wilting and yellowing, followed by browning and death of plants. Net blotch appears as a fine network of short brown streaks that lie both parallel and perpendicular to the leaf axis. The fungi can survive in diseased plant debris or on infected plants. The disease is spread by infected clippings, contaminated equipment, wind, or splashing rain.
Microdochium patch (Pink snow mold)Lawn and TurfDiseaseFusarium patch is a fungal disease common in western Washington. It is typically most severe on bentgrass and annual bluegrass at low mowing heights in shaded areas. Fescues, Kentucky bluegrass, and perennial ryegrasses may also be infected. The disease develops most rapidly during periods of cool, wet weather in spring and fall. Symptoms include small, watersoaked patches which may be 2" in diameter initially, then enlarge to 6" or more. Reddish-brown margins often surround the spots, which become tan or light gray. White to pinkish fungal growth may be present on the advancing edges. Patches may appear ring-like if grasses regrow in the center. Symptoms are most noticeable on short grasses (1/4") and less noticeable on longer grasses (1" or more). The fungus survives in the soil and on diseased grass and debris. In areas with snow cover, the fungus can grow beneath the snow as the snow melts.
MossLawn and TurfDiseaseMosses are small, simple, non-flowering plants. They are typically low-growing and somewhat yellowish-green in color. They grow vigorously in the cool, moist weather of fall, winter, and spring, when lawn grasses are less able to compete. Moss in lawns generally results from low soil fertility, high soil acidity, heavy shade, improper watering practices, diseased grass, poorly drained soil, compacted soil, or any combination of these. Permanent moss control depends on eliminating conditions which favor moss growth.
Necrotic ringspotLawn and TurfDiseaseNecrotic ringspot (NRS) is a fungal disease primarily occurring on Kentucky bluegrass in central and eastern Washington and Oregon. It is most common on 2- to 5-year-old lawns grown from sod. Infection occurs during early spring, late summer, or fall. The grass develops small (2"-5"), circular, yellowed areas with reddish-brown margins. These can expand to up to several feet in diameter. Roots are damaged and the infected patches lift easily from the soil. The grass often regrows in the center of the patches, leaving the dead rings characteristic of the disease. NRS can be seen throughout the growing season and causes a chocolate-brown discoloration of the roots and rhizomes not seen in similar patch diseases. NRS may superficially resemble Fusarium patch or yellow patch, both of which occur in fall and spring. NRS may also be confused with fairy ring.
Powdery mildewLawn and TurfDiseasePowdery mildew is a fungal disease affecting the leaf blades. Bluegrasses and fescues are the most commonly affected lawn grasses. Blades and sheaths of older leaves are covered with mats of fine, white or grayish fungal mycelia on the upper surfaces. Under favorable conditions, the fungus can spread rapidly and become quite dense. Infected leaves turn yellow, then tan to brown, and die back. Severe infections can kill grass plants or can weaken them to such a degree that other factors such as cold can kill the plants. Conditions favoring disease development include cool, humid, cloudy weather and heavily shaded lawns. The fungus survives primarily in infected plants.
Pythium crown and root rotLawn and TurfDiseasePythium crown and root rot is caused by fungi which can also cause damping-off of new grass plantings. The rot causes a general decline of the turfgrass in patches or in large areas. Symptoms may include poor color, thinning, and slow growth. During the cool, wet conditions which favor disease development, damage may first appear as small, diffuse yellow patches up to 3" in diameter. In warmer, humid weather, damage may first appear as small, brown to tan or bronze areas. Initial patches of either type may coalesce overnight to form large areas of wilted, dying grass. The crowns and roots of infected plants appear watersoaked and root volume and vigor is reduced. Both roots and crowns may be discolored. The fungi typically survive in infected plant tissues and plant debris. They may be spread by infected clippings, contaminated equipment, and water.
Red threadLawn and TurfDiseaseRed thread is a fungal disease common in cool, moist regions. It may occur on bentgrasses and bluegrasses, but is most common on red and chewings fescues and perennial ryegrasses. Infection can occur any time of year, but is most likely during fall, winter, and spring. Infected patches of grass first appear as watersoaked areas. The affected areas may be small to large and circular or irregular in outline. These later appear as diffuse areas of bleached or tan grass tips mixed with healthy grass. Fine pinkish to red threads of the fungus grow from the leaf tips. The fungus is spread by rain, wind, and contaminated mowers and other equipment. It can survive on infected grass and in the soil. Red thread infections are primarily an aesthetic concern, as they are rarely severe enough to kill grass. Low fertility greatly favors disease development.
RustsLawn and TurfDiseaseSeveral species of fungi cause rusts of turfgrasses. Typical symptoms include yellow specks on the leaf blades followed by development of yellow, orange, dark orange-brown, or red rust pustules on either or both leaf surfaces. Infection may also occur on stems and leaf sheaths. Severe rust infections can kill leaf blades and may cause the turfgrass to appear thin or weak. Weedy species can infest weakened turfgrass. Affected areas of the lawn may show a reddish, brown, or yellow tint. Rust diseases are more severe on slow-growing or stressed grasses (shade, drought, poor nutrition, and incorrect mowing height are possible causes of stress). The fungi overwinter in diseased grass and can be spread by wind. Rusts typically occur on bluegrasses, ryegrasses, and fine fescues.
Septoria leaf spot (Tip blight)Lawn and TurfDiseaseSeptoria leaf spot is a fungal disease of the leaves of many grasses. Gray-green spots develop near the leaf tips, later fading to yellow then grayish-white. The spots may reach an inch or more in length. Small brown to black fruiting bodies of the fungus typically appear in the dead areas. Overall, the infected areas of the lawn appear scorched. Disease development is favored by cool, wet weather, unmowed or long turf, and poor nutrition. The fungus typically survives in diseased plants and plant debris. It is spread by splashing water or contaminated equipment, but can also be carried on the seed.
Slime moldsLawn and TurfDiseaseSlime molds are related to fungi. They do not cause disease on turfgrasses as they feed only on decaying organic matter, but they can be an aesthetic concern. They emerge from the soil as a thin sheet of whitish to yellow slime and grow on the surface and up any support, including grass blades and other plants. Once in the air, the mold develops the reproductive phase, which consists of rounded, yellow to purple-brown masses which are often mistaken for insect eggs. These structures are typically present each year in the same area for about 1-2 weeks and will disappear if left alone.
Take-all patchLawn and TurfDiseaseTake-all patch is a fungal disease common on bentgrass, particularly on young plants. Symptoms first appear in late spring as small, brown, dead areas of grass approximately 2" in diameter. The patches continue to enlarge, often reaching a yard or more in diameter over a period of years. Roots and crowns are killed. The centers of killed areas may be invaded by weedy species, resulting in a doughnut-shaped dead ring. Mixed grass plantings may show thinned areas rather than distinct dead patches. The fungus survives in infected tissues and debris and can be spread by contaminated equipment. Take-all patch is most severe on 1- to 4-year-old bentgrass plantings, especially those on sandy soils. Bluegrasses and fescues are rarely infected.
ThatchLawn and TurfDiseaseThatch is a layer of plant debris which generally accumulates at the soil surface. It consists primarily of undecomposed stem, crown, and root materials. Grass clippings contribute little to thatch formation. In healthy lawns, thatch decomposition rates balance grass growth, resulting in relatively little accumulation. However, excess fertilization, overwatering, and improper mowing will aid thatch accumulation. Also, acid soils may result in reduced thatch decomposition rates. Thatch in excess of 1/2" should be removed, as it can prevent water penetration. Crowns and roots can develop in the thatch rather than in the soil, making frequent watering necessary and making lawns more prone to drought injury. Certain types of grass naturally develop more thatch. Creeping bentgrasses produce large amounts of thatch, and are not recommended for home lawns.
Typhula blight (Gray snow mold)Lawn and TurfDiseaseTyphula blight is a fungal disease which can occur beneath snow cover on unfrozen soil. Under snow, light yellow to gray circular areas develop. These range in size up to a foot or more in diameter. Grass leaves are matted together and may be covered with a fluffy, grayish to white fungal growth, particularly near the margin of the patch. Small dark fungal structures often speckle the white mats. In cool, moist conditions such as under wet leaves, the disease usually appears as circular, yellow or brownish areas 3"-6" across. Typically only the leaves are killed by Typhula blight, but occasionally roots and crowns are also killed. Excessive thatch, high late fall fertility, and poor drainage contribute to disease development. Typhula blight often occurs in conjunction with Fusarium patch.
Yellow patchLawn and TurfDiseaseYellow patch is a fungal disease which may affect bluegrasses, annual bluegrass, and bentgrasses. Symptoms are typically seen in fall, winter, and spring. Light brown to yellow patches and rings form on affected turfgrass. Lesions on the leaves are rarely seen. The patches may recur in the same locations whenever conditions are favorable. Cool, moist conditions favor disease development. Prolonged leaf wetness, excessive thatch, poor drainage, cloudy weather, and excessive fertilization also contribute to disease development.
AntsLawn and TurfInsectAnts are primarily a nuisance pest in lawns. Occasionally, they may kill the grass, causing an aesthetic problem. Various species may occur in lawns, including harvester ants which can have a severe sting.
BillbugsLawn and TurfInsectBillbugs are a problem in eastern Washington. They have not yet been detected in western Washington. Both the adults and larvae cause damage. Kentucky bluegrass is severely damaged, while bentgrass is not affected. Adult billbugs are dull gray or shiny black weevils with long, distinctive snouts. They are 1/4"-1/2" long and cause minor damage by feeding on grass stems. The larvae are legless white grubs with brown heads. They are about 1/4" at maturity. The larvae initially feed on the stems, then later move to the crown region and roots, cutting roots off just below ground. Aboveground, damaged grass appears dry and brown in irregular patches. The damaged sod is easily lifted away from the soil, exposing the grubs. Overwintering adults lay eggs from May to July.
Chinch bugsLawn and TurfInsectChinch bugs feed on the stems, injecting a toxic saliva as they feed. Damage typically appears in mid- to late summer. Affected grass turns yellow and dies. The damage often resembles drought stress, but grasses damaged by chinch bugs do not recover with watering. Damage is more severe on lawns with moderate or severe drought stress, but less damage is seen in shady areas. The adults are small black bugs with white wing markings. They are about 3/16" long. The immature bugs (nymphs) are reddish with black or white markings. Perennial ryegrasses and fine and tall fescues with high levels of endophytic fungi are resistant to chinch bugs.
CutwormsLawn and TurfInsectCutworms 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. Cutworms feed by chewing leaf blades or cutting through stems near the soil line. Cutworms typically spend the day just beneath the soil surface or in the thatch. Weeds are the primary food source for cutworms, which may spread into lawns when numbers are high. They cause little real damage to lawn grasses. Cutworm infestations may be common in older lawns, particularly those with a lot of bentgrass.
European crane flyLawn and TurfInsectThe larvae of the European cranefly feed on the crowns of grasses during the winter and spring. Damage can be severe in lawns, appearing as large patches of dead or dying grass. The grass usually recovers when the larvae stop feeding, but weed invasion may occur in the weakened areas. Adult craneflies are mosquito-like with long legs. The body is about 1" long. They emerge from lawns and pastures in late August through September and may gather on the sides of houses in large numbers. Eggs are laid in the fall. The full-grown larvae are about an inch long, gray-brown, and worm-like with a tough, leathery skin which gives them the common name "leatherjackets". They feed in the soil from fall through spring, pupating in the summer. They feed primarily at night and during cloudy weather on overcast days. Treatment is usually not necessary unless spring sampling indicates numbers in excess of 25/square foot. Also, well-established lawns that are properly irrigated and fertilized rarely need treatment even at numbers higher than this.
LeafhoppersLawn and TurfInsectLeafhoppers are slender, somewhat wedge-shaped insects that hop or fly just above the lawn surface when disturbed. They are variously-colored, from yellowish to green to gray-brown. The wings are typically held roof-like above the body, which is 1/4" or less in length. Nymphs (immature leafhoppers) are similar to adults but lack wings. Nymphs and adults feed on grass leaves and stems, causing blades to appear mottled or streaked with white. Damaged areas in lawns appear bleached or dried.
MolesLawn and TurfInsectThere are three species of moles in the Pacific Northwest which are considered a problem in landscapes. The Townsend's mole (Scapanus townsendii) is the most common and is found throughout western Washington and Oregon. The Pacific or coast mole (S. orarius) can be found along the coast and in areas of southeastern Washington and northeastern Oregon. It prefers drier, better-drained soils than the Townsend's mole. The California or broadfooted mole (S. latimanus) occurs in south central Oregon. All moles have short, velvety fur (usually grayish to black). The tail is very short and nearly hairless; the snout is slender and pointed, contains small needle-like teeth, and is also nearly hairless. Ears and eyes are inconspicuous. The forearms are short and stout, with shovel-like hairless paws and stout claws on the tips of the toes. The forepaws are tipped outward for digging. Townsend's moles average around 8 inches long; Pacific and California moles are slightly smaller. Moles are rarely seen aboveground, but they occasionally emerge from their tunnels where they are vulnerable to predators such as owls, dogs, or coyotes. Underground, moles build two types of tunnels. Permanent tunnels are typically 3 to 12 inches below the surface (but sometimes up to 40 inches deep) and are used daily for moving around their territory and collecting food. Temporary surface tunnels are built beneath the soil surface up to about 4 inches deep, leaving a raised ridge of soil. These tunnels are likely only used once for collecting food. Excess soil excavated when making tunnels is pushed to the surface, leaving characteristic conical mounds. Moles are very active travelers and excavate large tunnel systems in their home territory. Most yards actually have very few moles, but when they are active it can seem that there are dozens digging and making mounds. Moles feed primarily on invertebrates, with earthworms comprising much of their diet. They also feed on other organisms such as grubs, slugs, snails, and various adult and larval insects. Occasionally they will feed on plant parts, especially grasses, but moles seldom cause significant damage to plants in the landscape. Plant damage in the landscape attributed to moles is often actually caused by voles, small rodents which may also use the tunnel systems constructed by moles.
Sod webwormLawn and TurfInsectSod webworms are the larval stage of lawn moths. The adults are slender, grayish-white to tan moths with a wingspan of approximately 1". They typically fly at dusk in erratic patterns over the lawn and are attracted to lights. Mature caterpillars are 3/4"-1" long and grayish or greenish in color with brown spots. They feed at night, hiding during the day in tunnels of grass and debris tied together with webbing. Damage consists of leaf blades chewed off at the base of the plants. Grass shoots may die back, resulting in irregular brown spots in the lawn. Caterpillars and their droppings (frass) are usually present at the base of plants (in the thatch layer) in the damaged areas. Sod webworms are primarily a concern in eastern Washington, although they can be a problem in western Washington in periods of drought. Grasses which produce more thatch are more susceptible to damage.