Weed Identification

Black Medic

Medicago lupulina
Annual, broadleaf (occasionally as a short-lived perennial).
Regions: United States
Description: With its three leaflet, clover-like leaves, this legume is often confused with white clover. Low growing, with slightly hairy stems, it produces clusters of small, bright yellow flowers in late spring to early summer. Black medic is common in lawns from May through September. It is especially prevalent in dry soils where turf is spotty and in high-phosphorus soils. Usually an annual, it can be as persistent as a perennial.

Broadleaf Plantain

Plantago majo
Perennial, broadleaf
Regions: United States and southern Canada
Description: Broadleaf plantain has grayish green, ovular, ripple-edged leaves growing low to the ground. Contains narrow seed heads in a long cluster on a central, upright stem. Rosettes appear in mid-spring in thin and neglected turf. Seed stalks rise from early summer through early fall. The rosette tends to suffocate desirable lawn grasses. Plantain grows from seed and re-sprouting roots. Seed germinates best in rich, moist, compacted soil.

Clover

Trifolium repens
Perennial
Regions: United States
Description: The leaves are compound, with 3 broad leaflets, with tiny teeth on the edges, with a pale triangular mark appearing on each leaflet. Appears from May to September.

Crabgrass

Digitaria Ischaemum and D. Sanguinalis
Annual, grassy
Regions: United States.
Description: Smooth and hairy crabgrass have a prostrate growth habit with coarse, light green blades that are short, pointed, and hairy. This vigorous, warm-season annual grass grows rapidly from early spring until seed heads form in late summer to early fall. It grows especially well in lawns that are watered lightly, under-fertilized, poorly drained, and growing thinly. The plant spreads by seed, and to a lesser extent, by rooting from the lower swollen nodes of stems.

Curly Dock

Rumex crispus
Perennial, broadleaf
Regions: United States
Description: Bright, shiny green, lance-shaped leaves appear in spring. In summer and fall, the puckered wavy edges of the leaves are tinted reddish purple. Small greenish flowers appear on a tall, narrow spike coming from the center of the plant. Growing from a large, brownish taproot, curly dock is a perennial weed that grows most actively when grass is suffering from the stress of hot, dry weather.

Dallis Grass

Paspalum dilatatum
Perennial, grassy
Regions: Coastal states from New Jersey to California, as far north as Missouri
Description: Coarse blades, in an upright bunch-type growth with scaly appearance. Stems 2 to 6 inches long emerge from the plant center in a star type pattern. Seed heads sparsely branched on long stems and are dormant through winter and sprout early in spring. A summer weed in most areas, but grows year-round in mild climates, in low, wet areas.

Dandelion

Taraxacum officinale
Perennial, broadleaf
Range: United States
Appearance: Everyone recognizes the bright yellow flowers of dandelions; they appear in early spring and are followed by puffy seed heads. They arise from rosettes of lance-shaped leaves. Dandelions emerge in early spring, with flowering commencing as early as April and continuing through summer and fall. The plants reproduce from a long taproot, and from seeds. Seedlings can germinate at any time throughout the growing season.

English Daisy

Bellis perennis
Perennial, broadleaf
Regions: Northern United States
Description: Leaves range from nearly smooth to hairy, and form a dense cluster. The daisy-like flowers have bright yellow centers with white to pinkish outer rays. English daisy grows most rapidly in spring and fall and in all seasons on the West Coast if sheltered from drought and heat.

Ground Ivy

Glechoma hederaceae
Broadleaf
Range: United States
Appearance: Also called creeping Charlie, is a common lawn weed problem. Lawns in shaded areas and often with poorly drained fertile soil are typical sites for ground ivy to develop into a major problem. This plant may form extensive patches as it creeps along the soil and can move into sun areas. Stems are square. Leaves are arranged opposite of each other along stems, and are round to somewhat kidney shaped with rounded, toothed margins. Crushed leaves have a minty odor. Ground ivy has small funnel-shaped purplish-blue flowers. Appears from April To June.

Mouse-ear Chickweed

Cerastium fontanum vulgare
Annual or perennial, broadleaf
Regions: United States
Description: Aptly named, it has long, narrow, fuzzy leaves. Small, white flowers appear in late spring and early summer, followed by seed heads in mid summer. This weed grows most actively during spring and early summer when it spreads by means of creeping stems that root at the nodes. It grows close to the ground and can withstand low mowing. It grows vigorously in moist, poorly drained, and shaded areas.

Oxalis

Oxalidaceae
Perennial
Regions: United States
Description: has bright yellow flowers and green leaves. It grows upright. O. europaea (also called O. Oxalidaceae) is a perennial with seeds and rootstocks so that it sometimes appears to be a creeping vine. The leaves and stems are often purple or reddish.

Purslane

Portulaca oleracea
Annual, broadleaf
Regions: Eastern United States
Description: Sprawling, thick, fleshy stems with rubbery leaves. Tiny, yellow, five-petaled flowers open in direct sunlight. Cup-shaped seedpods produce small, black seeds that can lie dormant in the soil for years. Seldom found in the spring when the lawn is treated for other weeds. Thrives in hot, dry weather, spreading by sprawling stems, primarily in thin areas of the lawn or in new lawns seeded in summer.

Quackgrass

Agropyron repens
Perennial, grassy
Regions: United States except in the deep South.
Description: Quackgrass has light green to blue-green coarse blades that are rough on their upper surface. If not mowed, it can grow 5 feet or more in a single season. Narrow flower spikes rising from the plant resemble rye or wheat. The plant spreads by large, white rhizomes and grows quickly in spring and fall. It is especially stubborn in thin, undernourished turf. Quackgrass becomes quite obvious as it turns brown in summer.

Speedwell

Veronica officinalis
Perennial or annual, broadleaf
Regions: Eastern half of the northeastern United States, except in the deep South.
Description: There are several types of speedwell, all characterized by small, lobed, and numerous leaves, and by tiny white or purple flowers. The scallop-edged leaves are paired, growing opposite each other. Heart-shaped seed pods grow on the stems below the flowers. Speedwells are among the earliest lawn weeds to appear, often as early as late winter and are characterized by creeping stems that root at the nodes. They mature and thrive in cool, moist soils with thin turf.

Spurge

Euphorbia esula
Perennial
Regions: United States
Description: Erect stems support linear, alternate, and apetiolate leaves of a bluish-green hue and grows 6 to 36 inches in height. The species exhibits yellow-green inflorescence on an umbel near the top of the stem. A milky white sap (latex) is present in all parts of the plant, and aids in identification. This plant occurs primarily in non-cropland habitats, including roadsides, prairies, savannas, and woodlands. It is tolerant of a wide range of habitats, from damp to very dry soils.

Tall Fescue

Festuca arundinacea
Cool season perennial
Regions: Southern and Northwestern United States
Description: Tall fescue does produce short rhizomes but has a bunch-type growth habit - it spreads primarily by erect tillers. Individual tillers, or stems, terminate in an inflorescence, reach 3 to 4 feet in height, and have broad, dark green basal leaves. Leaves are glossy on the underside and serrated on the margins. The grass flowers in the spring and seed mature in early summer.

Wild Violet

Viola Pratincola
Winter perennial
Regions: Throughout the United States
Description: Wild violet is a winter perennial, growing 2 - 5 inches tall. It has either a tap root or a fibrous root system, and also can produce rooting stolons and rhizomes. The leaves are usually heart shaped, on long petioles with scalloped to shallow rounded margins. The flowers of wild violet appear white, blue and purple. Wild violet flowers are pansy-like with three lower petals and two lateral petals. Appears from March to June.

Yellow Nutsedge

Cyperus esculentus
Perennial, grassy
Regions: United States. Purple Nutsedge, is especially prevalent in the Southeast.
Description: Coarse, light green leaves grow upright from triangular stems, with seed heads appearing from July to October. Reproduces mainly from underground tubers; however, they can reproduce by seeds and underground stems. Tubers store food and are drought tolerant. Yellow nutsedge thrives in summer, especially under moist conditions and in closely cut lawns.


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Insect Identification

Ants

Symptoms: Most ants do not pose a problem as pests. The carpenter ant, however, is a different story. Carpenter ants may move from decaying portions of the wood into sound lumber in the process of enlarging the nest. They cut galleries with the grain following the softer parts of the wood.
Insect Appearance: The body of an ant is clearly divided into three sections: the head, the thorax, and the gaster. (The narrow waist is actually within the abdomen, so the part of the abdomen behind the waist is called the gaster.) The waist can be made up of one or two small segments, depending on the species.
Life Cycle: The pupa emerges as an adult with the entire life cycle lasting from 6 to 10 weeks. Some queens can live over 15 years, and some workers can live for up to 7 years.
Damage Threshold: Fifteen or more larvae per square foot indicates treatment is necessary.

Armyworms

Insect Appearance: The armyworm caterpillars are light tan to dark brown with yellow, orange, or dark brown stripes down the lengths of their backs. They are 3/4 inch to 2 inches long. Adult moths are tan or mottled gray with a wingspan of about 1 inch. They fly only at night or on overcast days. In daylight, they hide in the soil around grass roots.
Life Cycle: Moths appear in late spring to early summer and lay hundreds of eggs at a time on the grass. Larvae hatch from eggs within 10 days and begin feeding. You may see the larvae hanging from threads on the grass. In the South, there may be as many as six generations a year.
Damage Threshold: In excess of five larvae per square yard indicates infestation.
Control: Spray with Bacillus thuringiensis, carbaryl, chlorpyrifos, diazinon, neem, or pyrethrum, diazinon or chlorpyrifos lawn granules, which also work effectively.

Billbugs

Insect Appearance: Billbug larvae—which do most of the damage—are white, legless grubs about 3/8 inch to 1/2 inch long, with snouts used for burrowing and chewing off plants.
Life Cycle: Overwintering adults emerge in midspring when they often can be found crawling on sidewalks and driveways. Soon after emerging, they lay eggs on the stems of grass plants. Grubs generally emerge in May or June and then tunnel into the stems, from where they eventually will migrate into the root zone.
Damage Threshold: More than one grub per square foot of lawn.
Control: Spray grass foliage and thatch in spring when the adult billbugs are moving around. Use carbaryl, chlorpyrifos, diazinon, or neem.

Chinch Bugs

Insect Appearance: Adult chinch bugs are small, from 1/16 to 1/4 inch long, depending on the species. Most are black with white wings, each of which has a distinctive triangular black mark. Young chinch bugs are smaller, wingless versions of their parents, but are red with a white back stripe.
Life Cycle: Adult chinch bugs over winter in both the North and South and emerge as early as March. For the rest of the growing season, they feed by sucking the juice from grass blades, injecting a poison that causes blades to turn brown and die. They are especially active during hot, dry weather.
Damage Threshold: To find chinch bugs, push a bottomless 2-pound coffee can into the affected lawn area, about 2 inches deep. Fill it with warm water. Any chinch bugs present should float to the surface. If more than 20 chinch bugs appear, control is warranted.
Control: Sabadilla, chlorpyrifos, diazinon. Reduce nitrogen fertilizer, and plant resistant grass.

Cutworms

Symptoms: As with armyworms, cutworms leave small, 1- to 2-inch-wide patches of brown grass in newly seeded and established lawns; the plants are eaten off at soil level.
Insect Appearance: The larvae of cutworms are plump, smooth, and almost always curl up when disturbed. They can be various colors but are most often gray, brown, or black; some are spotted or striped. They often grow to 2 inches long. The moths are dark and fly at night.
Life Cycle: Moths lay their eggs in late summer, and after hatching, cutworm larvae overwinter in trash and clumps of grass. Larvae resume feeding early in spring (and only at night). They mature into moths in July or August.
Damage Threshold: Use the pyrethrum test (listed below), to determine how pervasive these insects are. If you find more than 10 larvae per square foot, it's time to act. Cutworms don't seriously damage grass unless there is a severe infestation. More damage may be done by birds scratching at the turf to feed on the larvae.
Control: Pyrethrum Test: Other insects, such as sod webworms, can be driven to the surface of the soil by drenching a patch of lawn with pyrethrum, a natural pesticide. Mix 1 tablespoon of a 1- to 2-percent pyrethrum pesticide in 1 gallon of water. Mark off about 1 square yard, and apply the entire gallon mixture as evenly as possible using a sprinkling can. If those insects are present, within a few minutes they will rise to the surface of the lawn

Grubs

Symptoms: Grass grubs attack the roots of most pasture plants, but their numbers are highest under susceptible species such as white clover and ryegrass and very low under the resistant lucerne and Lotus major. Tall fescue supports relatively high populations of grass grub but with little effect on plant production.
Insect Appearance: The larvae are C-shaped when relaxed, creamy white in colour, and have a light tan head and a horseshoe-shaped cluster of anal bristles. They moult (cast their skins) three times. Newly hatched larvae are about 5 mm long and weigh only 2-3 mg.
Life Cycle: Most grass grubs hatch in December and January and pupate 9-10 months later. They are found up to 150 mm below the soil surface. The first larval stage lasts about 3 weeks and the second about 6 weeks. The third instar is present until the following September or October, but completes its growth and stops feeding about July, depending on the conditions. The pupal stage lasts 3-4 weeks.
Damage Threshold: Grubs of all species feed on the roots of many plants, but prefer the fibrous roots of turfgrasses. As the root system is destroyed, sections of turf wilt, turn brown and can be easily pulled back to reveal grubs beneath. Secondary damage is also caused by skunks searching for grubs as food. Damage is most severe in the fall and the spring when the grubs are increasing in size rapidly and feeding near the surface.

Sod Webworms

Symptoms: One- to two-inch-wide dead patches with grass blades chewed off just above the thatch line. Usually prevalent in the hottest, driest areas of the lawn. Silky white tubes found nestled in the root area.
Insect Appearance: Sod webworm larvae are slender, grayish, black spotted caterpillars, approximately 3/4 inch long, and sluggish in their activity. They hide during the day in shelters constructed of bits of grass and debris. The buff-colored moths, which fly in zigzag patterns over the lawn at dusk, have two snout-like projections on their heads.
Life Cycle: Overwintering larvae emerge and begin feeding (at night or on overcast days) in spring. They mature into moths in early summer. Throughout the summer, the moths fly over the grass and drop eggs, which hatch into larvae and repeat the feeding cycle on the grass. There may be as many as three generations per season.
Damage Threshold: Fifteen or more larvae per square foot indicates treatment is necessary.
Control: Bacillus thuringiensis, carbaryl, chlorpyrifos, diazinon, neem, pyrethrum, resistant grasses.

 

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