Common Lawn Problems

PESTS

FUNGUS

WEEDS

LARVAAE

EUROPEAN CRANE FLY

ADULT

The adult stage of these pests looks like a giant mosquito with a wing span of more than an inch. Adults emerge in August and September and may be seen in or near infested lawns in large numbers.

They prefer moist soils, so are most likely to be found in irrigated turf, although most years we have enough rain for them to develop in almost any lawn. The adults fly, mate and lay eggs in August and September.

The larvae, called “leatherjackets,” grow to become nearly an inch-long and look like a brown caterpillar with no head or legs.

In October, the leatherjackets consume enough turf roots, stems and leaves to cause visible injury to lawns or golf courses. Turf damage begins to appear as a general thinning of the infested turf, but may progress to large dead patches.

Nearly mature larvae (caterpillars) overwinter in the soil and resume feeding in the spring (late April-early May) as temperatures begin to rise. Occasionally, damage will occur in the spring from overwintered webworms.

Adults begin to emerge in late May and early June and can be seen flying across lawn at dusk or just after dusk. Adult moths rest during the day in deep grass, ground cover, or in shrubbery. Females may drop up to 200 eggs in the grass while they are flying.

SOD WEBWORM

Eggs hatch in 5 to 10 days and the young larvae begin feeding in the soft areas between the veins of grass blades. After a short time the larvae become large enough to consume small portions of the grass blade so that the damaged leaves may appear notched. Later, the mature larvae construct silk-lined burrows in the thatch and begin to chew grass blades off just above the thatch line and pull them into their tunnels to consume.

Pupation takes place in late June to early July and second generation adults are usually observed shortly afterward.

Dollar Spot — Sclerotinia homoeocarpa

Leaf Spot — Bipolaris sorokiniana

Red Thread — Laetisaria fuciformis

Rust — Puccinia striiformis

Dollar spot is characterized by round, bleached-out or straw-colored spots, ranging from the size of a quarter to the size of a silver dollar. Spots appear as sunken areas in the turf, especially low mown turfgrass (0.5 inches or less). Fluffy white mycelia can be seen when fungus is actively growing during morning periods of heavy dew. Symptoms on individual grass blades appear as bleached-out or tan lesions that are often accompanied by reddish brown bands present at the outer edge of the leaf lesion (except on annual bluegrass).

Dollar spot occurs when daytime temperatures are between 59-88° F (15-31° C) and disease development is favored by warm, humid weather followed by cool nights that produce heavy dews

Symptoms first appear as small dark purple to black colored spots on the leaf blade. As the spots enlarge, the centers often turn light tan. In warmer temperatures (> 85° F), the entire blade often appears dry and straw colored. The disease is mostly confined to the leaf blades during the cool weather, but can infect leaf sheaths, crowns and roots during hot, humid weather.

Leaf spot is a warm-weather disease, but the pathogen overwinters as dormant mycelium in infected plants and dead grass debris. Leaf spot can become evident when temperatures reach 70° F (21.1° C). The disease is most severe when temperatures are above 90° F and humidity is high.

Red thread is a disease of slow growing turf. Red thread is easily recognized by the red to coral-pink fungal strands (stromata) produced on leaf blades and sheaths. When turf is wet, the fungal stroma looks gelatinous and fleshy. As the grass dries, the stroma also dries and becomes thin and thread-like. Infected turf often appears to be suffering from lack of water, often times symptoms resemble dollar spot. Under close examination of the grass blades reveals red to coral-pink stromata. Under conditions of high humidity, pink cottony flocks of arthroconidia can be seen in the patches.

Red thread occurs is favored by high humidity at temperatures between 60°-90° F (15.5° and 32° C). Cool, drizzly days of spring and fall are ideal for the development, and the disease spreads from plant to plant by growth of the stromata. These can be spread by wind, and mechanical equipment.

Rust diseases are characterized by yellow to dark brown urediospore infestations that, from a distance, make turf stands appear orange or yellow. These rust-colored urediospores protrude through the plants epidermis causing spots that elongate parallel to the leaf or stem axis. When rust is severe, areas of infected turf appear thin, weak and are have a red, brown, or yellow tint. Heavily infected plants may wither or die from excessive loss of moisture from rusted leaves.

Crabgrass

Yellow Nutsedge (Cyperus esculentus L.)

Wild Violet (P) — Viola papilionacea

When spring soil temps (at a depth of 2"-3") reach 55-60 degrees Fahrenheit, the first crabgrass seed will germinate. From mid-summer to fall, seeds are produced. The plants, themselves (but not the seeds) are killed by frosts in autumn.

Yellow Nutsedge (Cyperus esculentus L.) is a common weed found in many home lawns and other turf grass areas. The color, growth habit, and rapid growth rate make yellow nutsedge a prominent distraction in the aesthetics of high quality lawns.

Yellow nutsedge is distinctive and relatively easy to identify. The stems are erect, triangular-shaped and yellow-green in color. The leaves are also yellow-green, wide (0.38 to 0.50 inch) bladed with a thick mid-vein and a very waxy covering. The shallow, fibrous root system often produces many nut-like tubers, which are underground food storage organs. Each of these tubers can germinate and produce new plants. Each new plant can also produce rhizomes which can give rise to additional new plants.

Wild violet is a low-growing clumping perennial with a dense, fibrous root system and heart-shaped leaves that often cup toward the petiole to form a funnel shape. Wild violet is often considered difficult-to-control due to its aggressive growth, waxy leaves and resistance to most common herbicides.

Wild violet is most often found in shaded, fertile sites and prefers moist soils.

Flowers occurs in mid-May; usually violet colored, but can vary from deep-blue-violet to completely white. Plants spread by rhizomes and seed.