zoysia grass
Updated: August 16, 2022

Dead patches or brown spots are common symptoms of a lawn problem. However, they can be caused by disease, insects, or an abiotic issue like dog urine or fertilizer burn making a diagnosis challenging. 

Problems with the general appearance of the grass

Symptoms Possible Cause Management/Comments
General straw-colored or browning of cool-season turfgrass cultivars or turf appears dry and bluish-green in color.
 
Drought - first signs will be evidence of footprint impressions and lighter green or gray color of turf.
 
Cool-season turf cultivars will recover when rain or irrigation increases soil moisture
 
Rings or arcs of dead or green grass and mushrooms may be present.
 
Fairy rings -  rings or arcs of dead or green grass bordered by zones of darker green grass. More common on droughty sites and poorly nourished turf. Occurs on all turf cultivars year-round.

 

Aerate turf in fall,  maintain adequate
nitrogen fertility and adequate water during dry spells.
 
Circular, straw-colored patches. Summer patch - circular patches that range from 3 - 12 inches in diameter.
This disease occurs in bluegrass and fine fescue lawns 2 years or older, July through September.
 
Avoid excessive nitrogen especially in
spring. Use slow release nitrogen sources.
Increase mowing height, avoid light
frequent waterings and reduce thatch
build-up.
 
Irregular brown patches with white moths flying over the turf.
 
Sod webworms - brown caterpillars may be found at the base of the blades and in the thatch. Active from May through September.
 
Reseed damaged grass with tall fescue, or spray
with Bt insecticide that targets the caterpillars.
 
Straw colored patches surrounded by a ring of dark green turf. 
 
Dog urine - can resemble some diseases.
May kill the crown tissue (the growing point of a grass plant).
 
Heavy irrigation of the spots will promote recovery. Spot reseeding may have to be
done.
 
Banded streaks or irregular patterns. Fertilizer or chemical injury - grass may be stimulated at the margins. May kill the crown tissue.
 
Calibrate spreaders and sprayers for uniform and accurate application of materials. Do not fill spreaders on grass. Sweep any fertilizer that falls on hard surfaces back into the grass after filling the spreader. 
 
A large yellow area in grass near or downstream from a pool.
 
Chlorine damage - from pool water

Leach chlorine through the soil with water. Replant the damaged area.
 

Problems on individual leaf blades

Symptoms Possible Cause Management/Comments
Pale green to golden yellow turf blades. Chlorosis - iron or nitrogen deficiency.
Yellow streaks may form parallel to the leaf
veins.
 
Maintain adequate fertilizer levels.
Grass over high spots looks scalped.
 
Mower injury - crowns of plants exposed.
 
Raise mowing height or change mowing
direction.
 
Shredded leaf blade tips. Dull mower injury - tips appear gray and then turn tan. Sharpen mower blades.
Pink/reddish color on leaf blades. Red thread - pinkish- red, thread-like growths extending beyond leaf blades. The disease appears in patches and occurs in spring and fall on fine and tall fescue and perennial ryegrass species.
 
Maintain adequate nitrogen fertility levels.
Leaf blades covered with red, orange, or yellow powdery material. Rust diseases - turf may appear yellow or reddish from a distance. Occurs primarily on bluegrass, ryegrass, and zoysia.
 
Maintain adequate nitrogen fertility levels and reseed infected areas if necessary.
 
Leaf blades covered with a white coating. Powdery mildew - white coating, typically occurs in shady areas in the fall on bluegrass and fescue.
 

Reduce shade and improve air movement.  Avoid excessive nitrogen and drought stress.

Leaf blades covered with black sooty-like material.
 
Slime mold - not harmful. It is easily wiped off or removed. Blades remain green underneath. Occurs primarily in spring or fall after rain.
 

Wash off sooty material with a  hose or remove material by mowing.


 
Leaf/Blade spots Brown patch - elongated fungal lesions with chocolate brown margins. Entire leaves may turn brown and thinning may occur. Occurs in mid-summer, especially on tall fescue during periods of high daytime and evening temperatures and high humdidty.
 
Tall fescue turf maintained at proper
mowing heights and fertility rates will
recover in the fall. Some reseeding may be necessary in the fall to repair bare spots. 
 
Leaf/Blade spots Dollar spot - leaf lesions with a dark border and hour glass shaped spots.
Disease affects all turfgrass species.Common in late spring and in fall on turf with low fertility.
 
Avoid drought stress. Prevent thatch
buildup and soil compaction. Maintain
adequate nitrogen fertility and reseed damaged areas in the fall. 
 

Miscellaneous Issues

Symptoms Possible Cause Management/Comments
Black greenish crust on soil. Algae growth - on bare soil or in thin turf. Occurs in poorly drained or compacted areas, usually more severe in shade
 
Increase drainage and establish a thicker
stand of turf. Aerate compacted areas and
increase sunlight in shaded areas
 
Small green plants growing with turf. Moss - on bare soil or in thin turf. Occurs in poorly drained or compacted areas, usually more severe in shade.
 
Increase drainage and establish a thicker stand of turf. Aerate compacted areas and increase sunlight in shaded areas. Or plant a lawn alternative because it will be easier to maintain than grass in a shady are
 
Turf comes up easily, obvious lack of roots. White grubs - turf can sometimes be rolled up like a carpet. C-shaped grubs found in soil primarily from April - May (these do not cause lawn damage), and late August - September. Can be severe on bluegrass, ryegrass, and fine fescues.
 
Reseed the lawn in the fall with a tolerant turf species such as tall fescue or zoysia. Reduce lawn irrigation when beetles are flying in mid-summer. Adult beetles prefer to lay eggs in moist soil.
 
Numerous bees flying close to the ground.
 
Ground bees - small, fuzzy bees, nest in loose soil. Often in banks or road cuts. Not aggressive
 
Males have no stinger. They establish a mating territory and only appear
threatening. They are only around for a few weeks. No control necessary. They prefer areas of bare, sandy soil. Add a soil amendment and reseed the area. 
 
Mounds of soil in gravely or bare areas in turf. Cicada killers - large, black wasp with yellow markings on abdomen, hover above the lawn, nest in loose soil. Not aggressive.
 
Control generally not necessary. 
Blue-black wasp flying over lawn
during the day.
 
Scoliid wasps - 5/8 inch long, blue-
black wasp, yellow stripe on each side of abdomen. Not aggressive. They reduce grub populations. 
 
Parasites of white grubs. Do not attack people. Control not necessary. Adults often seen visiting goldenrod flowers in late summer.
 
Trails of raised soil running along surface of the lawn.
 
Moles - harmelss, have hairless pointed snout, small eyes, and no ears. Fore feet are large with webbed toes. 
 
Flatten tunnels. Tunnel below ground, feed on grubs, beetles, other insects. Help aerate soil.
1-2” inch diameter holes in ground.
1-2” runways may be visible on
surface.
 

Voles (meadow vole or pine vole) - mice- like with shorter tails and small ears. Meadow voles have surface runways, and pine voles have underground tunnels.

Often a problem in orchards and ornamentals. Keep lawn mowed. Flatten tunnels and use mouse traps. Move mulch away from base of trees. Pile mulch no more than 1” deep.
 
Cone shaped holes in ground. Turf may be Pulled up in patches.
 
Skunks - feed on grubs and other insects in lawns. Rake to level the soil and reseed in the fall or early spring.
Lawn is torn up in areas.  Raccoons - feed on grubs and other insects in lawns. Rake to level the soil and reseed in the fall or early spring.

Based on HGIC publication HG 63 IPM Series: Turf, authors: Dr. David Clement and Mary Kay Malinoski (retired), University of MD Extension Specialists.

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