The chart below outlines brief descriptions of symptoms of problems that might occur in your lawn. The chart includes problems from disease, insects, and pest animals and in each case leads you to a more detailed discussion of each item.
There is considerable discussion about lawn problems in the following files you may wish to review:
Dealing With Pest Insects In Lawns
Dealing With Weeds In Lawns
Dealing With Disease In Lawns
Dealing With Lawns In The Shade
| Occassional Problems In Lawns | |
|---|---|
| Symptom | Probable Cause |
| Circular patches of dead grass 1” to 3” across and larger. After snow melt, grass may be covered with white to pink mold. During late winter or in early spring. | Pink Snow Mold (Fusarium Patch) |
| During the heat of the summer, reddish-brown circular spots in the lawn 2 to 6 inches in diameter indicate Fusarium blight. Eventually the spots turn tan, then yellow, and increase in size until they grow together. Healthy turf may grow in the center of each infected circle, giving it a characteristic “frog’s-eye” look. Roots and crowns of grass plants are rotted. | Fusarium Blight |
| This fungus appears as tan or straw-colored spots the size of silver dollars. It thrives on dry, undernourished lawns. Small, white, cobwebby spots appear in the morning and turn brown later in the day. Infected areas may increase in number but they rarely grow together. | Dollar Spot |
| Large discolored patches surrounded by “smoke rings” in June, July or August. Especially on Tall Fescue or Perennial Ryegrass lawns. Kills oval to circular areas of grass up to 2 feet in diameter. Inside the patch, the grass dies and stays upright. A few plants of green grass may remain. | Brown Patch also called summer patch |
| In spring or fall on newly seeded lawns, blackened, water-soaked patches of flattened grass blades 2 to 6 inches in diameter enlarging to 2 feet across. In humidity, the diseased areas may also develop visible cottony fuzz. Grass usually dies in 24 hours, and new grass does not grow in denuded areas. | Pythium Blight |
| In late spring or early summer circular or irregular patches of scorched grass and fine red or rusty threads sticking up from diseased grass blades and stretching from leaf to leaf indicates red thread | Red Thread |
| In the spring or in fall, bright-green circular areas in the lawn growing more rapidly than the rest the turf suggests that the grass is infected with one or more species of fairy ring fungi. The zone of over-stimulated growth may be 4 to 12 inches wide, but the ring itself may reach 50 feet across. Eventually the overgrown patches of grass decline, and a circle of mushrooms often develops around the infected area. | Fairy Ring |
| In the spring or fall, a pale green cast and stunted growth of grass blades are signs of leaf smut, also called stripe smut. On individual blades, narrow gray or black stripes develop, which rupture and release masses of spores. The infected blades curl, tear easily and look shredded. If you drag a white cloth across the infected grass, it will be discolored by the black spores. | Leaf Smut |
| In the early spring or late fall reddish-brown to purplish-black spots with pale centers on grass blades are caused by leaf spot fungi. The spots develop on the blades, stems and crowns. Eventually the blades shrivel, crowns and roots rot and die and then irregular patches of thin grass develop in the lawn. | Leaf Spot |
| A thin white or grayish powdery coating on grass blades is a sure sign of powdery mildew. It often occurs in shaded areas when nights are cool and humid. Severe infection causes the grass to turn yellow and die. | Powdery Mildew |
| In late summer, rust disease first appears on grass blades and stems as small orange to reddish-brown powdery pustules. As they mature they turn from brown to black. Heavily infested turf becomes thin with an overall yellow-orange to reddish-brown color. Infected leaves turn yellow, wither and die | Rust |
| Slime mold first appears as white, yellow or gray puffy or slimy growths on grass blades, forming powdery puffs as they dry. Usually this growth appears in area of the lawn that is moist, shaded, and has poor air circulation. | Slime Molds |
| Mushrooms emerge through turf | Buried Wood |
| Mounds appear in middle of lawn and kill grass | Ants or Moles |
| In the fall you may see round, bare areas in the lawn. Armyworms look like caterpillars and can appear in large numbers, and will eat the grass right down to the soil. Armyworms usually feed at night. The damage they do resemble that caused by sod webworms. If you lift up the dead sod in these areas, you'll find armyworms in the soil. | Armyworm |
| In June or July damage is noted where the grass appears brownish or there may appear small circular patterns that turn yellowish and brown. Dead sections of grass will lift away easily from soil. | Billbug |
| In August and early September, suspect chinch bugs when you see large, distinct, circular patches, primarily in the sunny areas of your lawn, that turn yellow, then brown, and then die. These patches often first appear near sidewalks, driveways, streets, and other borders such as railroad ties or flagstones that reflect heat onto the lawn. The yellowish spots eventually spread outward into the rest of the lawn, showing the greatest damage at their centers where the chinch bugs congregate. | Chinch Bugs |
| Usually you don’t see fire ants first; you feel the stings | Fire Ant |
| Cats and dogs bring fleas in from outside, you see them in rugs and on white socks | Fleas |
| In late spring the webworms’ feeding causes small brown patches, 1 to 2 inches in diameter, to appear in the lawn where the thatch layer is exposed. These dead patches may be round spots or may look like lightning bolt streaks running across the lawn. By midsummer the damaged areas join together into larger patches. Infested lawns look their worst by July and August. | Sod Webworm |
| Grass seedlings in newly seeded lawn disappear, cut off at the base of the grass blade | Cutworm |
| Starting in June or early July you see irregular brown patches of grass. Increasing gradually over the season, the brown spots are most extensive by fall after a full season of grub activity. Suspect a grub problem where turf appears scorched. The sod lifts up easily in these spots because the roots have been destroyed. | Grubs |
| Areas of lawn turn brown and die; small mounds of soil become evident | Mole Cricket |
| Raised ridges of turf from shallow tunneling of moles. The grass dies on top of the ridges of the tunnels | Moles |
| In winter time when snow cover melts you see paths of dead grass | Voles |
| Conical shaped holes in the lawn | Skunks |
| Grass looks chewed and patches disappear; droppings are obvious. | Geese |
