Lawn Diseases


Anthracnose Foliar Blight and Basal Rot

(Colletotrichum graminicola)

Anthracnose foliar blight appears as irregular yellow or bronze patches of diseased turf. Symptoms on individual plants first appear as yellow or red lesions on the oldest (outermost) leaves, then progress to a blighting of younger leaves and shoots. Occasionally, fungal fruiting structures called acervuli can be observed with a good quality hand lens on diseased leaves and stems. Acervuli resemble small, black pin cushions and are the location of spore production. [Read more…]

Brown Patch

(Rhizoctonia solani)

Brown patch is a major summer disease of lawns and golf courses. The most susceptible grass species include perennial ryegrass, tall fescue, and the bentgrasses. Occasionally, brown patch becomes a problem on Kentucky bluegrasses in mid- to late-summer during extended periods of high temperature and humidity. [Read more…]

Damping-off Diseases

(Pythium, Rhizoctonia, and Fusarium spp.)

Damping-off diseases occur as seed rots and blights of seedlings. This disease seldom occurs on grass planted in early fall or early spring. However, in seedings from May to August, especially if hot, wet weather persists, seed may decay prior to germination, or new seedlings may become diseased and die. [Read more…]

Dollar Spot

(Sclerotinia homoeocarpa)

With regular watering of home lawns throughout much of the growing season, many turfgrass diseases, once problems only on golf courses and recreational turf areas, now appear commonly. Perhaps the most important of these is dollar spot.  On golf course greens cut at or below 5mm, this disease appears as white or tan spots of dead turf about the size of a silver dollar. Hence the name dollar spot. On home lawns cut at 25-75mm, dead areas may reach 50-100mm in diameter. [Read more…]

Fairy Ring

(Various Basidiomycetes)

Fairy rings typically appear as rings of dark green and fast-growing turf. They may also appear as rings of slow-growing or killed turf. The bands of affected turf are from 100-300mm in width, forming more or less continuous rings ranging from 1-60m across. In some instances, the center of a stimulated band may contain weakened or dead grass, or bands may have an inner zone of stimulated grass edged with dead or stunted turf on either side.  [Read more…]

Fusarium Patch

(Microdochium nivale)

Fusarium patch are diseases caused by the fungus Microdochium nivale. The causal organism of these diseases, Microdochium nivale, was formerly known as Fusarium nivale. To avoid confusion, Fusarium was retained as the disease name. Pink snow mold is a true snow mold since it develops under snow cover. [Read more…]

Leaf Spot and Melting-out Diseases

(Bipolaris, Drechslera, and Exserohilum spp.)

Leaf spot and melting-out diseases are incited by a group of fungi in the genera Bipolaris, Drechslera, and Exserohilum. These fungi used to be referred to as Helminthosporium and many individuals still use this name for convenience. Every cool-season grass species probably has a leaf spot/melting-out disease associated with it, but Kentucky bluegrass is particularly susceptible. [Read more…]

Necrotic Ring Spot

(Leptosphaeria korrae)

Necrotic ring spot is one of three patch diseases caused by root pathogens that are problems of cool-season turfs. The other two are summer patch of bluegrasses and fine fescues and take-all patch of creeping bentgrass. Though not all caused by the same fungus, these diseases have similar patch-type symptoms, the causal fungi are related and similar in appearance, and these fungi attack grass roots and crowns in a similar manner. [Read more…]

Powdery Mildew

(Erysiphe graminis)

This fungus first appears as isolated wefts of fine, gray-white, powdery growth on the upper surface of the grass leaf. This growth rapidly becomes more dense and may cover the entire leaf, giving the leaf a gray-white appearance. In severe outbreaks, entire portions of the turf stand may be dull white, rather than green. Individual leaves look as though they are covered with flour or white powder. [Read more…]

Pythium blight

(Pythium blight) 

Pythium blight, also known as grease spot and cottony blight, can be a highly destructive turfgrass disease, especially on bentgrasses and ryegrasses. Severe outbreaks can completely destroy the turfgrass within a few days if weather conditions favor disease development. [Read more…]

Red Thread and Pink Patch

(Laetisaria fuciformis and Limonomyces roseipellis)

These two diseases present similar symptoms and appear as irregularly shaped patches of blighted grass. From a distance, affected areas have a reddish or pinkish cast. These diseases are usually restricted to the leaves, leaf sheaths, and stems, but in severe cases, may kill the entire plant. In the early stages of infection, symptoms appear as small blighted areas on leaves that enlarge rapidly to cover most of the leaf. Affected leaves dry out and fade to a bleached straw color. [Read more…]

Rust Disease

(Puccinia spp)

There are a number of rust diseases that affect turfgrasses. A few of the more common rusts that occur on cool-season grasses include stem, stripe, crown, and leaf rust. Although there are differences among these diseases with respect to the symptoms and portion of the plant affected, they generally occur under the same environmental conditions. [Read more…]

Slime Molds

(Mucilago, Physarum, and Fuligo spp.)

Slime molds are different from most other turfgrass pathogens in that they do not directly infect the plant. Instead, this group of organisms feeds on microorganisms and decaying organic debris. During periods of warm, wet weather, slime molds migrate onto the surfaces of turfgrass leaves where they produce massive amounts of their reproductive structures, thus producing a white, blue, or gray patch. [Read more…]

Summer patch

(Magnaporthe poae)

Summer patch, sometimes called Poa patch, occurs on Kentucky bluegrass and fine fescues on lawns and grounds, and on annual bluegrass on golf course greens and fairways. Symptoms of summer patch on lawns, grounds or golf course fairways appear identical to necrotic ring spot. Hence, diseased specimens may have to be examined by a qualified diagnostician if positive identification is necessary. [Read more…]

Take-all patch

(Gaeumannomyces graminis)

This disease has been called Ophiobolus patch or Gaeumannomyces patch. Only bentgrasses are susceptible, so it is seen most commonly on golf course greens and fairways, where it can cause serious turf losses. [Read more…]

Yellow patch

(Rhizoctonia cerealis)

Yellow patch, which sometimes is referred to as cool temperature brown patch, occurs primarily on bentgrass and annual bluegrass putting greens, but may occasionally be found on Kentucky bluegrass lawns. [Read more…]