bluegrass originated from a single plant that developed from one of countless millions of bluegrass seeds sown over the years on the Merion Golf Club, Ardmore, Pa. That plant thrived and spread on the seventeenth tee until it formed a pure solid turf, which caught the eye of the golf course superintendent. A patch of the turf was sent to Arlington Farm, Va., in 1936. It was later transferred to Beltsville, Md., where it was extensively tested until 1950, when it was made available.

The consistent failure of common Kentucky bluegrass to form good turf under close mowing is an example of how mowing weakens a grass and causes a condition favorable to disease attack. The leaf spot fungus weakens and kills so many of the common bluegrass plants that open areas are produced, which afford favorable situations for crabgrass seedlings to develop rapidly.

H. vagans, the fungus that is destructive to the common Kentucky bluegrass, likes cool, wet weather; it is therefore more active in spring and fall. When hot weather (which is unfavorable for bluegrass) follows, the weakened turf cannot compete with weed invasion, especially crabgrass. Thus a fungus disease played an important part in producing conditions that made it necessary for researchers to initiate and develop a crabgrass control program with chemicals. Merion bluegrass turf, which is resistant to leaf spot, consistently contains less crabgrass than turf of common bluegrass grown under identical conditions. Since it is resistant to weed invasion, it produces a more attractive turf of better quality. The new bluegrass produces more vigorous rhizomes than the common bluegrass, and it can therefore spread faster. Merion bluegrass is more tolerant to heat and drought than were the other strains. The seed of Merion bluegrass is shorter and plumper and lacks the usual brown color found at the base of the common bluegrass seed. Seed experts are thus able to distinguish it from seed of other bluegrasses. Merion is not a "miracle grass" but it does give the home owner a better opportunity to have a lawn free of weeds, one that requires less irrigation and fewer mowings.

Since Merion bluegrass is not a heavy seed producer, it is taking somewhat longer than usual to increase the seed. It is expected that seed supplies will be ample within a few years and the prices will be much lower. Even at present prices, however, it costs very little more to establish a Merion bluegrass lawn as the recommended rate of seeding is much less than for common Kentucky bluegrass. The American Society of Agronomy's 1951 Turf Committee has recommended I pound of seed to 1,000 square feet or 44 pounds an acre as the maximum rate of seeding for Merion bluegrass.

The development of Tifton 57 Bermuda-grass by the Georgia Agricultural Experiment Station, the Department of Agriculture, and the United States Golf Association Green Section is another step toward better turf. It is a narrow-leaved strain and is resistant to a severe leaf spot and crown rot caused by a species of Helminthosporium.

U-3 Bermuda-grass is another improved selection. It is a fine-bladed, cold-hardy strain, which although discovered in Savannah, Ga., has found favor within the northern limits of the southern grass-growing areas where Bermuda is not expected to survive. It is finding increasing use in such sections as New Jersey, Maryland, Virginia, Missouri, Kansas, Oklahoma, and California. It requires close, frequent mowing and generous fertilization, but very little irrigation.

Meyer (Z-52) Zoysia is another promising disease-resistant grass that has shown up well under tests. It is an improved warm-season grass. It was developed by the United States Golf Association Green Section and cooperating agencies and named in memory of Frank N. Meyer, a Department plant explorer.

Meyer Zoysia is drought-tolerant. It needs less irrigation than do most grasses. It will grow on almost any soil. It is easy to mow when cut regularly and requires less mowing than many other grasses. It can be cut at heights of one-half inch to 4 inches without loss of vigor. It produces a firm, resilient turf which is very resistant to wear. It also does well in association with Merion bluegrass. Meyer Zoysia is a warm-season grass so it will be more useful for planting in the southern half of the United States, although it has lived in plots as far north as Massachusetts and Michigan. It has some undesirable characteristics. Like Bermuda-grass, Meyer Zoysia loses its green color in late fall after the first or second killing frost, but regains it in the spring about the time the weather is warm enough for people to begin using their lawns.

No seed of Meyer Zoysia is available, so vegetative planting by plugs of sod or sprigging must be done. Plugging or sprigging is done in the spring or late summer, the preferred time of planting.

BROWN PATCH, caused by the fungus Pellicularia filamentosa (Rhizoetonia solani), may attack susceptible turf wherever high temperatures and humidity prevail. It makes roundish areas that are 1 inch to 3 feet across or may extend over an entire putting green or large portions of lawns. The grass first turns dark and the leaves wilt. Gradually the area becomes light brown as the leaves die. When the fungus is growing actively, it produces grayish or black mycelium among the grass blades like a smoke ring. If the climatic conditions remain favorable and affected areas are not treated, the fungus will kill the grass to the point where reseeding may be necessary.

Brown patch has been controlled by a combination of mercury chlorides; 1 part corrosive sublimate to 2 parts calomel. Phenyl mercury acetate and lactate at dilutions of 1 1/4 ounce (10 percent active ingredient) to 5 gallons of water per 1,000 square feet applied as sprays are partly effective. A wettable thiram known as Tersan has been widely used.

Dollar spot, once known as small brown patch, is caused by the fungus Sclerotinia homoeocarpa. The injured spots are dark and water-soaked at first. Then they turn brown. Later they become straw-colored and are about 2 inches in diameter. The spots are usually regular in size and shape, but in cool, humid weather they may be so close together that they may merge into large, irregular areas of dead turf. When the fungus is actively growing in turf, a fine, white cobwebby mycelium may be observed in the early morning when the dew is still on the grass blades. In mild attacks of the fungus, only the uppermost grass blades may be injured. If the disease spread is checked then, the turf will recover quickly. When, however, the fungus is permitted to develop until all the leaf blades in an affected spot are destroyed, it may take many weeks for new grass to fill in the dead areas sufficiently to cover the scars of the disease.

The mercury chlorides, calomel and corrosive sublimate, are old standbys. The newer cadmium-containing fungicides, Cadminate, Puraturf 177, and Crag 531, are now recommended. Monthly applications of the cadmium compounds during the growing season are usually sufficient because of their good residual protection. The phenyl mercurials, Puraturf and PMAS, are effective but are apt to cause injury unless carefully applied.

Spot blight (grease spot or pythium blight) causes injury that appears in early morning as a circular spot surrounded by blackened grass blades, which are intertwined with mycelial threads of the causal fungus. The dark grass blades are water-soaked but soon either, becoming reddish brown, especially if the weather is sunny and windy. The spots, usually not more than 2 inches in diameter, generally occur in groups. They tend to form streaks apparently the fungus is spread by the mower or because of water in poorly drained low places. The disease can be very destructive in periods of high temperature and humidity, especially on poorly drained turf areas. Spot blight is usually more injurious to newly established turf, but if all conditions are favorable it will attack turf of any age. A sudden drop in temperature and a dry atmosphere checks its spread.

No satisfactory control measure has been developed for spot blight. Corrosive sublimate applied as a spray helps somewhat in checking it. One pound of iron sulfate in 30 gallons of water, applied to 5,000 square feet, may be worth trying. Copper sulfate at 3 ounces to 1,000 square feet gives partial control.

Copper spot makes coppery or orange areas, which usually are 1 to 3 inches in diameter. Close examination of the affected grass blades with a magnifying glass will reveal characteristic salmon-pink spore masses of the causal fungus, Gloeocercospora sorghi. The fungus seems to be active on grasses when the acidity of the soil is between pH 4.5 to 5.5.

The cadmium compounds are satisfactory in checking copper spot. The phenyl mercury formulations also are effective.

Snow mold is caused by several fungi, among them Typhula itoana and Calonectria n1valls (Fusarium nivale). They grow and spread beneath the snow cover, as the snow melts, or during winter rains. The first symptom is a dense, cottony growth of mycelium that covers patches of turf. The patches are 1 to 12 inches or more in diameter. Although it occurs as far south as Virginia, the disease is more prevalent in the northern part of the United States. Snow mold is usually more severe on greens located in low places or pockets and in places that have a deep covering of snow for long periods. The borders of greens are most often severely injured. Seaside and Highland bents are very susceptible.

Applications of mercury chlorides at the rate of 2 to 4 ounces to 1,000 square feet before the first snow is forecast, and again during a midwinter thaw, have given satisfactory control.

Bluegrass leaf spot first shows small, brown, round to elliptical specks. The cause is the fungus Helminthosporizim vagans. The spots enlarge and may extend the width of the infected leaf. The tissue in the center of the lesion dies and turns a straw color. A purplish-brown border may surround the straw-colored center. If the weather is cool and humid, spores are produced on the lesions and spread to other plants. Under favorable conditions, the lesions enlarge and may coalesce, involving most of the tissue of the leaf blade. The fungus may then spread to the leaf sheaths and to the crown of the plant, causing a crown and foot rot. The latter stage of the disease kills the grass plant, thins the turf, and leaves a bare spot for weeds to get started. Bluegrass leaf spot occurs wherever bluegrass grows. It is most severe in the spring and fall on grass that is closely clipped.

Merion bluegrass, which is resistant to leaf spot, offers a means of control. Fertilizing the bluegrass to stimulate new growth and raising the mower blades to allow longer leaves to develop will help overcome the disease.