Cool-season perennial grasses are used successfully as lawn grasses in higher altitudes where irrigation is available. Cool-season grasses are also used in combination with established bermudagrass to provide year-round green lawns.

This is a cool-season or northern turfgrass. However, if managed correctly, it is tough enough to tolerate southern summers and be used as a permanent lawn. Tall fescue is from Europe and is one of the most heat- and drought-tolerant northern grasses. It is a bunch grass and spreads by tillers; thus, it requires little edging and will not invade flower or shrub beds.

Tall fescue’s greatest advantages are its ability to grow well in fairly dense shade and that it can survive winters in the South without any problem. Plus, it stays green all winter. Tall fescue grows at its highest rate during spring and fall. Watering every 3 or 4 days during summer should be sufficient to keep it from going into summer dormancy. Water helps keep the soil cool. However, additional watering increases the potential for disease. Mowing at 2 inches or higher keeps the growing point cooler.

The old standard tall fescue variety is K-31 which is still available. However, many new varieties with finer blades and improved heat and shade tolerance are available, including Olympic, Rebel, Falcon and Houndog. For best results, a blend of three or four different Tall Fescues is recommended.

Perennial ryegrass and annual ryegrass are suited for temporary cool-season turfgrasses.

The ryegrasses are fine-leaved bunch grasses that spread by above-ground tillers. They are best adapted to cool, moist environments which are not found in New Mexico. In the United States, the northeastern and northwestern states are well suited to ryegrass. In the transition zone, perennial ryegrass may provide a permanent turfgrass. But in New Mexico, both species serve as cool-season annuals.

Ryegrasses are adapted to a wide range of soil conditions, but favor moist, well-drained, fertile soils. The ryegrasses possess little drought tolerance and must be irrigated during dry periods to ensure survival. Shade tolerance of the ryegrasses is good in southern climates where shade conditions reduce the extreme heat during summer. Perennial ryegrass often survives the hot, dry summers of the South in moderately shaded sites.

Both species of ryegrass are used for temporary grass cover during the fall and winter months in New Mexico. Their quick establishment from seed (rapid germination and rapid seed growth) makes them ideal for protection against erosion on newly prepared sites in the fall. They are also used to provide temporary green color during winter months when bermudagrass is dormant.

The ryegrasses have become very popular for overseeding athletic fields, golf courses and lawns during winter months. The improved turf-type perennial ryegrasses have greater cold tolerance, wear tolerance, disease resistance and persistence than the annual types. New varieties also have better turf characteristics -- finer texture, greater density, darker color and better mowing qualities.

At least 50 improved ryegrass varieties have been developed over the past 20 years. Most improvements have been in perennial ryegrass, although intermediate crosses have been made with annual ryegrass. Improvements in turf quality have been in the following areas:

Density, texture and color (Pennfine, Manhattan and Derby).

Mowing quality (Palmer, Manhattan II, Delray and Loretta).

Heat tolerance (Derby, Birdie, Palmer, Citation and Dasher).

Cold tolerance (Elton, Goalie, NK-200 and Norlea).

Disease resistance (Manhattan II, Palmer, Prelude and Delray).

Insect resistance (Repell).

Drought tolerance (Palmer and Prelude).

Kentucky Bluegrass can be established from either seed or sod. Sometimes Roughstalked Bluegrass, a finely textured, bright green perennial grass is mixed in shady lawn mixtures for its tolerance of shade, and damp soils along with creeping red fescue. Kentucky Bluegrass produces rhizomes but no stolons. These rhizomes help produce a thick dense turf. Leaf blades have a tip that is shaped like the front of a canoe. Leaves have a prominent midrib and fine obscure veins. Because Kentucky Bluegrass produces only rhizomes and no stolons, less thatch is produced than bermudagrass. Certain varieties of Kentucky Bluegrass are fairly shade tolerant, such as 'Glade' and 'Nugget'. Kentucky Bluegrass is sometimes sold as seed with other grasses. These may include fine fescue (for shade tolerance) and perennial ryegrass (used as a nurse or companion grass). Do not purchase seed of a Kentucky Bluegrass mixture which has 10% or more ryegrass seed in the mixture. Kentucky Bluegrasses are best planted in the fall in high desert locations or spring in mountain areas. Kentucky Bluegrass will not perform well in low desert areas, and should not be used in fall overseeding of bermudagrass lawns.

Three basic methods are available for establishing a turf — seed, sod or sprigs (stolons).

Regardless of the method chosen, preparation of the seedbed, sodbed or sprigbed is the same. Use a soil test to determine desirable seedbed fertilizer analyses and application rates. Production of a fine, firm soil surface is necessary for successful turf establishment.

The first step in preparing a new turf area is to remove all debris, such as stones, tree stumps and construction debris.

In many instances, the character of the soil must be altered considerable. A sandy loam soil high in organic matter is considered most satisfactory for turf. If the original surface soil is a heavy clay, it may be impractical to alter the nature of the soil, but organic matter can be added. This organic matter can be composted manure, well-decomposed sawdust (hardwood) or similar material. Organic matter must be thoroughly mixed in the top 4 to 6 inches of the seedbed. This mixing can be done by repeated cultivation operations such as rototilling. Also, the area should be graded properly to provide surface drainage.

The least expensive way to establish turf is by seed. The best germination temperature for cool-season turfgrasses is from 60° to 85° F. This means the best time to seed cool-season turfgrasses is in late summer to early fall. The second best time is in mid- to late-spring, but it’s better to seed in early fall as the soils are cooling down. New roots of cool-season grasses do not grow well in warm soil.

Warm-season turfgrasses are just the opposite of the cool-season turfgrasses in their reaction to temperature. The best temperature range for germination of warm-season grasses is from 70° to 95° F. Therefore, early summer is the best time to seed bermudagrass and other warm-season turfgrasses.

Not all turfgrasses produce seed, and if they do, they may not produce enough to be profitable or the seed may not "come true." This means that the plant produced from the seed will not necessarily look or act like the plant that produced the seed. These turfgrasses, such as Tifgreen Bermudagrass and ‘609’ Buffalograss, must be established by sprigs or by sod.

Seed quality can be evaluated by reading the seed test information that is required on every seed container. The seed test date should be current. Germination and purity should be as high as possible with a low weed and inert matter content. Buying certified seed insures that the variety you want is indeed the variety you are buying (Figures 4.4 and 4.5).

Although hand sowing can be satisfactory, the use of a small seed distributor is recommended. The seed should be divided into two equal parts, one broadcast as you walk back and forth in a given direction, the second sown as you walk back and forth at right angles to the first seeding. This method gives better distribution of seed.

Any turfgrass that spreads by a rhizome or a stolon can be grown and harvested as sod. Sodding is the most expensive way to establish turf. The best time to sod is when the turfgrass is actively growing. This means that the sod will root or knit down as quickly as possible. As with seed, certified sod is available and is the only real way to be sure the buyer is getting the stated variety.

A problem associated with using sod is the potential effect of differences between soil in the sod field and soil at the new site. If the sod is grown on soil containing a higher amount of clay and silt than the soil at the new site, a problem could develop. The sod may contain a very thin layer of soil that is physically very different from the underlying soil. This difference between the two soils can interfere with water drainage.

Lawns should be sprigged in the spring and early summer, though they may be plugged at any time during the growing season when adequate moisture is available. Sprigging is used primarily for establishing hybrid bermudagrasses.

The proper distance between sod blocks or sprigs depends on the rate of growth and on how soon a cover is desired. St. Augustinegrass plugs 2 to 4 inches in diameter planted on 2-foot centers should cover within three months if adequately watered and fertilized. Bermudagrass sprigged at 3 to 5 bushels per 1,000 square feet should cover within two months; zoysia may require an entire growing season. After sprigging bermudagrass and zoysia, the sprigs may be covered with a thin layer of topsoil or mulch. Press the sod blocks or sprigs firmly into the soil, and roll the soil to give a smooth surface for mowing.

When sodding a lawn, lay the sod blocks or rolls like bricks on a smooth surface that has been firmed. The surface should be free of footprints, stones, depressions and mounds. After the sod is laid, roll or tamp lightly and keep it moist until it is well rooted. Do not overwater! Topdressing with a sandy loam topsoil that is free of weeds, stones and other debris will help smooth the lawn.

Some turfgrasses that spread by stolons may be harvested and used to establish new turf. Sprigging costs more than seeding but less than sodding. Sprigs are sold by the bushel. A bushel of sprigs is equal to 1 square yard of shredded sod.

In the South, overseeding bermudagrass lawns for winter color is a common practice. The turfgrass used for this purpose is perennial ryegrass or annual ryegrass. Perennial ryegrass is generally the superior choice. The rate for perennial ryegrass is 4 to 5 pounds per 1,000 square feet, and the rate for Poa trivialis is 1 to 2 pounds per 1,000 square feet.

The most important issue associated with overseeding occurs in spring. Ideally, as the weather begins to warm and bermudagrass begins to "green-up," overseeded grasses should begin to die out. As overseeded grasses die, bermudagrass plants take their place. This is how it should work, but many times the weather does not get hot soon enough for the overseeding to die out quickly.

The presence of overseeding may act to suppress the return of the bermudagrass from dormancy, and the overseeded grasses may become weeds.

Perhaps the single most important cultural practice associated with lawn maintenance is mowing. When considering the possible effects of mowing on the turfgrass plant, remember that turfgrass is designed by nature to grow and mature at a height far in excess of the selected mowing height. The plant is forced to live at a much lower height. This must be done for the plant to fit the intended use. Mowing, in a sense, is not natural because it upsets the plants’ natural growth patterns.

To develop a good mowing program, one must know something about how the turfgrass plant functions. The first, or at least the most apparent effect of mowing, is the reduction of the plant’s leaf surface area. The leaf system manufactures and supplies the plant with carbohydrates. Carbohydrates to the plant are analogous to the food we eat. During the active growing months (spring and fall for cool-season grasses and summer and early fall for warm-season grasses), carbohydrate production is high, and the plant is able to store food reserves. During periods of stress or dormancy, the plant must draw on these reserves to survive.

Mowing at heights lower than optimum during periods favorable for carbohydrate storage for the specific turfgrass species may seriously impair the plant’s ability to develop adequate food reserves for stress or dormancy periods. The resulting death of the plant may falsely be attributed to heat or cold injury, when in fact the food reserves were not high enough to carry it through the period.

When part of the plant’s leaves are removed by mowing, its first priority becomes the re-establishment or replacement of its former leaf surface area. This flush of leaf growth requires carbohydrates and may reduce the supply of carbohydrates available to the root system for a short period. In the "pecking order" of the plant, the leaf system has priority over roots, rhizomes or stolons for carbohydrates. This demand for carbohydrates by the leaves after cutting may in fact result in a temporary reduction of root growth. The larger the amount or percentage of leaf tissue removed, the longer the root growth may be reduced.

Just as the amount of leaf surface removed has an effect on root growth, so does cutting height. There is a direct relationship between cutting height and total volume of the root system. The turfgrass plant, just like all other plants, develops a balance between its top parts and its root system. A certain size of root system is needed to support a certain volume of top growth and vice versa. If either the top parts or the root system is reduced, the plant reacts by reducing the other. When turfgrass plants are mowed, their top parts are reduced. The plant no longer needs the same size of root system, so for the plant to achieve balance, its root system is reduced. The more its top growth is reduced (i.e., the lower the cutting height), the shallower the root system becomes (Figure 4.6). A shallow root system may seriously impair the plant’s ability to withstand stress, especially drought stress.

Another important function of the leaf system is insulation. The growing points or crowns of most turfgrass plants are at or near the soil surface and are very high in the chemical activities that control growth processes. These areas of the plant are temperature sensitive. The upper optimum temperature range for cool-season turfgrasses is from about 60° to 75° F and for warm-season turfgrasses from about 80° to 95° F. When the temperature of the growing point goes above these ranges, the growth process begins to slow down. If the temperature of the growing point gets too high for a long enough period, especially with cool-season grass, the plant goes into summer dormancy.

The leaf surface insulates the growing point from high temperatures. As the leaf surface area is reduced, the amount of insulation available for the growing point is reduced. The lower the cutting height is from the optimum assigned to a particular variety, the more susceptible the plant is to high temperature injury. This is important when maintaining cool-season grasses.

Most turf areas, whether golf putting greens or home lawns, are subject to some degree of wear. The leaf surface area of a turfgrass protects the growing point of the plant from the direct mechanical injury associated with traffic. As the leaf surface is reduced, the overall wearability of the turf is reduced. Turfs cut at low heights are subject to high heat damage and may gradually thin out.

Mowing practices may also affect the occurrence of disease. Many times an increase in disease problems is observed with turf maintained below its optimum cutting height. This may be associated with the weaker type of turf plant that results from extremely low cutting heights.

Just as proper cutting height is important, so is the frequency at which the turf is cut (Table 4.4). Ideally, the frequency between mowing should be as long as possible to allow the plant to recover from the first cutting. Leaf growth rate and the intended use of the turf will, to a large degree, dictate mowing frequency. A single mowing should not remove more than one-third of the leaf surface; therefore, the application of nitrogen at high rates may force an increase in mowing frequency. This is especially true when high nitrogen rates are applied in a soluble form. For example, a golf course must be cut at fairly frequent intervals to provide a suitably dense putting surface. If, because of high growth rates, the frequency of mowing on other parts of the course becomes too frequent, the owner should consider adjusting both nitrogen rate and source. Slow-release nitrogen materials do not produce the lush, fast growth associated with soluble sources and thus should result in a longer period between mowings.

Selection of mowing equipment is dependent on a number of factors. Intended use of the area is at the top of the list. For example, a reel mower does a better job than a rotary mower at relatively low mowing heights. The cutting height used for a particular area can even affect the number of blades on a reel (Table 4.5). A rotary mower may do a much better job than a reel mower on lawns that have been assigned higher mowing heights because of the particular turfgrass variety.

In most turfgrass situations, clippings are not removed. Removal may be required when they interfere with the intended use of the turf (for example, a golf course putting green) or if they are too heavy and smother the turf. Generally, the shorter the clippings, the more deeply they fall into the turf and the more rapidly they decompose. Double cutting (running the mower over the same area twice) or using a mulching mower helps to shorten long clippings. Contrary to popular belief, clippings do not contribute to thatch. There is absolutely no need to pick up or remove grass clippings if a reasonable mowing program is followed. Mulching type mowers seem to be the mowers of the future because they produce the smallest clippings.

Mowing practices are extremely important in any turfgrass management program. Proper cutting height, proper mowing frequency and the development of a reasonable growth rate have a profound effect on the health and vigor of any turfgrass system.

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03/30/2002