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Chapter 8Turfgrass in

Tennessee

Learning Objectives1. Compare several important

turfgrass species and varieties

2. Explain terms when considering which turfgrass(es) to select

3. Describe the steps to prepare a firm, fertile and weed-free planting bed

4. Explain why the recommended seeding rate varies among turfgrass species

5. State the importance of adopting best management practices (e.g., timely mowing, fertilization, liming, irrigation, dethatching, mechanical aeration and topdressing) when maintaining turf

6. Explain what to consider when developing an effective turf fertilization program

7. Explain how successful renovation depends on proper timing, site preparation, seeding method and care after planting

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Tennessee Master Gardener Handbook 184

Despite there being more than 1,500 different grass species growing in the continental United States, only a few are classified as turfgrasses. Turfgrasses are plants that grow best in full sun and in nutrient-rich, well-drained soils. When main-tained at an appropriate height of cut in fertile, well-drained soil, a population of turfgrass plants controls erosion, produces oxygen, traps dust, cools the air and reduces glare. Many turfgrass species are long-lived perennials that tolerate drought, heat and cold. Short-lived turfgrass species are often used for rapid, tem-

porary erosion control or to over-seed dormant bermudagrass.

The management of turf can be divided into five major categories: selection, estab-lishment, maintenance, renovation and pest management. Four of the five are included in this chapter. Information regarding turfgrass diseases, insects and weeds, and their control, is presented in other chapters.

Selecting the Right TurfgrassSelecting a turfgrass that is adapted to the climate and the soil of a particular site is a very important part of any turfgrass management plan. The goal is to plant a variety or variet-ies capable of providing the desired quality at a reasonable maintenance level and cost. The challenge is that Tennessee is between the cool-humid climatic zone to the north and the warm-humid climatic zone to the south, therefore, no turfgrass is free of environmen-tal stresses. Thus, depending on the location, a warm-season or a cool season grass may be appropriate. For example, warm-season grasses, such as Bermudagrass and Zoysia are the predominate turfgrass species maintained at elevations approaching sea level in south-west Tennessee. Cool-season turfgrasses are usually well adapted in East Tennessee, which is mostly mountainous, with broad, fertile valleys. Cool-season grasses also perform well in the hills of the Highland Rim surrounding the Central Basin, where elevations can reach 1,000 feet or more. Finally, both warm- and cool-season turfgrasses are maintained in limestone-based, phosphorus-rich soils of the Central Basin. The selection of an appropri-ate warm- or cool-season species and variety reduces the amount of time and money spent establishing, maintaining and renovating turf.

Turfgrass in Tennessee

Figure 2.

Illustration by Gary Dagnan

Figure 1. Turfgrass Plant


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Table 1. Common and Botanical Names of Turfgrass Species Maintained in Tennessee

Common name Botanical name

Cool-Season

Bluegrass Poa spp.

Hybrid Poa pratensis L. x Poa arachifera Torr.

Kentucky Poa pratensis L.

Rough Poa trivialis L.

Fescues Festuca spp.

Chewings Festuca rubra L. ssp. falax Thuill., Festuca rubra var. commutata Gaud.

Hard Festuca longifolia auct. non Thuill.

Sheep Festuca ovina L.

Slender creeping Festuca rubra L. ssp. trichophylla, Festuca rubra var. littoralis Vasey

Strong creeping Festuca rubra L. rubra

Talla Festuca arundinacea Schreb.

Ryegrass Lolium spp.

Annual, Italian Lolium multiflorum Lam.

Intermediate Lolium hybridum , hybrid of Lolium multiflorum Lam. + Lolium perenne L.

English, perennial Lolium perenne L.

Warm-Season

Bermudagrass Cynodon spp.

Common, Improved common Cynodon dactylon (L.) Pers.

Hybrid Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Davy.

Centipedegrassb Eremochloa ophiuroides (Munro.) Hack.

Charlestongrass, St. Augustinegrassb Stenotaphrum secundatum (Walt.) Kuntze.

Zoysia spp.

Chinese, Japanese or Korean Common Lawngrass Zoysia japonica Steud.

Manilagrass Zoysia matrella (L.) Merr.

Mascarenegrsass, Korean velvetgrass Zoysia tenuifolia Thiele,c Zoysia pacifica (Goudsward) Hotta &

Kuroki

Hybrid Zoysia japonica Steud. x Zoysia tenuifolia Thiele, Zoysia japonica Steud. x (Zoysia matrella (L.) Merr. x Zoysia tenuifolia Thiele)

a Tall fescue is the cool-season turfgrass species most often planted in Tennessee.b Centipedegrass and St. Augustinegrass are seldom planted in Tennessee due, in part, to a lack of low-temperature hardiness.c The species Zoysia tenuifolia appears to have been misidentified and is now identified as Zoysia pacifica.

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Warm-season TurfgrassesWarm-season turfgrasses grow best in late spring, summer and early fall when air temperatures rise above 70 degrees F. These warm-season turfgrasses are dormant and may be injured by extreme low temperatures during cold winter months. Warm-season turfgrasses include Bermudagrass, centipedegrass, St. Augustinegrass and Zoysia.

BermudagrassBermudagrass is an aggressive, low-growing and very persistent sod-forming turfgrass. Plants are spread by stolons and rhizomes. Bermudagrass grows best in full sun and is intolerant of shade. Leaves and stems become straw-brown as plants enter dormancy each fall. A healthy, actively growing bermudagrass turf is dense, resistant to weed invasion and capable of recovering from injury very quickly.

Bermudagrass is adapted to soils ranging in texture from sand to clay. Plants do not usually grow well in infertile, poorly drained soils. The nitrogen (N) fertility requirement of bermudagrass is high, ranging from 0.5 to 1.5 pounds of nitrogen per 1,000 square feet per growing month. Because it produces an exces-sive layer of thatch, bermudagrass requires routine dethatching. The species is susceptible to several patch diseases including pink snow mold, brown patch and spring dead spot.

There are two main types of bermudag-rass, vegetative or clonal types and seeded types. Vegetative, clonal-type bermudagrass varieties vary in overall quality, vertical and lateral growth rate, disease resistance and low- temperature hardiness. Clonal bermu-dagrasses do not produce viable seed and must be established from sprigs, plugs or sod. Seeds of Common bermudagrasses are often used to establish home lawns and utility turfs because they have better quality, low-temperature tol-erance, rooting and spring dead spot resistance than clonal bermudagrasses.

CentipedegrassCentipedegrass is a medium, coarse-textured, light-green, sod-forming turfgrass. Plants spread slowly by short, thick, centipede-like stolons from which the species gets its name. The low maintenance requirement of centi-pedegrass contributes to its popularity as a lawngrass. However, in Tennessee, a general lack of low-temperature tolerance severely lim-

Figure 5. St. Augustinegrass Turf

Figure 4. Centipedegrass Turf

Figure 3. Bermudagrass Turf


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its its use. Roots of centipedegrass are shallow compared to other warm-season turfgrasses. Centipedegrass has good drought tolerance and fair shade tolerance. Disadvantages, in ad-dition to low-temperature intolerance, include susceptibility to nematodes and very poor performance in alkaline soils. Due, in part, to its slow vertical growth rate and limited tolerance of heavy foot traffic, centipedegrass is not recommended for use in lawns receiving heavy foot traffic. A condition known as “cen-tipedegrass decline” can be a problem if the turf is mowed too closely, over-fertilized and drought-stressed. Symptoms of centipedegrass decline appear in the spring as large brown patches of dead plants.

St. AugustinegrassThis fast-growing, high-temperature-tolerant turfgrass is also known as Charlestongrass. In the Southeastern U. S., St. Augustinegrass is often maintained in fertile, well-drained soils throughout the coastal regions along the Atlantic Ocean and the Gulf of Mexico. A lack of low-temperature tolerance severely limits the use of St. Augustinegrass as turf in Tennessee. Generally, St. Augustinegrass has poor wear tolerance and often requires routine dethatching and watering. Some varieties are susceptible to a virus referred to as St. Augus-tine Decline, or SAD. Chinch bug is a com-mon insect pest.

ZoysiaZoysia is one of the earliest species to be used as turf. Although plants usually grow slowly, this sod-forming species forms a dense, uni-form turf. When sprigged or plugged, many varieties require two or more years for total coverage. Unlike bermudagrass, leaves and stems that develop from nodes on stolons and rhizomes grow upright (~90 degree angle). Leaves are very stiff and stems are tough, two attributes that contribute to excellent wear resistance but can cause mowing difficulties. The drought, heat and salinity tolerance of Zoysia is excellent. Due, in part, to the limited rate of growth of lateral stems, Zoysia recovers very slowly from injury compared to bermu-dagrass and St. Augustinegrass. Zoysia tissue resists decay, which is one reason the species produces excessive thatch. Intensely man-aged Zoysia often requires dethatching once each year. Low-temperature hardiness, leaf width and growth rate vary among the three species of interest in Tennessee. Rankings of low- temperature hardiness, leaf width and rate of growth by species are: Z. japonica > Z. matrella > Z. pacifica.

Similar to Bermudagrass, there are two types of Zoysia: Vegetative or clonal types and seeded types. The vegetative type has a range of resistances to drought and pests per variety. The seeded types often vary in color, density, disease and insect resistance, leaf width and rate of growth. Seeds are often pre-treated or coated before packaging in an effort to improve germination and speed the growth of seedlings.

Figure 6. Zoysia Turf

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Cool-Season TurfgrassesCool-season turfgrasses grow best in the spring, early summer and fall and often experi-ence heat and drought stresses during hot, dry summer months. Most are prone to disease when the weather is warm and humid. Cool-season turfgrasses include bluegrasses, fescues and ryegrasses

BluegrassesMost bluegrass species grow best in cool-hu-mid or transitional climates. Some are peren-nials with strong rhizomes or stolons, others are upright, bunch-type annuals. Kentucky bluegrass (Poa pratensis L.) is managed as

Figure 7. Kentucky Bluegrass Turf

Table 2. A Comparison of Several Warm-Season Turfgrassesa

Characteristic Species

Bermudagrass Centipede-grass St. Augustinegrass Zoysia, Z. Japonica

Common Improved

Ability to recover high high low high low

Disease potential high high low high high

Establishment method

seed, sod, sprigs, plugs


seed, sod, sprigs, plugs sod, sprigs, plugs


Establishment rate fast medium-fast medium medium-fast slow-medium

Fertility requirement high high low medium-high medium

Growth habit sod-forming (rhizomes, stolons)sod-forming(rhizomes, stolons)

sod-forming (stolons)

sod-forming (stolons)

sod-forming (rhizomes, stolons)

Leaf texture medium - coarse medium -fine medium - coarse medium - coarse coarse

Mowing height adaptation low - medium low - medium medium high medium

Mowing quality good good Fair poor fair

Shoot density medium medium -high Low low - medium medium

Thatch production medium - high high Low medium high

Cold tolerance poor - fair poor - fair Poor poor good

Drought tolerance excellent excellent Poor fair excellent

Heat tolerance excellent excellent Excellent excellent excellent

Salinity tolerance good good Poor good fair - good

Shade tolerance very poor very poor Poor good fair

Soil acidity good good Excellent poor fair

Submersion good good Poor fair poor

Wear good good - excellent Poor fair excellent

a Comparisons of warm-season turfgrass species are ‘relative’ and are intended to serve as a quick reference only. Varieties within species often vary in disease potential, drought tolerance, establishment vigor, fertility requirement, high-temperature tolerance, leaf texture, low-temperature tolerance, mowing quality, recovery rate, salinity tolerance, shade tolerance, shoot density, soil-acidity tolerance, submersion tolerance, thatch production and wear resistance.


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turf in Tennessee. Recently, turfgrass breed-ers have successfully developed hybrid blue-grasses, commonly referred to as heat-tolerant or HT bluegrasses, from Kentucky bluegrass and a heat-and-drought-tolerant species (Poa arachifera Torr.)

Kentucky BluegrassKentucky bluegrass, a widely used perennial turfgrass for lawns in temperate and sub-arctic climates, is probably the most recognizable species in the U.S. Plants grow best in fertile, well-drained soils in full sun or light, open shade. They establish very slowly from seed. A lack of establishment vigor, relatively shallow root system and limited shade, wear and soil acidity tolerance, restrict the use of Kentucky bluegrass to parts of north central and upper east Tennessee. Many sod producers plant a 90:10 (by weight) tall fescue: Kentucky bluegrass seed mixture. Kentucky bluegrass is darker green than many varieties of tall fescue and strong, vigorous rhizomes improve the tensile strength of sod.

FescuesThere are more than 100 species of fescue. There are two main categories of fescues for lawn use: fine-leaf and course fescues. Chew-ings, hard, sheep, slender creeping and strong creeping fescues are categorized as fine-leaf fescues. Due to wide leaf blades, tall fescue, the most common cool-season species main-tained in home lawns in Tennessee, is catego-rized as a coarse fescue.

Chewings FescuesThis light- to medium-green, bunch-type fine-leaf fescue species is cold- and shade-tolerant. Chewings fescue is deeply rooted and often forms a denser, more upright turf than strong creeping fescue. A lack of stolons and rhi-zomes contributes to its poor traffic tolerance and recuperative capacity. Although tolerant of drought, chewings fescue is often dormant during hot, dry summer months. The species is prone to disease during hot, wet weather and can produce an excessive amount of thatch. In Tennessee, chewings fescue is not generally as persistent as strong creeping fescue and hard fescue. Chewings fescue grows best in slightly acidic, infertile and well-drained soils, and is a common component of seed mixtures intended for use in shaded landscapes in north central and upper east Tennessee.

Hard FescueHard fescue, a non-creeping species, resembles sheep fescue, however, leaves are usually gray-ish-green or dark green, tougher and wider. Although shallow-rooted and less tolerant of drought compared to several other fescues, hard fescue has superior heat tolerance and of-ten remains green during hot summer months. Seeds of several improved hard fescue varieties are being mixed with other fine-leaf fescues to establish low- maintenance turfs in shade in north central and upper east Tennessee.

Sheep FescueSheep fescue has very stiff, upright leaves and, once established, requires very little mainte-nance. It is tolerant of low temperature and drought and grows well in infertile, acidic, sandy or gravelly soils. Sheep fescue is most often used for soil erosion control and reclama-tion. The distinct, blue or grayish-blue color limits its use in seed mixtures.

Slender Creeping FescueSlender creeping fescue is native to Europe, where it is found growing in pastures, lawns and undisturbed, shady sites. Plants have hair-like leaves and spread by small, short rhi-zomes. The species is adapted to dry, infertile soils and is sometimes used as a component of seed mixtures intended for use in shade in north central and upper east Tennessee.

Figure 8. Creeping Red Fescue

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Strong Creeping FescueStrong creeping fescue is also referred to as creeping red fescue and has longer and thicker rhizomes than slender creeping fescue. The species is valued for its shade tolerance and low maintenance requirement. Strong creeping fescue usually forms a thin, coarse-textured, drought-tolerant sod. Like slender creeping fescue, strong creeping fescue is often mixed with other fine fescues for use in shaded landscapes in north central and upper east Tennessee.

Tall FescueTall fescue is a bunch-type coarse fescue species with wide leaves and deep roots. Tall fescue grows best in moist and fertile, clay soils. Plants have a moderate rate of growth and spread by tillers and very short rhizomes. Although tall fescue has excellent heat and drought tolerance, pesticide applications are often required to control brown patch, white grubs, crabgrasses and goosegrass. The species does not usually produce thatch as quickly as bermudagrass, Kentucky bluegrass, St. Augustinegrass and Zoysia, yet dethatching before fall inter-seeding often promotes seed contact with soil and the uniform emergence of seedlings.

RyegrassesDue to rapid seed germination and seedling growth, ryegrasses were once planted as nurse grasses in seed mixtures (e.g., 10 percent by weight) with slower-growing cool-season species including the fescues and Kentucky

bluegrass. Unfortunately, these aggressive, robust and temporary species can dominate a preferred turfgrass species by competing for nutrients, sunlight and water. Intermediate and perennial ryegrasses are sometimes used to overseed dormant bermudagrass turf. Annual ryegrass (Lolium multiflorum Lam.) is widely used to provide temporary ground cover and soil erosion control until a perennial turf can be planted.

Intermediate RyegrassIntermediate, or transitional ryegrass, is a hybrid of annual and perennial ryegrass. Seeds of intermediate ryegrass may germinate quickly and seedlings may grow very rapidly compared to perennial ryegrass. Some varieties of intermediate ryegrass may be less tolerant of high temperature and drought than peren-nial ryegrass and may “transition” or die in response to high- temperature stress much earlier in the spring. Other high-temperature-tolerant varieties resemble perennial ryegrass and may transition in mid-summer.

Perennial RyegrassPerennial or English ryegrass, a short-lived bunchgrass introduced from Europe, is seldom used as permanent turf in Tennessee. The species generally does not survive high- or low- temperature extremes. Although peren-nial ryegrass tolerates a much lower mowing height than either Kentucky bluegrass or tall fescue, leaves of many varieties are very strong and fibrous, traits that can result in poor mow-ing quality. Perennial ryegrass, like Kentucky bluegrass, has limited shade tolerance.

Figure 9. Tall Fescue Turf


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Table 3. A Comparison of Several Cool-Season Turfgrassesa

Characteristic

Species

Kentucky bluegrass

Fescues Perennial ryegrassChewings Strong creeping Hard/sheep Tall

Ability to recover high low medium-low low medium medium

Disease potential medium - high medium - high medium - high medium - high medium - high medium

Establishment method

seed, sod, sprigs, plugs seed, sod seed, sod seed, sod seed, sod seed, sod

Establishment rate slow medium medium medium medium fast

Fertility requirement medium -high low low low medium medium

Growth habit sod-forming (rhizomes) bunchsod-forming (rhizomes) bunch

bunch (short rhizomes) bunch

Leaf texture medium fine fine fine coarse medium - coarse

Mowing height adaptation medium medium - high medium - high medium - high high medium

Mowing quality good good good good fair - good poor

Shoot density high high high high low medium

Thatch production medium medium medium medium low low

Tolerance

Cold good medium medium medium medium poor

Drought fair good good good good fair

Heat medium fair fair fair good fair

Salinity poor poor poor poor medium medium

Shade poor excellent excellent excellent good medium - good

Soil acidity low medium medium medium high low

Submersion medium low low low high medium

Wear medium medium medium medium high medium - higha Comparisons of cool-season turfgrass species are ‘relative’ and are intended to serve as a quick reference only. Varieties within species often vary in disease potential, drought tolerance, establishment vigor, fertility requirement, high-temperature tolerance, leaf texture, low-temperature tolerance, mowing quality, recuperative potential, salinity tolerance, shade tolerance, shoot density, soil-acidity tolerance, submersion tolerance, thatch produc-tion and wear resistance.

Figure 10.

Dormant Bermudagrass overseeded with Perennial Ryegrass

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Establishing a TurfSome turfs are established from seed, oth-ers from sod, plugs or harvested segments of stolons or rhizomes called sprigs. Regardless of establishment method, the date of planting, the site preparation and the care developing turfgrasses receive determine if a planting is successful.

Planting DateIn Tennessee, late August to mid-October is considered an ideal time to seed bluegrasses, fescues and ryegrasses (Table 11-4). Although wet, rainy weather may make soil prepara-tion very difficult, fescues and ryegrasses are also seeded in late winter or early spring. Bluegrass seeds germinate slowly compared to fescues and ryegrasses. Young, shallow-rooted bluegrass plants growing from seed planted

in spring are often killed by hot, dry weather in summer. For best results, plant seeds, plugs or sprigs of bermudagrass, centipedegrass, St. Augustinegrass and Zoysia between May 1 and June 30. Warm, moist weather in late spring and summer favor growth of these warm-season turfgrasses. Sod can be installed almost any time of year as long as the planting bed is not frozen. However, several weeks or months may be required before a newly sodded turf can be trafficked.

Table 4a. Common Planting Methods and Preferred Timing for Establishing Several Turfgrasses

Species Planting Method Preferred Timing

Cool-Season

Bluegrass, hybridPoa pratensis L. x Poa arachifera Torr. sod, seed

late summer - early fall, late winter - early spring

Bluegrass, KentuckyPoa pratensis L. seed late summer - early fall

Bluegrass, roughPoa trivialis L. seed late summer - early fall

Fescue, chewingsFestuca rubra L. ssp. falax Thuill., Festuca rubra var. commutata Gaud.

seed late summer - early fall, late winter - early spring

Fescue, hardFestuca longifolia auct. non Thuill. seed


Fescue, sheep Festuca ovina L. seed


Fescue, slender creeping red Festuca rubra L. ssp. trichophylla, Festuca rubra var. littoralis Vasey


Fescue, strong creeping red Festuca rubra L. rubra seed


Fescue, tall Festuca arundinacea Schreb. sod, seed


Ryegrass, annual (Italian) Lolium multiflorum Lam. seed


Ryegrass, intermediate Lolium hybridum, hybrid of Lolium multiflorum Lam. + Lolium perenne L.


Ryegrass, perennial (English) Lolium perenne L. seed


a Sod can be installed all year long as long as the planting bed is not frozen.


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Preparing the SitePrepare the planting bed according to the 3f Rule: A bed should be fertile, firm and free of large stones, debris and troublesome weeds. To attain a “3f ” bed, follow these steps:

1. Submit a soil sample for testing six weeks before the intended planting date. A soil sample can be taken using a trowel, garden spade or soil tube. Collect several small samples of soil to a depth of 6 inches (e.g., 1 sample per 1,000 square feet or 45 samples per acre. Discard plant material before placing these in a clean container to dry. Thoroughly mix the dry samples to-gether before transferring one-half pint of soil (the representative sample) to the soil sample box. Homeowners frequently sub-mit samples from both the back and front yards. Please contact your county Exten-sion office for soil sample boxes, informa-tion sheets and instructions for submitting

Figure 11. Samples of Soil from the Planting Bed

Collect several samples of soil randomly from the planting bed.

Table 4b. Common Planting Methods and Preferred Timing for Establishing Several Turfgrasses

Species Planting Method Preferred Timing

Warm-Season

Common or improved common bermudagrassCynodon dactylon (L.) Pers.

sod, plugs, sprigs, seed late spring - early summer

Hybrid bermudagrassCynodon dactylon (L.) Pers. x Cynodon transvaalensis Davy.

sod, plugs, sprigs late spring - early summer

CentipedegrassEremochloa ophiuroides (Munro.) Hack. sod, plugs, sprigs, seed late spring - early summer

St. AugustinegrassStenotaphrum secundatum (Walt.) Kuntze. sod, plugs, sprigs late spring - early summer

Chinese, Japanese or Korean Common LawngrassZoysia japonica Steud.

sod, plugs, sprigs, seed late spring - early summer

ManilagrassZoysia matrella (L.) Merr. sod, plugs, sprigs late spring - early summer

Mascarenegrass, Korean velvetgrassZoysia tenuifolia Thiele,b Zoysia pacifica (Goudsward) Hotta & Kuroki


HybridZoysia japonica Steud. x Zoysia tenuifolia Thiele, Zoysia japonica Steud. x [Zoysia matrella (L.) Merr. x Zoysia tenuifolia Thiele]


a Sod can be installed all year long as long as the planting bed is not frozen.b The species Zoysia tenuifolia appears to have been misidentified and is now identified as Zoysia pacifica.

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soil samples to the University of Tennessee Soil Testing Laboratory in Nashville.

2. Stockpile existing topsoil before contour-ing and major excavation begins.

3. Establish the ‘rough’ grade. Hard subsoil can be loosened using a disk, roto-tiller or sub-soiler before spreading topsoil.

4. Uniformly redistribute topsoil. About 12½ cubic yards of topsoil are required to create a 4-inch layer per 1,000 square feet surface area. Heavy clay soil can be amended with topsoil, sand or organic materials. Soil aeration and water infiltra-tion are usually improved when 4 or more inches of loamy topsoil or coarse sand are mixed with 1½ to 2 inches of clayey soil. Mature compost or sawdust (e.g., 5 or more years old) can be mixed with soil to increase the organic matter content,

reduce clay concentration and stimulate microbiological activity. Organic matter is usually mixed with soil at a rate of 10 to 15 percent by volume.

5. Install sub-surface drainage and the irrigation system after establishing the rough grade and redistributing topsoil. Drainage pipe is usually placed at least 6 inches below the soil surface and irrigation mainlines, well below the frost line (e.g., 12 to 18 inches).

6. Remove stones and debris that may block turfgrass roots or restrict the movement of water from the surface into the soil. Stones greater than 2 inches in diameter should be removed from the top 4 inches of the planting bed.

7. Control weeds. Perennial weeds including dallisgrass, green kyllinga, ground ivy and nimblewill can be difficult to control in established turfs. A herbicide application (e.g., glyphosate) before planting can re-duce the populations of these troublesome weeds in the future.

8. Apply “starter” fertilizer and lime accord-ing to soil test recommendations.

9. Till the soil. Disking or roto-tilling to a 4- to 6-inch depth will loosen the soil and mix fertilizer and lime throughout the turfgrass root zone.

10. Fine grade and roll or mat to smooth and firm the surface of the planting bed. Hand raking and a lightweight, water-ballast or power roller work well in small areas. A tractor-drawn, cultipacker, heavy steel drag mat or plank drag are effec-tive on large areas. The planting bed will require further rolling or matting if foot-prints are deeper than 1 inch.

Turfgrass SeedA viable turfgrass seed is a mature floret harvested from the inflorescence or seed head of flowering plants. Each fruit, or caryopsis, contains a seed with an embryo, or miniature plant, and an endosperm, a source of food for the developing seedling Figure 13.

Grass seeds come in many shapes and sizes. Seeds of tall fescue are relatively large and long compared to Kentucky bluegrass. There are about 2,200,000 Kentucky bluegrass seeds per

Figure 12. Rolling or Matting of the Planting Bed

Further rolling or matting of the plant-ing bed is necessary if footprints are deeper than 1 inch.

Figure 13.

Fruit, or cary-opsis, contain-ing a seed with an em-bryo, an endo-sperm and a source of food. (Illustration by Gary Dagnan)


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pound and 230,000 tall fescue seeds per pound (Table 5). Mechanical injury during combin-ing and seed cleaning can reduce the viability of seeds. The normal percentages of viable seeds in a package of seeds and seed purity also vary among turfgrass species.

Seed BlendsBlending varieties of the same turfgrass spe-cies may be advantageous when, for example, varieties in the blend have superior tolerance to one or more insects or disease but no one variety resists all the insects and diseases that normally occur. Presently, blends of highly compatible varieties of bermudagrass, strong creeping fescue, Kentucky bluegrass, peren-nial ryegrass and tall fescue are marketed in Tennessee. In mature turfs, it is usually very difficult to distinguish between varieties with similar colors and textures.

Seed MixturesThe range of adaptation of single-species plantings may be very limited. Traditionally, mixtures of two or more turfgrass species have been used when the micro-climate and soil texture vary throughout the landscape. Mix-

ing seeds of several species may improve the insect, disease and wear resistance, recupera-tive capacity and shade tolerance of a turf. However, mature turfs established from a seed mixture may appear patchy due to isolated areas of individual, contrasting species.

Always consider seed count when selecting a seed mixture. Varieties in a mixture are listed by weight rather than by number of seeds. One pound of a mixture of 80 percent Kentucky bluegrass, 10 percent strong creeping fescue and 10 percent perennial ryegrass by weight contains about 95.4 percent (1,760,000 seeds) Kentucky bluegrass, 3.3 percent (61, 500 seeds) strong creeping fescue and 1.3 percent (23,000 seeds) perennial ryegrass by seed number.

Seed CoatingsSeeds may be coated with lime, fertilizer and/or a fungicide. Coatings may enhance the growth rate of seedlings or protect them from harmful fungi. They also increase the weight of the seed “unit” and decrease the seed count per pound.

Table 5. Approximate Number of Seeds Per Pound and Minimum Acceptable Purity and Germination Percentages of Several Turfgrasses

Species Approximate Number of Seeds Per Pound Minimum Purity (%) Minimum Germination(%)

Cool-Season

Bluegrass, Kentucky 2,200,000 90 75

Fescue, chewings 500,000 95 80

Fescue, sheep 530,000 95 80

Fescue, strong creeping 615,000 95 80

Fescue, tall 230,000 95 85

Ryegrass, annual 230,000 95 90

Ryegrass, perennial 230,000 95 90

Warm-Season

Bermudagrass, common (hulled) 1,750,000 95 80

Centipedegrass 410,000 45 65

Zoysia japonica 1,000,000 90 70

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The Seed LabelThe package label contains valuable informa-tion regarding the quality of the seeds inside. The label of turfgrass seed lots sold, distribut-ed, transported and offered for sale in Tennes-see must contain the following information:

▪ Name of the kind and variety for each turfgrass seed present in ex-cess of five percent of the whole and the percentage by weight of each in the order of its predominance

▪ Lot number or other lot identification ▪ Net weight ▪ Origin ▪ Percentage by weight of inert matter ▪ Other crop seeds (e.g., percent-

age by weight of varieties other than those listed on the label)

▪ Percentage by weight of all weed seeds ▪ Germination percentage (exclusive

of the germination of hard seed), percentage of hard seed and the cal-endar month and year of the test for each named turfgrass seed

▪ Name and number per pound of each kind of restricted, noxious weed seed

▪ Name and address of the com-pany or person labeling, sell-ing or offering the seed for sale

Seed lots may also be guaranteed true-to-type, or certified, from a genetic standpoint. Seeds in a container with a blue tag have been tested according to procedures established by the Association of Official Seed Certifying Agencies (AOSCA) and have met stringent certification standards for genetic purity and identity.

SeedingSmall areas can be planted by broadcasting seed by hand or by using a crank-type, shoul-der seeder or walk-behind seeder/spreader. Tractor-drawn or tractor-mounted seed drills and cultipacker seeders are commonly used to plant large areas. As its name implies, a hydro-seeder is used to deliver seeds to the seedbed in water. Hydraulic mulch, fertilizer, lime and a tackifier can be added with seeds to produce a seed-bearing, hydromulch that resists erosion. Hydromulching is especially effective when planting slopes too steep for “conventional” planting. Pneumatic seeders are used to top-dress or “cap” the planting bed with a mixture of compost or soil and seed.

Seeding RateThe recommended seeding rate for each species (Table 11-12) is based on seed size and viabil-ity. Small-seeded species such as bluegrasses and bermudagrass require a lower seeding rate than species that yield relatively large seeds (e. g., perennial ryegrass and tall fescue). Plant-ing too many seeds most often results in a very dense stand of weak, poorly developed and disease-prone seedlings.

The amount of time required for seeds to germinate varies among turfgrasses. Cyclic air temperatures of about 59 to 82 degrees F favor the rapid germination of seeds of cool-season species. Temperatures of about 68 to 95 degrees F, promote germination of seeds of warm-season species.

Figure 14. Hydroseeder


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Calculating Pure Live Seed

The retail price of a seed lot is influenced by turfgrass species and variety, seed germination percentage and purity. A calculation to determine the percentage of pure live seed (PLS), where PLS (%) = [seed purity (%) x seed germination (%)] ÷ 100, makes it possible to compare two or more containers of seeds and identify the best value.

The least expensive seed lot on the basis of price per pound is not always the best value. Consider Seed Lots A and B in the following example:

Seed Lot ACost = $1.31 per poundSpecies .................................................................................................................... Tall Fescue - Falcon IIOrigin .................................................................................................................................................. OregonTested ....................................................................................................................................... July 29, 2004Germination ................................................................................................................................................ 95Other Crop ............................................................................................................................................... 0.15Weed Seed ................................................................................................................................................. 0.5Noxious Weeds ......................................................................................................................................... 0.0Inert ................................................................................................................................................................1.4Seed Lot BCost = $1.28 per poundSpecies ................................................................................................................... Tall Fescue - Falcon IIOrigin ........................................................................................................................................ WashingtonTested ............................................................................................................................... ..August 1, 2004Germination .............................................................................................................................................. 90Other Crop .................................................................................................................................... ........... 0.4Weed Seed ................................................................................................................................................ 0.4Noxious Weeds ........................................................................................................................................ 0.0Inert ............................................................................................................................................................. 1.2

Seed Lot APLS (%) = [Germination (%) x Purity (%)] ÷ 100Germination (%) = 95Purity (%) = 100 - 0.15 - 0.5 - 1.4 = 100 - 2.05 = 97.95PLS (%) = [95 x 97.95] ÷ 100 = 9305.25 ÷ 100 = 93.0525

Seed Lot BPLS (%) = [Germination (%) x Purity (%)] ÷ 100Germination (%) = 90Purity (%) = 100 - 0.4 - 0.4 - 1.2 = 100 - 2.0 = 98PLS (%) = [90 x 98] ÷ 100 = 8820 ÷ 100 = 88.20

The following formula is used to compare the retail price of two or more seed lots on the basis of PLS (%):

Retail price per pound PLS = [retail price per pound PLS (%)] x 100

Seed Lot A: ($1.31 ÷ 93.0525) x 100 = 0.01407 x 100 = $1.41

Seed Lot B: ($1.28 ÷ 88.20) x 100 = $ 0.01451 x 100 = $ 1.45

Although the retail price of seed lot A is 3 cents higher per pound than seed lot B, seed lot A is 4 cents less per pound PLS and is the best value.

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Vegetative Planting TurfgrassSoddingSodding is one example of vegetative plant-ing. Solid sodding with recently harvested turfgrass plants and soil provides immediate cover. Sod is often harvested as slabs or blocks 16 inches wide and 24 inches long or in big rolls. One pallet usually holds about 50 square yards of block sod and weighs 2,000 pounds or more. Less soil is shipped with turfgrasses having a strong network of stolons or rhizomes

compared to those with a bunch-type growth habit. Big roll sod is harvested in rolls 24, 30 or 48 inches wide and up to 100-feet-long or in two cut rolls, each 21 or 24 inches in width. Big roll sod is often installed in large land-scapes with few obstructions.

Before sodding, the planting bed should be made moist, but not saturated. Sod pieces should fit together tightly but should not be stretched or overlapped. Begin installing sod pieces along a line or straight edge. Blocks should be staggered much like bricks in a wall. Seams or cracks between the installed blocks or rolls should be filled with topsoil similar in texture to the soil below. Light rolling or tamping sod after it is in place will help re-move air pockets and ensure contact with soil.

To reduce the potential for loss of plants due to extreme high temperatures and dehy-dration, sod should be installed within 24 to 48 hours of harvest. When blocks of sod that have been on the pallet too long are installed, plants along block edges that received light during transport often grow well while plants in shaded blocks exposed to extremely high temperatures often die. Temperatures near the center of a pallet of block sod or a big roll can rise very quickly to more than 120 degrees F.

Table 6. Recommended Seeding Rate and Seed Germination Interval of Several Turfgrasses

Species Recommended Seeding Rate (Pounds Per 1,000 Square Feet)Approximate Number of Days to Germinate

Cool-Season

Bluegrass, Kentucky 1½ to 2 14 to 21

Fescue, chewings 3 to 5 6 to 14

Fescue, red 3 to 5 6 to 14

Fescue, sheep 3 to 5 6 to 14

Fescue, tall 5 to 8 6 to 12

Ryegrass, annual 4 to 6 3 to 7

Ryegrass, perennial 4 to 6 3 to 7

Warm-Season

Bermudagrass, common - hulleda ½ to 1 10 to 20

Centipedegrass ½ to 3 10 to 20

Zoysia japonica ½ to 3 10 to 14

a The seeding rate should be doubled when using unhulled seed.Unhulled seed often requires 14 to 21 days or longer to germinate.

Figure 15. Blocks of Sod, Staggered like Bricks in a Wall


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PluggingZoysia is probably the species most often established by plugging. Plugs are small pieces of sod, usually 2 or more inches in diameter or width, which are marketed in trays or cut from harvested sod. More than 320 plugs, each 2 inches by 2 inches, can be cut from one square yard of sod. Plugs are usually spaced on 6- to 12-inch centers (6 to 12 inches between plugs in a row and 6 to 12 inches between rows. Hand-held plug cutters are often used to plug small turf areas. Tractor-drawn plugging machines designed to cut and plant plugs from blocks of sod work well when plugging large sites. Soil around each plug should be tamped or lightly rolled after planting. The surface of the planting bed should be level with the soil surface of newly planted plugs. Depending on plug size and spacing, plugging may require from three to ten times more planting material than sprigging.

Sprigging, Stolonizing and Hydrosprigging

A sprig is a section of stem with crowns and roots that is cut from a rhizome or stolon. When properly harvested, transplanted and maintained, a sprig is capable of producing a turfgrass plant.

Sod can be cut or pulled apart to provide sprigs for planting. Sprigs are also mechanical-ly harvested and sold by the bushel. Through the years, two different bushel measurements have evolved. In the southeastern U.S., sprigs are usually sold by the Georgia (GA) bushel. A GA bushel, sometimes referred to as an industry standard bushel (ISB), provides a volume of sprigs at harvest equal to 0.4 cubic feet. One square yard of hybrid bermudagrass sod usually produces one GA bushel of sprigs. A Texas (TX) bushel is based on the U. S. cus-tomary measurement system where one bushel of harvested sprigs is 2150 cubic inches or 1.24 cubic feet in volume, about three times greater than a GA bushel. In the western U.S., sprigs are sometimes sold by the TX bushel.

Sprigs are often placed 2 or more inches apart in furrows or holes that are 1 to 2 inches deep. Commercial row planters usually plant sprigs in furrows 4 or 6 inches apart, then firm soil around each sprig. The narrower the spac-ing between sprigs in the furrow and between furrows, the greater the planting rate. Usu-ally, two to ten or more bushels (GA) of sprigs may be planted per 1,000 square feet. Sprigs that are planted by hand should be tamped or lightly rolled immediately after planting. Roll-ing may also be very beneficial after sprigging with a commercial sprig planter. Ideally, about one-third of each sprig should remain above the soil surface after planting.

Stolonizing is essentially broadcast sprig-ging using stolons. The harvested planting material is uniformly broadcast mechanically or by hand, much like straw mulch. Stolons are then covered with 1/8 to ¼ inch (0.3875 to 0.775 yard per 1,000 square feet) of soil or pressed into the surface of the planting bed using a cultipacker, stolon disk, roller or roto-tiller. Planting rates generally range from five to 20 or more bushels (GA) per 1,000 square feet. For example, in Tennessee, the planting rate of turf stolonized with hybrid bermudag-rass in late May is most often much lower [e.g., 10 bushels (GA) per 1,000 square feet] than

Figure 16. Plugs Spaced on 6- to 12-inch centers

Figure 17. Commercial Row Planters Planting Sprigs

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that [e.g., 20 bushels (GA) per acre] of a turf stolonized in late June or early July.

Hydrosprigging is a variation of hydroseed-ing where stolons or sprigs are broadcast in water over the planting bed, rather than seeds. Fertilizer, mulch and a tackifier can be added with the vegetative material before the slurry is applied under pressure to the soil surface. Pumps can push the sprig-containing slurry as far as 1,000 feet through a 1 ½-inch hose. This vegetative planting method is especially effective when planting slopes and diversion channels where only minimal soil surface disturbance is permissible.

Care After Initial PlantingWaterSoil moisture level is critically important when establishing turf. Newly planted sprigs dry out very quickly and die if they do not receive water within a few minutes after planting. Although irrigation timing is less critical when plugging and sodding (soil in each plug and piece of sod holds moisture and nutrients near plant roots), a newly plugged or sodded planting bed should be irrigated within a few hours after planting. Similarly, the germina-tion process begins as seeds take in water. New plantings may require light daily irriga-tion (e.g., 1/8 to ¼ inch or from about 75 to 150 gallons per 1,000 square feet), for several weeks to maintain a moist soil surface while plants produce new leaves and roots develop. As plants mature and roots reach a greater soil depth, more water can be applied less often (e.g., ½ inch or about 300 gallons per 1,000 square feet every two or three days). See more information in the Irrigation section of Turfgrass Maintenance below.

MowingMow often. Do not remove more than one-third of the leaf area when mowing. For example, begin mowing upright, bunch-type species such as chewings fescue, hard fescue, perennial ryegrass and tall fescue at a 2 inch cutting height when plants reach an aver-age height of 3 inches. Begin mowing lower growing, sod-forming species including hybrid bermudagrass and Zoysia at a 1½-inch cutting height when plants reach an average height of 2 ¼ inches. Mower blades must be sharp to avoid lifting young plants from the soil surface and to limit leaf bruising or tearing. Mow when leaves are dry.

FertilizingThe application of ½ pound of nitrogen per 1,000 square feet three to five weeks after seeding or sodding will support continued plant growth. After sodding, if high or low temperatures have stressed plants, Nitrogen should not be applied. Fertilizing newly plant-ed plugs and sprigs on 1 to 3 week intervals at a rate of 1 pound of nitrogen per 1,000 square feet per application promotes rapid shoot growth and ground coverage. After fertiliz-ing, reduce the potential for foliage “burn” by

Figure 18. Stolonizing

Figure 19. Beginning of Germination Process

The beginning of the germination process; seeds taking in water.


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irrigating immediately with at least ½ inch of water.

Weed ControlA pre-emergent herbicide control crabgrass and goosegrass seedlings before they emerge from the soil. Pre-emergence herbicides must be applied before seeds of these summer annu-al weed grasses germinate. However, applying pre-emergence herbicides too soon after seed-ing turf can cause severe damage. For more detailed information on which pre-emergence herbicides to spray and when to spray them, please see Chapter 19, Weed Science.

Post-emergence herbicides are sprayed after weeds emerge from the soil. They are most effective when applied to young, actively growing weeds. However, the application of certain post-emergence herbicides can severely injure or kill newly planted turfgrasses. Several weeks or months may be required before plants can tolerate a post-emergence herbicide treat-ment. For more detailed information on weed control, please see Chapter 19, Weed Science.

Fallen Tree LeavesIt is seldom necessary to remove straw or hay mulch after seeding. If high winds or heavy rains cause windrows or heavy accumulations of mulch, rebroadcast the organic material as uniformly as possible over bare or thinly mulched areas. Too many tree leaves lying on a turf can also cause problems. A heavy layer of

leaves can block light and increase the relative humidity of the microenvironment under-neath. Weak turfs are often disease-prone. Routinely sweep, vacuum, rake or blow leaves off the surface of newly planted turfs.

Diseases and InsectsYoung turfgrass plants with poorly developed roots and leaves may be severely damaged by several fungi and insects. Species of Bipo-laris, Colletotrichum, Fusarium, Pythium and Rhizoctonia can cause disease. When weather conditions favor the development of a disease, fungicide application(s) may be needed to protect seedlings. For more information on plant diseases, see Chapter 17, Plant Pathol-ogy. Armyworms, cutworms and sod web-worms damage young turfs by eating leaves and stems. White grubs, the larvae of scarab beetles, feed on roots and other below ground plant parts. Turf should be inspected often for signs of insect and disease activity. When large white grub populations exist, turf can often be rolled back like a carpet. For information regarding when grubs and other insect pests are active in turf, see Table 11-13. For more information about insects in general, please see Chapter 18, Entomology.

Table 7. The Activity of Several Insect Pests of Turfgrasses in Tennesseea

Insect Pest Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec.

Armyworms Xb X X X X X X

Billbugs X X X X

Chinch Bugs X X X

Cutworms X X X X X X X

Fall Armyworm X X X X X

Green June Beetle Grub X X X X X

Sod Webworm X X X X

White Grubs X X X X X X X X

a From: Hale, F. A. 2002. Commercial Turfgrass Insect Control. The University of Tennessee Agricultural Extension Service PB1342b X indicates that insect pest activity is commonly observed this month. The application of an insecticide or biocontrol agent may be required to prevent severe turfgrass injury.

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Mulches and MulchingMulching a newly planted seedbed can conserve water, control erosion and protect seedlings from extreme high and low tempera-tures. Weed-free straw and hay are commonly used as mulch. Straw or hay should be broad-cast uniformly over the seedbed such that 50 to 75 percent of the soil surface is covered with mulch. As a general rule, one 50-pound-bale will cover 1,000 square feet. A chemical “binder” is often applied at the tip of a me-chanical mulch blower as straw is blown over a sloped seedbed. Compost, peat moss and pulp fiber are also used as mulch. Applying a 1/8- to 1/4-inch layer of these organic materials after planting and rolling provides many of the benefits of mulching with straw or hay.

Biodegradable Erosion Control Blankets

Biodegradable erosion control blankets are used to stabilize erosion-prone soils while seedlings develop. Excelsior blankets com-posed of photodegradable netting and a matrix of wood fibers, are rolled out and stapled after seeding. Netting secures fibers to the soil surface while biodegradable staples hold the blanket in place. The fibers often expand in thickness when moistened. Excelsior blankets with plastic mesh on both sides are designed to reinforce turfgrass roots long after wood fibers have decomposed. Blankets containing straw and a mixture of wood and synthetic fibers are also available.

Turfgrass MaintenanceTurfgrasses require routine maintenance. Mowing, fertilization and irrigation are the primary maintenance practices needed to keep turfs healthy. Sometimes, turfs benefit from supplementary maintenance practices such as dethatching, mechanical aeration and topdressing.

Primary Maintenance Practices: MowingProper mowing is an essential part of any effective turfgrass maintenance plan. For best results, mow often at an appropriate cutting height. Sod-forming or creeping turfgrasses including bermudagrass, Kentucky and hybrid bluegrasses, centipedegrass and Zoysia tolerate a lower cutting height than the fescues, which have a bunch-type growth habit (Table 11-15). Turfs cut too low usually result in weak and weedy turf. Summer annual weed grasses such as large crabgrass and goosegrass usually thrive in tall fescue turfs mowed at a cutting height lower than 2 inches. Turfs cut too high often become sparse and uneven as long leaves droop and restrict air flow among plants.

Seasonal changes in cutting height may improve the heat, cold and drought tolerance of turfgrasses. Increasing the cutting height of tall fescue from 2¼ to 2 3/8 inches can result in up to a 30 percent increase in leaf surface area capable of photosynthesis and much deeper rooting.

More vegetation on the soil surface result-ing from an elevated cutting height provides greater insulation against high and low temperature extremes Mow when the turf is dry and remove no more than one-third of the aerial shoots at a time. Routinely scalping turf most often results in poorly rooted turfgrasses. Plants recovering from scalping by mobilizing energy stored in roots may not replace those carbohydrates, proteins and sugars that have moved upward to support the growth of new leaves and tillers.

To determine the mechanically set cutting height (bench setting) of a mower, the mower should be placed on a firm, level surface and the distance from the surface to the cutting edge of the blade(s) should be measured. The effective cutting height is the actual height of plants immediately after mowing. This may be

Figure 20. Biodegradable Erosion-Control Blankets


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slightly higher than the bench setting when the soil is firm and the mower wheels ride on plant tissue above the soil surface. If the soil is soft and moist, the effective cutting height may be equal to or lower than the bench setting.

Changing the direction of mowing usu-ally forms pleasing stripes and patterns. For example, a square pattern is created by mow-ing a turf previously mowed in an alternating north:south direction at perpendicular angles, to the east and west. Similarly, a triangular pattern is formed when a third alternating direction is added. For example, the turf is mowed along a line northeast:southwest in addition to north:south and east:west. Chang-

ing direction reduces soil compaction and turfgrass wear by more uniformly distributing the weight of the mower over the area being mowed.

Clippings can be broadcast over the turf surface as it is mowed, or collected and added to a compost pile. Short clippings are not generally considered to be a major cause of thatch. In fact, as clippings decompose, they give back 13 essential nutrients to the soil. However, if plants grow excessively tall before mowing, too many long clippings may remain on the surface for an extended period of time, blocking incoming sunlight and accumulating as thatch. If turfgrasses grow too tall between mowings, gradually lower the cutting height over a period of two or three mowings.

MowersThree basic kinds of power mowers are avail-able for mowing turfgrasses: Reel mowers, rotary mowers and flail mowers. Reel mowers are most effective when used to mow creeping turfgrasses at cutting heights from 1/4 to 2 ½ inches. Curvilinear blades mounted on a rotat-ing reel guide leaves to a stationary bedknife where they are cut by a shearing action.

Rotary mowers require less horsepower than reel mowers and are more effective when mowing taller (e.g., 1½ to 3½ inches) turf with an uneven soil surface. Rotary mowers utilize a blade parallel to the soil surface with sharp

Table 8. Growth Habit and Optimum Cutting Height Range of Several Cool- and Warm-Season Turfgrasses

Turfgrass Growth Habit Mowing Height (inches)

Climatic Conditions

Cool-Season Cool/Moist Hot/Dry

Chewings fescue Bunch, tillers 1.0 to 2.0 1.5 to 3.0

Hard fescue Bunch, tillers 1.0 to 2.0 1.5 to 3.0

Kentucky bluegrass Creeping, rhizomes 1.5 to 2.25 2.25 to 3.0

Strong creeping fescue Creeping, rhizomes 1.0 to 2.0 1.5 to 3.0

Tall fescue Bunch, tillers and short rhizomes 2.0 to 3.0 2.5 to 3.5

Climatic Conditions

Warm-Season Warm/Moist Cold/Dry

Bermudagrass, common Creeping, rhizomes and stolons 1 to 2 1.75 to 3

Bermudagrass, hybrid Creeping, rhizomes and stolons 0.75 to 1.5 1.25 to 2

Centipedegrass Creeping, stolons 1 to 2 1.5 to 3

St. Augustinegrass Creeping, stolons 2 to 3 3 to 4

Zoysia Creeping, rhizomes and stolons 0.75 to 1.5 1.25 to 2

Figure 21. A Riding Reel Mower

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edges on each side of a vertical rotating shaft to cut turfgrass leaves Mulching mowers and accessories for conventional rotary mowers create short grass clippings that are returned to the turf as it is mowed.

Roadside and utility turfs are often mowed with flail mowers. A flail mower has many flattened steel, v-shaped cutting blades suspended on steel chains or arms that are hinged to a horizontal shaft that rotates above the turf at high speed as the mower moves. Each cutting blade can swing back when it contacts rock, debris and other obstructions, a feature resulting in less mower repair. Due to the limited distance between the flail tips and the mower housing, tall vegetation is quickly reduced to very fine clippings. When turf is mowed with a rotary or flail mower, leaf blades are cut by a tearing-action rather than a shearing-action. This wounds more leaf tissue increasing the potential for moisture loss and disease.

Avoid serious damage to turfgrass leaves by keeping the cutting edges of bedknives, reels and blades sharp. Flail and rotary mower blades must usually be replaced or sharpened at least once each year. The sharpness of reel blades and bedknives can be maintained by back-lapping at least twice annually. Backlap-ping involves brushing a “lapping” compound (e.g., emory powder + oil slurry) on cutting edges as the reel rotates backwards. Even with routine backlapping, reels and bedknives may become very dull by the end of the mowing season. These can often be reconditioned by grinding.

Primary Maintenance Practices: FertilizingThere are 16 nutrient elements required for plants to survive and produce seed. Please refer to Chapter 3, Soils and Plant Nutrition, for a detailed explanation of the role each of these elements plays in plant survival. Also, refer to Table 16 for the amounts of each of the nutrients and their deficiency symptoms in turfgrass.

Figure 22. Zoysia Cut with a Reel Mower

Figure 23. A Riding Rotary Mower

Figure 24. Tall Fescue Turf Cut with a Rotary Mower


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Table 9. Amounts of Essential Mineral Elements Commonly Found in Turfgrasses and Associated Deficiency Symptoms

Element Normal Amount in Plant Tissue Comments, Deficiency Symptoms and Frequency

Macronutrient percent - dry weight

Primary

Nitrogen 3 to 5

Associated with turfgrass growth and color; found in amino acids, chlorophyll, enzymes, proteins and vitamins; usually moves from roots to leaves quickly (e.g., 15 hours); deficient plants lack color and vigor; and older leaves may first turn pale green, then yellow, as deficiency symptoms progress toward the base of the leaf blade. Deficiency frequency - common.

Phosphorus 0.2 to 0.5

Critically important in the transfer and storage of energy; affects the transfer of genetic information; found in plant cell membranes and DNA; relatively immobile in most soils and less likely to move into soil solution and leach than nitrate; leaves deficient in P often become narrow and have a tendency to curl, darken and develop a purple or red pigmentation; and deficiencies most often observed as plants develop from seed. Deficiency frequency - occasional.

Potassium 2 to 3

Activates enzymes; involved in photosynthesis and the regulation of water release from the plant into the air; plants deficient in K do not grow well and are not very tolerant of traffic, drought, heat and cold; diseases including dollar spot, Fusarium patch, red thread and Rhizoctonia blight are often more severe in turfs low in K; leaves often droop and yellow from the outer edges toward the center as K becomes deficient in plants. Deficiency frequency - occasional.

Secondary

Calcium 0.2 to 0.4

Found in plant cell walls; required for cells to divide and flowers to form; maintains internal ‘balance’ among other essential nutrients including K and Mg; new stems and leaves deficient in Ca are often curled and stunted and the margins of young leaves may first turn pale green, then reddish brown. Deficiency frequency - rare.

Magnesium 0.1 to 0.7

Necessary for the formation of proteins; found at the center of the chlorophyll molecule; improves P uptake from soil; involved in many internal reactions that are regulated by a variety of enzymes; and lower, older leaves of plants deficient in Mg may first appear blotched and red before yellowing. Deficiency frequency - occasional.

Sulfur 0.1 to 0.6

Several vitamins and the amino acids cystine and methionine contain S; plants deficient in S cannot use nitrogen and most often have pale, yellow-green leaves; margins of leaves of sulfur-deficient plants often appear scorched; and a 15:1 N:S ratio is considered normal in dry tissue of turfgrasses receiving adequate amounts of both essential mineral elements. Deficiency frequency - occasional.

Micronutrient ppm - dry weight

Boron 3 to 20

Affects the development of plant cell walls and is believed to be necessary for the transport of sugars; plants low in B grow very slowly and do not complete their life cycle; and growing points of plants deficient in B may develop yellow streaks and leaves are often stunted. Deficiency frequency - rare.

Chlorine NAStimulates photosynthesis; believed to be involved in nutrient balance in plant cells; found in chlorides; and Cl deficiency is uncommon in turfgrasses. Deficiency frequency - rare.

Copper 5 to 40

Involved in the formation of a number of growth- promoting compounds; and tips of the youngest leaves of plants deficient in Cu may appear bluish and some axillary buds may die. Deficiency frequency - rare.

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Fertilizer-Herbicide CombinationsSome herbicides are mixed with extended-release fertilizers to provide essential mineral nutrients while controlling weeds. Combina-tion products containing a post-emergence herbicide and a fertilizer with a low foliar-burn potential are often referred to as “weed-and-feed” formulations. Most of these products work best when applied while dew is present so that the herbicide moves from the fertil-izer granules onto leaf tissue of weeds before granules move through thatch and into contact with soil. Fertilizer-herbicide combinations are most effective when applied at the proper time and according to label directions. Use of a weed-and-feed product is not recommended when turfgrasses are experiencing heat, cold and drought stresses, or when target weeds are old and have woody or waxy stems.

Considerations when Developing a Fertilization PlanSoil Test ResultsPhosphorus and potassium are relatively im-mobile, moving downward very, very slowly in most native soils. The amounts of these two primary macronutrients available for uptake by turfgrasses can be determined by a soil test. If soil test results indicate a low level of phosphorus and potassium, these nutrients can be applied to turfs at rates greater than the turfgrass requirement for each. This will result in increased amounts of phosphorus and potas-sium in the soil. Technology is also available in many soil-testing laboratories to determine the amounts of calcium, magnesium and sulfur, as well as micronutrients in the soil. These tests are especially beneficial when managing turfgrasses in soils with a limited nutrient-holding capacity (e.g., containing large amounts of sand) or a relatively high leaching potential. A tissue test serves as a ‘snapshot’ of

Table 9. Amounts of Essential Mineral Elements Commonly Found in Turfgrasses and Associated Deficiency Symptoms (continued)

Element Normal Amount in Plant Tissue Comments, Deficiency Symptoms and Frequency

Micronutrient ppm - dry weight

Iron 50 to 300

The micronutrient most often deficient in turf; associated with turfgrass color; improves frost resistance and reduces dehydration of some turfgrasses in winter; required for chlorophyll production; found in several enzymes that enable plants to absorb oxygen and release carbon dioxide; and tissue between veins of new leaves may yellow as Fe becomes limited. Deficiency frequency - common.

Manganese 22 to 240

Required for the formation of chlorophyll; influences photosynthesis and plant growth rate; involved in several plant enzyme systems; leaves of Mn-deficient plants often bend, yellow between veins and become spotted as tissue dies in distinct spots; plants low in Mn usually feel soft to the touch and leaves wither or roll; and an extremely high level of Fe in plants can result in a Mn deficiency. Deficiency frequency - occasional.

Molybdenum 2 to 8

The micronutrient required in smallest quantities; necessary for utilization of nitrogen; tends to accumulate as plants mature; and highest concentrations are usually found in leaf blades. Deficiency frequency - rare.

Zinc 8 to 60

A component of several plant enzymes; required for chlorophyll production; believed to be involved in the formation of many growth regulating compounds; too much P in the soil can precipitate Zn, making it unavailable for plant uptake; leaf development and rate of growth of plants deficient in Zn is severely restricted; stunted leaves may first turn yellow, then bronze as Zn becomes unavailable; and leaves may dry and appear white as the deficiency advances. Deficiency frequency - rare.


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the nutrient content of turfgrasses at the time the sample was taken. In addition to reporting the results of nutrient tests, both soil and tissue test reports usually contain specific fertilizer recommendations.

Turfgrass Species and VarietyNitrogen fertility requirements vary among turfgrasses (Table 18). Many varieties of bermudagrass and Kentucky bluegrass require a higher level of nitrogen fertility to maintain optimum growth and stand density compared to fine fescues (chewings, hard, sheep and strong creeping) or centipedegrass. Turfs low in nitrogen are usually weak and thin while those receiving excessive amounts of nitrogen are often diseased, weedy and prone to insect attack. Turfgrasses requiring relatively high levels of nitrogen often have a higher require-ment for phosphorus than those requiring less nitrogen.

Soil TextureHeavy, fine-textured soils containing large amounts of clay usually hold more nutrients and water than light, sandy soils. Therefore, plants in heavy, fine-textured soils need to be fertilized less frequently then plants in light, sandy soils.

Climatic ConditionsA successful fertilization program is one that delivers an appropriate level of nutrition to support plant growth during favorable climatic conditions and sustains turfgrasses exposed to environmental stresses. Nitrogen-containing fertilizers should be applied to cool-season

The Turf Fertilizer Label

Fertilizers applied to turfgrasses often contain all three pri-mary macronutrients and may contain one or more second-ary macronutrients and several micronutrients. Information regarding the nutrient content of a fertilizer is printed on the label (Figure 11-27. Information regarding the nutrient content of a fertilizer is printed on the label.) Fertilizer analysis with a 20-5-15 F contains 20 percent nitrogen, 5 percent phosphate (P2O5) and 15 percent potash (K2O) by weight. A 50-lb. bag of 20-5-15 contains:

0.5 x 20 = 10 pounds of N

0.5 x 5 = 2 ½ pounds of P2O5

0.5 x 15 = 7 ½ pounds of K2O

Since the fertilizer label reports percent P2O5 and percent K2O (by weight) rather than percent elemental P and K, the fol-lowing formulas are useful when converting pounds of P2O5 to pounds of P and pounds of K2O to pounds of K.

P2O5 x 0.44 = P

K2O x 0.83 = K

In addition to 10 pounds of nitrogen, a 50-lb. bag of fertilizer with a 20-5-15 analysis contains:

0.5 x 5 x 0.44 = 0.5 x 2.2 = 1.1 pounds of P

0.5 x 15 x 0.83 = 6.2 pounds of K

Table 10. Nitrogen Fertility Requirements of Several Turfgrasses

Turfgrass Relative Nitrogen Fertility Requirement Amount of Nitrogen Required (lbs. nitrogen/1,000 ft2/ growing month)

Annual ryegrass Medium 2/5 to 1

Bermudagrass High ½ to 1 ½

Centipedegrass Very low 1/10 to 4/10

Chewings fescue Low 1/5 to 3/5

Creeping bentgrass High ½ to 1 ½

Creeping red fescue Low 1/5 to 3/5

Kentucky bluegrass High ½ to 1 ½

Perennial ryegrass Medium 2/5 to 1

Tall fescue Medium 2/5 to 1

Zoysia Medium 2/5 to 1

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turfgrasses during late summer, fall, late win-ter and early spring (e.g., September, October, November, March and April). They should not be applied in May, June, July and August when cool-season turfgrasses experience heat and drought stresses and are prone to disease. Fertilize warm-season turfgrasses during spring, summer and early fall (e.g., from late April through early September), when weather favors plant growth. Avoid fertilizing warm-season turfgrasses too late in the fall and too early in the spring when nitrogen promotes the growth of annual bluegrass and winter annual broadleaf weeds like chickweed, henbit and purple deadnettle.

Turf Quality ExpectationThe desired level of turfgrass quality influ-ences the amount of fertilizer applied annually. Fertilization can affect both the visual quality and the function of turf. Aerial shoot density, color, smoothness and uniformity of turf often increase with increasing soil fertility (provided nutrients are applied at appropriate rates and do not reach excessively high levels in the soil).

BudgetProduct cost often affects fertilizer selection, frequency of fertilization and application rates. Extended-release (e.g., methylene urea, poly-mer-coated urea, sulfur-coated urea and urea formaldehyde) nitrogen sources are generally more expensive per pound of nitrogen com-pared to highly water-soluble nitrogen sources such as urea and ammonium nitrate. However, due to the greater potential to burn turfgrass foliage, quick-release nitrogen sources must be

applied more frequently at much lower rates compared to extended-release sources.

LimingApplying ground agricultural limestone (lime) to turf neutralizes acids and increases soil pH. Lime is available in calcitic and dolomitic forms and may be pulverized or pelletized. Calcitic lime contains mostly calcium carbon-ate. Dolomitic lime, a combination of calcium carbonate and magnesium carbonate, supplies turfgrasses with both Ca and Mg. Although hydrated or builder’s lime may be used as a source of Ca and will raise the pH of the soil, it is caustic, difficult to spread and can irritate the skin. Particles of ground calcitic and dolo-mitic lime are compressed to form granules or pellets. Although it is more expensive, pellet-ized lime is usually much easier to spread than pulverized lime.

Lime can be applied to turf at any time during the year. Do not mix fertilizer with lime and do not apply lime immediately before or after fertilizing with nitrogen. The weight and size of fertilizer particles are often much different than lime particles or pellets. Mixing and applying lime and fertilizer at the same time often results in the uneven distribution of one or both. Applying lime immediately before or after certain fertilizers (e.g., urea) can result in the loss of nitrogen by volatilization. Some of the nitrogen contained in the fertilizer is rapidly converted to ammonia and, subse-quently, lost to the atmosphere.

Apply lime according to soil test results. No lime is needed if the soil pH is 6.0 or higher. If the pH of the soil is below 6.0, the acid

Figure 25. Pelletized Lime


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content is considered high enough to require adjustment and an application of lime is recommended. As the soil pH drops below 6.0 and the soil acidity increases, mineral nutrients including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and molybdenum become less available to turfgrasses. Turf-grasses may turn dark-green and grow faster as nutrients become more available following the application of lime.

Do not apply more than 50 pounds of lime per 1,000 square feet of turf per application. If soil test results indicate the need for more than 50 pounds of lime per 1,000 sq. ft., two or more applications may be needed, 6 months apart. Drop or gravity spreaders are preferred when applying pulverized lime. Although centrifugal or rotary spreaders effectively broadcast pelletized lime, they are not recom-mended for the application of pulverized lime.

Primary Maintenance Practices: IrrigationActively growing turfgrasses usually contain at least 70 percent water by weight. During the growing season, most turfs use from 1/10 inch to 3/10 inch of water daily. An estimated 3 percent or less of the total water taken up by turfgrasses is used for photosynthesis. Most of the water that moves from the soil into plant roots is used to move minerals from the soil throughout the plant, to transfer sugars produced in leaves to other plant parts, and to buffer the plant from extremely high and low temperatures.

In Tennessee, the total quantity and distri-bution of precipitation is not ideal for main-taining consistently healthy turf. Turfgrasses receiving no supplemental water usually expe-rience severe drought stress sometime during the growing season. The amount of moisture in the soil can be estimated by using a pocket knife to probe the soil, noting the resistance to penetration by the knife blade. Addition-ally, as plants wilt and leaves roll in response to drought, they reflect a color much different from that of turgid plants with fully expanded leaves. Turf in need of water is often blue-green or smoke-gray. Footprinting can also be an indicator of low soil moisture. If footprints remain visible for several hours, the turf is most likely in need of water.

Irrigation should be done during the morn-ing hours (e.g., 5 a.m. to 11 a.m.) to limit the time water droplets remain on leaves and the amount of water lost to evaporation. Water deeply, to a soil depth of 6 inches. The applica-tion of too little water too often can result in shallow roots. Because actively growing turf-grasses require 1 to 1½ inches of water each week, many irrigation contractors and land-scape professionals set automatic controllers to deliver about ½ inch of water twice each week.

Irrigation Systems and System Components

Hose-end sprinklers have been used to water small turf areas since the late 1800s. How-ever, a properly designed, permanent sprinkler system is much more efficient and convenient. System components most often include a back-flow preventer, an automatic controller or “timer,” plastic (polyvinylchloride) pipe, sole-noid-activated valves, risers, sprinkler heads, nozzles and wiring. Moisture sensors can also be installed to activate the system before turfgrasses begin to suffer severe drought stress and stop irrigating before soils reach saturation and soil water moves below plant roots. For more information on watering see Chapter 4, Water Management.

Figure 26. Permanently Installed Irrigation System Model

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Supplementary Maintenance Practices: DethatchingTurfgrasses produce leaves, roots, tillers and sometimes stolons and rhizomes, as they grow. When plant tissue dies, it is sloughed off, pro-viding energy for many beneficial soil micro-organisms. The rate of decomposition of plant tissue varies depending on the temperature, moisture level, pH and biological activity of the soil. When turfgrasses grow at an exces-sive rate, or in unfavorable soil and climatic conditions, the decay process is slow and organic matter accumulates on the soil surface as thatch. Some species produce more thatch than others. Bermudagrass, bluegrasses, St. Augustinegrass and Zoysia generally produce much more thatch than centipedegrass, chew-ings fescue, hard fescue, perennial ryegrass and tall fescue.

All healthy turf has some thatch. In small quantities, thatch benefits the turf because it increases the impact absorption and wear tolerance of turfs. However, excessive thatch limits rooting and restricts water flow into the soil. Mechanical dethatching is normally recommended when turfgrasses develop more than ½ inch of thatch. To determine the depth of thatch, remove pie-shaped wedges of soil and grass from several areas of turf and mea-sure the thickness of the dark, organic layer.

To control thatch in small areas, a hand rake can be used. Dethatching rakes with several small, curvilinear blades mounted close together are available at many hardware stores and garden centers. Walk-behind vertical mowers can also be used to remove thatch. Engine horsepower and the width and spacing of blades or tines usually vary by manufacturer. Thatch is lifted as vertical mowers move across the turf. These machines are usually most effective when adjusted such that the blades or tines penetrate the entire thatch layer, barely striking the soil below. A turf vacuum or blower may be used to remove loosened organic matter from the turf after dethatching. Flexible-tine dethatchers or spring-type at-tachments for rotary lawn mowers may not be very effective when large quantities of thatch must be removed from a dense turf. Tines may flex or spring back when they contact the turf rather than penetrating the thatch layer and lifting organic matter.

Fescues, bluegrasses and ryegrasses usually recover quickly following early spring or fall dethatching. Removing thatch before broad-casting seeds can improve seed contact with soil and improve seed germination. Bermudag-rass, centipedegrass, St. Augustinegrass and Zoysia can be dethatched in late winter, when the species are dormant, or after green-up, when rising air temperatures promote rapid plant growth.

In addition to mechanical dethatching, a strategy for managing thatch includes

1. Soil testing to determine if an application of lime is necessary to maintain popula-tions of soil microorganisms that decom-pose thatch

2. Using nitrogen sparingly to supply the required amount of nutrient while avoiding excessive aerial shoot growth

Figure 27. Plug or Wedge of Soil and Grass from Turf

Figure 28. Mechanical Dethatcher


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3. Improving surface or sub-surface drainage and adjusting irrigation to avoid saturated soils

4. Using integrated pest management prac-tices (cultural, biological and chemical) and selecting and applying pesticides at rates that have a minimal effect on earthworms and other beneficial organisms involved in the natural ‘breakdown’ of organic matter in soil

5. Core aerifying to relieve soil compaction, improve water infiltration, ‘oxygenate’ the soil and mix soil cores and the beneficial organisms they contain, with thatch.

Supplementary Maintenance Practices: Mechanical AerationIf a turf is heavily trafficked, there is soil compaction to a depth of two or more inches. Compaction restricts the rate that water and nutrients move from the surface into the soil. Plants growing in compacted soils are often weak and poorly rooted due, in part, to a lack of oxygen. Turfs can be “selectively” cultivated to relieve soil compaction.

CoringWalk-behind and tractor-drawn core aeri-fiers remove small cores of plants and soil and deposit them on the turf surface. Cores may be 2 ½ to 3 or more inches long if turfs are aeri-fied when the soil is moist. The core diameter, usually from 1/4 to ¾ inch, is dictated by the inside diameter of the hollow tines installed on the aerifier. The coring pattern of a rotary-mo-tion aerifier depends on the distance from tine to tine on each aeration disc and the spacing between discs. The coring pattern of a vertical-motion aerifier is influenced by the operating speed and the distance between tines.

Direct benefits of coring include an increased rate of water infiltration and an im-proved turfgrass response to fertilizers. Coring turf before broadcasting seed can improve seed contact with soil. A steel drag mat, a piece of chain link fence or a vertical mower can be used to shatter cores after they dry. Mixing the soil from aeration cores with thatch can help speed the rate of decomposition of the organic layer.

Figure 29. Walk-Behind and Tractor-Drawn Core Aerifiers

Figure 30. A Tractor-Drawn, Rotary Motion Core Aerifier

Figure 31. A Small, Pull-Type Slicer

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Slicing and SpikingSlicing and spiking are less intense forms of selective cultivation than coring. Slicing is the process by which a turf is penetrated by v-shaped knives mounted on rotating disks. Similarly, turfs may be spiked using machines with solid tines or flat-pointed blades to pen-etrate thatch and soil. The benefits of slicing and spiking are usually short-lived compared to coring. However, timely slicing or spiking may temporarily improve turf health until climatic conditions improve and a core aerifier can be used.

Supplementary Maintenance Practices: RollingClayey soils that move or shift during wet-dry or freeze-thaw cycles may lift turfgrasses and expose roots to air. Similarly, tunneling by moles often dislodges plants from the soil and the ridges they produce while constructing the tunnels interferes with mowing. Rolling moist turf with a lightweight, water-filled or power roller can help firm plants to soil and level the surface. Heavy rollers can severely compress soil and should not be used to correct surface undulations caused by improper grading, ani-mal activity or the weather.

Supplementary Maintenance Practices: TopdressingOccasionally, a thin (e.g., 1/8 to 1/4-inch) layer of soil or mature compost may be distributed over turf after coring to level the soil surface or improve the root-zone. The topdressing material is usually worked into the turf using a drag mat or brush after each application. Serious problems associated with soil layer-ing can be avoided by using a topdressing soil that matches the texture of the underlying soil. Topdressing and matting mature compost after coring can stimulate biological activity in the underlying soil, improving the turfgrass rooting environment. Nutrients in the top-dressing soil or compost often promote plant growth and improve color. Four-tenths of a cubic yard of topdressing material is required to create a topdressing layer 1/8 inch deep per 1,000 square feet of turf. Generally, when topdressing, no more than ¼ inch of soil or ½

Figure 32. A Topdresser

Figure 33. Large Brown Patch Disease in Tall Fescue Turf

Figure 34. Masked Chafer Grubs

Photo from Frank Hale.


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inch of mature compost should be broadcasted over an actively growing turf.

Renovating a Weak and Weedy TurfSooner or later, diseases and extended peri-ods of hot, dry or cold and wet weather may severely damage turf. Weak turf is usually weedy and may be unresponsive to mowing, fertilizing and watering. Turfs that cannot be improved by routine maintenance can be re-established using conventional methods to destroy the existing stand, till the soil and plant the seed. Renovation is an alternative to conventional re-establishment. Renovation involves planting without completely tilling the soil and often, without totally destroying all the vegetation (Table 11-19).

Well-drained sites with a relatively smooth soil surface and contour and more than 50 percent turfgrass cover, are candidates for renovation. Timing, site preparation, planting method and care after planting, are very im-portant considerations when revitalizing weak turf by interseeding.

Selecting a TurfgrassRenovation provides the opportunity to upgrade existing turfs by introducing a new, improved species, variety, mixture or blend. Select turfgrasses that will provide the ap-propriate quality, are compatible with existing varieties and are adapted to local climate and soils. Each year, varieties of bermudagrass, fine-leaf fescues, Kentucky bluegrass, peren-nial ryegrass, tall fescue and Zoysia are evalu-

ated at universities across the United States in cooperation with the National Turfgrass Evaluation Program. Local county Extension professionals can also suggest turfgrasses for a given location.

Preparing to Plant for Turf RenovationYoung turfgrass plants do not compete very well with large, established plants. Small areas of thin turf may be tilled with a hoe or roto-tiller before being fertil

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