Lawn Management PDF

AGR-206 Lawn Management By Gregg Munshaw and A.J. Powell Jr., Plant and Soil Sciences. Revised by Kenneth Clayton, Plant and Soil Sciences. grow. Kentucky is in the transitional climate...

AGR-206 Lawn Management By Gregg Munshaw and A.J. Powell Jr., Plant and Soil Sciences. Revised by Kenneth Clayton, Plant and Soil Sciences. grow. Kentucky is in the transitional climate zone, where we In this chapter: have hot summers and cool winters. Because of this, there is no single turfgrass that is perfectly adapted to our climate. Lawn Establishment 01 Due to its name, many believe that Kentucky bluegrass is the Turfgrass Terminology 04 best grass choice for Kentucky. However, because Kentucky bluegrass generally lacks heat tolerance, it can struggle and Lawn Renovation 06 become diseased during warm summers. Depending on budget Lawn Maintenance 06 and level of maintenance desired, many grasses can be grown throughout Kentucky. However, to minimize the impact on the For More Information 16 environment, a turfgrass that will not require frequent inputs to look good should be selected. Generally, Kentucky bluegrass is somewhat adapted to Central and Eastern Kentucky, bermu- T urfgrass is the foundation of a quality landscape. It dagrass and zoysiagrass to Western Kentucky, and tall fescue improves the beauty of other ornamentals and pro- throughout the state. Also, red fescues or ryegrasses may be vides a safe recreational surface. Quality lawns greatly desirable in some situations. For most lawns throughout the increase the economic and sociological value of urban homes. state, tall fescue is the best choice due to heat and drought tol- They beautify and reduce the often harsh urban environment erance. All of the grasses, however, differ in their performance by decreasing noise, glare, heat, dust, and mud. Lawns and and qualities. Table 15.1 gives certain characteristics that will other recreational turfgrass areas are an integral part of our help identify many lawn and weed grasses. daily activities. Sod is grown in Kentucky for all species except perennial As trees and ornamentals within a landscape mature, turf- ryegrass and fine fescue. grass becomes less obvious and somewhat less important. In immature landscapes, however, the importance of a uniform Kentucky Bluegrass (Poa pratensis) turfgrass cannot be overstated. Millions of individual grass Many cultivars of Kentucky bluegrass are sold in Kentucky. plants (Figure 15.1) form the turfgrass, but collectively the The common types, such as the cultivar Kenblue, are persistent grass plants become one landscape plant. Just as an individual when maintained at high mowing heights, at low nitrogen tree or shrub should have uniform shape, the turfgrass should fertility, and with minimum traffic. Many improved cultivars be uniform in texture, color, height, and density. Whether the have better summer quality and improved heat tolerance and turfgrass is cut high or low, has coarse or fine texture, is fast or disease resistance. However, to determine how a cultivar sold at slow growing, or is dark or light green is of little importance your local store/sod farm will perform in Kentucky, visit www. in landscaping for non-recreational turfgrass. Uniformity is ntep.org to check current and previous data. the key to quality. A list of common turfgrass terminology and Adaptation—Grows best on well-drained soils in full sunlight; sources for further information may be found in this chapter. very poor performance in Western Kentucky. Major qualities—Fine texture, good resiliency, good spreading Lawn Establishment habit, relatively slow growth. Major problems—Very poor traffic tolerance; not adapted to To establish turfgrass with the greatest potential for uni- shade; severe white grub susceptibility; diseases such as leaf formity, quality, and management ease, select the best grass spot and melting out often cause thinning in May and June; for your needs and establish it properly. Use the right mowing irrigation required when maintained with high-nitrogen fer- practices, fertilization, irrigation, and pest controls to maintain tilization; becomes semidormant (brown) when not irrigated that uniformity. during the summer; slow seed germination (10-21 days); very If your lawn isn’t established properly, you may never achieve poor seedling vigor, causing slow establishment; not adapted a quality lawn, and your maintenance costs may be prohibitive. to clay soil; will creep into landscape beds. Seeding rate—two pounds pure live seed per 1,000 square feet. Choosing the Best Grass Mixtures—Can be mixed with perennial ryegrass or fine fescue as indicated in this chapter. The right grass for Kentucky lawns may not be the one you like best but rather the one that is best adapted and easiest to CHAPTER 15 Lawn Management Table 15.1. Characteristics of some turfgrasses and perennial grass weeds. Stolons Rhizomes (aboveground (belowground Bud Grass stems) stems) Texture1 Ligule2 Leaf3 Other Characteristics Red fescue No Few F S F Narrow, needlelike blades, usually folded. Creeping bentgrass Yes No F L R Often grows in moist areas; grows in patches; stolons usually white; veins prominent. Rough bluegrass Few No F L F Boat-shaped tip; dual veins in midrib; grows in patches. Kentucky bluegrass No Yes M S F Boat-shaped tip; dual veins in midrib; smooth leaf. Perennial ryegrass No No M S F Underleaf shiny; red stem base; veins prominent. Nimblewill Yes No M Sh R Aerial tillers; short leaves; compressed sheaths; grows in patches; stolons usually green; rooting at lower nodes. Quackgrass No Yes M M R Claw-like clasping auricles; blue-green color. Bermudagrass Yes Yes C-F Mh F Upright tillers grow at 30°-60° angle from lateral stems; some hairs on leaf surface; sheaths round; long stolons. Zoysiagrass Yes Yes C-F Mh R Tillers grow at 90° angle; sheaths compressed; tuft of hairs at collar; hairy on leaf surface; very knotty nodes. Tall Fescue No No C S R Leaf margin serrated; red stem base; veins prominent. Timothy No No C L R Bulbous base. Orchardgrass No No C L F Stem very flat; blue-green color. Dallisgrass No No C L R Hairs grow on leaf margin. 1 Texture: F = fine, M = medium, C = coarse 2 Ligule: S = short, M = medium, L = long, h = hairy 3 Bud leaf: F = folded, R = rolled Tall Fescue (Festuca arundinacea) Seeding rate—Six pounds pure live seed per 1,000 square feet. Tall fescue is used for lawns, hay, and pasture throughout Mixtures—Mixtures with other species such as Kentucky Kentucky. When properly seeded and managed as a lawn, bluegrass are not recommended except where sod is grown however, it has little resemblance to the tall fescue in pastures. specifically for transplanting purposes. Although it is normally a bunchgrass, when a dense cover of Fine Fescues (Festuca rubra, Festuca ovina, Festuca trachyphylla, tall fescue is established in a lawn, leaf coarseness and clumping etc.) are not problems. To determine how a cultivar sold at your local store/sod farm These fine-leaf grasses are often designated as creeping red, will perform in Kentucky, visit www.ntep.org to check current chewings, hard, or sheep fescue. Fine fescue is a niche grass that and previous data. will tolerate some shade, drought, and low fertility. New, turf-type cultivars are more finely textured and denser Very little fine fescue is grown in Kentucky, thus cultivar cultivars than Kentucky 31 (KY 31), and they may have more recommendations are not specifically available. See www.ntep. brown patch disease problems. They are best for highly main- org for top-performing cultivars from other states. tained, more formal lawns. KY 31 is best for large acreage, Adaptation—Poorly adapted except where some shade is pres- minimum-maintenance turfgrass areas, and slopes that need ent; not adapted to heavy shade or heavy traffic. to be stabilized. Turf-type tall fescues more closely resemble a Major qualities—Tolerant to low fertility; tolerant to droughty good Kentucky bluegrass lawn than pastures. and acid soils; fine texture. Adaptation—Most widely adapted turfgrass for use Major problems—Poor traffic tolerance and often clumps in Kentucky. when heavy traffic imposed; becomes semi-dormant (brown) Major qualities—Adapted to full sun or medium shade; per- in summer when located in full sun; susceptible to severe grub forms well on heavy clay to sandy soils; good traffic tolerance; damage; lateral spread is very slow; will not survive continuous no serious insect problems; very competitive with weeds; little heavy-nitrogen fertilization. if any irrigation required (except in severe drought); faster to Seeding rate—Two pounds pure live seed per 1,000 square feet. establish than Kentucky bluegrass. Mixtures—When a turfgrass area includes both full sun and Major problems—Requires more frequent mowing than shade, a mixture of approximately 50 percent to 80 percent Kentucky bluegrass; some brown patch disease problems Kentucky bluegrass and 20 percent to 30 percent (by weight) during hot summers; turf has little resiliency; lateral spread is fine fescue may be seeded. very slow. 15-2  Lawn Management CHAPTER 15 Mixtures—For quick establishment and increased erosion control, seed no more than 10 percent to 15 percent by weight (approximately one-quarter pound per 1,000 square feet) with Kentucky bluegrass (1¾ pounds per 1,000 square feet); do not seed with tall fescue or fine fescue. Bermudagrass (Cynodon dactylon) Bermudagrass occurs naturally in many Kentucky lawns and is most often considered a weed. Native bermudagrass, often called “wiregrass,” is usually found or planted in hot, dry loca- tions where it is difficult to grow cool-season grasses. Cultivars should be selected that are adapted to Kentucky winters. To determine how a cultivar sold at your local store/ sod farm will perform in Kentucky, visit www.ntep.org to check current and previous data. All bermudagrass cultivars must be planted in late May or early June. Adaptation—Mainly adapted to full sun and well-drained soils. Major qualities—After establishment, bermudagrass is tolerant to low fertility and drought and makes a resilient, traffic-tolerant turfgrass. Major problems—Difficult to mow (requires sharp mower); not shade tolerant; is dormant (brown) from approximately early October to early May; winterkill can be a concern during especially cold winters; because of its creeping habit of growth, bermudagrass often becomes a serious pest in gardens and Figure 15.1. Physical structure of a grass. flower beds and will rapidly creep into a neighbor’s lawn. Planting rate—Plug on one-foot centers, sprig in six-inch Perennial Ryegrass (Lolium perenne ) rows one foot apart, or (for large areas) broadcast two to seven bushels of shredded sprigs over 1,000 square feet and cover by Most perennial ryegrass cultivars are not reliable and form light disking or soil topdressing. a clumpy, open turfgrass that has little appeal and poor persis- Seeding rate—(Seeded varieties), one pound per 1,000 square tence. Several new, improved, fine-leaf perennial ryegrasses are feet for non-coated seed, or two pounds per 1,000 square feet available. These blend well with Kentucky bluegrass when it is for coated seed. necessary to obtain quick cover, protect the soil from erosion, or seed out of season. Zoysiagrass (Zoysia japonica) To determine how a cultivar sold at your local store will This is an excellent summer grass for areas with full sunshine perform in Kentucky, visit www.ntep.org to check current and or moderate shade and heavy summer traffic. previous data. Zoysiagrasses in general are known for having better cold Adaptation—When seeded alone, ryegrasses may not survive tolerance than bermudagrasses. Several cultivars are available the summer unless irrigation and disease control are provided. that are adapted to the transition zone climate. To determine Although not adapted to heavy shade, they can survive it some how a cultivar sold at your local store/sod farm will perform in years and are easily established among the surface roots of trees. Kentucky, visit www.ntep.org to check current and previous data. Major qualities—Fine texture similar to Kentucky bluegrass; Adaptation—Zoysiagrass has moderate shade tolerance so more tolerant than other grasses to heavy clay and compacted may be used in sun and shade situations. It has excellent winter soils; germinates quickly (five to seven days); excellent seedling hardiness and will grow throughout Kentucky. vigor; great traffic tolerance; can be mowed short (approxi- Major qualities—After establishment, extremely tolerant to mately one inch); will often dominate nimblewill and other low fertility and drought and makes a very resilient, traffic- weed species; can be seeded with minimum soil preparation. tolerant turfgrass; very competitive against weeds and has few Major problems—Somewhat difficult to mow (requires sharp pest problems; will grow very slowly and thus will not require mower); susceptible to summer brown patch disease; has little frequent mowing; spreads slowly, so not as invasive as other heat tolerance; needs summer irrigation if thick stand is estab- creeping grasses. lished; sod has little resiliency. Major problems—Dormant (brown) from October to early Seeding rate—Four pounds pure live seed per 1,000 square May; can become thatchy, especially if overfertilized. feet when broadcast seeded. 15-3 CHAPTER 15 Lawn Management Turfgrass Terminology Scalp—To remove an excessive quantity of functioning green leaves at any one mowing, resulting in a brown appearance with exposed Annual, summer—A plant that completes its life cycle, from seed, in one crowns, lateral stems, and dead leaves. growing season. Scum—A layer of algae on the soil surface of thinned turfgrass. Annual, winter—A plant that initiates growth in the fall, lives over winter, Slowly available fertilizer— A fertilizer that designates a rate of dissolution and dies after producing seed the following spring or summer. of nitrogen that is less than that obtained from completely water- Blend—A combination of two or more cultivars of a single soluble (readily available) fertilizers. turfgrass species. Sod—Plugs, squares, or strips of turfgrass with adhering soil; can be Bunch-type growth—Plant development by tillering at or near the soil used in vegetative planting. surface; no lateral stems produced. Sprig—A stolon, rhizome, or tiller used to establish new turfgrass or Clippings—Leaves cut off turfgrass by mowing. plants in furrows or small holes. Cool-season turfgrass—Turfgrass species best adapted for growth during Stolon—An elongated stem that grows along the surface of the cool portions (60°F-75°F) of the growing season. Examples: Kentucky ground and from which leaves and roots develop at the nodes. bluegrass, tall fescue, fine fescue, perennial ryegrass. Thatch—A layer of undecomposed or partially decomposed turfgrass Coring—A method of turfgrass cultivation by which soil cores are roots and stems situated above the soil surface and constituting the removed using hollow tines or spoons. upper stratum of the medium that supports turfgrass growth. Cultivation—Disturbance of the soil without destruction of the turf- Tiller—A lateral shoot, usually erect, that develops intravaginally from grass. Examples: coring, spiking, aerification. axillary buds. Cutting height—On a mower, the distance between the soil surface and Turf—A covering of mowed vegetation, usually a turfgrass, grow- the plane of cut. ing intimately with an upper-soil stratum of intermingled roots and stems. Dethatch—To remove an excessive thatch accumulation, usually by a mechanical practice such as vertical mowing. Turfgrass—A species or cultivar of grass that is maintained as a mowed turf. Foliar burn—Injury to leaf tissue caused by dehydration due to contact with high concentrations of certain fertilizer salts or chemicals. Verdure—The layer of aboveground, green, living plant tissue remain- ing after mowing. Herbicide—A pesticide used for controlling weeds. Warm-season turfgrass—Turfgrass species adapted to favorable growth Irrigation—Application of water to turfgrass by either hand-set sprin- during warm portions (80°F–95°F) of the growing season. Examples: klers or by automatic means using electronic controllers. zoysiagrass, bermudagrass. Localized dry spot—A dry spot of sod that resists rewetting by normal rainfall or irrigation. Usually associated with an accumulation of thatch, a high spot, shallow soil over buried debris or rock, or major fungal activity that renders the soil hydrophobic. Soil Preparation Mixture—A combination of two or more species. Proper soil preparation is critical to the establishment and Mowing frequency—The number of times the lawn is mowed per week long-term quality of a lawn. Soil conditions are very poor on or month. many lawn sites, because the lawn was the last consideration Mowing height—The distance above the ground surface at which the instead of the first. The following factors should be strongly turfgrass is cut during mowing. considered when starting a new lawn. pH (soil)—A numerical measure of the acidity of the soil. A pH of 7 is neutral, above 7 is alkaline (basic), and below 7 is acidic. Grading Reel mower—A mower that cuts turfgrass by means of a rotating reel of Ideally before a new lawn is established, the topsoil should blades that passes across a bed knife fixed to the mower frame, thus be stockpiled to the corner of the lot prior to house construc- giving a shearing type of cut. tion. After the house is finished, all building debris should be Renovation—Turfgrass improvement involving replanting into existing removed from the lawn area. This is a step that most contractors live and/or dead vegetation. skip, and they simply push the topsoil over the construction Resiliency—The capacity of the turfgrass to spring back when balls, debris. If you are building a house, insist that the site is thor- shoes, or other objects strike the surface, thus providing a oughly cleaned prior to moving topsoil. The subgrade should be cushioning effect. sloped away from the house in order to reduce the possibility Rhizome—An underground elongated stem with new plants springing of water entering the basement. After the subgrade has been from nodes along the stem. completed, the stockpiled topsoil can be respread. With four Rotary mower—A mower that cuts turfgrass by high-speed impact of a to six inches of good topsoil, establishment and maintenance sharp blade rotating in a cutting plane that is parallel to the of your lawn can be a pleasure rather than a nightmare. Often turfgrass surface. contractors will remove some of the topsoil from the yard and leave you with one-half to one inch of topsoil, which results in many challenges in growing lawns and landscape plants. 15-4  Lawn Management CHAPTER 15 Soil Amendments extremely hot and dry summers, however, sodding should It is hard to purchase good topsoil. Frequently, the home- be delayed, or the soil should be watered to cool it just prior owner ends up getting soil much poorer than what is already to installation. there, and often it is seriously infested with weed seed. Vegetative strains of bermudagrass and zoysiagrass are Adding large quantities of organic matter is the best way normally sprigged or plugged and should be established dur- to improve a poor soil. Peat moss, well-decomposed sawdust, ing May or June after the soil is warm. Seeded bermudagrass well-rotted and weed-free manure, sewage sludge, or compost should be planted at the same time, so the turfgrass can be well will improve soil that is either too sandy or contains too much established before a potentially bad winter. clay. Use two to three cubic yards of organic matter for each Seed, Sod, or Vegetative Planting 1,000 square feet of lawn area. The organic matter should be spread evenly over the surface and thoroughly mixed into the Kentucky bluegrass and tall fescue lawns can be seeded or upper four to six inches of soil before seeding. sodded, while improved strains of bermudagrass or zoysiagrass are most usually planted from existing vegetative material. Soil Lime and Fertilizer preparation is the same, regardless of the planting method used. The soil should be tested to determine exact lime and fer- Seeding is usually accomplished with a rotary seeder or the tilizer needs. Your local office of the Cooperative Extension commonly used seed and fertilizer spreader. For uniform dis- Service can provide soil cartons and the information you will tribution, the seed should be divided into two equal lots, which need for performing soil tests. The soil should be taken from should be seeded at right angles to each other. It is imperative the completed grade, rather than the subgrade. Soil tests are that the seed is lightly covered by soil (referred to as seed-soil very inexpensive and can be conducted at any time of the year. contact) for good germination. Cover the seed by raking lightly Many soils throughout Kentucky do not require additional or rolling, and avoid a smooth surface. It is best to mulch the phosphorus or potassium. Because applying fertilizers to soils area with clean straw or other suitable material. Mulch will help that do not require them can be serious pollutants, no fertil- keep moisture at the soil surface and minimize soil movement izers or lime other than nitrogen should be applied without (erosion) before the grass can hold it in place. The mulch cover- taking a soil test. Refrain from applying nitrogen until seeds ing should be thin enough to expose approximately 50 percent have germinated and roots are able to remove nutrients from of the soil surface, which usually requires approximately one the soil. Nitrogen applied at seeding will have a higher tendency bale of straw per 1,000 square feet of area. It is important to to leach through the soil or runoff with rain with no plants to water frequently in order to keep the soil surface moist until remove nutrients or slow water movement on the soil surface. seedlings become established, especially if a mulch is not used. Before ordering or obtaining sod, be sure you are prepared for its installation. It is generally best to establish a straight Planting line lengthwise through the lawn area. The sod can then be Before Planting laid on either side of the line with the ends staggered, as when A newly graded lawn area should be allowed to settle before laying bricks. planting. Two or three good rains or irrigations will aid in the The better the sod quality, the easier it is to transport and settling. Puddles of water that form during a rain or irrigation install it. Quality sod is light, does not easily tear apart, and indicate low spots that need to be leveled or have drainage generates a root system quickly. Sod is perishable and should installed. Excessive water on the lawn is as bad or worse as not not remain on the pallet or stack longer than 36 hours. The enough water. Good surface drainage is a must! presence of mildew and distinct yellowing of the leaves is usu- The final seedbed should be firm and free of large clods, ally good evidence of reduced vigor. rocks, and discarded building materials. Installing sod is an art. A sharpened concrete trowel is very handy for cutting pieces, forcing the sod pieces tightly When to Establish together, and leveling small depressions. Just as seed-soil con- There are only certain periods each year when temperature, tact was important above, sod-soil contact is also important. moisture, and weed competition favor successful seeding Immediately after the sod is laid, it should be rolled and kept of lawns. moist until the sod is well-rooted into the underlying soil. Any The best time to seed cool-season grasses such as Kentucky air spaces between the sod and soil will cause those areas to dry bluegrass or tall fescue is from mid-August through early out, and rooting will be impaired. October. The second-best time is from mid-February to mid- Vegetative planting, using either sprigs or plugs, is the com- March, and not later than mid-April. Due to weed competition mon method used in establishing high-quality bermudagrass and moisture stress, late spring to midsummer seedings are and zoysiagrass. Once again, plant material-soil contact is seldom successful. critical for success. Sprigs can be either broadcast over an area Sod of Kentucky bluegrass and tall fescue can be installed and covered lightly with soil or can be individually planted on almost anytime except midwinter, when soil is frozen. During 6- to 12-inch centers. In either case, the individual sprig should 15-5 CHAPTER 15 Lawn Management have one end about two inches below the soil surface and the Success is best achieved when: other end above the soil surface, so that a node or joint with Existing grass and/or weeds are almost entirely killed by some leaves extends aboveground. Sprigs can be purchased insects, disease, drought, or non-selective herbicides. by the bushel or can be purchased as sod and then shredded. The majority of existing grass and weeds can be completely One bushel of sprigs is approximately equivalent to one square removed with a dethatching machine. yard of sod. Plugs of zoysiagrass are commonly available and Renovation can be accomplished in early fall or early spring. are one to two inches in diameter and one to two inches deep. The surface can be kept moist for about two weeks with The plugs should be fit tightly into prepared holes and tamped irrigation. firmly into place. Sprigs and plugs should be kept moist until they are well established. Vegetatively planted bermudagrass Sowing the Seed can be fully grown in one to two months, while zoysiagrass may The seed should be evenly spread over the area at the rate take a year or longer, depending on planting density, environ- of two pounds per 1,000 square feet for Kentucky bluegrass, mental conditions, and cultivar. six pounds per 1,000 square feet for tall fescue, or two to four Caring for New Lawns pounds per 1,000 square feet for perennial ryegrass or red fes- Moisture is probably the most important consideration cue. Rake the seed lightly into the seedbed or traverse the area immediately after planting. Regardless of the method used for again with the dethatching machine for good seed-soil contact. planting, the soil must be kept moist for two to three weeks. If using a power seeder, seed only about one pound per Mowing should not be delayed just because the 1,000 square feet per pass and make multiple passes, if possible. lawn is new. After the turfgrass begins to grow, mow to If only making one or two passes, you can broadcast three to recommended heights. four pounds per 1,000 square feet before making the last pass. Remember, chances of success are good if you seed during late August and September, fair during late February or early Lawn Renovation March, and very poor from mid-spring to August. Preparing a Seedbed Proper Care Little success can be expected if you just broadcast seed on Newly seeded areas should be watered immediately after the soil surface. In order for seed to germinate and survive, it seeding. Watering should continue as long as necessary to must have good soil contact. Sometimes a heavy raking will obtain satisfactory germination and growth. The surface should loosen the soil surface sufficiently, but most often the surface be kept consistently moist without forming puddles. Begin is hard, and weeds or dead grass make raking difficult. mowing as soon as some of the grass grows higher than the A vertical mower or dethatching machine can often be desired mowing height. Keep the mower blade sharp as a dull rented from a local lawn supplier or equipment-rental agency. blade can rip young plants out of the soil. Not only will vertical mowing or dethatching loosen the dead If the area is seeded in spring and crabgrass is a potential grass and weeds, it will leave shallow grooves or slits in the problem, apply a preemergent crabgrass herbicide immediately soil surface. Seeds falling into these slits are much more likely after seeding. Siduron (Tupersan) or mesotrione (Tenacity) are to germinate and live. For best results, it may be necessary to the only preemergent herbicides that can be used. A second traverse the area several times in different directions in order application should be applied in late spring or early summer. to disturb the soil sufficiently. Follow the specific label directions. Most commercial lawn companies and some rental agencies Caution: Germination of desirable grasses may be decreased have power seeders. These machines vertical mow/dethatch if broadleaf weed killers such as 2,4-D have been applied one and distribute the seed in a single pass; however, it is still desir- to two weeks before seeding. These herbicides should not be able to seed in multiple directions to avoid missing any areas. applied to young seedlings. Before applying these herbicides, wait until the new grass has grown enough to be mowed at Selecting the Right Grass least twice. Assuming that the lawn is established to an adapted grass, it is usually more desirable to seed the same species as the existing grass in order to maintain uniform appearance. Do not seed Lawn Maintenance coarsely textured grasses like KY 31 tall fescue into a Kentucky The intensity of turfgrass maintenance varies with the home- bluegrass lawn. Turf-type tall fescue is the preferred renovation owner’s inclination, expertise, available working hours, and grass, as it has a similar texture to Kentucky bluegrass. Kentucky budget. It also varies greatly depending upon your soil and the bluegrass is very difficult to establish within an existing lawn— grass species in place. There are certain maintenance practices, the seeds are very small and seedling vigor is low. however, which are necessary for quality turfgrass. 15-6  Lawn Management CHAPTER 15 Table 15.2. Optimum mowing height for some grass species. Removal of Clippings and Thatch Species Height (in) Unfortunately, most people still believe clippings increase Kentucky bluegrass 2-3 thatch, which is the tightly intermingled layer of organic mat- Tall fescue 2.5 - 4 ter that sometimes accumulates between the soil surface and Creeping red fescue 2-3 the green leaves. Research has shown, however, that thatch Perennial ryegrass 1-2 is caused by species (grasses that produce rhizomes and Bermudagrass 1 - 1.5 Zoysiagrass.75 - 1 stolons have greater thatch), too much nitrogen fertilization, acidic surface soil, frequent irrigation, and a low population of earthworms. Mowing Clippings have no effect upon thatch accumulation. They Some of the most serious mistakes are mowing lawns too contain 75 percent to 85 percent water and are easily decom- closely, too infrequently, or using a dull mower blade. posed into humus. Research has shown that thatch is made Below-optimum mowing heights restrict root development, up of about 60 percent dead and living roots and rhizomes, and the grasses become susceptible to disease, heat and drought with the remaining 40 percent composed of dead stems, leaf damage, traffic injury, and weed infestation. Check the blade sheaths, and crown tissue—all highly ligneous (woody) and height and follow the guide in Table 15.2. slow to decompose. Mowing is somewhat injurious to grass because it removes When clippings are not removed, they occur only in the a portion of the youngest, most active leaves. Unless the tiller upper surface layers as “pseudo” thatch. This pseudo thatch can is beginning to flower, which usually occurs in late spring, the be raked out of the turfgrass, but raking it out won’t reduce a growing point of each stem is located near the soil surface and problem with real thatch, which cannot be removed with a rake protected from the mower blade. Therefore the grass plant is because it is tightly interwoven by a mass of roots. Real thatch just a series of leaves that we often call a pseudostem. The true can be removed only partially with mechanical dethatchers. upright growing stem does not develop until the flowering Thatch is currently not a problem in most cool-season grass process begins (Figure 15.2). lawns. It never accumulates in tall fescue, moderately fertilized The general rule is to mow often enough so that no more lawns, or in lawns with a healthy earthworm population. than one-third to one-half of the leaf is removed at any one Many people also remove clippings to reduce disease prob- mowing. If the grass grows too tall between mowings, increase lems. Removing any biomass does help slow down a fungus, the mowing height—do not cut it all off at one time. Removing but Kentucky lawns seldom have a serious disease problem. half or more of the leaf blade in any one mowing results in a When they do, the disease almost always occurs during the hot negative impact on the root system. Remember, the lower you summer when the turfgrass is growing slowly and producing mow, the more frequently you need to mow. few clippings. A sharp mower blade makes mowing easier and results in Some people remove clippings to prevent windrowing or a better looking and healthier turfgrass. Dull blades result in a globs of wet clippings left on the lawn’s surface. Mow more fre- longer healing time for the leaf, which can result in increased quently to avert this problem. As mentioned previously, mow- disease pressure. Further, dull blades require more power to cut ing should be repeated when the leaves have grown about 30 through the leaf, resulting in increased fuel usage. You may need percent to 50 percent above the previous mowing height. If you to sharpen the mower two to three times a year. are mowing at a two-inch height, mow again when the turfgrass reaches a height of about three inches. If it rains for a week and the height reaches five inches, raise the mower to three inches for the next mowing. After a couple days, lower the height back to the original two inches and mow again. Don’t take off all the leaves at once because it increases the amount of clippings that shade the remaining grass, often causes the mower to pile up or windrow the clippings, weakens the grass by removing its tiller tiller tiller photosynthetically active leaves, and looks unsightly. You need to mow frequently during April and May, when almost 50 percent of the total annual growth occurs. Some cheaper mowers do a poor job of distributing clip- pings even when conditions are great. However, all mowers work best when the grass leaves are dry, the grass has grown no more than 50 percent higher than the previous mowing tiller, tiller,immediately immediately tiller, immediately tiller, tiller, aafew tiller, afew fewdays days days height, and mower blades are sharp. A common complaint after after aftermowing mowing mowing after after after mowing mowing mowing against returning clippings is that the homeowner does not Figure 15.2. Grass tiller and pseudostem after mowing. 15-7 CHAPTER 15 Lawn Management like the look of the clippings on the lawn. However, if the lawn Fertilization is mowed properly and leaf clippings are short, they don’t look unsightly because they filter down between the remaining grass In order to sustain a quality lawn, nitrogen fertilizer must be leaves and quickly decompose. applied annually to help maintain turfgrass uniformity and a Some mowers are advertised as mulching mowers that cut good, green color, while also reducing weed problems. However, or shred the leaves into smaller fragments. These mowers work if fertilizer is applied improperly or at the wrong time, you can as advertised; however, to prevent clogging of the mower, the lose these benefits. turfgrass must be dry and mowed often. Soil Test Another reason for removing clippings is to remove the Randomly collect one to two pints of soil from the top few mess—clippings tracked into the home and scattered onto the inches of the lawn and take it to the local Extension office. sidewalk or driveway—and create a slightly neater appearance The University of Kentucky Soils Testing Lab can determine on the surface of dense turfgrass. But is removing clippings if phosphorus (P), potassium (K), or lime are needed. The worth the problems it creates? No! recommended rates of nutrients can be applied with a fertil- Finally, not removing clippings helps the environment. It’s izer containing only P (for example, triple superphosphate not necessary to use landfills to dispose of vegetative material 0–46–0) or K (for example, muriate of potash 0–0–60), or that will decompose into something as useful and safe as humus. by using a complete fertilizer, such as 10–10–10, 17–17–17, So what can we do with grass clippings? That’s easy! Don’t 10–20–10, etc. Once you get a high level of P and K in the soil, collect them in the first place. Clippings add fertilizer back to little additional P or K may be needed for several years. As was the lawn, maybe as much as 25 percent of the lawn’s annual mentioned previously, many soils throughout Kentucky do not needs. One thousand square feet of a well-fertilized lawn can require P or K due to parent material or many years of fertilizing produce as much as 400 pounds (dry weight) of clippings per with these products. Additional applications of these nutrients year. These clippings average about 4.8 percent nitrogen, 0.7 to soils with adequate levels is a waste of your money and can percent phosphorous, and 2.6 percent potassium, and they also have a negative impact on the environment. have minute quantities of many minor nutrients—good stuff. If you must collect clippings, use them yourself. First, con- Timing sider spreading them lightly over a low-maintenance turfgrass Fall is the best time of year to apply nitrogen to cool-season area, vacant lot, etc. Scatter them; don’t dump them into a pile. grasses, such as Kentucky bluegrass and tall fescue (Table 15.3). Second, consider using them as a mulch around ornamen- In response to fall nitrogen, the turfgrass develops a better root tals or between rows in the garden to reduce weed compe- system, becomes very dense, and has much better color in tition, conserve soil moisture, and supply nutrients as the late fall and early spring. By eliminating or minimizing spring clippings break down. Apply them at least an inch thick and fertilization, you prevent the heavy flush of growth that occurs turn them under in the fall to improve soil tilth and supply with it, develop a better root system, and develop a more heat- additional nutrients. tolerant, weed-free turfgrass. Third, consider composting the clippings and using the com- If for some reason nitrogen was not applied the previous post to modify soil in the garden or in plant pots. Grass clippings fall, an application during early spring will improve green-up. alone are sometimes difficult to compost since they become Even if fall nitrogen was applied, it is helpful in some years with very dense and anaerobic, often causing an odor problem. It is heavy spring rainfall to apply a half-rate of nitrogen in late May best to compost a mixture of clippings, tree leaves, wood chips, or early June, but only if necessary to improve color. Crabgrass garden weeds, etc. You can often hasten composting by keeping and other summer annual weeds respond to the nitrogen the pile moist and by occasionally adding some soil, nitrogen much more than bluegrass or fescue. The more you fertilize fertilizer, and lime. cool-season grasses with nitrogen in spring and summer, the When using clippings as a mulch or compost, be aware more you need to irrigate, control thatch, and use chemicals to that such compost may contain weed seed such as crabgrass. control weeds, insects, and diseases. A lush, green lawn may Also, make sure that the lawn has not been sprayed with a not be worth these problems. herbicide within a few days of mowing, because residues from Late spring to early summer is the best time to fertilize ber- certain broadleaf weed herbicides may cause damage to the mudagrass and zoysiagrass, since they are warm-season grasses mulched plants. and perform best during hot summer months. Finally, because clippings are full of nutrients, it is important to sweep or blow them off sidewalks and back onto the lawn. How Much Nitrogen to Apply Clippings that are washed into the stormwater system act just A good rule is to apply about one pound of actual nitrogen like fertilizer and can cause algal blooms in ponds and lakes. per 1,000 square feet per application. Most home lawns will perform well with only two pounds of actual nitrogen per year. Additional nitrogen may be warranted for lawns that have a lot of traffic from kids or pets or are heavily irrigated. Lawns 15-8  Lawn Management CHAPTER 15 Table 15.3. Schedule for nitrogen application to lawns. Maintenance Applications Cool-Season Grasses1 Warm-Season Grasses Level per Year (Kentucky Bluegrass and Fescue) (Bermudagrass Zoysiagrass2) Low 1 Oct-Nov Jun Medium 2 Sept-Oct, Nov-Dec May, Jul High 3 Sept-Oct, Oct-Nov, Nov-Dec Apr, Jun, Aug Very High 4 Sept-Oct, Oct-Nov, Nov-Dec, late May-early June (1/2 rate) Apr, May, Jun, Aug 1 Red fescue and all cool-season grasses grown in shady lawns should be fertilized only once per year. 2 Zoysiagrass needs only minimal nitrogen after lawn is fully established. Table 15.4. Examples of fertilizers and rates needed leaves. However, if they are applied in the fall and early winter for 1 lb of actual nitrogen per 1,000 sq ft. as suggested and at the proper rate, they will seldom, if ever, Fertilizers Rate (lb) burn a turfgrass. The biggest problem with these fertilizers is Farm the lack of calibration and application information on the bag. Ammonium Nitrate (34-0-0) 3 You have to calculate the correct amount to apply and calibrate Urea (46-0-0) 2.2 the spreader to get the appropriate coverage. 10-10-10 10 Depending on the type of spreader used, it is sometimes 5-10-10 20 difficult to get only 2.2 or 3 pounds of fertilizer evenly spread in Specialty a 1,000-square-foot area. Without experience, it often appears 24-4-4 4.5 that too little fertilizer is being applied, and the temptation is 16-6-8 6 to apply more. Be careful! Applying more than 1½ to two times 27-4-9 3.5 the recommended rates will greatly increase the burn potential 20-5-10 5 and cause an excessive flush of growth. An application of 10 32-4-8 3 pounds per 1,000 square feet, such as with 10–10–10, is easier to Note: Rates apply 1 lb N per 1,000 sq ft of lawn. detect in the grass. However, the burn that results when apply- ing more than 15 pounds per 1,000 square feet is even more receiving more than two pounds of actual nitrogen per year will serious with these mixed fertilizers because of the potassium often require additional mowing and pest control. The fertilizer salts that are included. analysis tag indicates actual nutrients and the first number (as Most of the specialty fertilizers also contain a certain in 10–6–4) indicates the percent of nitrogen, so you can easily amount of slow-release nitrogen, which is indicated on the calculate the pounds of actual nutrient in a bag. For example, bag under the heading “water-insoluble nitrogen” or “coated a 50-pound bag of 10–6–4 contains five pounds (50 x 0.10 = 5) nitrogen.” Usually the amount of this slow-release nitrogen is of actual nitrogen. It also contains three pounds (50 x 0.06 = 3) less than one-third of the total amount of nitrogen in the bag. of P2O5 and two pounds (50 x 0.04 = 2) of K20. The remainder Slow-release nitrogen adds safety in application, but the small of material in the bag (50-(5+3+2) = 40), i.e., 40 pounds, is called amount of it that’s included doesn’t really provide good long- the filler or carrier. To apply one pound of nitrogen per 1,000 term nitrogen availability. square feet, you would need to apply 10 pounds (10 x 0.10 = 1) Most of the specialty fertilizers can be programmed exactly of the 10–6–4 fertilizer. the same as you would program a farm fertilizer. Table 15.4 shows both farm fertilizers and hypothetical If you do not remove clippings, most specialty fertilizers fertilizers representative of many specialty fertilizers with high contain sufficient P and K to maintain the soil level. Therefore, nitrogen and low phosphate levels. once you correct any soil deficiency, continual use of specialty fertilizers will be sufficient for P and K for many years. Farm Versus Specialty Fertilizers Spreader Calibration Lawns can be fertilized either with the specialty fertilizers, which are often sold in garden centers, or with farm fertilizers. Spreader calibration becomes necessary if you use a fertil- The main advantages to the specialty fertilizers are their nor- izer brand that does not have calibration information or if the mally good nutrient ratios, uniformity in particle size, low burn bag information does not include your spreader model. Since potential, and the printing of calibration and application rate the density and granule size of fertilizers are quite variable, it information on the bag. sometimes becomes necessary to recalibrate the spreader for Farm fertilizers are usually three to five times less expensive, almost every application. but they have some disadvantages. Farm fertilizers such as When using a drop-type push spreader, begin by guessing ammonium nitrate and 10–10–10 must be used with caution at a spreader setting, then apply a known amount (such as five because of their burn potential. You should not apply them pounds) to a test area and determine the square footage covered during extremely hot weather or when moisture is on the grass (length multiplied by width) or apply the fertilizer over a plastic 15-9 CHAPTER 15 Lawn Management sheet or sidewalk area of known square footage and collect and through lawn spreaders in sufficient quantities and is very dusty. weigh the fertilizer deposited. The dolomitic limestone is also usually slightly more expensive After calculating the rate applied per 1,000 square feet, if because it contains some magnesium carbonate as well as the first guess was right, treat the lawn at that setting. If not, calcium carbonate (ag lime). Since our Kentucky soils contain readjust the spreader and follow the same procedure until the sufficient quantities of magnesium, the dolomitic limestone is correct calibration is achieved. not needed. Calibrating to a half-rate setting and going over the yard A bagged, pelleted-lime product is available in many lawn twice will ensure a more uniform coverage and color. and garden stores. This product flows freely through lawn It is somewhat easier to calibrate a rotary-type push spreader spreaders and is not extremely dusty. It is, however, more expen- or a hand-crank (shoulder strap) rotary spreader than a drop- sive than agricultural lime and must be used at equivalent rates. type spreader, since the width of coverage with those spread- Hydrated and burned lime can often be purchased. Although ers is much greater (10 to 25 feet). Measure a test area of lawn somewhat lesser quantities than other limestone types are (for example, a side yard that equals 2,000 square feet). Put the needed to reduce the acidity, some burn problems may occur. correct amount of fertilizer (for the 2,000 square feet) into the Gypsum (calcium sulfate) is often sold as a substitute for lime or spreader with the opening adjusted to be just slightly larger than as a soil conditioner to loosen a heavy clay soil. It is not effective the size of the individual granule. If more than two or three in changing pH or improving the structure of Kentucky soils. passes are required to dispense the fertilizer, then select another known area (for example, the backyard). Increase the size of the Core Aerification opening and continue to refine the calibration until the total Core aerification is a mechanical cultivation process in amount needed is spread in a couple of passes through the yard. which cores of soil, about three-quarters of an inch by three Calibration is not easy and usually requires more time inches, are removed from the soil surface with an aerifier and than the application itself. Because of wear and rust, spreader then scattered back on the soil surface. On heavily trafficked openings often change in relative size. Whether the calibration golf greens and athletic fields, core aerification is extremely information from the bag or your actual calibration is used, beneficial in reducing compaction and organic accumulation always recheck to see if the approximate amount of fertilizer on the surface, as well as smoothing the surface. Core aerifica- is actually used. tion may be somewhat beneficial for home lawns to penetrate After completing the fertilizer application, immediately surface organic matter that sometimes becomes hydrophobic clean the spreader. Because of its high salt content and abil- and to provide some leveling as the soil cores are distributed ity to absorb moisture, fertilizer left in a spreader will cause back into surface depressions. On the other hand, core aerifica- immediate rusting. Also, do not let the wash water from the tion is not as beneficial for lawns as it is for sport turf surfaces spreader run onto the lawn. It may cause uneven growth or because of the following: excessive burning. Surface compaction, which is caused by heavy traffic, is not usually a problem on lawns. Liming Clay, the dominant soil texture on most urban lawns, is dif- A soil pH test is required to determine the extent of soil ficult to penetrate with the aerifier, and clay soil cores are acidity. The pH test should be run every two or three years, hard to extract from the coring tines. especially if the lawn is under high maintenance. Natural It is difficult to influence the surface significantly. To achieve weathering of soils and the addition of acid-forming fertilizer best results, cores need to be made on two-inch-square or can lower the pH sufficiently to reduce the growth and quality three-inch-square centers, which is hard to achieve with of most grasses, especially Kentucky bluegrass. However, due to aerifiers available on the consumer market. limestone parent material in many Kentucky soils, our soils are Coring just before broadcasting seed is often suggested as a naturally high in pH and may improve with some acidification. method for renovating lawns. This is not effective, however, Liming without the need to lime can tie up nutrients in the soil unless the grass/weed cover is very thin and the extracted soil and weaken the overall health of the lawn. can be considered as topdressing for the seed. If the aerifier The limestone normally purchased at rock quarries is cheap only extracts cores on six-inch-square or eight-inch-square but very coarse, and it is difficult to apply in lawn spreaders. centers, then effectiveness will be nil. It is probably most easily applied by shovel from the back of a pickup truck. Often as much as 100 to 300 pounds will be Watering required per 1,000 square feet. Water a lawn only during excessively dry periods once it Agricultural limestone is recommended if the soil is acid. is established. Frequent, shallow watering should always be Finely ground agricultural limestone is often sold through gar- avoided. It causes shallow rooting and encourages crabgrass den centers in 50-pound bags as agricultural lime or dolomitic invasion and diseases. limestone. Like rock quarry limestone, it is also difficult to get 15-10  Lawn Management CHAPTER 15 Water thoroughly when you do water. The soil should be wet which it is safe to apply it, and certain safety precautions. Always to about four inches deep, which usually requires one-half to read the label. one inch of rainfall or irrigation. You can check with a probe Broadleaf weeds are generally characterized by netted veins or knife to see the depth of moisture. in their leaves. Examples are dandelion, plantain, chickweed, Early morning is the best time of the day to water, but unless ground ivy, henbit, white clover, spurge, and knotweed. Such a serious disease problem exists, evening watering causes few, weeds are most often controlled selectively after they ger- if any, problems. Lawns can also be watered at midday, but you minate. These postemergence herbicides are absorbed into can expect increased evaporation loss. the leaf. They then move through the plant and kill the roots, Remember that localized dry spots, which frequently appear underground stems, and the aboveground plant. Such systemic during the summer months, are often misdiagnosed as insect herbicides include 2,4-D; MCPP; and dicamba. Many products or disease problems. contain a mixture of two or three of these chemicals in order To differentiate localized dry spots from disease or insect to get a broad range of control. For example, 2,4-D is an excel- patches of dying grass, always probe the soil first, using a screw- lent dandelion killer, and dicamba is best for white clover. A driver, soil probe, shovel, etc. If the top one to two inches is mixture of the two will give maximum control of both species bone dry—powder dry—the problem is likely localized dry and many others. spot. Correcting it with a pesticide is impossible. Combination products containing 2,4-D, MCPP, and dicamba will kill almost all broadleaf weeds that grow in lawns. Pest Control An exception is wild violet, which must be sprayed at least two times with triclopyr, a common brush killer, or mesotrione. Pests can include weeds, insects, disease, and animals such These chemicals are most safely applied in spring or fall, as moles. when the weeds are actively growing. Hot summer applications We misdiagnose disease and insect problems all too fre- may injure desirable grasses, and if the soil is dry, the weeds quently. When you see dying patches of grass during the probably won’t be controlled. For the most effective control summer, always check the soil before treating with a pesticide. of broadleaf weeds, make applications in the fall when winter Weeds annuals are present. This will allow you to control perennial and annual broadleaves with one application. These products can be An adapted turfgrass species that is properly established, purchased as a spray or granular material. Generally products mowed, and fertilized will have few weed problems, but all applied as a liquid are most effective. If a granular chemical is weeds won’t be eliminated. used, the foliage should be moist with dew before application Keep in mind that a plant becomes a weed when it grows to ensure that the granules stick to the leaf. where it is not wanted. That means plants that are considered If these materials contact the leaf or are applied above the desirable in some crops or waste areas can become serious root zone, they may injure ornamentals. Read all cautions on lawn weeds. For example, many people believe that clover the label. is desirable in turfgrass because it fixes nitrogen so that the Grassy weeds—Grassy weeds are characterized by parallel leaf turfgrass seldom needs fertilization. Others strongly object to veins. They are not often affected by the broadleaf herbicides its white flowers because they disrupt a lawn’s uniformity and described previously. attract bees that may sting bare feet. Also clover often leaves a Annual grassy weeds, such as crabgrass and foxtail, are best stain on clothing that is difficult to remove. Another example of this paradox is tall fescue. Although tall fescue is the best controlled with preemergence herbicides that are applied before the weeds germinate. These herbicides should be applied adapted lawn grass in Kentucky, many consider it objection- before April 1 in Western Kentucky and before mid-April in able in Kentucky bluegrass lawns because of its coarseness and Central and Eastern Kentucky. Examples are Pendimethalin clumping growth habit. Kentucky bluegrass can also creep into (Pre-M), benefin + trifluralin (Team), prodiamine (Barricade), landscape beds and become a weed. and dithiopyr (Dimension). Mesotrione (Tenacity) and siduron Broadleaf weeds—Chemical herbicides are used to control (Tupersan) are the only commercially available preemergence weeds. Some can be applied to control a specific weed but not crabgrass herbicides that can be applied in the spring at the damage the desirable grass. With other herbicides, all green same time that desirable grasses are seeded. Other preemergent vegetation to which the herbicide is applied will die. Sometimes herbicides, if used, would prevent germination of the desirable these herbicides are persistent in the soil, and further reseed- grasses as well. ing of desirable grasses cannot be accomplished for months Postemergence crabgrass herbicides include fenoxaprop or even years after the herbicide application. Some herbicides (Acclaim Extra), quinclorac (Drive XLR8), mesotrione must be applied before weeds germinate (preemergence), and (Tenacity), and topramezone (Pylex). These products should be others must be applied after weed emergence (postemergence). applied while crabgrass is small and easier to control. Mature Knowing the nature of the herbicide is a must. The herbicide weeds typically require several applications to control. label describes the weeds controlled, the desirable grasses on 15-11 CHAPTER 15 Lawn Management Perennial grassy weeds such as tall fescue clumps, nim- drops, the grubs quit feeding and move deeply into the soil blewill, and bermudagrass are more difficult to control without for the winter. They resurface during spring and begin feeding also killing desirable turfgrass. A herbicide such as glyphosate again. Almost no turfgrass damage occurs in spring because (Roundup) will kill almost all grasses and weeds that are green the turfgrass has an extensive root system that is easily regener- when sprayed. Treated areas must be reseeded or sodded with ated during the good spring weather. In May and June, white desirable grasses. Nimblewill is best controlled with mesotri- grubs pupate (resting stage) and emerge as adults after one one (Tenacity), and bermudagrass with topramezone (Pylex). year’s development. Always read the label for proper herbicide selection and use. Large dead patches on your lawn, up to 20 feet in diameter, Almost all grassy weeds require multiple applications for may develop in grub-infested areas. During late August through complete control. early November, homeowners should carefully look for any discolored grass. The drying sod can be rolled back like a carpet Insects to expose the grubs. If the sod can be easily pulled back and Only a few of the insects that are present in a lawn actually numerous grubs are found, an insecticide such as trichorfon cause damage. By far the most common damaging insect in can be applied immediately and watered into the turfgrass Kentucky lawns is the white grub. Other insects such as the (enough water to wet the soil to one-half inch depth) to prevent sod webworm, bluegrass billbug, and chinch bug are potentially further damage. damaging to Kentucky lawns, but their population is seldom For lawns with a history of white grub problems, insecticides sufficient to cause serious problems. containing chlorantraniliprole, imidacloprid, clothianidin, or Successful control of turfgrass insects depends upon detect- thiamethoxam are available for preventive applications. Those ing their presence before they cause serious damage. This products should be applied before egg hatch, ideally between requires frequent inspections, looking for signs such as blades late May and mid-July, and watered into the turfgrass. chewed off at ground surface; roots chewed off and sod easily Although moles may feed on grubs, an insecticide applica- dislodged; old insect casings or shells on the lawn surface; birds tion won’t starve or kill them, because they feed primarily on feeding heavily in the lawn; presence of moles or skunks causing soil- inhabiting insects, mainly earthworms. Insecticides used damage; and moths or beetles flying over the surface in the late to kill grubs should not kill earthworms, either. evening or early night. Milky disease or milky spore disease, often sold to bio- Injury from heat and drought are often mistaken for insect logically control grubs, has not proven effective in Kentucky. injury. Applying insecticides will certainly not control dam- It targets only Japanese beetle grubs and may not be effective age caused by the localized dry spots that frequently appear in on the targeted species. late spring or summer. Before assuming insect damage, always Sod webworms—Although sod webworms are present in check to see if the underlying surface inch of soil is dry. Even almost all turfgrass, they seldom cause damage to lawns. Sod though potentially damaging insects may be present, they may webworm adults are beige to grayish-white in color, with a not cause turfgrass damage if the turfgrass is properly watered. wingspread of about three-quarters of an inch. These moths Insecticides can kill desirable as well undesirable insects, are frequently seen during the growing season flying over and if they are used improperly or overused, additional serious lawns at dusk. The eggs laid by the female moths hatch in about insect problems or thatch buildup can occur. two weeks. The caterpillars are grayish to beige in color, have White grubs—White grubs are the most serious pest problem small dark spots on their bodies, and may reach a size of three- in Kentucky bluegrass lawns but seldom cause problems in tall quarters of an inch long. As they mature, they build silk-lined, fescue lawns. They devastate Kentucky bluegrass by feeding on grass-covered tubes near the soil surface. These larvae feed by the root system, which deprives the individual plants of mois- chewing off grass blades near the plant crown. ture. In addition, moles, skunks, and even birds may further Turfgrass damaged by sod webworms will show isolated damage the lawn while feeding on white grubs. yellow-to-brown patches of grass a few inches in diameter. Grubs are the larvae of any hard-shelled beetles. The most The infected areas will appear to be closely grazed, and small common of these beetles in Kentucky is the masked chafer, green-to-tan pellets of excrement may be located within the which is light tan and about one-half inch long. The Japanese damaged areas. Birds feeding on these caterpillars will often beetle, which is increasing in Kentucky, is about one-half inch leave obvious probe holes in the turfgrass thatch. long, metallic green, and has coppery-brown wing covers. Chinch bugs—Chinch bugs will occasionally infest a Kentucky White grubs (larvae of the masked chafer and Japanese beetles) bluegrass lawn, especially if the lawn is heavily contaminated have stout, white bodies and brown heads, are one-half to three- with creeping bentgrass. Scattered patches of grass will turn quarters of an inch long, and are curled into a C-shape. The yellow or brown due to the sucking of plant fluids by the young beetles lay eggs a few inches below soil level, mainly in June and nymphs. Even when full grown, the black and white chinch July. The grubs hatch in three to four weeks and begin feeding bugs are only about one-quarter inch long and are difficult to on grass roots, so almost all turfgrass damage is done from late find. The immature nymphs are only about one-twentieth of August through early November. When the soil temperature an inch long and may be reddish in color. 15-12  Lawn Management CHAPTER 15 Bluegrass billbugs—In May or June, Kentucky bluegrass lawns applied in spring or early summer, encourages brown patch. are sometimes infested with bluegrass billbugs, a dark gray- to- Development of this pathogen can be discouraged by proper black insect. Damage will occur as spotty patches of yellow- mowing (not allowing the grass to get more than one-third taller ing grass. The one-third-inch-long adult lays eggs within the than normal mowing height before it is removed) and heavy but stems of grass plants, and the hatched larvae feed in the stems. infrequent summer irrigation. Extremely tall mowing heights As they develop, the white, legless grubs leave the stems to may also promote brown patch. feed externally on the plant crown, near which masses of fine, Summer patch—Summer patch mainly occurs on heavily sawdust-like frass can be found. fertilized, dense Kentucky bluegrass lawns. During the hot (85°F–95°F) summer, scattered light-green patches varying in Turfgrass Disease size from two to six inches in diameter develop first along side- Numerous diseases occur in Kentucky lawns, but the use walks, drive-ways, and especially on south-facing (hot) slopes. of fungicides to control these diseases is generally not recom- With continued hot weather, these patches fade to a dull tan mended. Diseases often require multiple fungicide applications, and then to a light straw color. Some apparently healthy plants which not only are expensive but difficult for the homeowner to may be surrounded by the discolored turfgrass, giving a frog- apply evenly. Most diseases do not completely kill the turfgrass, eye effect. This disease can be controlled by timely fungicide and considerable recovery can be expected during the following applications, which are extremely expensive. The best control cool season of spring or fall. Also, the extent of these unsightly is obtained by following a fall nitrogen fertilization program diseases can generally be minimized by proper mowing, moder- and proper summer irrigation. ate nitrogen fertilization, and infrequent irrigation. The most Red thread—Red thread (pink patch) is very common on common disease problems are described below. Kentucky bluegrass and perennial ryegrass lawns and can be Leaf spot and melting out—Leaf spot and melting out (helmin- found from February through November. The symptoms are thosporium) is a very common disease on Kentucky bluegrass. similar to that described for dollar spot, but red thread disease When infected, the lawn will appear chlorotic; areas the size of also causes small pink-to-reddish threadlike growths to emerge a golf ball or coffee cup may be very brown in color. Upon close from tip ends of blighted leaves. During moist periods, a pink inspection, individual leaves will be shown to have tan spots slime may cover the leaves and mat many leaves together. The with dark margins. Most damage occurs in spring and early damage is not extremely destructive, and the turfgrass will summer, and complete turfgrass recovery is usually evident completely recover by late fall. A light application of nitrogen by late fall. and heavy, infrequent irrigation is usually as effective in masking Dollar spot—Dollar spot mainly affects Kentucky bluegrass the disease as a fungicide treatment. lawns. It can be active throughout the growing season but Localized dry spot—Localized dry spot is the most serious causes most damage when soil moisture is low and dew or fog summer problem encountered on Kentucky bluegrass lawns. is excessive. The disease appears as small, tan spots that are from It first appears as patches of brown or dying grass, two to four the size of a silver dollar to a coffee cup. Light brown or reddish inches in diameter. Localized dry spot continues to grow in margins on the spots will be obvious if the individual leaves a circular pattern, and it mimics any number of diseases and are inspected closely. If disease pressure becomes extreme, insect problems such as grubs, sod webworms, dollar spot, red the spots can coalesce to form large brown areas. The damage thread, and summer patch. is not often serious, but it can be very unsightly until growing As is the case with most serious lawn pest problems, dry conditions improve. A light fertilization with nitrogen and spot most often occurs on lawns with south-southwest fac- deep, infrequent irrigation is often needed to improve growing ing slopes, a severe thatch problem, heavy traffic, open sun conditions enough to mask the damage. areas, and heavy clay with shallow soil. These traits most often Brown patch—Brown patch is most prevalent on perennial describe “front” lawns. After a good summer rain, a turfgrass ryegrass and tall fescue lawns. It is mainly a hot-weather disease with localized dry spot will usually improve for only two to (85°F–95°F) but sometimes can occur in late winter to early three days. The improvement doesn’t last long, because little spring when grass top growth has been allowed to accumulate moisture penetrates the soil. If the soil will only take one-tenth and lodge. This disease is characterized by circular dead or inch of water per hour, then a rain falling at one inch per hour is brown turfgrass areas that may be a few inches to several feet of little value. In addition, when a thatchy lawn becomes dry, the in diameter. The outer edges of the infected area may have a thatch becomes water repellent. Hours of light rainfall would gray, smoky color, particularly in early morning. While dew be needed to penetrate the thatch. or surface moisture is present, you can often detect a mass of You have to irrigate to correct dry spot. Most sprinklers cobwebby-looking mycelium that tends to make the leaves apply water very slowly, at rates of one-quarter to one-half slimy. This disease can cause unsightliness and can thin tall inch of water per hour. If the water begins to run off before fescue turfgrass enough to increase its coarseness. Brown patch you have thoroughly wet two to three inches of surface soil, is difficult to control with fungicides, since damage can occur wait an hour or so before continuing irrigation. The only way almost overnight. Heavy nitrogen fertilization, especially when to know how deeply you have wet the soil is to probe the soil 15-13 CHAPTER 15 Lawn Management with a knife, screwdriver, soil probe, bulb planter, etc. After Talpirid or Tomcat Mole Killer are new products that use you’ve thoroughly irrigated two to three inches of surface soil, fake worms with an injected rodenticide called bromethalin. do not repeat irrigation until the surface begins to dry again. If These gummy-type worms can be placed into active runs or the weather is extremely hot and dry and the soil is very bad, mounds and appear to be the best solution for ridding lawns it may only be four to five days before the surface dries. If the of moles. These can be placed into active runs or mounds to weather is fairly cool at night, repeat irrigation is usually not give immediate mole kill. needed for one to two weeks. With luck, you will also get some Here’s the best method when using these fake worms: helpful rainfall during that period. Remember, when diagnosing When you see an active run or mound that is a day or two old, lawn problems, always check the soil first. place a fake worm within the run’s empty space or within the empty space below the mound. The run (void) is only an inch Moles or two below the grass and is easy to locate. The mounds are Moles are typically a serious problem in lawns with good usually six to 18 inches above the underg