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Lawns

For decades, Americans have enjoyed lush, green turfgrass lawns for backyard play, their role in beautiful landscapes and their spans on the golf course or sports field. Today, lawn care varies greatly by function, grass type and the homeowner’s preferences.

Light Requirement. All turfgrasses require sunlight to grow. Some will tolerate partial shade, but none will perform well in full shade. Grown here, turfgrass is generally unthrifty, thin and poor quality.

Types of Turfgrass

Turfgrass species is a group of grasses that have similar growth and identification characteristics. In selecting a turfgrass species for lawn, two important characteristics to consider are the life cycle and adaptability of the grass to temperature. Grass species can have an annual life cycle or a perennial life cycle. Since most home lawns are intended to be permanent, perennial grasses are ideal. In regards to their adaptability to temperature, turfgrass are classified in two groups: cool-season and warm-season grasses.

Cool-Season Grasses

In Ohio, cool-season turfgrass is recommended for lawns. Cool-season turfgrass grows best in the spring and fall when air temperatures are between 60 F and 75 F and soil temperatures are between 50 F and 65 F. During the high heat of summer, cool-season turfgrass may become dormant. Cool-season grasses are easy to establish with seed. Common cool-season grass species include Kentucky bluegrass, perennial ryegrass, tall fescue and fine fescue.

RECOMMENDED COOL-SEASON PERENNIAL GRASSES FOR OHIO LAWNS

Kentucky bluegrass, with proper management, can form a fine-textured, high quality lawn. This perennial, sod-forming grass produces rhizomes with the ability to make new bluegrass plants. This ability enables bluegrass to recover from damage and fill in thin areas of the lawn. During hot, dry conditions, bluegrass tends to become dormant. If high quality turf is desired during the summer, lawn irrigation is often necessary.

Kentucky bluegrass requires moist, well-drained soils to develop into a high quality lawn. It won’t tolerate extreme acid or alkaline soils and does not perform well in heavy shade. Kentucky bluegrass seed is slow to germinate (10 to 30 days) and slow to establish. When seeded during the spring or summer, weeds can become a problem. Kentucky bluegrass can be established with seed or sod. For a high quality lawn, medium to high levels of management will be required, including regular applications of fertilizer. Kentucky bluegrass responds well to mowing heights of from 2” to 2½”.

Perennial ryegrass is a perennial, fine to medium-textured species with the potential to develop into a high quality lawn. Perennial ryegrass has rapid seed germination (3 to 10 days) and seedling establishment. This species has a bunch-type growth pattern and forms dense turf through tillering. It does not produce rhizomes, so it is not as quick to recover from damage as Kentucky bluegrass and does not effectively fill in thin areas of the lawn. Since it germinates quickly, perennial ryegrass makes a good choice for areas needing quick cover such as hillsides or heavy traffic areas. Generally, a 100% perennial ryegrass lawn is not recommended. Instead, it should be mixed with another grass like Kentucky bluegrass.

Perennial ryegrass prefers well-drained and medium to high fertility soils. It has moderate tolerance of drought and shade but requires irrigation to maintain a high-quality appearance during hot, dry conditions. Mow it to 2” to 2½” for the best performance.

Tall fescue is more coarsely textured than other recommended turfgrass species. However, the new “turf-type” tall fescue cultivars are an improvement over the old “Kentucky 31” cultivar and will form an acceptable turf for home lawns. Turf-type tall fescues are less coarse, grow more upright, tiller more readily and have a darker green color. “Kentucky 31” is not recommended if a high quality lawn is desired.

Tall fescue is a perennial, durable, bunch-type grass. It does not recover quickly from damage, and since it is a bunch-type grass, it doesn’t effectively fill in thin areas in the lawn. The seed germinates in 7 to 14 days, but the seedlings are somewhat slow to establish themselves. Once established, tall fescue is a deep rooted plant that is the most heat and drought tolerant of all the recommended species, often remaining green during most Ohio summers without supplemental irrigation. Tall fescue can persist in low maintenance situations and tolerates low soil fertility. It prefers well-drained soils in sunny locations, but it is moderately shade tolerant. Tall fescue is more tolerant of shade than Kentucky bluegrass and perennial ryegrass but not as shade tolerant as fine fescue. New seedlings are prone to winter injury, but mature lawns will endure most Ohio winters. Mowing heights for tall fescue lawns range from 2” to 3”.

Fine fescue is a perennial, narrow-leaved, fine-textured species that maintains itself acceptably under the conditions of shade, low soil moisture and low fertility. In fact, over-fertilization and over-watering can lead to a decline in quality. Fine fescues do not adapt well to hot weather, poorly drained soils and high traffic areas. Fine fescue grass seed is relatively slow to germinate (7 to 14 days), and the seedlings are somewhat slow to establish themselves. Like Kentucky bluegrass, fine fescue tends to go dormant during hot and dry conditions, so supplemental irrigation may be required to maintain a high quality lawn during the summer. Fine fescues perform best when mowing heights are 2” or more. Common species of fine fescue include ‘Creeping Red Fescue,’ ‘Chewings Fescue’ and ‘Hard Fescue.’ While these fescues are generally not preferred for the home lawn, they may be found in some mixtures and blends (particularly shady mixes/blends) on the market.

COOL-SEASON PERENNIAL GRASSES NOT RECOMMENDED FOR OHIO LAWNS

Bentgrass. The primary use of bentgrass in Ohio is on golf course greens and fairways. Bentgrass is an extremely fine-textured, cool-season perennial grass that will form an extremely high-quality turf when managed correctly. However, bentgrass is not suitable as a lawn grass, because it is too expensive to maintain and too time consuming for most homeowners.

Warm-Season Grasses

In Ohio, warm-season turfgrasses are not recommended for lawns. These grasses grow best when the air temperatures are between 80 F and 95 F and soil temperatures are between 70 F and 90 F. Warm-season grasses actively grow during Ohio summers, but these grasses lack any cold tolerance, so from mid-fall through mid-spring, these grasses are brown, dormant and very unattractive. Common warm-season grass species include zoysiagrass, bermudagrass and buffalograss.

Lawn Establishment

Seeding or sodding is the normal method for establishing a lawn in Ohio. There are advantages and disadvantages to both methods.

Seeding

Lawns are seeded by planting grass seed on a prepared seedbed. Turfgrass in Ohio should be seeded spring or late summer and fall. The late summer and fall seeding (mid-August to mid-September) is considered the best because there is less competition from weeds and the temperatures during establishment are better for rapid growth and root development. If turfgrass is seeded in the spring, irrigation may be required during the summer.  

  • Advantages: The cost of seeding is usually less than sod, and more species/cultivar choices are available to match the planting site. Since the new turf develops in the location and environment where it will grow, the plants may be more compatible with the soil and growing conditions, making the lawn more tolerant of environmental stresses and pest problems.
  • Disadvantages: In Ohio, seeding times are limited to when the weather is cool (spring, late summer/fall and winter). The development of a full, healthy lawn is slow which can allow weeds to develop and is not as instantly appealing as a sodded lawn. Since every section of the lawn does not develop the same, re-seeding may be required to fill in blank or thin spots, which further delays the development of a high quality lawn. It takes three to five years to develop a quality lawn from seed.

Turfgrass Seed. Selecting the right turfgrass is an important decision when establishing a lawn. It is important to select a species that meets the aesthetic expectations for the lawn while being compatible with the environment and the intended level of management. When purchasing grass seed, bags may contain a mixture or blend of grass seed.

Grass Mixtures - A mixture is comprised of more than one species of grass (e.g., Kentucky bluegrass and fine fescue). It may be an advantage to plant grass mixtures to take advantage of the strengths of each species. For example, if a lawn has both sun and shade, the Kentucky bluegrass will adapt better to the sunny locations, and the fine fescue will adapt better to the shady locations. The drawback to mixtures, particularly when compatible grasses aren’t used, is the lawn may not be as uniform in appearance as a lawn seeded with only one species.

Grass Blends - A blend consists of two or more varieties of the same species. Blends can also be useful in lawns with variable environments, since each variety in the blend may react differently to environmental conditions and pest problems.

Seeding Rates. According to Selecting Turfgrasses for Lawns by Joe Rimelspach & Todd Hicks of The Ohio State University, follow these recommended seeding rates per 1,000 square feet.  

  • Kentucky bluegrass (100%) – 2 lbs.
  • Perennial ryegrass (100%) – 7 lbs. to 10 lbs.
  • Turf-type tall fescue (100%) – 8 lbs. to 12 lbs.
  • Fine fescues (100%) – 5 lbs.
  • Kentucky bluegrass (90% to 95%) and perennial ryegrass (5% to 10%) – 2 lbs. to 4 lbs.
  • Kentucky bluegrass (30% to 50%) and fine fescue (50% to 70%) – 2 lbs. to 5 lbs.
  • Kentucky bluegrass (5% to 15%) and turf-type tall fescue (85% to 95%) – 8 lbs. to 12 lbs.
  • Kentucky bluegrass (45% to 60%), perennial ryegrass (5% to 10%), and fine fescue (30% to 50%) – 3 lbs. to 5 lbs.

Sodding. Lawns are sodded by laying strips or squares of sod (growing turfgrass and the attached layer of soil) onto a planting site. The strips or squares are laid together tightly to produce a complete cover of turfgrass. Kentucky bluegrass and tall fescue are the most commonly used turfgrasses for sod in Ohio. Sod can be laid at any time during the growing season, as long as the ground isn’t frozen and water is available for irrigation. However, these Ohio cool-season grasses establish better during the spring and late summer/fall.

  • Advantages: Sodded lawns are more aesthetically pleasing sooner than seeded lawns and an instant lawn can be laid any time during the growing season. Sodded lawns can safely be used sooner than newly seeded turfgrass and there are less issues with soil, dust and mud.
  • Disadvantages: The cost of sod is higher than seeding a lawn, and large volumes of water are required for establishment. Since the sod can shrink, weeds may develop between the pieces. Because the sod was not produced in the same environment as a lawn, it may not be as compatible as a seeded lawn and may take longer to establish. Plus, its performance may be limited. 

Planting a Lawn

  • Seeds need ~¼” of soil over them when spread.
  • Walk on dirt after spreading and covering.
  • Cover with a light layer of peat moss, or other organic matter (such as straw or hay). This helps to conserve moisture and prevent drying.
    • Plan on one bale of good straw per 1,000 square feet of planting site.
    • If done correctly and not too heavily, the straw will not need to be removed from the planting site.
    • The grass seedlings will grow through the mulch, and the straw will eventually decompose.
    • Raking the straw off the planting can actually damage new grass seedlings.
  • Water well.

Soil Preparation

Good preparation of the planting site prior to seeding or sodding a lawn is essential for good lawn establishment. The following should be done prior to seeding or sodding a new lawn:

  • Take a soil test to determine the soil pH and fertility levels at the planting site. Fertilize and amend the soil as needed based upon soil test results.
  • Do not apply pre-emergent herbicides to a planting site, unless the herbicide is labeled as safe for that use. There are very few preemergent herbicides available that are labeled as safe for turfgrass planting sites.
  • Eliminate existing weeds at the planting site using a non-selective herbicide or selective broadleaf herbicide. Perennial grassy weeds are particularly difficult to selectively control in lawns. Herbicides are a valuable tool for eliminating weeds from the planting site, but many have restrictions on when grass can be safely planted after the herbicide is applied. Consult the herbicide label for more information.
  • Eliminate stones and dirt clods from the planting site. Grade the site to eliminate holes and to slope the soil away from buildings to avoid drainage problems. If topsoil, compost, peat moss or some other organic material is to be added to the existing soil, incorporate them at this time to a depth of 2” to 4”.

Seeding Lawns

Different turfgrasses have different seeding rates which vary by seeds’ size and weight. The key to success is providing adequate seed coverage. For bunch-type grasses, adequate coverage is even more important, since these types don’t effectively fill bare and thin spots. Remember to follow the recommended rates and uniformly spread across the planting site. On the other hand, excessive seeding can produce crowded, weak and unthrifty plants.

After the seed is in place, it is important to achieve good seed to soil contact. This can be accomplished by using a lawn rake to lightly mix the seed into the upper ¼” of the soil. Mulch the planting site with a thin layer of straw to conserve moisture and prevent drying. When finished mulching, the soil should still be visible beneath the straw. Plan on one bale of good straw per 1,000 square feet of planting site. If done correctly and not too heavily, the straw will not need to be removed from the planting site. The grass seedlings will grow through the mulch, and the straw will eventually decompose. Raking the straw off the planting can actually damage new grass seedlings.

Watering seeds is the most crucial activity during the germination process. Remember to water throughout to prevent poor germination, seedling failure and unsatisfactory results. After the seeds are planted, irrigate frequently and lightly to wet the upper ½” of soil. The planting site must be watered throughout the germination process. If at any time during this process the soil dries out to critical levels, seedling death can occur. Once the grass seedlings mature, begin to water more infrequently but more thoroughly and deeply than before.

Post-Care for Newly Seeded Lawns:

  • Limit traffic during the first growing season to avoid injuring the new seedlings.
  • Fertilize the newly seeded area after the new seedlings reach a height of 2”. Water thoroughly after fertilizing.
  • Use the “⅓ rule” when mowing a newly seeded lawn. That means never removing more than ⅓ of the leaf during a mowing. Since most cool-season grasses should be maintained from 2” to 3” in height, mow the lawn when it reaches a height of 3” to 4½” tall.
  • Post-emergent broadleaf herbicides should not be applied until the lawn has been mowed three times after planting. This will protect the new seedlings from unintended herbicide damage.

Sodding

Purchase fresh, healthy sod from a reputable dealer and lay it immediately after purchase. Generally, sod comes in 18” wide strips that are up to 6’ long. Most sod is harvested at a soil depth of ¼” to ½”. Sod with less soil depth is easier to install because it is lighter weight and will generally root faster than sod with excess soil. Lay the sod in a brick-like pattern with the edges tightly butted together. Do not stretch the sod, since it will shrink and leave gaps. On slopes, it may be necessary to use small pegs to hold the sod in place until it roots, ideally within 14 days.

After laying the sod, use a lightweight roller to ensure good sod-to-soil contact. Initially, irrigate heavily until the water soaks through the sod to the soil below. Continue irrigating frequently to keep the sod from drying out and encourage rooting into the soil below the sod pieces. Water is critical until the sod becomes established.

Post-Care for Newly Sodded Lawns

  • Fertilize using a normal fertilization schedule.
  • Mow the new sod at the desired height, removing no more than ⅓ of the leaf blade in a single mowing.
  • After the sod has firmly rooted to the soil, core aeration can help the turf develop a deeper, healthier root system. Core aerate in the spring or fall following the installation of the sod.

Mowing Turfgrass

  • Mowing grass too short is not good.
  • Return the clippings back into the lawn (aka a mulching mower).

Height & Frequency

Turfgrass is the highest maintenance plant in a landscape, and mowing is the most time-consuming task. When done at the proper height and frequency, a lawn will be healthier and more aesthetically pleasing. Proper mowing removes no more than a third of the leaf blade with a single mowing. In Ohio, most cool-season grasses should be mown at a height of 2” to 3”. Mowing at the proper height aids in weed control and promotes root development.

As a rule of thumb, mow at the high end of the range when temperatures are warm and lower as the temperatures drop. Research indicates the following advantages when a lawn is mown at 3”:

Grass grows more vigorously because more leaf surface is available for photosynthesis. Roots tend to grow deeper making the lawn more drought tolerant. The crown of the plant is kept cooler because of the shade from the leaf blades. The soil and roots are shaded, decreasing water needs and reducing weed seed germination. Lush, thick growth helps to crowd out weeds. The soil temperature stays cooler which is a better growing environment for cool-season grasses.

Generally, when lawns are cut too short, the grass has a poorer root system, less vigor and is more susceptible to environmental and pest problems.

Frequent mowing by the “⅓ rule” is best for the health of the plant. Unfortunately, there is not an absolute rule for the number of days between mowings. The height of the grass and the weather should be the determining factors for deciding when to mow. When possible, avoid mowing wet turfgrass. Wet grass tends to clump when mown and if the clumps are left on the lawn, they can cause damage to the grass underneath. Removal of grass clumps may be necessary to avoid damaging a lawn. If left with no other option, it is better to mow wet grass than to let it grow too tall. If the grass does get too tall, raise the mower to the highest position to avoid removing more than a third of the leaf blade.

Grass clippings return nutrients to the soil. Research indicates that up to a fourth of a lawn’s nitrogen requirements can be met by recycling grass clippings. The clippings should be fine enough to disappear into the turf. Returning grass clippings to the soil is highly recommended and more environmental friendly.

The mowing pattern is the direction a lawn is mowed. It should be changed frequently to avoid causing soil compaction and wear patterns in the lawn. A varied mowing pattern can prevent the continuous scalping of high spots and uneven mowing in locations where turns are made.

Lawn Mowers

  • Rotary Mowers. A rotary mower has a blade that spins on a horizontal plane from a central rod. Most home lawn mowers are rotary mowers, including hand and riding mowers. The advantages of rotary mowers are:
    • Ability to cut tall grass.
    • More versatility of movement when mowing the lawn.
    • Less expensive to purchase.
    • Mower blades are easier to sharpen.
Reel mowers have multiple blades mounted on a cylinder. The blades cut the grass against a bar. Reel mowers are used by golf courses for the precise, low mowing required for greens and fairways. They cut cleaner and cause less damage to turf. However, they are less able to mow tall grass, so mowing must be done more frequently. High quality reel mowers are more expensive to purchase, and the blades may need to be sharpened by a professional.

Mower Maintenance. Proper maintenance of a lawn mower is important. Mower blades should be sharpened regularly. Dull mower blades can leave ragged leaf tips which can give a brown appearance to a lawn. Regular maintenance of power lawn mowers is important. Cleaning filters, changing oil and spark plugs, and maintaining the body of the mower can extend a mower’s useful life. See the owners’ manuals for proper maintenance instructions.

Watering Turf

Water is essential for plant maintenance and growth. Water dissolves nutrients in the soil and carries them through the plant, so they can be absorbed and used by the plant. During Ohio’s hot summers, cool-season turfgrass will often go dormant without watering. When the average daily air temperature is above 60 F, the soil can lose ¼” or more water per day. Most Ohio turfgrass needs one inch of water every five to seven days.

Timing of Watering

There are many factors to consider when deciding to water. Visible signs can include a color change in the turf or leaving foot impressions when walking through a lawn instead of the turf bouncing right back. Factors to consider when deciding when to water should include the following:

Depth of Roots: Roots grow where there is available water. Short daily sprinklings result in shallow root systems. Deeply watered lawns have root systems that tend to grow much deeper into the soil. Since deep rooted lawns have much more area from which to draw water, they can go longer between watering. Newly seeded or sodded lawns have shallower root systems than established lawns, so they must be watered more frequently.

Soil Conditions: Loam soils provide the most optimal conditions for absorbing and holding water. Sandy soils, because they have less water holding capacity, require more water and more frequent watering than other soil types. Clay soils can hold more water but are much more likely to have absorption issues and runoff problems if watered too heavily. Compacted soils do not absorb or hold much water. Deep, slow watering is even more important for these problem soils.

Type of Grass Grown: Kentucky bluegrass and perennial ryegrass lawns are not as drought tolerant and are more likely to go dormant than tall fescue or fine fescue lawns.

Weather Conditions: Cool-season grasses can go dormant and turn brown during hot, dry Ohio summers. Many homeowners want to maintain green lawns during the summer, despite unfavorable growing conditions. To attempt to prevent dormancy, supplemental watering throughout the period of unfavorable weather must be done to maintain active growth and green color. Dormancy allows the plant to use minimal stored food and remain alive until the conditions change. Most healthy lawns will recover from periods of dormancy, so homeowners can save money on watering by accepting brown turf during occasional dry spells. However, if dry weather becomes a drought that lasts more than four to six weeks, watering may be necessary to prevent the grass from dying. During a drought, supplemental watering of ½” of water every 10 days is recommended to prevent the grass crowns from drying out. Drought damage is even more severe when temperatures are high.

Watering Practices

The best time to water is morning through mid-afternoon. Water applied late in the day may not have enough time to evaporate before nightfall. When water stays on the blades for long periods of time, the probability of a disease infection increases. Fungal diseases require moist conditions for infection, growth and reproduction. Light sprinklings by hand in the evening create the ideal conditions for many fungal diseases to develop. Watering in the middle of a hot, dry summer day also has disadvantages. Since evaporation is at its peak, less of the water is actually available to the plant. In fact, up to 20% of the water applied during hot, dry conditions actually evaporates from the leaves and soil surface before soaking into the ground.

Depth of watering is critical for lawn health. During the summer, turfgrass usually requires one inch of water per week. This amount will wet most soils to a depth of six to eight inches. To determine the amount of time to irrigate when using a sprinkler, place several straight-sided containers in a grid pattern throughout the area being watered. Record the amount of time it takes to collect one inch of water in the containers and use that as a reference when watering. With most sprinklers, it will take at least one hour to apply one inch of water.

When doing the straight-sided container test, check that each container is filled with approximately the same amount of water. Sprinklers may not uniformly distribute water throughout the area being watered. Many sprinklers drop more water near the sprinkler than at the end of their range. For that reason, overlapping the sprinkling areas may be necessary to apply the desired amount of water throughout the lawn.

Soil Fertility & Fertilization

Homeowners should take a soil test every three to four years to determine soil fertility levels then fertilize based upon the test’s recommendations.

  • Soil samples need to be 2-3” deep.
  • Don’t include the grass.
  • For each area (e.g., front yard vs back yard): Need to take 10-15 samples typically. Mix the samples together in a bucket.
  • Dry soil is best

Soil Nutrients & pH

Soil Nutrients. Turfgrass requires at least 16 essential nutrients for normal growth. Some nutrients are needed in large quantities and some are needed in very small amounts. Regardless of the amount needed, a deficiency of any of these nutrients can limit the growth and appearance of a lawn.

The three most important nutrients required by turfgrass are nitrogen, phosphorous and potassium. Grass clippings returned to the soil will replenish some nutrients but not enough to supply all of a lawn’s fertilizer needs.

Nitrogen is the most important nutrient needed by turfgrass. It promotes leaf growth and dark green coloring. Nitrogen is the nutrient that most quickly leaves the soil, leaching out with rain and supplemental water. When nitrogen is deficient, growth slows and the color can become pale and yellow. Too much nitrogen can also cause problems. Rapid growth will require more frequent mowing and an undesirable buildup of thatch.

When selecting nitrogen fertilizer for a lawn, homeowners should carefully read the label to determine the type of nitrogen found in the fertilizer. Products containing 30% to 50% slow-release nitrogen are recommended. Higher quality lawn fertilizers provide a combination of slow- and fast-release nitrogen for a combination of quick greening and steady growth. If applied incorrectly, fast-release nitrogen is more likely to burn turfgrass than slow-release nitrogen.

  • Water Insoluble Nitrogen (WIN): Slow-release nitrogen to provide a steady supply of nitrogen over several weeks.
  • Water Soluble Nitrogen (WSN): Fast-release nitrogen for a quick greening of the lawn. Follow label instructions when using WSN. Watering the lawn after an application may be required to avoid burning the turfgrass.

Phosphorous is important for strong root growth and is especially important when starting a new lawn. Most starter fertilizers contain high percentages of phosphorous. Since phosphorous does not move quickly through the soil, it should be incorporated into the soil to a depth of three to six inches prior to planting the lawn. Phosphorous is needed by established turfgrass in very small amounts, so many commercial fertilizers no longer contain phosphorous for lawn maintenance. Since phosphorous is more likely to run-off the soil than nitrogen, homeowners should avoid broadcasting fertilizers that contain phosphorous when large rain events are expected within 48 hours after the application.

Potassium is important for hardiness, disease resistance and the ability to recover from injury, which is important for lawns subjected to heavy foot traffic. Winterizing fertilizers often contain a higher percentage of potassium than fertilizer formulations used in the spring and summer.

Secondary Nutrients.

Calcium, magnesium and sulfur are considered secondary nutrients and only occasionally need to be added to lawns. Calcium and magnesium are usually only needed when a soil is too acidic, and liming the soil generally corrects the deficiency. Sulfur deficiencies are rarely an issue in Ohio.

Micronutrients.

Occasionally, seven micronutrients - boron, chlorine, copper, iron, manganese, molybdenum and zinc - are needed for turfgrass in very minute amounts. Of those, iron deficiencies are the most likely in turfgrass. Deficient turfgrass plants appear mottled yellow, instead of the uniform yellow found with nitrogen deficiencies. Ohio’s iron deficiencies in plants are more likely to be caused by its alkaline soils or over liming than actual iron deficiencies in the soil. Acidifying the soil (see below) or using an iron-containing fertilizer will usually correct the problem.

Soil pH is a measurement of the acidity or alkalinity of the soil. Soil pH values range from 0 to 14, with values below 7.0 considered acidic and numbers above 7.0 considered alkaline. Most cool-season turfgrass grows best in soils ranging from 6.0 to 7.2. When soil pH is outside of the preferred range, nutrient availability can be affected and as a result, the turfgrass may perform poorly.   When a soil test reveals that a soil is too acidic, lime should be added. Use only ground limestone, dolomitic lime or high calcium lime on lawns. Lime can be applied at any time throughout the year, but the best time is in the fall. Too much lime can be detrimental to the soil and plants, so lime should only be applied based upon soil test recommendations.

Annual Fertilizer Requirements

Fertilization is necessary for an attractive, healthy lawn. Fertilized lawns grow more vigorously and have better resistance to environmental stresses and pest problems. Annual Nitrogen Requirements (per 1000 square feet)

  • Kentucky bluegrass: 3 lbs. to 4 lbs.
  • Perennial ryegrass: 3 lbs. to 4 lbs.
  • Tall fescue: 2 lbs. to 3 lbs.
  • Fine fescue: 2 lbs. to 3 lbs.

Frequency. The number of applications made during the year is important. To maintain high quality turfgrass, at least two applications of fertilizer are required per year. If two applications are applied, then higher rates of nitrogen are required (1 lb. to 1.5 lbs. per 1000 square feet per application) and some slow-release nitrogen should be included to provide nitrogen over an extended period of time. A four-application program requires less nitrogen per application (0.5 lbs. to 1 lb.) and more fast-release nitrogen can be used with shorter timing between applications.

Nitrogen Fertilizer Calculation
Example formulation: 25-0-3
Example pounds of nitrogen desired: 1 lb.
Calculation: 1 / 0.25 = 4 lbs. of 25-0-3 fertilizer required to apply 1 lb. of nitrogen

Timing. The best times to fertilize cool-season grasses are spring, late summer and fall. Fertilizer applications in the summer during periods of heat and drought can injure the plants.

The most important time to fertilize turfgrass is late summer (early- to mid-September). Fertilizing in late summer helps turfgrass to recover from droughts and summer heat. Late summer is also the time when cool-season grasses store carbohydrates. Carbohydrates are used for root growth, pest tolerance and winter hardiness. Nitrogen applied in late summer will encourage leaf growth but not as much as in the spring.

The advantages of a late fall (mid- to late-November) application is that nitrogen is used primarily by the roots, since foliar growth is limited. Late fall applications are also known as winterizing fertilizers. Winterizing fertilizers often contain higher amounts of potassium to aid with plant hardiness. Late fall applications should be done before the soil freezes.

Spring applications of fertilizer encourage green up and foliar growth. Over-applying nitrogen in the spring produces excess growth and uses up food reserves needed for root growth and disease resistance.

Fertilizer Application Programs

Two applications: Mid- to late-spring (May- to early-June) and late-summer (early to mid-September) Three applications: Mid- to late-spring, late-summer and late-fall (mid- to late-November) Four applications: Early-spring (late-March to early-April), mid- to late-spring, late-summer and late-fall.

Organic vs Inorganic Fertilizers

While most organic fertilizers are less likely to burn plants, their nutrients are slower to be available to the plants than inorganic fertilizers. Organic fertilizers are more expensive and have significantly lower N-P-K ratios, so more must be applied to reach the same level of nutrients provided as inorganic fertilizers.

Fertilizer Spreaders

The two most common spreaders for applying granular fertilizers are drop spreaders and broadcast spreaders. Both types of spreaders have adjustable settings to vary the amount of fertilizer used. Consult the fertilizer bag for the appropriate spreader settings. Remember to shut off the spreader when approaching the end of a run and keep it closed when turning, backing up or stopping. Use a normal walking gait to produce an even dispersal of the fertilizer. If a spill occurs, gather up any excess fertilizer and water the area to avoid fertilizer burn.

Drop spreaders require more passes across the lawn than broadcast types. Overlap wheels to avoid stripes of unfed grass. Also, take care to not overlap too much to prevent over-applications and subsequently burn or cause uneven excess growth.

Drop seeders are more useful for reseeding than for fertilizing.

Broadcast spreaders distribute fertilizer over a wider area with a whirling wheel under the spreader box. They require fewer passes across the lawn than drop spreaders, so they are easier to use on larger lawns. Check the width for a uniform application. The width of the application can be checked on pavement, but the fertilizer should be cleaned up afterwards to avoid any fertilizer run-off.

Liquid fertilizers can be applied easily and quickly especially by commercial lawn care companies, but homeowners may sacrifice accuracy of the rate and evenness of the application when using liquid fertilizers.

Common Turfgrass Problems

To keep up-to-speed with current turfgrass issues, watch the Turfgrass Times videos available at Buckeye Yard & Garden onLine (bygl.osu.edu).

Rebuilding areas or establishing new areas would use fertilizers with high phosphorous. Be cautions though: phosphorous is generally controlled tightly by state law. Erosion blankets are excellent ways to repair areas.

Thatch in Lawns

Thatch is an intertwined organic layer of dead and living shoots, stems and roots that develops between the above-ground foliage and the soil surface. Thatch build up begins when the lawn produces organic debris faster than it can be broken down. Although some grass clippings are found in the thatch layer, they don’t significantly contribute to thatch build up in lawns.

Thatch forms a barrier preventing water and nutrients from penetrating into the soil. Grasses with vigorous growth habits and lawns on high-fertility programs can build up thatch rapidly. However, proper maintenance can keep thatch at manageable, healthy levels. At an ideal ¼” to ½” in thickness, thatch reduces soil temperature in the summer and can reduce some compaction problems in lawns with heavy use. However, a thatch layer greater than ½” can prevent water and nutrients from reaching the soil. Pesticides also do not penetrate thatch layers well, so pest control can be adversely affected.

Thatch Control.

Core aeration is effective for controlling thatch and for improving soil compaction problems.

A core aerator is a heavy machine with hollow metal tubes that is moved across the lawn to pull plugs of soil. Removing soil plugs allows air, water and nutrient to more easily penetrate the soil. The plugs should be broken up into the thatch, so their microorganisms can help to break down the thatch layer. Core aerate when the soil is moist, not wet. In Ohio, soil conditions are usually better for core aeration in the fall. Core aerate once a year, if thatch is thicker than ½”; otherwise, once every other year is sufficient.

Power Rakes and Vertical Mowers - Previous recommendations for thatch control have included power rakes or vertical mowers. They slice through the thatch and bring it to the surface. However, these machines also tear up the grass and cause damage to the lawn, so they are no longer the preferred method for thatch control.

Turfgrass Weeds

A lawn weed is any plant that is not wanted in the lawn. They compete with turfgrass for space, water and nutrients and are detrimental to the appearance of a lawn. The best defense against weeds is a dense, healthy stand of turfgrass. When weed problems become significant, herbicides can help to reduce weed numbers. However, if the lawn is thin and unhealthy, the weed problems will return.

Weed Identification and Life Cycles. Turfgrass weeds can be divided into two categories – grassy weeds and broadleaf weeds. Once the weed has been identified, it is important to determine its’ life cycle. The life cycle determines how it reproduces, when it grows and what the best control strategy should be. Control strategies are different for grassy and broadleaf weeds as well as annual and perennial weeds.

Grassy weeds look like turfgrass. They have straight, narrow leaves and parallel veins. Grassy weeds are more difficult to control in turfgrass than broadleaf weeds.

Broadleaf weeds - Broadleaf weed leaves are broader than grasses and their leaves can come in many shapes and sizes. Broadleaf weed growth patterns can be upright or creeping. Broadleaf weeds can be selectively controlled in turfgrass.

Annual weeds complete their life cycle in one year. They grow from seed, flower, produce new seed and die within one year. Depending upon when the seed germinates, annual weeds can be further classified as winter annuals or summer annuals. Winter annuals germinate in late summer or fall, overwinter and then produce seed in the spring. Summer annuals germinate in the spring and produce seed in the summer through early fall.

Perennial weeds persist from year to year, reproducing from seed but primarily spreading with underground roots, rhizomes, nutlets and other plant parts. Perennial weeds are more difficult to control than annual weeds, because their reproductive parts are in the soil. Left uncontrolled, perennial weeds can spread and take over a lawn.

Herbicides for Turfgrass

Pre-Emergent Herbicides. Pre-emergent herbicides are most commonly used to control annual grassy weeds and are available for application with lawn fertilizers. They form a barrier on the soil surface to keep seeds from germinating. They must be applied before the weeds germinate and need to be uniformly spread across the lawn. Granular products must be watered in to form the protective barrier. Any holes in the barrier will allow weeds to germinate. Pre-emergent herbicides also prevent desirable seeds from germinating, so seeding a lawn cannot be done if pre-emergent herbicides have been applied. Pre-emergent herbicides are usually effective for eight weeks.

Selective Post-Emergent Herbicides. Selective herbicides can control some weeds without harming the turfgrass. There are fertilizers available that contain selective post-emergent herbicides. Most broadleaf weeds can be controlled using selective herbicides. There are very few selective herbicides available for grassy weeds. Selective herbicides are most effective when applied to small, actively growing weeds. Selective herbicides should not be watered in after application, since the herbicide must remain on the weed for at least 24 hours for maximum effectiveness.

Non-Selective Post Emergent Herbicides. Non-selective herbicides can control both grasses and broadleaf plants. Unfortunately when used in lawns, desirable turfgrass will also be killed. The use of non-selective herbicides should be limited to spot treat perennial grassy weeds or to kill everything, including the turfgrass, when a lawn is being completely renovated.

Turfgrass Weed Management

Annual Grassy Weed Control - Timing is critical for controlling annual grassy weeds in turfgrass with pre-emergent herbicides. Most annual grasses produce seed in the fall and germinate in the spring when soil temperatures reach 50 F and sufficient soil moisture exists. Pre-emergent herbicides should be applied at least two weeks before the conditions are right for germination. Approximate spring germination dates for annual grassy weeds are:

  • Northern Ohio: May 1 to May 15
  • Central Ohio: April 15 to May 1
  • Southern Ohio: April 1 to April 15

Crabgrass and foxtail are common annual grasses that germinate in the spring, so control for those weeds should occur before the dates listed above. Annual bluegrass is the exception to the rule. Pre-emergent herbicides for this winter annual should be applied in the early fall and then again in the early spring.

Post-emergent herbicides are a secondary strategy for controlling annual grassy weeds since they’re limited in number and must be applied after weeds appear. When using post-emergent grass herbicides, some discoloration can occur in the lawn, but the damage should be temporary.

Perennial Grassy Weed Control - Perennial grassy weeds are difficult to control. Unlike annual grasses, there are no good stages to control perennial grassy weeds. Perennial weeds that spread using rhizomes and stolons are more difficult to control than clump grasses. Perennial grassy weeds in turfgrass are best controlled with post-emergent herbicides applied when the weeds are young and actively growing. Pre-emergent herbicides for perennial grassy weeds in lawns are not effective.

Selective herbicides are not an option for most perennial grassy weeds. The one exception would be tall fescue, which can be selectively controlled in some lawns. However, it is not possible to selectively control tall fescue in a perennial ryegrass lawn.

Non-selective herbicides are the most effective way to control perennial grassy weeds. However, it can be a long, unsightly process, since the turfgrass will also be killed. Clump grasses, like tall fescue, can be spot treated with a non-selective herbicide or they can be dug out of the lawn. Perennial grasses that spread, like nimblewill or quackgrass, are more difficult to control with one herbicide application. While the original plant may be killed, often the rhizomes and stolons will survive to start new weeds. Repeat applications are almost always needed. When perennial grassy weed problems are severe, the best option may be to kill everything, including the lawn.

Broadleaf Weed Control

Many broadleaf weeds are easy to selectively control with post-emergent herbicides in mature lawns. Ideally, broadleaf weeds should be controlled when they are young and actively growing, so knowing the life cycle of the weeds is important for good control. Environmental conditions and the structure of the plant are also important. Spring annual weeds are also known as “summer spoilers”, because they are more adapted to the harsh growing conditions of summer than cool-season turfgrasses. Most have thick or waxy leaves that prevent water loss. Control of “summer spoilers” can be challenging because stressed turfgrass is more prone to injury from herbicides. Environmental conditions and the stress level of the turfgrass should be considered before applying herbicides during the summer. Fall is the best time to control most broadleaf weeds, and spring is the next best time of year. Most broadleaf weeds emerge and are actively growing during these time periods.

Many broadleaf post-emergent weed control products contain a mixture of two or more herbicides to increase the spectrum of weeds controlled. Broadleaf post-emergent herbicide formulations can be granular or liquid. The following are some tips for better broadleaf weed control with post-emergent herbicides:

  • Read the label and use the correct herbicide rate.
  • Apply herbicides when the weeds are young and actively growing.
  • Contact with the weed is essential. When using a granular product, weeds should be wet from irrigation or dew prior to application. Do not irrigate the product in or apply when rain is expected within 24 hours after application.
  • Do not apply herbicides when temperatures are over 85 F. Damage to turfgrass is more likely when temperatures are hot.
  • Apply during sunny weather. Weeds take in more herbicide when they are actively producing food.
  • Apply herbicides when soil moisture is adequate, and the turfgrass isn’t stressed.
  • Delay mowing for 3 to 5 days after application.
  • Do not apply herbicides to newly seeded or sodded lawns. Wait four to six weeks after laying sod or until seeded lawns have been mowed three or four times.

Nutsedge Control - Nutsedge is easily spotted in lawns. This perennial weed has a triangular stem, yellow-green color and faster-than-turfgrass growth habit. Since it is not a true grass or a broadleaf weed, it is more difficult to control than many weeds. The perennial prefers moist areas and reproduces from seed, rhizomes and nutlets. Selective herbicides are labeled for nutsedge, but repeat applications will probably be required for effective control.

Turfgrass Insects

Lawns are the home to many insects - some harmful and some beneficial. It is not desirable or possible to eliminate all insects from a lawn. Homeowners must consider two primary factors in evaluating extent of the damage done by turfgrass insects: 1) the number of insects present and 2) the general health of the turf. When lawns are healthy, they can withstand more damage and recover quicker from infestations of turfgrass insects.

There are two general classifications of turfgrass insects, surface pests and subsurface pests.

Surface pests feed on the stems and leaves. Subsurface pests feed in the soil/thatch zone.

Signs of Insect Damage

  • Surface Insects
  • Grass blades are chewed off.
  • Turf is yellow, burnt-orange or brown.
  • Spotted or striped caterpillars are present in the lawn.
  • Moths are present across the lawn.
  • Large numbers of birds are present and feeding in the lawn.

Subsurface Insects

  • The turf wilts suddenly.
  • The turf feels spongy underfoot.
  • The turf can be rolled back like carpet.
  • The grass blades are chewed off just below the soil surface.
  • Skunks, raccoons and moles dig up the lawn.

Surface Insect Management

Chinch Bugs

Chinch bug nymphs are bright red-orange with a white band. As they mature, they change colors from orange-red to gray to black. The adults are 1/5-inch long with white wings.

Life cycle: All stages of the insect are damaging to turfgrass, and all of the stages can be present at one time. Two generations of chinch bugs usually occur per year in Ohio. Adults overwinter in the thatch and lay their eggs from mid-April through May. The first generation damage peaks from late June to mid-July and the second generation can occur through August. Heavy rain in late May and June during egg hatch will reduce the survival of chinch bugs.

Damage: Chinch bugs suck juice from the plant, turning the grass blades yellow and then brown. Damage begins with irregular patches in open, sunny areas and is worse on drought stressed turf in hot weather. Regular watering of turf may help to reduce the problem. When present, fast-moving insects can be seen at the base of the stems. Chinch bugs prefer Kentucky bluegrass, perennial ryegrass, fine fescue and bentgrass.

Natural enemy: When conditions of cool, wet conditions persist, the presence of the naturally occurring fungus Beauvaria will attack the bug. Big-eyed bugs are a natural predator of chinch bugs, but they usually don’t build up to significant numbers until damage is already present in the lawn. Big-eyed bugs can be mistaken for chinch bugs because they have a similar size and shape. Before spraying, identify the insects to determine if it is the harmful chinch bug or the beneficial big-eyed bug.

Control: If chinch bugs are a recurring problem, early sprays have been used to reduce spring populations. To give season-long control, spray over-wintering adults with insecticides from mid-April to mid-May. First generation nymphs can be treated from mid-May to mid-June and second generation nymphs can be treated from mid-July to late August.

Cutworms

There are many different cutworms in Ohio, but the most common are the black cutworm, bronze cutworm, variegated cutworm and army cutworm. The coloring for cutworms can vary greatly, from brown, to green, gray or black. They can be spotted or striped. Adults are moderate sized brown or black moths with various colored splotches or stripes.

Life cycle: The larval stage damages turfgrass. The adults are moths. One to three generations can occur per year. Cutworms overwinter as mature larvae or pupae. Adults lay their eggs on blades of grass.

Damage: Cutworms get their name because they cut plants off at the ground. Caterpillars feed at night. The presence of birds feeding can be an indication of cutworms. Cutworm larvae burrow into the soil or use holes created by core aeration. They cause brown spots around their holes from feeding.

Golf courses: Cutworms prefer closely mown turf and for that reason, they are more of a problem for golf courses than lawns. Golf courses and homeowners should core aerate in the early spring or fall when cutworms are less active. Tall fescue and endophyteenhanced perennial ryegrass are resistant to most cutworms. 

Control: Predators and parasites are effective for controlling light infestations. Soap flushes can be used to detect larvae and traps (pheromone or light) can be used to monitor for adults. Insecticides can be used when larvae are noticed and damaging the turf. Since the caterpillars feed at night on the soil surface, insecticides should be applied late in the day and irrigation is not necessary.

Greenbug aphids

Greenbug aphids are small, light green, soft bodied, pear-shaped insects. Most are wingless, but female aphids can have wings.

Life cycle: The nymphs and adults are very similar in appearance. Generations of aphids are continuous throughout the growing season. Populations often migrate into Ohio from the south, but they can overwinter in the egg stage. During dry weather, aphid populations can build up rapidly.

Damage: Greenbug aphids feed by sucking juices from the plant, turning the grass blades yellow to orange in color. The damage often occurs under trees first. Tall fescue and other endophyte-enhanced turfgrasses are generally resistant to problems.

Natural enemies: Greenbug aphids have many natural enemies including lady beetles, lacewings and parasitic wasps. However, predators may not be able to keep up with aphid numbers during hot, dry weather.

Control: Greenbug aphids are easy to control with insecticides. Apply liquid formulations to active populations from June through August. Granular insecticides are not effective against this pest.  

Sod webworms

Sod webworms undergo a metamorphosis from a caterpillar-like worm to a moth-like insect. Sod webworms prefer Kentucky bluegrass and fine fescue lawns. Tall fescue and endophyte-enhanced ryegrasses are immune to problems.

Life cycle: The larval stage does the damage to turfgrass. Caterpillars are ¾ inch long, cream to dull gray in color, and have many pairs of dark spots on their body. Adults are gray to tan colored with long snouts. Sod webworms have two generations in Ohio. Larvae overwinter under the thatch layer and adults drop their eggs into the turf.

Damage: Larvae chew on the grass blades and shoots, causing irregular patches of brown turf. Damage can be observed in May, late June to early July and again in August. Larvae construct silken tunnels in the thatch. Probing birds and large numbers of moths flying over the turf in the evening are indicators of a sod webworm problem. Damage to turfgrass can often be outgrown, if the lawn is irrigated.

Natural enemies: Predators like ground or rove beetles usually keep populations in check. Bacillus thuringiensis (Bt) is effective against webworm larvae.

Control: Webworms are also easily controlled with insecticides. Soap flushes can be used to detect larvae. If necessary, treat larvae when they are noticed and damage is evident.

Subsurface Insect Management

Billbugs

Billbugs affect Kentucky bluegrass, perennial ryegrass and fine fescue. Tall fescue and endophyteenhanced ryegrasses are resistant to problems.

Life cycle: The larvae are the damaging stage. They are grub-like, fat, legless and ⅜ inch long. The tail end is larger than the head. The head capsule is orange to brown in color. The adult is a weevil, ⅜ inch long with a snout. The adults overwinter in thatch or the surrounding area. Usually, there is only one generation in Ohio. Adults lay their eggs in late April through May.

Damage: Damage is evident in mid-June through July. Damage from billbug is easily confused with other problems. Damage appears as spotty patches of yellow strawcolored or dead grass. The damage often occurs near sidewalks and driveways, but the entire lawn can be affected. When the grass is pulled, injured plants break off easily at the soil line. Billbug larvae burrow into the stem, hollowing them out. Larger larvae chew on the stems, crowns and roots.

Control: Light to moderate infestations can be outgrown with irrigation and fertilizer. Chemical control of billbug is difficult. The most common strategy for chemically controlling billbug adults are contact or stomach insecticides applied when the adults become active in the spring, usually late April through mid-May. Larvae should be controlled in the first three weeks of June when they have exited the grass stems. Unfortunately, considerable damage may have already been done to the lawn.

White grubs

White grubs are the larvae of various beetles, including Japanese beetles and May/June beetles.

Life cycle: The larval stage damages turfgrass. White grubs are white to gray in color with brown heads. They have six legs, are “C” shaped and are ¼ to 1½ inches long. Larvae can be identified based upon the spine patterns found on the underside of the abdomen. The life cycle of a white grub depends upon the beetle. Most have one generation per year. Some grubs are considered “annuals”, taking one year to complete their life cycle. Examples would include Japanese beetles, chafers, June beetles and Asiatic garden beetles. May/June beetles take two to five years to complete their life cycle. Different from the beetles mentioned previously, the black turfgrass ataenius has two generations per year and overwinters as an adult.

Damage: White grubs feed on turf roots from May through June, and then again from September to October. Damaged turfgrass wilts, browns and may die. Because the root system has been damaged, the sod may pull up easily like a carpet. Skunks, raccoons and moles may dig up the sod in search of white grubs, causing additional damage to the lawn. Damage from white grubs can vary from year to year based upon the number of grubs present in the soil. Soil moisture and rainfall are major influences on grub development. In years with above average rainfall, grub populations generally increase. For that reason, irrigated lawns are more commonly attacked by white grubs than non-irrigated lawns. Droughts in July and early August can significantly reduce grub numbers because the eggs and young larvae need moisture for survival.

Chemical control: Chemical control of grubs can be preventative or curative. Preventative treatments may be necessary if the lawn has a history of white grub infestations. Preventative treatments contain insecticides with long-term residual activity and should be applied from mid-May through mid-June. If grubs have not previously been a problem, curative treatments can be used. Homeowners should sample for grubs and if the number of grubs is over the threshold, insecticides should be applied from mid-July to mid-August. Research by Cornell University has shown that healthy lawns can withstand white grub populations of 6 to 8 per square foot. Populations over 10 white grubs per square foot may damage the lawn and treatment should be considered, particularly if the turfgrass is stressed.

Other controls: Alternative treatments are available, but their effectiveness is variable. The most widely available biological control is milky spore. Milky spore (Bacillus popilliae) is a bacterium that attacks white grubs. Unfortunately, recent studies have shown that milky spore performs poorly in Ohio soils. Mechanical trapping (Japanese beetle traps with bags) is another option, but they are not effective for controlling white grubs. Populations of beetles may actually increase in the area where mechanical traps are deployed.

Turf Disease

There are three elements required for a turfgrass disease to occur. If any of the elements are missing, the disease will not develop. The three elements of the turfgrass disease triangle are:

  1. A pathogen or disease-causing organism.
  2. A susceptible turfgrass.
  3. The right environment for the disease to develop.

Most turfgrass diseases are caused by fungi. They occur naturally and can be found in both healthy and diseased turfgrass. Whether or not a diseases occurs, often depends upon the other elements being in place. Selecting turfgrass species and cultivars that are resistant to certain diseases can reduce or eliminate problems.

Healthy stands of turfgrass are less prone to the development of diseases and if a disease does occur, healthy turfgrass can recover more quickly with less significant damage done. Proper mowing, fertilizing, watering and thatch management are key factors for maintaining a healthy lawn and reducing diseases.

Fungicides may be effective for some diseases, but they are only effective for a short period of time. Since the weather cannot be controlled, the most effective way to control diseases is by selecting resistant turfgrasses and managing the lawn properly. If fungicides are required for turfgrass, preventative treatments are the most effective way to control diseases. Preventative fungicides are applied to turfgrass to create a protective barrier before the disease occurs. Curative treatments are not effective for managing turfgrass diseases. Often the best way to correct recurring disease problems is to renovate the lawn and plant resistant species or cultivars of turfgrass.

Types of Turfgrass Diseases

Leaf Diseases mainly cause cosmetic damage to the leaf. They usually aren’t fatal to the grass plant. They can weaken the turfgrass, but the lawn will usually recover when the environmental conditions change. Fungicide treatments can prevent leaf diseases, but are not usually needed.

Crown and root diseases can eventually kill the grass plant. Lawn areas with dead grass plants will not recover and will require renovation. Chemical controls are not effective for controlling crown and root diseases.

A Calendar Year of Turfgrass Diseases

Source: Ohio State University Extension Bulletin 841-8, A Study Guide for Commercial Turfgrass Applicators

Winter (Cold Weather from 32 F to 45 F)

  • Snow Mold
    • Identification: White or gray areas of matted leaves, sometimes with pink borders.
    • Grasses affected: All cool-season grasses.
    • Environmental conditions:
      • Turfgrass too tall going into the winter.
      • Abundant snow cover and moisture.
    • Cultural management:
      • Rake leaves to improve light and air to the plants.
      • Mow at the proper height and continue mowing turfgrass until it stops growing in the fall.
    • Fertilize properly to avoid lush growth before winter.
    • Chemical control: Possible if timed correctly with a preventative fungicide.

Spring to Early Summer (Cool Weather from 45 F to 60 F)

  • Leaf Spot
    • Identification: Small brown or purple spots on the leaves.
    • Grasses affected: All cool-season turgrasses, particularly common Kentucky bluegrass.
    • Environmental conditions: Cool, moist, cloudy weather.
    • Cultural management:
      • Do not scalp turfgrass. Mow at the proper height and frequency.
      • Avoid light, frequent watering.
      • Avoid fertilizing to the point of rapid top growth.
      • Use resistant turfgrass species and cultivars.
    • Chemical control: Possible if timed correctly with a preventative fungicide.
  • Red Thread
    • Identification: Spots on the leaf. Pinkish-red threads sticking out of the leaf blade. Pinkish spots in the lawn.
    • Grasses affected: All cool-season turfgrasses, particularly perennial ryegrass, fine fescue and certain cultivars of Kentucky bluegrass.
    • Environmental conditions: Prolonged periods of dampness.
    • Cultural management:
      • Fertilize at the proper rate and frequency
      • Mow at the proper height and frequency. 
    • Chemical control: Possible if timed correctly with a preventative fungicide.
  • Patch Diseases (Yellow Patch, Necrotic Ring Spot)
    • Identification: Begins as round yellow patches of turfgrass. Later, the patches turn brown and have green weeds/grass in the center. The crowns and the roots are dead.
    • Grasses affected: Kentucky bluegrass, fine fescue and bentgrass.
    • Environmental conditions: Cool, wet weather, heavy thatch.
    • Cultural management:
      • Core aerate to reduce thatch.
      • Avoid moisture stress.
      • Use resistant turfgrass species and cultivars.
    • Chemical control: No control for yellow patch. Extremely difficult for necrotic ring spot.

Summer to Early Fall (Warm Weather from 60 F to 75 F)

  • Dollar Spot
    • Identification: Small round spots of bleached turfgrass. Light tan bands on the leaf with a reddish border. White “cobwebs” may be present in the morning when dew is present.
    • Grasses affected: Kentucky bluegrass, fine fescue and bentgrass.
    • Environmental conditions: Droughty soil conditions with humid weather. Morning dews.
    • Cultural management:
      • Use resistant turfgrass species and cultivars.
      • Avoid light, frequent watering.
      • Avoid nitrogen deficiency.
      • On golf courses, remove dew from greens by dragging with a hose or by syringing.
    • Chemical control: Possible if timed correctly with a preventative fungicide.

 

Summer to Early Fall (Hot Weather Greater Than 75 F)

 

  • Brown Patch
    • Identification: Overall circular patches of brown turfgrass. Tan spots on the leaves.
    • Grasses affected: All cool-season turfgrasses, particularly tall fescue.
    • Environmental conditions: Moist, humid conditions. Light, frequent watering in warm weather.
    • Cultural management:
      • Mow at the proper height and frequency.
      • Water deeply and at the proper frequency.
      • Avoid heavy nitrogen fertilizer.
    • Chemical control: Possible if timed correctly with a preventative fungicide.
  • Melting Out
    • Identification: Thinning, irregular areas of brown turfgrass. Brown leaves.
    • Grasses affected: All cool-season turfgrasses, particularly Kentucky bluegrass.
    • Environmental conditions: Previous severe leaf spot in the spring. Hot, dry summers.
    • Cultural management:
      • Irrigate properly.
      • Raise mowing heights.
      • Use resistant turfgrass species and cultivars.
    • Chemical control: Possible if timed correctly with a preventative fungicide.
  • Pythium Blight
    • Identification: Leaves are “greasy” and dark, then brown “cobweb” growth appears on the leaves.
    • Grasses affected: All cool-season turfgrasses, particularly perennial ryegrass and bentgrass.
    • Environmental conditions: High humidity and wet areas (more of a problem for golf courses).
    • Cultural management:
      • Avoid excess watering and mowing of wet grass.
      • Improve soil drainage.
      • Avoid excess nitrogen.
    • Chemical control: Possible if timed correctly with a preventative fungicide.
  • Fairy Ring
    • Identification: Darker green circles or arcs during moist weather. Brown circles of grass during dry summers. Fungi (mushrooms & toadstools) often grow in the circles.
    • Grasses affected: All cool-season turfgrasses.
    • Environmental conditions: Fungi growing on buried stumps or organic matter in the soil below the turfgrass.
    • Cultural management: Mask the symptoms with core aeration, irrigation and moderate fertility. In critical areas, replace the soil and reseed the lawn, but the condition will likely return.
    • Chemical control: There are no chemical controls.
  • Patch Diseases (Summer Patch)
    • Identification: Overall circular patches of brown turfgrass. Tan spots on the leaves.
    • Grasses affected: All cool-season turfgrasses.
    • Environmental conditions: Moist, humid conditions. Light, frequent watering in warm weather.
    • Cultural management:
      • Mow at the proper height and frequency.
      • Water deeply and at the proper frequency.
      • Avoid heavy nitrogen fertilizer.
    • Chemical control: Possible if timed correctly with a preventative fungicide.

Late Summer to Fall (45 F to 60 F)

  • Powdery Mildew
    • Identification: White powdery mold on leaves.
    • Grasses affected: Kentucky bluegrass and fine fescue.
    • Environmental conditions: Shaded, low-light, moist areas.
    • Cultural management:
      • Improve air and light to turfgrass by pruning trees and shrubs.
      • Use resistant turfgrass species and cultivars.
    • Chemical control: Not necessary. This disease does little damage to the turfgrass.
  • Rust
    • Identification: Yellow-orange pustules on the leaves. When disturbed, the spores leave orange coloring on shoes. Grasses affected: Kentucky bluegrass and perennial ryegrass.
    • Environmental conditions: Slow growing turf due to low nitrogen fertility, compaction or shade. Summer heat and drought stress.
    • Cultural management:
      • Use resistant turfgrass species and cultivars.
      • Maintain healthy and vigorous turf.
      • Avoid evening irrigation.
    • Chemical control: Possible if timed correctly with a preventative fungicide. 

Moles in Turf

Moles are insectivores and eat insects not plants. Still, they can cause significant damage to lawns while searching for food. The damage is usually in the form of tunnels or mounds, which provide them with covered travel lanes to search for insects. The most common mole in Ohio is the eastern mole (Scalopus aquaticus). Moles are 6” to 8” long and weigh three to six ounces. Every year, females can have litters of two to six moles. Less than 50% survive to breeding age, but significant populations can still develop in home landscapes.

Contrary to popular opinion, grubs are not the primary food source of moles. Research shows that earthworms are actually their primary food source, so eliminating grubs from a lawn will have little effect on the population of moles in a landscape. Most home remedies are also ineffective for controlling mole populations. These include mothballs, castor oil, bleach, human hair, red pepper, chewing gum and ultrasonic devices. The most effective and practical method for controlling moles is trapping.

Trapping Moles. There are three types of traps that are effective for moles, harpoon traps, scissor-jaw traps and choker loops. To ensure safety for people and pets, it is important to follow the instructions provided with the traps. Trapping moles is most successful in the spring and fall, particularly after rains, because the tunnels are shallower in the soil. During the summer and winter, moles tend to be deeper in the soil, making them more difficult to locate.   The most productive location to trap moles is in their permanent tunnels which are used several times daily. Meandering tunnels in the lawn are constructed to search for food and are used only occasionally, so trapping there will not be as productive. To identify main runways, look for generally straight tunnels that have numerous branches where meandering tunnels start. Main runways will often follow fence rows, sidewalks, foundations or other man-made obstacles. Active runs can be determined by stepping down one spot in the tunnel, marking the location and checking to see if it gets repaired within a day or two. Do not collapse the entire runway. If the tunnel gets reopened, then an active tunnel has been found and the traps can be placed. If successful, the moles should be removed immediately from the tunnel and the traps should be reset.

Moles dig 18’ / hr.