Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: WEDNESDAY, April 21, 1993 TAG: 9304210101
SECTION: CURRENT PAGE: NRV-13 EDITION: NEW RIVER VALLEY
SOURCE: Joe Hunnings
DATELINE: LENGTH: Long
\ MOWING: Frequent mowing is an important part of turf maintenance. It is best to remove no more than one third of the vegetation at one mowing. If mowed too closely, root growth is slowed. This reduces the lawn's tolerance to heat and drought. Also, weeds are more likely to invade closely cut lawns.
\ MOWING HEIGHTS: Kentucky bluegrass, 1 1/2-2 1/2 inches; tall fescue, 2-3 inches; creeping red fescue, 2-3 inches; perennial ryegrass, 1 1/2-2 1/2 inches.
Selecting higher mowing heights during summer months for cool-season grasses will reduce stress levels of the turf; at the same time, it will increase the likelihood of the grass surviving drought. Lower mowing heights in fall will aid leaf collection.
Be sure to keep your mower blade sharp! Using a dull blade causes excess leaf damage and depletes the plant's stored reserves during the stress-filled summer months. Eventually the plant is not able to heal the mowing wound. The open wound becomes a site of fungal entry, leading to a diseased lawn. A white cast over the surface of the turf is a good sign of a dull blade.
\ CLIPPINGS: Lawn clippings can be effectively recycled to the turf as long as they disperse well and are not clumped on the lawn. They are not a major contributor to thatch, and they provide nutrition to the lawn as they decompose. If you must collect your clippings, consider using them for compost or mulch.
\ FERTILIZATION: Minimize or avoid spring and summer fertilizer applications. Research in Virginia has proved that spring nitrogen applications of one pound of nitrogen per 1,000 square feet actually reduced root numbers by as much as 40 percent.
Fall fertilization on the other hand enhances the quality of cool-season grasses such as fescue HOEIN' & GROWIN' JOE HUNNINGS and bluegrass. The advantages of fall fertilization include better density and root growth, less spring mowing, better fall-to-spring color, fewer weed problems, better drought tolerance and less summer disease activity. The amount of fertilizer to apply and the timing of application can affect both turf and ground-water quality. Contact your local extension agent or turf professional for recommendations.
\ PH ADJUSTMENT: Soils in Virginia are typically acid, and it may be necessary to add lime occasionally to keep the soil pH near 6.2, the ideal for quality turfgrass. A soil test every two to three years will tell how much lime to apply.
\ IRRIGATION: Deep, infrequent irrigation (so water penetrates six to eight inches deep) will encourage deep root growth, efficient water use, and turfgrass quality. The best time to water a lawn is early morning when evaporation is minimized. Early evening or night watering leaves the lawn wet at night, which increases the potential for disease.
A light sprinkling of the surface encourages root development near the surface and increases weed seed germination. The resulting, limited root system requires frequent watering and constant surface moisture.
Lawns can use an inch or more of water per week in hot, dry weather. If rainfall does not provide this much water, the lawn should be watered when the soil begins to dry out, but before the grass actually wilts (areas of the lawn will begin to turn blue-green). If you choose not to water, Kentucky bluegrass can be allowed to go dormant (turns straw-colored and stops growing). It can stay that way until rainfall returns and the grass naturally greens up again. While dormancy is a natural method of drought survival of Kentucky bluegrass, many fluctuations between dormancy and active growth weaken the lawn. Watering during the fall when more favorable growing conditions exist and evaporation is less encourages recovery of the lawn. Tall fescue has a deep root system in deep, well-drained soils and can survive moderate drought periods.
Periodic maintenance
\ DETHATCHING: In some years it may be necessary to remove thatch, the tightly interwoven layer of living and dead stems, leaves and roots between the green grass and the soil surface. A layer of thatch less than a half-inch in thickness can be beneficial to the grass, as it is similar to mulch and provides many of the same benefits. Too much thatch provides a habitat for insects and disease and makes the grass less tolerant of heat and drought.
If the lawn's thatch is more than a half-inch thick, dethatching will be beneficial. Timing is critical; dethatching should be done during low-stress periods. Kentucky bluegrass and other cool-season grass lawns should be dethatched in early fall or early spring. Bermuda grass and zoysia grass should be dethatched June through July. Dethatchers can be rented; they deposit the thatch debris on top of the lawn, where it can be raked up and composted.
\ AERATION: If soil is heavy or compacted, or if thatch is a problem, aeration may be necessary. Roots need oxygen as well as water and nutrients; compacted soil prevents the flow of oxygen from the atmosphere to the roots. Aeration is best done by a machine that forces hollow metal tubes into the ground and brings up small cores of soil. When this is done, the soil should be moist - neither too wet nor too dry. Other "aerators" punch holes in the soil with a spiked roller; while they may aid water retention, they actually increase soil compaction. Soils are aerated during the same season as dethatching.
\ WEED CONTROL: Weed control can be minimized by good mowing and fertilization management, which help grass compete with weeds. Broadleaf or grassy weeds can be perennial, annual or biennial. Control methods and timing vary depending on the weed species.
\ DISEASE CONTROL: Proper management will greatly reduce a lawn's susceptibility to disease. Disease damage may be difficult to identify, because many of the same symptoms also are caused by bad management or by natural factors, such as competition from tree roots. Most lawn diseases are caused by fungi; fungicides can be applied to control them.
\ INSECT CONTROL: Many types of insects occur naturally in a lawn; most of them are not harmful and do not require control unless the pest population builds up enough to cause visible damage. Close examination of the turfgrass is the most effective way to identify insects.
The most common above-ground insect pests in Virginia lawns are chinch bugs and sod webworms; both feed on grass leaves and stems. Below ground the most common pests are white grub larvae and weevil or billbug grubs; these feed on plant stems and roots.
If a weed, disease or insect problem is evident, your extension agent or turf professional can help identify the pest and suggest controls.
\ QUALIFY FOR FREE FERTILIZER: If you would like to be eligible for a free supply of fertilizer for one application to your lawn, come to a lawn care and composting workshop May 6 at 7:30 p.m. at the Parks and Recreation Community Center, Patrick Henry Drive, Blacksburg. The program is sponsored by the Montgomery County Cooperative Extension, Blacksburg and Total Lawn Care.
by CNB