PRB Articles


Selecting Sod

Whether you do or don’t believe in global warming, drought conditions are definitely evident after reviewing the U.S. Drought Monitor (www.drought.unl.edu). One way that municipalities and park agencies can lessen the demand on local aquifers is to carefully select the type of sod used in greenbelts and athletic fields. The variety of turfgrass in today’s market is vast and, in many cases, distinct to certain regions of the country. Modern turfgrass, with all of its science and engineering, is far different than the backyard grass you used to mow growing up. The turfgrasses of today are more efficient at managing common stresses (cultural, chemical and environmental). The direct or indirect byproduct of this development has been sod that is drought-resistant.

I recently had the opportunity to speak with Erin Boyd Wilder with Sod Solutions about drought-resistant turfgrasses. Her family has been farming in North Florida for six generations, and has been in the sod business for over 20 years. Wilder understands turfgrass, as well as where the industry is headed; this is illustrated as she fields a few questions on drought-resistant/tolerant turfgrasses and the best management practices to follow:

1. For states experiencing drought conditions, turfgrass that can reduce a municipality’s water use is in great demand. What type of performance can today’s turfgrass offer?

There are many turfgrass varieties marketed today, including some that were developed in the 1950s. It is clear, however, that the future of turf--and landscapes in general--demands grasses that use less water, fewer chemicals and less maintenance. Therefore, more advanced grasses have been developed that require fewer inputs while retaining good aesthetics.

2. What is the difference between drought tolerance and drought resistance?

Drought tolerance is the ability of a turfgrass to go dormant (turn brown or off-color) during the active growing season due to insufficient water, and then recover when water returns.

Drought resistance is the ability of a turfgrass to stay green for a period of time without water, while maintaining acceptable quality standards.

3. What are some general water-use requirements for these grasses?

The answer is simple--don’t overwater! All turfgrasses, once established, require ¾ to 1 inch of water once a week early in the morning. Although soil type and climate do play a role, the amount of water is of particular importance.

4. What are some water-use problems or traps professionals encounter, and what are the corrections needed to resolve these issues?

Again, the most common problem is overwatering. Upon installation, new turf should be watered only as needed to keep the turf moist for the first two to three weeks. Once the turf has rooted, the rule in question #3 applies. Watering early in the day allows the surface to dry and avoid disease from excess moisture; the cooler morning temperatures and low light also help avoid high evaporation rates. Soil types, as well as the season, can dramatically alter one’s water needs. Check with local experts for specific conditions and recommendations.

5. What is an example of a drought-resistant turfgrass?

St. Augustine grasses are drought-resistant. These grasses have received a lot of negative press lately, and have been touted as “thirsty” grasses or “water guzzlers.” This reputation is undeserved and probably compounded by the fact that homeowners have a tendency to overwater. Actually, St. Augustine grasses generally have good-to-excellent drought resistance. Palmetto and Floratam St. Augustines will hold their green color for a longer period of time during droughts. St. Augustines, however, are not very drought-tolerant, and may be severely damaged during extended periods without water.

Note: The description below is an example of a drought-resistant St. Augustine; however it is not necessarily a representation of all varieties.

Characteristics

· Overall good shade tolerance

· Good drought resistance--stays green longer

· Variety of cold tolerances

Common Stresses

· Improper height for variety (varies from 1.5 to 4 inches); allow to grow slightly taller in shaded areas

· Improper mowing--only a quarter of the leaf blade at a time

· Overwatering, high humidity and shade

· Shock--reduce by wetting soil 1 inch prior to installation

· Disease--reduce high nitrogen (N) sources with a balanced, slow-release fertilizer

Weed Management

· Selective control of Bermudagrass and crabgrass

· Restrictions on the use of chemicals (i.e., farm, commercial, and residential uses)

· Blending of weeds better in St. Augustine

Insect Management

· Identifying the pest

· Chinch bugs and lawn caterpillars, such as tropical sod webworms, grubs and fall armyworms.

· Chinch bugs are the most serious insect problem. The damage resembles large dead and/or dry patches in the grass.

· Tropical sod webworm damage has patchy areas that are grayish in color, and often starts near landscaping. “Notching” occurs on the blades of grass, and adults are often resting in a curled position when grass is parted and examined during the day. Fall armyworms show similar damage to the tropical sod webworm, but the damage is more uniform and less patchy. Both can be controlled with numerous contact insecticides and pyrethroids.

6. What is an example of a drought-tolerant turfgrass?

Empire turf is a zoysia grass that uses dormancy as a defense mechanism when water is shut off for an extended period. As soon as the first rain appears or watering is permitted again, Empire’s emerald-green color returns. Now, for grasses that don’t have a drought-tolerant characteristic, going without water for a certain period of time can severely damage or kill the grass. Once a non-drought-tolerant turfgrass turns brown, no amount of watering is going to bring it back to an acceptable quality standard.

Note: The description below is an example of a drought-tolerant zoysia; however, it is not necessarily a representation of all varieties.

Characteristics

· Deep root structure

· Excellent drought tolerance

· Soft to the touch

· Cold-tolerance with fall-color retention

· Traffic tolerance

· Salt tolerance

· Growth habit that inhibits weeds more than St. Augustines

Common Stresses

· Disease--overwatering a contributing factor

· Overfertilizing--excessive N causes thatch buildup

· Mowing above 2 inches causes thatch buildup

· Chemical products--use only those labeled for specific species of zoysia grass

· Harsh herbicides

· Improper grade, creating persistent wetness

Weed Management

· A healthy Empire lawn will inhibit weeds more than a St. Augustine lawn

· Selective control of Bermudagrass and crabgrass

Insect Management

· Identifying the pest

· Hunting billbug, mole crickets and lawn caterpillars, such as tropical sod webworms and fall armyworms

· Billbugs are the most serious insect problem. Symptoms resemble disease and drought, where the turf pulls easily from the soil surface, adult and larval forms are present, sawdust-like frass, and there is evidence of chewing on the stems of the turf.

· Mole cricket damage shows distinct tunneling, and can be controlled on contact with various pyrethroids, or by using timing-based products during peak hatch.

· Tropical sod webworm damage has patchy areas that are grayish in color, and often starts near landscaping. “Notching” occurs on the blades of grass, and adults are often resting in a curled position when grass is parted and examined during the day. Fall armyworms show similar damage to the tropical sod webworm, but the damage is more uniform and less patchy. Both can be controlled with numerous contact insecticides and pyrethroids.

In years past I recall discussing with associates the chemical and environmental stresses that turfgrasses face. However, it appears that cultural stresses, while always present, have only recently been defined. What types of stresses fall under this classification and why?

“Cultural stressors” are the various maintenance-related stresses to turf. Examples include fertility practices, overwatering, improper mowing and allowing turf to sit on a pallet and build up heat. A few ways to reduce cultural stresses are to follow proper best-management practices or BMPs. For example, the proper BMPs for Empire zoysia grass are:

· Three pounds of N per 1,000 square feet per year

· Iron sources for color

· Avoiding ”wet feet” by watering ¾ of an inch once a week

· Mowing at 1 to 2 inches, but slightly taller in shaded areas

It is widely accepted as a best practice that when laying new sod, a smooth grade, pre-irrigation and reducing pallet time all aid in a successful installation. What are some other BMPs during or after installation that should be adhered to?

Another important installation step is staggering the pieces while keeping tight edges--this allows for minimal weed growth while the turf is taking root. It’s also important to begin watering new turf within 30 minutes of installation.

In addition to following BMPs, a comprehensive program that is proactive rather than reactive is recommended; inputs, including water, chemicals and maintenance, can be reduced if a proactive approach is developed. Learning about the local areas’ environmental conditions, soil types and proper turf-variety selection will be beneficial for preserving resources.

If upgrading to a drought-resistant turfgrass is not economically viable, consider following the BMPs with the sod you have. This will provide a better opportunity to reduce the environmental impact and improve your bottom line.

Steve Yeskulsky is a CPRP currently working in the parks and recreation industry in Sarasota, Fla. He can be reached via e-mail at syeskulsky@verizon.net

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