WARM SEASON GRASSES

Warm season grass lawns are actively growing from mid-April to mid-October. They are termed "warm season" grasses because they grow during warm weather. Most produce stolons and/or rhizomes. Stolons are above ground runners, while rhizomes are under ground runners. Both are stems that help produce plants and help warm season grasses fill in areas and recuperate after stress events.

Bermuda grasses, (Cynodon spp.), have two general categories common and hybrid. Common bermuda has leaf blades which are 1/8" (3mm) wide, and attach themselves to the grass shoot at intervals of about 1/4" (6mm). This leaf width and leaf arrangement give common bermuda a "medium" texture appearance. Common bermudagrass is best mowed between 1 1/2 --2 1/4" with a rotary mower. Common bermudagrass is easily established from seed. Hybrid bermudagrasses are the result of mating common bermudagrass with African bermudagrass. The result is a plant which has fine leaf texture and does not produce pollen or seed. Certain hybrid bermudagrasses have narrow leaf blades (1/16") (2mm or less) and are attached very closely to each other on the main shoot. They also have more individual shoots per square inch of turf than common bermudagrass. Because of the dense growth habit, hybrid bermudagrasses tolerate and require shorter mowing heights. Tifgreen (Tif 328) can be mowed at 1/4" or less with special maintenance practices. Most hybrid bermudagrasses are adapted to mowing heights of 1/2-1 1/4" with a reel mower. Higher mowing heights of 1 1/2 -- 2" with a rotary mower can result in puffy turf which is subject to scalping. The hybrid variety E-Z Turf (Midiron) appears more like common bermudagrass than the other Tifgreen hybrids. It is easily mowed with a rotary mower, and does not scalp from puffiness which occurs at higher mowing heights. Hybrid bermudagrasses are established from vegetative plant parts and not from seed. It is commonly established through sodding, stolonizing, and to a lesser extent plugging. For more information, see Extension Bulletin No. 8752, Hybrid Bermuda Lawns.

Newly developed seeded bermudagrasses are becoming increasingly available on the commercial market. Since they produce seed, they must produce pollen. Newly released seeded bermudagrasses with are being sold as improved turf types.

Some are substantial improvements over "Arizona Common", some are not much different. Some of the advertised features include:

• darker green color

• lower growth habit and subsequently shorter mowing heights

• improved drought tolerance

• less seed head production

The first generation of "improved turf-type seeded bermuda grass" include the following cultivars:

• Numex Sahara (NMSU)

• Sonesta (NMSU)

• Guymon (OSU)

Other varieties released include:

• Sun Devil

• Paco Verde

• Mirage

• Yuma

Many others are being tested for potential release. Some of these are included in the germplasm tests at the Desert Turf Center in Tucson. Others are "extra" proprietary and are not regularly tested by universities. Therefore, there is very little data to support claims or adaptation to Arizona. Major breeding programs include experiments for evaluating mowing height and fertility interactions of some of this new germplasm. Until further notice, treat the seeded types as you would "AZ-Common".

There are tests underway in Oklahoma to evaluate cold hardiness of bermudagrass, in order to increase its range of use. The cultivar "Midron" (sold as E-Z Turf), Mirage and "Guymon" have good cold tolerance. These two go dormant earlier in the fall, and store more food reserves. "Midiron" does NOT produce seed, it is a sterile variety which produces no pollen. "Guymon" is a wide leaf blade seeded types, but it has short internodes. It is very unique in this characteristic. "Guymon" will produce pollen and seed. Bermudagrass should be established at a rate of 1.0 to 1.5 lbs. of seed per thousand square feet. The last type of bermudagrass is a "seeded-hybrid." This is a special case. The variety "Princess," or the Princess "brand" and related proprietory commercial brands of seed are lawn-type bermudagrasses which are termed hybrids. This is because of the special arrangement of seed plants in the production field. In this sense, it qualifies as a "seeded hybrid." It does however, make pollen and seed, if allowed to, in a mowed lawn.

St. Augustine, (Stenotaphrum secundatum) grass has stolons but no rhizomes. Stems are flattened, with wide, dull green leaves that lay flat on the ground. St. Augustine does better in the shade than both bermuda and zoysiagrass. St. Augustine grass is established by either sod, plugs, or occasionally by seed. It produces a thick thatch over time and is slow to grow back from a severe verticutting. It does not take to overseeding. Like bermudagrass, it does go dormant (turns brown) during the winter months when it is cold. It has a limited use in our state for low elevation lawns which receive moderate shade conditions where a brown winter turf is acceptable. Newer varieties are currently under university testing.

Zoysiagrass, (Zoysia species), is slow to establish when compared to bermuda grass but is more tolerant of shade. Zoysia grass has both stolons and rhizomes. Leaf-blades are borne at right angles to the stalk. Ligules have short dense hairs. There are several species of Zoysia japonica, which is common Japanese lawn grass. It is shade tolerant, but not as much as St. Augustine. It is quite slow to establish, especially from plugs. It is best established in June by either sod, or seeding, if seeds are available. The seeding rate is 2.0--2.5 lbs. per 1000 square feet. Zoysiagrass seed contains dormant seed that will not germinate right away. Ask for "dormant treated seed" if you must have zoysiagrass. This seed is treated with an additive or receives a cold (chilling) treatment which overcomes the dormancy of the seed. Although it has both rhizomes and stolons, zoysiagrass is slow growing, especially when compared to bermudagrasses. Like St. Augustine, it does not tolerate overseeding with ryegrass. However, it usually does retain its green color longer in the fall than most bermudagrasses. Common Japanese lawn grass can be mowed with a sharp reel mower at 1.25 inches, or with a rotary mower at 1.5 to 2.0 inches. Zoysiagrass will become thatchy and puffy with time. When a verticutting is called for, it is best done in early June followed by a fertilization with a complete fertilizer (N--P--K). Zoysiagrass use has diminished rapidly. Sod types are generally not available in Arizona.

Buffalograss, (Buchloe dactyloides) has become popular in the trade literature. Buffalo grass is a native grass which occurs as different land races from southern Mexico to North Dakota. It is a warm season grass and is more closely related to bermuda grass than cool season grasses. Here in Arizona, its asset is that it can go 2 weeks without water at higher elevations, if good soil moisture conditions allow it. In the early and mid 1980s, Texas A & M and the University of Nebraska began collecting and breeding Buffalo grass for turf. Buffalo grass has male and female plants (dioecious), with occasional and rare plants having both sexes. Seed from the female is expensive because the seed capsules (burrs, which contain 2-3 seeds each) are low to the ground and require careful harvest and cleaning.

The seeded types (which result in a mixed population of male and female plants) available on the market for general utility turfs area as follows:

• "Texoka" released around 1960 by Dr. Kneebone.

• "Sharp's Improved". Mid 1960s.

• "Bison" Released in 1991 by Oklahoma State University

• "Tatanka" in 1996 by FMK

• "Cody" in 1996 by FMK

All five of these cultivars can be used as forage or low maintenance turfs.

It turns out that female plants on average have better turf quality attributes than males (darker color, shorter internodes, higher stolon densities, etc.). As a result, Universities and sod companies have released single female clone varieties for turf. Those available in Arizona that are sold as sod are:

• "Prairie" Buffalo grass

• "NE 609" Buffalo grass

NE 609 is the lower growing and darker green of the two. A new release from Nebraska is NE 315, which is also darker yet.

Buffalo grass has the following general traits:

• Likes the warm weather (dormant in the winter below 3000 feet and dormant in the fall at higher elevations).

• Has a low water use rate.

• If it runs out of water in the summer, it will enter drought induced dormancy. That is, it will turn brown, just as it does in the winter. If observed side by side with bermuda grass, the Buffalo grass takes longer to wilt and holds it's color longer. However, when irrigation is applied after stress, the Buffalo grass takes longer to recover than bermuda grass. The more repeated cycles of stress, the slower the Buffalo grass will be in recovering. This is more critical for turfs used at low elevation (3000 feet and below).

• At low desert elevation, it looks like there is no real advantage to Buffalo grass over bermuda grass in water use.

• Mowing height is 2.0 inches (as the preferred base height). Mow with a rotary mower. Raise to 2.5 or 3.0 inches in poor soils and/or minimal irrigation.

• Buffalo grass has a lower nitrogen requirement than bermuda grass. You can slow the grass down and actually weaken it with too much fertility. It needs maybe 1.0 lbs -N-/1000 ft²/year, preferably in split applications of 1/2 lb. in June and July or August (May is a possible substitution for June, also). If in a non-irrigated situation, apply the fertilizer in the middle of the rainy season.

• Since it has a lower growth rate than bermuda grass, its recuperative capacity is less. Therefore, the current Buffalo grass varieties are not recommended for use in high traffic situations, as they would not grow back fast enough during constant use. At higher elevations, Buffalo grass may be more adaptable at 3,500 feet and above. Mow it at 2.5 inches as the base height if it gets standard turf maintenance.

• Shade: The commercially available germplasm is not shade tolerant. There are some types from Mexico that are more shade tolerant.

• Buffalo grass is not salt tolerant. There are genotypic differences, but its a far cry from bermuda grass salt tolerance.

• Plant seed in June! Don't wait till July. The sooner the better. If you have only the monsoon to water, you must plant during that time. Seed at 1.0 - 1.5 lbs of pure live seed per 1000 ft². Check the label to see how much seed is dormant the first year. Some seed may be pretreated to eliminate dormancy. If using sod (Prairie, NE 609, etc.) plant the sod in June as the first choice. You can also plug. The plugs and sod will loose color after transplanting, even under proper watering. They will start to green up after two weeks and then stolons (they have no rhizomes), will be produced.