Description. Carpetgrass (Axonopus affinis) is a creeping, stoloniferous, perennial warm season grass. It is characterized by flat, two-edged runners or stolons; by wide leaves with blunt, rounded tips and by long, slender seedstalks that terminate with two branches, very similar to crabgrass. Stolons are flat, widely branched and root at each node.
Leaf sheaths are strongly compressed with fine hairs along the outer margin and densely pubescent around the nodes. The ligule is very short with a fringe of short hairs. The leaf blade is wide, flat, broadly rounded at the base, blunt at the tip and often fringed with hairs.
The seedstalk is tall, slender and often drooping. It branches at the apex into two slender, one-sided spikes, sometimes with a third spike below. Spikelets are oblong, acute, 2 to 25 mm long, pale green or tinged with purple, solitary on alternate sides of the rachis and forming two rows. The lower glume is absent, the upper as long as the spikelet. The anthers are yellowish white or slightly tinged with purple. Seed are yellowish brown and about 1.25 mm long.
Adaptation and Use. Carpetgrass is best adapted to the middle and
lower southern states. It has about the same cold hardiness as centipedegrass
and is well adapted to moist, sandy soils. It thrives in areas too wet for
bermudagrass and tolerates more shade than bermudagrass.The ability of carpetgrass to thrive under low fertility makes it suitable for use on low maintenance areas such as parks, roadsides, airports and golf course roughs. Its most objectionable characteristic, frequent and prolonged production of seedstalks, limits its use on lawns. Frequent mowing with a rotary mower is required to maintain a nice looking carpetgrass lawn.
Establishment. Carpetgrass, like all small seeded grasses, requires a loose, smooth and firm seedbed. In heavier soils, disking or rototilling, dragging and rolling may be necessary to develop a good seedbed.
Carpetgrass can be established from seed or sprigs. Seeding is often easier and less expensive. For a quick cover broadcast two pounds of carpetgrass seed per 1,000 sq. ft. of lawn. Rake the lawn lightly after seeding to help cover the seed. A grass drill can also be used effectively for planting carpetgrass seed. For large plantings, where a quick cover is not critical, plant 15 to 20 pounds of carpetgrass seed per acre. Again, a grass drill is the most effective means of seeding carpetgrass.
Seed carpetgrass after the last expected frost in the spring. Mid-April to May are ideal months for seeding carpetgrass. Do not seed after September 15.
Keep the soil moist, but not wet, for about two weeks after seeding. Continue light, frequent watering until the seedlings are rooted and beginning to spread. After the lawn is established, usually 8 to 10 weeks after seeding, water only as needed to prevent severe drought stress.
Carpetgrass does well on acid soils and on soils with a low fertility. However, establishment is hastened by light applications of a complete fertilizer. Apply a complete fertilizer at one pound of nitrogen per 1000 sq. ft. at planting time and at monthly intervals thereafter until the lawn is covered with carpetgrass. Lime is not necessary unless the soil pH is below 5.0
Management. Carpetgrass lawns need frequent mowing during summer months to keep the seedstalks cut. During the growing season, new seedstalks are produced about every five days. If allowed to grow, the seedstalks grow to about 12 inches tall and produce an unsightly lawn.
Carpetgrass should be mowed to a height of 3/4 inch to 2 inches, depending on its use. The grass will tolerate the shorter mowing heights for use on golf course fairways with a 5-day mowing schedule. Where mowing is less frequent, the taller mowing height produces the best results. A rotary or flail mower is necessary to remove the tall seedstalks that develop with less frequent mowing.
Carpetgrass will thrive on moderately acid, low fertility soils. Under these conditions, it will crowd out bermudagrass. On roadsides, golf course roughs, parks and other low maintenance sites, carpetgrass will survive without fertilization. But, on more frequently mowed sites such as lawns, fairways, etc., occasional applications of nitrogen are needed. Late spring and early fall applications of nitrogen at 30 to 40 pounds per acre (1 pound per 1000 sq. ft.) are adequate to meet nitrogen requirements. Soil test recommendations relative to phosphorus and potassium should be followed.
Carpetgrass is not as drought tolerant as bermudagrass. On droughty soils or during periods of drought stress, occasional watering is needed to maintain carpetgrass. On moist sites where bermudagrass is not adapted, carpetgrass will thrive without supplemental water.
Pest Management. Carpetgrass is susceptible to common soilborne diseases such as brownpatch and Pythium and to most leaf spot diseases, but rarely do these diseases justify fungicide applications on carpetgrass. The grass usually recovers with little injury when environmental conditions change. The exception might be brownpatch in the fall which can produce unsightly turf for several months.
White grub and, in the southeastern states, mole crickets can cause serious injury to carpetgrass turf. Again, where infestations of these insects can cause a problem, insecticides are available to effectively control them.
Where weeds are a problem in carpetgrass turf, the hormone-type herbicides can be used for broadleaf weed control. Also, most preemerge herbicides are safe on carpetgrass and can be used for crabgrass control.