- Weed Control during Establishment
- Using Bahiagrass in Sod-based Rotations with Agronomic Crops
- Pest Management
Bahiagrass (Paspalum notatum Flugge) is a long-lived, perennial warm season grass that is grown extensively in the southeastern United States (Figure 1). It is most commonly used as a pasture species, but can be used for hay production, erosion control, and wildlife habitat. Bahiagrass can also be used in "sod-based rotation" sequences that have been found to suppress pest problems (nematode and disease issues) in crops such as peanuts.
Bahiagrass is a deep-rooted, sod-forming species that is well adapted to a wide range of soils and conditions in this region. It spreads by short, stout stolons and is a prolific seed producing plant. Bahiagrass will grow on soils too poorly drained for bermudagrass, is more shade tolerant than bermudagrass, and can be used in woodland pastures (silvopasture).
Bahiagrass has many desirable characteristics such as: (1) tolerance to close grazing, (2) general freedom from severe disease and insect infestations, (3) good drought tolerance, (4) adequate forage quality, and (5) a low to moderate fertility requirement for the maintenance of good stands. Though it persists in pastures with a low level of management, it responds well to proper fertility and management.
Bahiagrass is particularly well suited for use in pastures (Table 1). It produces forage earlier in the spring and later in the fall than bermudagrass since it is less affected by decreasing day lengths and cool temperatures. Unfortunately, bahiagrass forage is less digestible than 'Coastal' bermudagrass of the same age (maturity). The use of good grazing management to keep the bahiagrass between 2 and 6 inches will keep the quality relatively high (54 to 56 percent TDN and 10 to 11 percent CP) and allow for better utilization.
Origin and Types
Bahiagrass is native to South America and is widely distributed in Argentina, Brazil, Paraguay and Uruguay. Several types of bahiagrass have been introduced into the United States since 1913 and differ in cold tolerance, growth characteristics, and forage production.
Common bahiagrass was first introduced into Florida in 1913. It has short, broad leaves and stout stolons. Common is relatively slow to establish and less productive and cold hardy than the later introductions. Common may be found growing in old pastures in some areas, but is no longer planted.
Pensacola bahiagrass was introduced into the United States from South America in the late 1930s (probably in ballast discarded from ships visiting the port at Pensacola, Florida). E. H. Finlayson, a county Extension agent, found this cultivar growing in streets and vacant lots near Pensacola's docks. It is now the most widely grown variety in the United States. Compared to common and other varieties, it has longer and narrower leaves, taller seed stalks, and produces seed earlier. It is more winter hardy than the common and Argentine varieties. Growth begins early in spring and continues until mid-summer when the seedheads mature. Late summer growth is slow and low quality. Pensacola is fairly resistant to ergot, a smut disease affecting the seedheads of some grasses and causing health problems in cattle. Use Pensacola on less fertile soils and in pastures that will not be well managed. Once Pensacola is established, it can be maintained more easily than most pasture grasses.
Argentine was introduced from Argentina in 1944. It has wider and darker green leaves than Pensacola (Figure 2). It is also less cold tolerant and a poorer seed producer than Pensacola. Argentine starts growth later in spring but produces more forage in late summer and early fall than Pensacola. Argentine may also be better adapted to poorly-drained soils than some other introductions. It is less frost tolerant than Pensacola and is very susceptible to ergot.
Paraguay 22 is so named because it is believed to have been introduced from Paraguay. It is a short, coarse, narrow-leaved variety and is less productive than Pensacola. It has been used as a general-purpose turfgrass but seed are no longer available. It is similar to Argentine in growth habit but slightly more upright and more productive than Paraguay. It is not as cold tolerant as Pensacola.
Tifton-9 was a selection from Pensacola that was released in 1987 by the Georgia Coastal Plain Experiment Station. Compared to Pensacola, it is less tolerant of close grazing. However, Tifton-9 has much greater seedling vigor, a more upright growth habit and generally produces up to 25 percent more forage with digestibility equal to Pensacola. Tifton-9 does not develop a dense sod like the other bahiagrasses and can be established with 8 to 10 pounds of seed per acre if drilled. A higher seeding rate may result in quicker stand development.
AU Sand Mountain was developed and released by Auburn University. It was originally selected from a patc 0195 h of Pensacola that had been planted in the early 1960s on what later became the Sand Mountain Research and Extension Center in northeast Alabama. This variety is more winter hardy than any other bahiagrass variety evaluated in Georgia. It performed and persisted well in yield trials at the Northwest Georgia Research and Education Center near Calhoun. When planted farther south, AU Sand Mountain has fo 5380 rage production between Pensacola and Argentine.
TifQuik, a variant of Tifton-9, is a newly released variety that has proven to have superior seedling vigor and quicker stand formation. The yield potential and other characteristics of TifQuik are essentially the same as Tifton-9.
UF-Riata was developed and released by the University of Florida. It is more cold tolerant in Florida and tends to grow later in the fall and earlier in spring. In central and south Florida, UF-Riata stays green much of the year and may provide slightly better disease resistance than other varieties. It has matched the yield of Tifton-9 and TifQuik in trials at Tifton and has been observed to stay green a few days longer than the other varieties in the trial. However, UF-Riata has not yet been well studied in more northern locations in Georgia.
Other varieties that have been used or previously studied but are currently of minor importance include Tifhi-1, Tifhi-2, Paraguay 22, Riba, and Wilmington.
Information about currently recommended varieties of bahiagrass may be found on the "Forage Species and Varieties Recommended for Use in Georgia" web page.
Establishment Recommendations Timing
The best time to plant bahiagrass is in the early spring on upland soils or in late spring on low, moist soils. Plantings made later in the summer can be successful but weed competition (primarily aggressive summer annual grasses, such as crabgrass, goosegrass, and crowsfootgrass) can be a problem. Dry weather can also slow bahiagrass establishment. Bahiagrass can be successfully seeded in early fall in south Georgia.
Seed Size and Dormancy
Bahiagrass seed are small and should be planted shallowly, no more than 1/4- to 1/2-inch deep. This will allow for quicker emergence and promote seedling vigor.
Bahiagrass seed have variable germination rates. Some seeds germinate quickly after planting while others may not germinate until the following year. Generally, 50 to 60 percent of the seed will germinate within 30 days. TifQuik is the exception, as most of its seed will germinate readily within one to two weeks after planting if soil conditions are favorable.
Variable germination is the result of a waxy seed coat that limits potential uptake of water. The seed coat has a germination flap through which the seed absorbs moisture for germination. The opening of this germination flap depends on soil temperature, seed production conditions, seed storage conditions, and other factors. In many cases, seed stored for a year have a higher germination percentage than when the seed are first harvested. Seed scarification improves germination for common bahiagrass, but it is usually not necessary for the other bahiagrass varieties.
Seed dormancy is often much lower in some varieties than in others. As a result, seeding rates are higher for some varieties than others (see "Seeding Rates" section).
Bahiagrass may be planted in several ways. No-till planting methods should be employed if there is a risk of soil erosion (e.g., sloping land). Many local conservation districts or similar organizations may have a no-till drill that can be rented or borrowed. No-till establishment methods can result in an acceptable stand of bahiagrass, but often require high seeding rates (see "Seeding Rates" section) and control of existing vegetation. It is critical that the existing stand/crop and any weeds are destroyed. Sometimes this requires two applications of a non-selective herbicide (four to six weeks apart).
If the risk of soil erosion is minimal, conventionally-tilled seedbed preparation can be used to establish bahiagrass. When conventional seedbed preparation and establishment techniques are employed, it is recommended that the "stale-seedbed" method be used. In this method, the first step is to destroy the existing vegetation by spraying with a non-selective herbicide. Next, recommended levels of lime and/or nutrients (based on soil test results) should be added so that they can be incorporated into the soil during the tillage phase. The land can then be tilled, disced, and packed. This also allows for any leveling or smoothing of the soil surface that may be necessary. The tillage and packing steps should be completed at least one month prior to planting so that the soil can settle/firm before planting. Properly packing and firming of the soil is necessary to prevent the seed from being planted too deeply. As a rule of thumb, footprints left in prepared soil that are approximately 1/4-inch deep indicate a firm seedbed. In addition to allowing the soil to become firm, this will allow many of the weeds in the disturbed soil to germinate and emerge. These weeds can then be destroyed using a non-selective herbicide within a few days of planting.1
Once the seedbed is prepared, seeds may be drilled into the soil or broadcast on top of the soil. When broadcasted, the seed must be covered with soil (no more than 1/4- to 1/2-inch deep) with either a light disking or a cultipacking. Seeding and cultipacking at the same time using a cultipacker-seeder (e.g., Brillion seeder) also works quite well. Seeds can be more precisely placed into the seedbed when drilled. However, the small seedbox attachment must be used to plant bahiagrass because the seed are too small to be accurately measured in the grain drill seed cups.
Seeding rates vary with variety and planting method. When using Pensacola or a Pensacola-type variety, the seeding rate should be 12 to 15 pounds of seed per acre when the seed are drilled into a prepared seedbed. When broadcasting seed onto a prepared seedbed or using no-till methods, increase the seeding rate of Pensacola-type varieties to 18 to 20 pounds per acre.
Tifton-9 and TifQuik have much better seedling vigor than other Pensacola-type varieties and lower seeding rates can be used for these varieties. As a result, the seeding rate for Tifton-9 and TifQuik is 8 to 10 pounds per acre on prepared seedbeds and 12 to 15 pounds per acre when broadcasting or planting with a no-till drill.
Fertility at Establishment
Prior to planting, apply any needed lime, P, or K (according to soil test recommendations). Avoid applying N before or at planting, as this may increase annual grass emergence before bahiagrass. Apply 35 to 50 pounds of N per acre after the seedlings emerge and start to grow. With early planting dates, a second application of 50 to 75 pounds of N per acre in early- to mid-summer may be necessary to promote rapid coverage.
Good weed control during the establishment phase is essential. Newly-established bahiagrass may be less competitive with annual grasses and broadleaf weeds. A thick cover of weeds slows stand establishment by shading the emerging bahiagrass seedlings. Weak stands due to poor seedling establishment can thicken over time. If plants are well distributed over the field, managing the stand to reduce weed competition will increase the opportunity for stand improvement.
Once the bahiagrass seedlings reach a height of 8 inches, broadleaf weeds can be controlled with 2,4-D. Care should be taken when using 2,4-D in new plantings since this herbicide does have some pre-emergence activity on grass seed germination and may adversely affect bahiagrass seeds that have not yet germinated.
Currently, there are no herbicides that selectively control annual grasses in newly established bahiagrass. Mowing is the only option when these grasses are a problem in a newly-established field. The mowing height should be adjusted such that little (if any) of the bahiagrass foliage is cut. Mowing once a month (or more frequently) may be necessary, depending on the level of grass competition. Once established, bahiagrass can suppress most weeds and mowing may or may not be necessary.
Carefully managed rotational grazing can accomplish a similar effect, but the animals must be managed to minimize grazing pressure put on the bahiagrass. Cattle should not be allowed to graze new plantings of bahiagrass in the spring months. Heavy trampling may result in destruction of the young plants.
See the Georgia Pest Management Handbook and check with your county Extension agent for additional information and current recommendations.
Though it will persist in low-fertility soils, bahiagrass is responsive to good soil fertility. When it is used in a livestock operation, a good liming and fertility program is essential to the production of good forage yields and to economic returns.
Bahiagrass is very responsive to N fertility (Table 2). After establishment, annual applications of 100 to 200 pounds N per acre should be used for good forage production. For better distribution of forage growth, divide the N into two or more applications during the growing season. Higher rates of N per acre should only be used in very intensive grazing or hay production systems.
As in all good fertility programs, soil testing should be the basis for making amendment decisions. Apply lime, P, K, or any other needed soil amendments based on soil test recommendations. All of the P can be applied at any time during the year. Apply half of the K in the early spring and the other half in the summer to prevent luxury consumption of this nutrient by the plant.
Bahiagrass is less sensitive to soil pH than many crops. Applying lime to maintain the soil pH at 6.0 ensures that pH will not be a limiting factor for the bahiagrass, any crops that are overseeded into the bahiagrass, and any crop that may follow bahiagrass in the rotation.
Improvements in nearly all facets of crop production have been reported when row crops are grown after bahiagrass compared to following other row crops (Figure 3). This includes the most important factors to producers—yield and crop quality. Yet, there are other proven improvements that result from such rotations. In terms of soil environment, which greatly contributes to the sustainability of agricultural systems, factors such as reduced erosion, build-up of soil organic matter, root growth and depth of penetration by the succeeding crop, water infiltration, earthworm population, and soil tilth all change for the better. From a row crop standpoint, the most important benefit is usually from reduced incidence of numerous pests. Research results have shown a reduction in early and late leaf spot (Cercospora arachidicola and Cercosporidium personatum, respectively) diseases in peanut, decreased southern blight/stem rot/white mold (Sclerotium rolfsii) in peanuts and cotton, and fewer thrips (Flankliniella fusca), leading to less tomato spotted wilt virus (Tospovirus) in peanuts and tobacco. In addition, it is reported that peanut and soybean root-knot nematode (Meloidogyne spp.), reniform nematode (Rotylenchulus reniformis), and soybean cyst nematode (Heterodera glycines Ichinohe) infestations may decline following bahiagrass since it is a non-host to these pests (McGlohon et al., 1961; Rodriguez-Kabana et al., 1988; Rodriguez-Kabana et al., 1989; Johnson et al., 2000; Katsvairo et al, 2006). Collectively, these factors can result in savings from reduced inputs such as a less frequent need for irrigation, elimination of one or more fungicide spray events, and potentially reduced applications of expensive specialty herbicides due to bahiagrass outcompeting weeds.
(Photo Credit: Dr. David Wright, University of Florida)
In addition to the potential for improved yields and reduced inputs for the row crop enterprise, the inclusion of livestock can be a very successful capital venture that diversifies the farm operation and may serve as a profit center. This can buffer and insulate the farm operation from market fluctuations and, perhaps, catastrophic weather events. Even operations that do not wish to incorporate ownership of livestock could still benefit from similar systems (e.g., contract grazing, selling hay/seed of pasture grasses to nearby cattlemen, etc.). Though an economic analysis should be conducted to determine if a sod-based rotation using bahiagrass is economically feasible in a specific scenario, this may be a profitable rotation system for some farms in the Southeast.
If bahiagrass is to be used in the rotation, it is recommended that it stay in stand for two years, followed immediately by peanuts or soybeans, then by a subsequent cotton crop (Do not plant cotton immediately after bahiagrass, since there are reports of excessive and rank vegetative growth in cotton that followed bahiagrass).
Bahiagrass has many uses, but it is most commonly used as a pasture species or as a hay crop. Bahiagrass is also an excellent grass species for erosion control and wildlife habitat. Bahiagrass also been increasingly used in "sod-based rotation" sequences (see inset, "Using Bahiagrass in Sod-based Rotations with Agronomic Crops").
Well-managed pastures can carry about one animal unit (e.g., a cow-calf pair) per acre from April to mid-October under typical growing conditions. The quality of grazing is highest during the early spring and begins to decline during mid-summer.
Improved varieties such as Tifton-9, TifQuik, and UF-Riata produce 10 to 15 percent more total forage and provide a slightly higher carrying capacity than Pensacola. However, bahiagrass varieties do not differ substantially in forage quality (Muchovej and Mullahey, 2000).
All bahiagrass varieties produce most of their forage close to the soil surface, regardless of fertilization (Table 3). In fact, approximately 60 percent of the total forage produced is within 2 inches of the soil surface. Thus, bahiagrass pastures should be grazed close for best forage production and animal performance.
Though overgrazing is undesirable, most bahiagrass varieties can withstand intense, close grazing pressure. Bahiagrass generally grows more prostrate under close grazing and becomes even more compact. Under extremely high grazing pressure, bahiagrass will produce almost all of its leaf area so close to the soil surface that the animals cannot defoliate it (i.e., below the level at which the animals can graze). As a result, bahiagrass is the most grazing-tolerant species used for forage production in Georgia.
By overseeding winter annual grasses and legumes into bahiagrass, the grazing season can be extended and the quality of the forage can be increased. Unfortunately, the compact and dense nature of bahiagrass sods is generally not as good for overseeding as bermudagrass sods. Overseeding with winter annuals such as rye, oats, annual ryegrass, crimson, and arrowleaf clovers can be successful if the soil fertility and weather provide a favorable environment for winter annual growth. However, it is necessary for the bahiagrass sod to be mowed or grazed as short as possible in early October and lightly disked prior to establishment. Winter annuals should not be overseeded until late fall, just prior to the first frost.
During the spring transition, when bahiagrass begins to regrow, winter forages should be removed either by grazing, haying, or mowing. This reduces the competition from winter forages for light, moisture, and soil nutrients when bahiagrass begins its spring growth.
|Table 3. Forage availability from Pensacola bahiagrass at various heights as affected by N rate.|
|Cutting Height||N Application Rate (lbs N/A)|
|Percent of Forage at Cutting Height (%)|