Washington County Cooperative Extension Service

Pasture Management

Bermudagrass

Improving Established Bermudagrass

Old bermudagrass stands may be revitalized with less effort and cost than is required for planting new stands. Therefore, before investing money in re-sprigging or planting alternate forage crops, a producer should first compare the economics of improving their existing resources.

The primary reason for a weak bermudagrass stand is inadequate soil fertility. When properly fertilized, bermudagrass will often crowd out most weed species and maintain a vigorous, healthy stand. Without proper fertility, bermudagrass pastures can become weed infested. This results in a reduced carrying capacity of the management unit and decreased animal performance.

Effective herbicidal weed control requires proper identification of target weed species, selection of the most effective herbicide, and treatment at the appropriate time. Regardless of the herbicide used, always follow label directions.

Some producers believe that bermudagrass yields may be increased by soil aeration, and they periodically till pastures to relieve what is often referred to as a "sodbound" or "rootbound" condition. A three-year study at Chickasha, Oklahoma found that disking or chiseling caused severe yield reductions in 4 out of 6 tests and no significant increase of forage was noted.

The most critical aspects of managing bermudagrass are a proper fertility program, stage of maturity at harvest, and in the case of grazing, the stocking rate. The producer has complete control over these management options and careful attention to all three can result in a profitable bermudagrass based enterprise.

Decisions regarding fertilizer should generally be to either apply no fertilizer or fertilize for optimum production. In many cases, it may be more economical and efficient to increase the fertilizer rate on fewer acres of better ground. The amount of production may equal or be even higher, but expenses may be reduced. Reasonable nitrogen fertilizer rates appear to be 150 to 200 pounds of actual nitrogen per acre in split applications of 50 pounds each for grazing or one application for early summer hay production.

Ideally, the grazing management should be designed to ensure that bermudagrass is harvested at an optimum stage of maturity based on the kind and class of animals that will consume the forage. For growing animals, the accumulated bermudagrass forage should not exceed three weeks of age. When considering bermudagrass for either a hay harvest or grazing by mature animals, accumulated bermudagrass should not be in excess of 4 to 5 weeks of age. Bermudagrass that is overly mature will have low nutritive value, and protein supplementation will be necessary to meet maintenance and/or growth requirements for certain classes of livestock.

Bermudagrass, where adapted, can play a vital role in livestock production programs. The species has the ability to tolerate a wide range of growing conditions and is more tolerant of close grazing and relatively heavy stocking rates than many other forage grasses.

Bermudagrass also has the ability to produce large quantities of dry matter for either grazing or hay. However, it is not a magic plant. Bermudagrass does require a sound fertility program and other management inputs. Given the management it requires, bermudagrass can provide the warm season perennial grass base for a profitable production system.

Tall Fescue

Tall fescue ( Festuca arundinacea Schreb) is a cool season, perennial bunchgrass that came to North America from Europe in the late 1800's. Since the discovery of a field of fescue in eastern Kentucky in 1931 and the subsequent release of the Kentucky 31 variety in 1943, tall fescue has become the dominant cool season perennial grass in the southeastern United States. Most commonly referred to as "fescue," tall fescue is used for forage, erosion control, and turf.

Oklahoma is on the western edge of the area of adaptation for tall fescue, but the grass grows well in the eastern one third of the state, where the average precipitation is greater than 35 inches per year. In eastern Oklahoma, it is the most persistent of the cool season perennial forages presently available. Many older, established stands that originated from KY-31 tall fescue have persisted under conditions of low fertility, low soil pH, and overgrazing.

Fescue Establishment

A major issue of concern to producers interested in establishing tall fescue pastures is whether or not to use an endophyte-infected or endophyte-free fescue variety. If the primary objective is livestock performance, most researchers would suggest planting only endophyte-free fescue (0% infection level). Endophyte-free tall fescue allows for animal performance similar to animals grazing other high quality, cool season perennial forage grasses. Producers should check the seed bag tag for endophyte content.

Plant new stands of endophyte-free fescue only on the better soils that have good water holding capacity. The site must be free from existing endophyte-infected seed and existing fescue plants. Management strategies designed to prevent seed production from infected fescue for one year prior to planting endophyte-free fescue should be utilized.

Oklahoma does not have recent yield data for many of the new endophyte-free fescue varieties, but data from surrounding states along with Oklahoma data would suggest there is little difference as long as an adapted variety is selected. Some varieties are Stargrazer, Dovey, Mozark, Martin, KY-31 (endophyte-free), and Triumph. Fawn is an old variety that has not persisted well in trials in Oklahoma or Kansas.

Fertilizing Tall Fescue

Fertilizer use on fescue, or any other crop, should always be based on a reliable soil test. A soil test is the only way to determine how much phosphorus and potassium is required annually to maintain production and efficiently use the nitrogen applied.

The soil test will also indicate the pH level and how much lime to apply if the pH is too low. Fescue will tolerate a pH as low as 4.5, but legumes in a fescue pasture require a lime application if the pH is below 6.0.

The amount of nitrogen is determined by establishing a yield goal or the amount of forage required. Sixty to eighty pounds of actual nitrogen per acre is enough for optimum fall growth in most years. Fall production is normally limited by insufficient moisture and favorable growing conditions if 80 or more pounds of nitrogen is applied September 1.

Fescue Growth

In Oklahoma, fescue typically has a split growing season. Tall fescue generally begins growth in late August or early September, becomes semi dormant during the midwinter months of December, January, and February, begins spring growth during late February, and becomes reproductive during May. Tall fescue usually becomes dormant again during the midsummer months of June, July, and August.

Fescue grows best when the average temperature is above 45° and grows very little when the average temperature is below 34° or above 85°. Tall fescue will typically produce one-third of its annual production during the fall and the remainder in the spring.

The Endophyte

The term "endophyte" refers to a fungus that is hidden within a plant and may be either parasitic or symbiotic in its relationship with the host plant. Laboratory testing has confirmed that a high percentage (85%+) of Oklahoma’s tall fescue is infected with the fungus Acremonium coenophialum, commonly referred to as the fescue endophyte. Research has demonstrated that this fungus is the primary causal agent of the fescue toxicity experienced by livestock. The fescue endophyte produces an alkaloid, ergovaline. This alkaloid is responsible for the symptoms associated with most forms of fescue toxicity (fescue toxicosis, summer slump, agalactia, fescue foot, and bovine fat necrosis).

The fungus is spread only through seed that has been produced from an endophyte-infected plant. Fungus-free seed will produce fungus-free plants that will remain non-infected throughout their lifetime. There are no known chemical or non-chemical treatments that will remove the fungus from infected fescue plants. Researchers have found that the endophyte does not grow in all portions of the fescue plant; however, the alkaloid ergovaline is found in all portions of the plant and is highest in the developing seed head and lowest in expanded leaf blades.

Endophyte Effects on Host Plants

Both the endophyte and the fescue plant benefit from their relationship. The fescue plant provides the endophyte a source of nutrition, protection from the environmental elements, and a means of reproduction. The endophyte either produces a number of other alkaloids or is responsible for plant production of the alkaloids that provide the plant with resistance to insects, nematodes, and certain environmental stresses such as drought. The endophyte also enables the fescue plant to tolerate close, continuous grazing.

The removal of the endophyte from the fescue plant and the resulting removal of the alkaloids causes the fescue plant to be more susceptible to insects, certain plant diseases, and drought and less tolerant of close grazing.

Fescue Toxicity Effects on Livestock

The alkaloid compounds produced as a result of the fescue-endophyte infection create a number of adverse effects in grazing livestock. The beef cattle industry alone experiences an estimated $600 million annual loss due to endophyte-induced alkaloids.

Cattle

Fescue toxicity is manifested as three distinct maladies: fescue foot, summer slump (fescue toxicosis), and bovine fat necrosis.

Fescue foot is characterized by a dry, gangrenous condition involving the extremities of animals grazing endophyte-infected tall fescue.

Summer slump typically occurs during the warm months of the year. Affected animals experience elevated body temperatures, higher respiration rates, a rough hair coat, reduced forage intake, and poor overall performance as measured by average daily gain, conception rates, or milk production.

Bovine fat necrosis is a condition in which hard fatty deposits develop in the abdominal cavities of cattle.

Horses

Mares grazing endophyte-infected tall fescue during late stages of gestation are subject to several negative aspects of fescue toxicity. These include abortions of foals; prolonged pregnancy; foaling problems that can lead to the death of either the foal, the mare, or both; thick or retained placentas; and agalactia (poor milk production).

The usual recommendation for gestating mares is to remove the animals from tall fescue pastures 60 to 90 days prior to parturition.

Managing Infected Fescue to Minimize Livestock Problems

There are two basic approaches to minimizing the negative effects of endophyte-infected tall fescue: learn to manage the grass properly, or renovate the existing fescue. Those who successfully utilize tall fescue have learned to manage using one or more of the following suggestions:

Interseed with legumes.
Avoid excessive nitrogen application.
Remove cattle during hot weather when performance begins to decline.
Ergovaline concentration is higher in stems, seed heads, and seeds compared to leaves. This indicates that fescue toxicity problems may be reduced by keeping pastures grazed short.
Bale excess tall fescue for hay when seed heads appear.
Avoid feeding highly infected fescue hay to cattle grazing highly-infected fescue pastures.
Dilute toxic effects of endophyte-infected tall fescue pasture or hay. This may be accomplished by feeding grain or high quality non-fescue hay.

Randy L. Pirtle, County Extension Director