Management Of
Endophyte-Infected and Endophyte-Free Tall Fescue
In Mississippi

With an estimated 35 million acres of tall fescue being grown in the United States, it is the country's most important perennial cool-season grass. Tall fescue is planted on an estimated 600,000 acres in Mississippi, in pure stands and in mixtures with other grasses and legumes. Acreage and interest in tall fescue are increasing, because of the need for a perennial cool-season grass and because of improvements being made in the quality of new varieties for forage and hay.

Tall fescue is grown throughout most areas of Mississippi, but it grows particularly well on the Prairie and Flatwood soils, where moisture is adequate during periods of maximum growth. High pH soils of the Prairie and Delta are especially well-suited for tall fescue, and it responds well to lime in all other soils where lime is needed. With high summer temperatures, less water-holding capacity, and severe nematode infestations in sandy soils of South Mississippi, performance of fescue is better in the upper part of the state.

The Fescue Endophyte -- Most of the tall fescue being grown is the Kentucky-31 variety, which was discovered in 1931 in Kentucky. Since its release, it has been planted throughout the fescue-growing region. Researchers have discovered that most fescue has always been infected with an endophyte fungus that grows throughout the plant between the cell walls. The word endophyte means that the fungus is hidden within the plant and cannot be seen with the naked eye. When the plant is producing seed in the spring, the fungus grows up the hollow stem and into the developing seed.

Fungus-Free Fescue -- Beginning with the release and spread of Kentucky-31 tall fescue, producers and researchers have been aware of decreased animal performance with the grass. Chemical analyses show the grass to be of high quality, but animals do not always perform well on tall fescue, especially during certain times of the year. Symptoms include the following items:

• Low forage intake;
• Low weight gain;
• Low milk production;
• High respiration rates;
• High body temperatures (with water and shade used to cool body temperature);
• Rough hair costs;
• Less time spent grazing;
• Excessive salivation;
• Reduced blood serum prolactin needed for milk production; and
• Reduces reproductive performance.

Other species of animals, especially horses, have experienced problems with fungus-infected tall fescue. Mares have experienced abortions, prolonged gestation, difficult birth, and foal deaths. Also, mares may produce little or no milk (Ball et al.). Researchers at several locations, however, found that similar animals in different pastures performed much better than others. Plant analyses indicate the presence of the endophyte fungus in pastures where the animals perform poorly, while animals perform well on fungus-free pastures.

Table 1. Average animal gains from several experiments comparing fungus-infected and fungus-free tall fescue

	ADG	G/A
Fungus Free	1.6	400
Fungus Infected	0.6	200

ADG = Average daily gains, in pounds
G/A = Gains per acre, in pounds

Since the discovery that fungus-free fescue has improved animal performance, researchers, plant breeders, and seed producers have spent much time in producing fungus-free fescue seed. It was concurrently discovered that without the fungus, the tall fescue plant did not adapt to the management strategies of the old fungus-infected fescue. Fungus-free pastures often were hard to establish, and some stands were completely lost in a short period of time. Since 1985, when the first plantings were made, producers have learned to establish and maintain good fungus-free fescue stands for up to 9 years. Several theories are attributed to having a successful stand establishment. These theories include the following:

• Some varieties, regardless of fungus, may be better adapted to grazing conditions.
• Animals may overgraze fungus-free fescue, because the intake restriction is eliminated.
• Research shows insects prefer fungus-free fescue.
• Fungus-free fescue is less drought-tolerant than is the fungus-infected fescue.

Following are some suggestions on how to deal with fungus-infected and fungus-free fescue pastures.

Fungus-Infected Fescue

Grazing Management -- Research and farm experiences show that close grazing during the cool season will reduce animal production problems with fungus-infected fescue. This is probably a dilution factor, with less fungus and/or less toxic chemicals present in the new growing leaf tissue. As seed heads begin to emerge, clipping and heavy grazing may help reduce toxicity occurrences, since the hollow stems and seed are high in fungal components. Mature tall fescue is more toxic, is less nutritious, and contains less protein and more fiber; therefore, it is less digestible than leafy, immature fescue.

Fertilizer Management -- Use soil tests to determine phosphate and potash needs. Excessive nitrogen rates may increase toxicity. Some producers apply only 30 pounds per acre in the fall for stockering cattle during the cool season. High rates of nitrogen can also decrease the legume component in grazing mixture. Cow-calf producers may use some summer nitrogen to stimulate summer grasses, such as crabgrass, dallisgrass, and/or bermudagrass. These grasses may help to dilute the fescue toxicity problem, and animals prefer them more than fescue in the summer period.

Pasture Rotation -- Moving cattle off fungus-infected fescue from April through September will greatly increase cow and calf performance. The land area can then be used for spring hay production to feed animals during the winter. Since fescue is not productive during this time, there is a lack of forage for grazing. Summer conditions increase fescue toxicity, and livestock perform better on crabgrass, dallisgrass, and/or bermudagrass during this time.

Dilution -- Research and farm experiences show that cattle perform much better on fungus-infected fescue when it is diluted with other forages or feeds. Legumes, such as red and white clovers, are often grown with fungus-infected fescue. These legumes also reduce the need for nitrogen fertlizer, which otherwise increases fescue toxicity. Other grasses, such as crabgrass, dallisgrass, and/or bermudagrass, are preferred by cattle and may help to decrease problems with fescue toxicity. Using feeds such as corn or purchased mixed feeds also should help reduce fescue toxicity and aid recovery of animals that have been removed from toxic pastures. This increases production costs to the livestock producer.

Replacement or Renovation -- Some livestock producers, especially horsemen, prefer to rid their pastures of fungus-infected fescue. When weather conditions are appropriate for promoting active growth, chemicals such as glyphosate (Roundup) or paraquat (Gramoxone) can be sprayed to kill the grass. Disking also can be used in dry weather, but established endophyte-infected fescue is difficult to kill with moisture in the soil. In either situation, you need to graze and/or clip to eliminate current-year seed heads. Furthermore, crop rotation with soybeans or a summer crop such as a sorghum sundangrass hybrid may help eliminate plants from old fungus-infected seed.

Using Endophyte-Infected Tall Fescue

• Overseed with red and white clovers every 1 to 3 years.
• In June, stimulate summer grasses in tall fescue with nitrogen fertilizer or manure.
• Reduce nitrogen fertilizer in the spring.
• Move breeding animals to summer grasses in April.
• Use baled, infected tall fescue in May to control seed heads, reduce weeds, and stimulate summer grass.
• Broadleaf weed control may be difficult with clovers included in the mixture.

Fungus-Free Fescue

Seeding -- Check with your county Extension agent for latest research and farmer-proven varieties. Well-limed, fertilized, and prepared seedbeds will help get good stands, and pure stands are preferred in order to reduce competition. A 25-pound seeding rate per acre is recommended. If clover is desired in the tall fescue, consider adding it in the following years, since dry weather may reduce clover during establishment. Since fungus-free fescue is a high quality grass, the need for clover is reduced, and increased nitrogen may be used for additional cool season growth following establishment. September to October seedings are preferred for better root and plant development.

Fertilizer Management -- Soil test for lime, phosphate, and potash needs. Hold nitrogen rates to 50 pounds per acre for establishment, since high nitrogen encourages seedling diseases and stand loss. After establishment, split applications of nitrogen may be used for fall and spring growth without fear of toxicity problems that were associated with the old fungus-infected fescue. Do not apply nitrogen after mid-April (then no more than 30 pounds per acre) and before September, since warm-season nitrogen will harm the fescue and stimulate competition from warm-season species.

Grazing Management -- After a stand of fungus-free fescue is established, one of the main keys to maintaining it is grazing management. Since fungus-free tall fescue is higher quality and more sensitive to management, it must be protected from grazing more than the fungus-infected fescue. Animals prefer fungus-free grass and will overgraze the young, tender grass during establishment. One farmer says that you must let it form a "stump" before you increase grazing pressure. The formation of a good, thick stand of basal growth is important to the life of a new stand. (At least a 4- to 6-inch stubble during grazing is preferred.) This is especially important going into the summer period for cooling the soil and promoting basal tissue needed for future cool-season growth. Severe summer heat and low soil moisture can be stressful, especially on young, tall fescue.

Summer Rest -- Planting fungus-free fescue in pure stands on good tall fescue growing soils is recommended, so that livestock can be removed during the hot, dry summer period. If fungus-free fescue is not growing, do not let livestock graze or trample it. Overgrazing will result in a greater stand loss than with fungus-infected fescue.

Reinfestation -- Spread of the endophyte from one pasture to another has to be by means of viable seed with the fungus. Spread of endophyte in established fungus-free pastures does not occur unless infected seed or plants are present. West et al. (1987) reported infected plants withstand drought and insect feeding better than do the endophyte-free plants. Infected plants could result in an increase of endophyte. Shelby et al. (1989) showed that a substantial percentage of fescue feed survived passage through the digestive system. Their recommendation is to remove cattle from infected pastures and feed a diet free of endophyte seed for a minimum of 48 hours before placing cattle on endophyte-free pastures.

Fall Management -- Determine soil fertility needs by taking soil samples before new fall growth begins. If phosphate and potash are needed, it is generally best to apply them in a mixed fertilizer with nitrogen. Make these applications from early to mid-September, from north to the remainder of the southern areas. If soil tests are not available, the equivalent nitrogen in 200 pounds of ammonium nitrate, or 500 pounds of 13-13-13, may be used.

On well-established, fungus-free tall fescue, begin late fall and early winter grazing when growth is 4 to 6 inches. If grazing is not needed, additional "stockpiled" growth may be accumulated for later grazing. Thus far, there have not been any "fescue foot" problems with fungus-free fescue under these conditions, as sometimes occurred with fungus-infected fescue. The carbohydrate content of "stockpiled" fescue has been shown to be high, resulting in high-quality feed.

Managing Endophyte-Free Tall Fescue

• Use viable, certified seed.
• Plant a mixture of two or three varieties.
• Do not overgraze at establishment or later.
• Provide good soil fertility and maintain pH greater than 6.
• Fertilize with N in fall and spring.
• Provide a full summer's rest (June to September).
• Add clovers in years two and beyond.

References

Ball, Donald M., Garry Lacefield, and Carl S. Hoveland. "The Fescue Endophyte Story." Funded by the Oregon Tall Fescue Commission.

Ball, Donald M., Marshall Putnam, Garry Lacefield, and Carl S. Hoveland. "Fescue for Horses - Problem or Opportunity." Funded by the Oregon Tall Fescue Commission.

Essig, H. W., B Aremu, C. E. Cantrell, F. T. Withers, Jr., and D. J. Lang. 1993. Grazing Management of Endophyte-Free Fescue Pastures. Professional Animal Scientist. 9:107-113.

Kimbrough, E. L. and D. J. Lang. 1993. "Forage: Tall Fescue in Mississippi." Mississippi State University Extension Service Information Sheet 830.

Lang, D. J. 1992. Stand Persistence of Endophyte-Free Tall Fescue. IN: 1992 Cattleman's Day Report. N. W. Cox and W. B. McKinley (eds.), Mississippi Agricultural and Foresty Experiment Station Information Bulletin 223:23.

Lang, D. J., R. Elmore, F. T. Withers, Jr., and H. W. Essig. Renovation of Declined Endophyte-Free Tall Fescue Pastures. 1993. IN: Livestock Day Report. N. M. cox and W. B. McKinely (eds.). MAFES Bull. 243:62.

Shelby, R. A., S. P. Schmidt, R. W. Russell, and W. H. Gregory. 1989. Spread of Tall Fescue Endophyte by Cattle. Alabama Agric. Exp. Stat. Leaflet 104.

West, C.P., E. Izekar, A. Elm, R. T. Robbins, and K. E. Turner. 1989. Endophyte Effects on Drought Tolerance, Nematode Infestation and Persistence of Tall Fescue. Proceedings of the Arkansas Fescue Toxicosis Conference. Special Report 140.

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Publication 1982
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director