An agricultural researcher here is looking at using perennial tall fescues in East Texas as possible replacement annual winter forages.

"The problem with the annual winter forages is that they have to be replanted every year," said Dr. Gerald Evers, forage management expert with the Texas Agricultural Experiment Station.

Winter forages allow beef producers to reduce one of the largest out-of-pocket costs during the winter – feed costs. But re-establishing winter forages every year is expensive. On average, a producer spends from $20 to $40 per acre in seed costs, fertilizer and field operations, Evers said.

Tall fescues are perennials, and unlike winter annuals such as ryegrass, could – if managed correctly – last years. But current fescues, though well adapted for climates and soils in the Midwest, are not so well adapted to most soils in southern climates, he said.

The sandy soils of the South are the limiting factor in maintaining a tall fescue stand in East Texas, Evers said. Tall fescues become dormant as average temperatures rise and the length of day increases in early summer. Becoming "dormant" means they cease growing and shut down many of their metabolic processes.

But a summer rainfall can "wake up" tall fescues, causing new top growth, regardless of temperature and day length. As the sandy soils of East Texas and the South quickly dry out, the summer temperatures cause the new growth to die. It is this cycle of dormancy, wake-up, then dormancy again, that can kill out tall fescue stands, Evers said.

"Repeated growth initiation followed by senescence of top growth ... causes depletion of carbohydrates in the root system, resulting in grass stand deterioration," he said.

Another issue is that tall fescues are infected with a fungal endophyte that is toxic to beef cattle and other livestock. Endophyte is Greek for "in the plant," meaning the fungus grows throughout the plant's tissues and is not confined to its exterior.

Though not lethal, the endophyte's toxic effect on animal health becomes more severe during the summer. Animals grazing older fescues realize lower weight gains, experience reproductive problems and, in extreme cases, have reduced blood circulation to their extremities.

Ironically, this same endophyte confers grazing tolerance and drought and disease resistance to tall fescue.
"Without the endophyte cattle will graze out tall fescue and kill a stand in two or three years," Evers said.
But Evers suspects both these detriments to many U.S.-grown tall fescues may not be present in new varieties of Mediterranean origin now being developed in New Zealand.

First, these varieties cease growth when day length and temperatures rise regardless of serendipitous rainfall. These varieties are know as "obligatory" summer-dormant types.

"A preliminary experiment planted at Vernon, Texas, in October 2000, proved that an obligatory summer-dormant tall fescue had superior summer drought resistance and persistence after three growing seasons," Evers said.

Second, some varieties carry an endophyte that is not toxic to animals. Called "endophyte safe," these fescues have the same grazing tolerance and drought and disease resistance as the older fescues.

In this year's experiment at the Texas A&M University Agricultural Research and Extension Center at Overton, Evers will compare three tall fescue varieties with different levels of summer dormancy.

The three varieties will be an "obligatory" summer-dormant type, a summer-active type, a highly summer-dormant type and Jesup, a summer-active tall fescue adapted to the southeastern United States.

Two lines are of the obligatory summer-dormant variety, one without endophyte and one with the safe endophyte. Jesup also has the safe endophyte.

Evers has planted seed of all varieties in pots. These will be grown outside throughout the late winter and spring. In mid-May, Evers will move half the plants into a greenhouse. No moisture will be given to the greenhouse fescues in order to simulate drought conditions.

"The idea is to see if drought affects their entering dormancy," Evers said.

As summer approaches, Evers will move all the plants to growth chambers, where temperature, light and soil moisture will be strictly controlled.

The idea is to find out to what degree fluctuating temperature and moisture affects summer dormancy in all varieties.

"Different growth chamber treatments will determine how temperature interacts with the various levels of summer dormancy in tall fescue on starting and maintaining dormancy," he said. "Placing the pots outside in mid-August under natural day length and temperature with moisture will determine plant survival from previous treatments and document the time the various levels of summer-dormant tall fescue germplasm will break dormancy in Northeast Texas."

If tests this year and the next show promise, the next step will be to see how cattle perform grazing tall fescue, Evers said.