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A Grass Roots Analysis of Tall Fescue
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The survival of America's small farms depends on
some pretty basic factors. And sometimes they are right at our feet.
In the Southeast's tall fescue belt—stretching from Arkansas and Missouri
to Georgia, North Carolina, South Carolina, and Virginia—many farmers
realize how important the tall fescue at their feet is to their success.
Many of these farmers are also within a small-farm belt, where more than half
the farms are less than 180 acres and are mostly pasture, hayfields, and
woodlots. The farms usually have fewer than 30 beef cows. The farmers typically
have another job in town.
Any major improvements in tall fescue would really help these farmers. They
love the fescue because they can plant it and pretty much forget it. It
competes well with other grasses and weeds, and it lasts for 10 to 20 years
without requiring reseeding.
But there's a flip side to that love. The very reason fescue grows so well is
also the reason farmers hate it: Tall fescue is usually infected with a fungus.
This fungus helps the fescue survive tough conditions but also produces many
compounds that are poisonous to cattle if they graze on it continuously.
ARS has been part of 30 years of research
to help these small farmers by lessening the impact of fescue toxicosis, the
name for the problems created for cattle by the fungus-produced toxins.
Lately, that research is paying new dividends and attracting intense interest
from farmers.
In 1977, microbiologist Charles W. Bacon in the ARS Toxicology and Mycotoxin
Research Unit in Athens, Georgia, working with ARS chemist James K. Porter, ARS
animal scientist Joe D. Robbins, and University of Georgia colleague E.S.
Luttrell, made the first direct link between the fungus and cattle symptoms.
A farmer had asked them to find out why cows in one area were spending most of
their time in a pond instead of in the field. Bacon and Porter took fescue
samples from the field where the cows didn't seem to be eating and from another
field where the cows were grazing. They found the fungus only in the field with
the fasting cows.
The main problem farmers have with fescue toxicosis is in the summer. When the
weather is hot, the alkaloids from the fungus cause "summer
syndrome." When cows that are already hot eat infected fescue, they get
even hotter because the alkaloids change their ability to regulate body
temperature. The cows stop eating and seek shade or a pond to cool off.
Later, scientists found out that fescue's good qualities were also attributable
to the fungus-fescue relationship, although they didn't understand how it
worked.
The discovery by ARS agronomist David P. Belesky, at the Appalachian Farming
Systems Research Center, in Beaver, West Virginia, of one way the positive side
of the relationship works adds momentum to fescue toxicosis research. Belesky's
work is described in the article The Grass Farmers Love To Hate (p. 4).
The article also mentions progress on a vaccination for fescue toxicosis. ARS
animal scientist John A. Stuedemann, at the J. Phil Campbell Natural Resources
Research Center, in Watkinsville, Georgia, has developed a prototype for a
vaccine that may one day be used to immunize cattle and horses against the
fungal toxins.
Another tactic in battling fescue toxicosis is to develop varieties with a
friendlier, less toxic fungus strain. This work is being carried out at several
facilities, including Bacon's unit, the ARS Dale Bumpers Small Farms Research
Center, in Booneville, Arkansas, and several universities.
Bacon's unit is focusing on obtaining friendlier fungi by genetically modifying
the fungus, in collaboration with scientists at the University of Kentucky and
at Watkinsville. The researchers hope to eventually map the entire genome of
the fungus Neotyphodium. The team is also evaluating toxicity of the
alkaloids from genetically modified and natural strains, including changes
caused by the plant and bacteria in a cow's rumen.
Research at the Booneville center is taking three different angles:
- how farmers can use other forages and supplements to feed cattle during the
summer months when infected fescue is most toxic
- ways to cross-breed cattle for more resistance to summer syndrome
- the effects of fescue toxicosis on cattle reproduction.
ARS scientist Georgia C. Eizenga, formerly with an ARS forage unit in Kentucky
and now with the Dale Bumpers National Rice Research Center in Stuttgart,
Arkansas, developed lines of tall fescue specially bred to help develop better
varieties.
Her colleague, Timothy D. Phillips, formerly with ARS and now with the
University of Kentucky, is maintaining the collection. He is also continuing
the work of his ARS predecessor, Robert C. Buckner, who pioneered the use of
wide hybridization between ryegrass and tall fescue and released the first
fungus-free fescue varieties.
ARS, the universities, and seed companies are working together to offer farmers
as many options as possible. But, particularly for small farmers, the only good
options are the affordable ones.
David K. Brauer
Agronomist and Head of Dale Bumpers
Small Farms Research Center
Booneville, Arkansas |
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"Forum" was published in the
July 2000
issue of Agricultural Research magazine.
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