by Janice Elmhirst and Elizabeth Hudgins
You may have heard that endophytes help turf to grow well but did you know they can be toxic to animals that graze on them? If you are a seed or sod producer, this article may be of interest to you in order to determine which seed might be best for certain sites.
What are endophytes?
An endophyte is a type of fungus that lives inside the grass plant. Unlike disease-causing fungal pathogens, endophytes are symbiotic which means the interaction benefits both the fungus and the plant.
Although several endophytic fungi have been found, Acremonium species are the most frequently reported. Endophytes are most common in turf-type tall fescue and perennial ryegrass. Since the fungus grows within the plant, endophyte-containing seed produces endophyte-containing plants and seed. The fungus does not spread from plant to plant in the field.
How do they help?
Endophytes provide a natural system of plant protection from certain insects, diseases, and drought-stress. Turf breeders have nurtured this symbiotic relationship by selecting endophyte-containing grasses over endophyte-free ones as well as inoculating the turf with selected endophyte strains ("endophyte-enhanced" seed).
Some of the benefit that is provided by endophytes is from the natural chemicals they produce. Although some of these chemicals are toxic to insects, they also can be toxic to grazing animals.
How do they harm?
Endophyte toxins such as ergovaline or lolitrem B can injure horses, cattle, sheep, and other animals that feed on fresh or dried grass, seed, or seed cleanings. The severity of the injury depends upon the type of animal and the type and level of toxin. Levels in dried grass gradually decline over time.
Lolitrem B toxicity is observed in livestock grazing on perennial ryegrass containing endophyte toxins. Animals develop "staggers" and may shake and fall down. Ergovaline toxicity, "fescue toxicosis", occurs in livestock grazing on endophyte-containing fescue. Symptoms include loss of appetite, rapid breathing, high body temperature, loss of hooves ("fescue foot"), and death in some cases.
How should they be used?
Managers of golf courses, athletic fields, and lawns do not need to be concerned about endophytes. Endophytes will provide a benefit to their turf. Sod and seed producers, however, may want to be careful about where their products will be used. Advise consumers establishing pastures or seeding areas where livestock may graze to choose endophyte-free varieties. Planting grass that is endophyte-free in areas to be grazed by livestock is the best prevention. Sod and seed producers who provide grass clippings for livestock feed should ensure that only non-endophyte grass is used.
Most forage-type grasses do not contain endophytes. Turf-type varieties are not used in hay production.
How can I find out?
Most perennial ryegrass and turf-type tall fescue varieties grown in BC are not endophyte-enhanced. Your seed supplier may be able to tell you. Among varieties that commonly contain endophytes are 'Brightstar' and 'Brightstar II' perennial ryegrass and 'Apache II' and 'Coronado' tall fescue. Turf containing these varieties should not be fed to animals.
Mixing grass clippings and seed cleaning with other hay will dilute any toxin present, but without a test it is hard to say what a "safe" level is or how much dilution is needed, since toxin levels and animal reactions can vary.
A laboratory at Oregon State University provides testing for ergovaline and lolitrem B in seed and grass. Grass clippings must be air-dried in the dark and at least one U.S. gallon (about a large plastic grocery bag) of dried grass is needed for testing. The cost is $35 U.S. per toxin, per sample. For further information on endophyte toxins or testing, growers may contact the Oregon lab at (541) 737-6541 or Elizabeth Hudgins at BCMAF, Abbotsford at (604) 556-3029.
Janice Elmhirst and Elizabeth Hudgins are plant pathologists with the BC Ministry of Agriculture and Food in Abbotsford, BC.
Turf Line News April/May 2000
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