Endophyte in Forage and Turf Grasses
Definition: An endophyte is a fungus that grows inside a plant. The endophyte does not infect the plant cells, but grows in the intercellular spaces, usually just under the leaf surface. The fungus grows as mycelium, a hair-like-structure, which look like hairs in the plant cells when viewed under a microscope. Endophytes are good for plants but are often harmful to grazing animals.
Endophyte Life Cycle: Keep in mind that the objective of every living organism is to survive and perpetuate the species. The endophyte begins its life cycle in the grass seed and then grows with the plant until it reaches the flower, where it becomes part of a new seed crop. This is the way the endophyte continues its life, sort of "hitching a ride" with its plant host. No other reproductive mechanism has been identified for the endophytes of forage and turf grass. Also, as far as we know, the only form of transmission of the endophyte from plant to plant is through the seed. An endophyte cannot be transmitted from an infected plant to an uninfected plant in the field by direct contact or transfer through soil, water or air. This gives rise to the "chicken and egg" type questions; but the answer to those questions will be left to researchers of the future.
Mutual Benefit: Endophytes do not exist naturally outside their plant hosts, and the plant hosts are healthier and produce more seed when they contain an endophyte. Greater seed production benefits both the plant and the endophyte. The plant provides a hospitable environment where the endophyte can grow. In association with the plant, the endophyte produces several chemicals that increase the plant's resistance to insects, disease and even mammals. This is a symbiotic or mutualistic relationship. Interestingly, the chemicals produced by the endophyte/plant association can not be produced by either the endophyte or plant by themselves.
Presence: Endophytes are not present in all forage and turf grass species. For example, neither Kentucky bluegrass nor orchardgrass contain entophytes. There is a specific type of endophyte for each species of grass that is infected. Not all endophytes are bad for grazing animals. The best example here is the endophyte that is sometimes associated with annual ryegrass. It has no affect on animals at all! The important grass species where endophytes regularly occur are perennial ryegrass and the fescues.
Turf: Endophytes are present in many fescues, both tall and fine fescue, and perennial ryegrass varieties. As stated above, endophytes make plants healthier. This is great for the lawn. In fact, many varieties of turf perennial ryegrass and turf fescue are developed with elevated levels of endophyte to ensure good performance. But, because certain endophytes can cause problems for any animals that graze or are fed endophyte infected grass, it is a good rule of thumb to never feed lawn grass clippings to animals, including the pet rabbit, or use turfgrass seed in a pasture.
Forage: Domestic animals, particularly horses, that graze or eat endophyte infected grass may develop severe health complications. Cow health may also be adversely affected eating endophyte infected grass. The health problems come primarily from harmful alkaloids produced by the endophyte/ plant association (see Mutual Benefit above). For this reason. perennial ryegrass and tall fescue used in forage production should have low or zero levels of endophyte. Research has determined that endophyte presence in less than 5% of the seed is not harmful to animals grazing or feeding on plants grown from those seeds.
Establishing a New Pasture: When a pasture formerly containing endophyte infected plants is reseeded, care must be taken to ensure that a minimal number of plants from the old pasture volunteer or remain in the new pasture. Volunteer plants can grow from either old plant parts or from seed in the soil (seed which would have been produced when the pasture was allowed to get too mature before harvest, can survive in the soil for years waiting for the right conditions to germinate). As time passes, the volunteer, high endophyte plant percentage may increase in the pasture. If there are enough volunteer, high endophyte plants initially, the pasture may eventually revert back to containing primarily high endophyte grasses. It looks like the new seeding plants have become infected with endophyte, but as stated earlier this is not the case. To control volunteer plants, utilize both herbicide and tillage prior to reseeding.
Summary: Endophytes are not an issue if proper care is taken and products are utilized only for their intended purposes. The Agway turf and forage product line has taken the guess work out of the endophyte issue. Agway turf grasses and turfgrass mixtures will perform well and should be used as turf and not as animal food. All Agway forage grasses and mixtures containing forage grasses are safe for animals when properly utilized (please note the alsike warning regarding horses; this is not an endophyte issue, alsike is a legume and contains no endophyte). In nature, wild animals avoid eating grasses that contain endophyte which are bad for them. Even domestic animals will avoid endophyte infected grass if given the choice.
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