Seed containing N. coenophialum can be treated with fungicides to kill the fungus. A more simple and less expensive method is to store the seed for a year at non-air-conditioned ambient temperatures before planting (see Chapter 23). Neill (1941) reported that E- plants could be obtained from infected seed following 12 mo of storage. Early grazing trials involving E- tall fescue resulted in normal conception rates and milk production for cows, and improved weight gain in steers compared to cattle grazing E+ tall fescue (Hoveland, 1993). Many persons promoted planting of E- tall fescue as the most convenient method of correcting endophyte-induced production problems. This would have been more successful had the E- plants possessed the same persistence as E+ plants. However, the mutualistic symbiosis between the endophyte and the grass (see Chapter 14) confers a number of benefits to the host, including drought, disease, and insect resistance or tolerance and ability to compete with other plants. Endophyte free stands of tall fescue were neither capable of withstanding the grazing intensity used commonly with E+ tall fescue pastures, nor short periods of drought common in the fescue growing region (Bouton et al., 1993; Thompson et al., 2001). Therefore, beef producers who planted E- fescue faced reduced forage yield, stand losses, and weed invasions, and were forced to carry out costly re-establishment practices.

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