Changes in Neotyphodium coenophialum infestation levels in tall fescue pastures due to different grazing pressures

• Published in: Crop science Vol. 38; no. 1; pp. 201 - 204
• Main Authors: Gwinn, K.D, Fribourg, H.A, Waller, J.C, Saxton, A.M, Smith, M.C
• Format: Journal Article
• Language: English
• Published: Madison, WI Crop Science Society of America 01.01.1998; American Society of Agronomy
• Subjects: ACREMONIUM COENOPHIALUM; ALIMENT POUR ANIMAUX; Animal productions; Biological and medical sciences; BOEUF; BUEY; BULLOCKS; Cattle; FEEDS; FESTUCA ARUNDINACEA; FORAGE; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Grasses; GRAZING; GRAZING INTENSITY; INFESTACION; INFESTATION; INTENSIDAD DE PASTOREO; INTENSITE DE PATURAGE; PASTOREO; Pasture; Pastures; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; PATURAGE; PERSISTENCE; Pest control; Phytopathology. Animal pests. Plant and forest protection; PIENSOS; PLANT POPULATION; POBLACION VEGETAL; POPULATION VEGETALE; STEERS; TENNESSEE; Terrestrial animal productions; Vertebrates; United States; North America; Tennessee; America; Monocotyledones; Ox; Epidemiology; Field experiment; Fungi; Animal effect; Gramineae; Angiospermae; Beef cattle; Fungi Imperfecti; Ungulata; Festuca arundinacea; Thallophyta; Symbiosis; GRAZING INTENSITY; Castrated animal; Bos taurus; Grazing; Infection; Vertebrata; Acremonium coenophialum; Mammalia; Grassland management; Pasture; Endophyte; Poisoning; Spermatophyta; Level; Artiodactyla; Fodder crop; Infestation
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci1998.0011183X003800010033x

Infection of tall fescue (Festuca arundinacea Schreb.) with the mutualistic fungal endophyte Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon and Hanlin results in numerous biochemical and physiological changes that increase host persistence. This study was conducted to determine effects of steer (Bos taurus L.) grazing on changes in endophyte infestation levels of tall fescue pastures. Eighteen 1.2-ha pastures were seeded in 1992 in 20-cm drill rows involving combinations of high, medium, or low grazing pressure and 'Ky 31' tall fescue infested with N. coenophialum at four levels ranging from endophyte-free (E-) to 80% infestation (E+). Pastures were grazed for about 10 mo. each year from fall 1993 until summer 1996, although animals on some of the high grazing pressure pastures occasionally had to be removed because of insufficient forage. Endophyte levels were monitored yearly with protein-A sandwich enzyme-linked immunosorbent assay (PAS-ELISA). Stand density of tall fescue remained satisfactory throughout the study. After 2 yr, endophyte infestation levels in low grazing pressure pastures were at the same level as at the beginning of the study, and E+ levels remained constant in all pastures that started at high E+, regardless of grazing pressure. However, in high and medium grazing pressure pastures, E+ levels increased by 20 to 30%. Based on these data, we conclude that moderate and high grazing pressures influence endophyte infestation level of pastures and must be taken into account when designing pasture management systems