Ergot alkaloids are toxins produced by Epichloë coenophiala (Morgan‐Jones & W. Gams) C.W. Bacon & Schardl, a fungal endophyte that infects tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] and causes fescue toxicosis in livestock. Previous studies have reported the distribution of ergovaline among anatomical parts during reproductive development. This study was conducted to determine the vertical distribution of ergovaline and total ergot alkaloids throughout the vegetative canopy of tall fescue. Between October 2012 and April 2014, whole tillers were harvested four times from a stand of Epichloë‐infected ‘Kentucky 31’ tall fescue near Alton, MO. Harvests occurred in April before boot stage and in October before killing frost. Tillers were sliced into four segments: 0 to 5, 5 to 10, 10 to 15, and >15 cm, where 0 cm was the soil level, and >15 cm was the top of the canopy. Segments were analyzed for ergovaline and total ergot alkaloids. For tillers harvested in April, ergovaline concentration averaged 272 μg kg−1 dry matter (DM) in the 0‐ to 5‐cm segment and decreased linearly upward through the canopy. In October, break‐point regression indicated that ergovaline concentration averaged 1121 μg kg−1 DM in the 0‐ to 5‐cm segment and ≥70% less above 5 cm. Total ergot alkaloid distribution patterns resembled ergovaline distribution in October; total ergot alkaloids averaged 2585 μg kg−1 DM in the 0‐ to 5‐cm segment and >60% less in the upper portion of the canopy. These findings should encourage field advisors to consider variation of toxicity within the canopy of tall fescue when formulating grazing recommendations.

A fungal endophyte, Epichloë coenophiala (Morgan‐Jones & W. Gams) C.W. Bacon & Schardl, naturally infects tall fescue [Lolium arundinaceum (Schreb.) Darbysh.]. The common, toxic endophyte produces ergot alkaloids that cause the livestock disorder known as tall fescue toxicosis. Strains of E. coenophiala that produce little or no toxic ergot alkaloids are referred to as “novel” endophyte associations and offer a solution to tall fescue toxicosis. The objective of this study was to determine differences in animal preference and ground cover among commercially available novel endophyte‐infected tall fescue cultivars. Six cultivars of novel tall fescue and controls of common, toxic endophyte‐infected and endophyte‐free tall fescue were evaluated for animal preference, forage mass, forage removal, forage quality, and ground cover during a 2‐yr grazing trial at Linneus, MO. Plots were grazed over nine grazing events by beef cattle (Bos spp.) during the 2‐yr study, and some animals were fitted with GPS collars to determine which cultivar was grazed first and most often. ‘BarOptima’, a soft‐leaf cultivar, was grazed first and most frequently. Forage mass, forage removal, and forage quality measurements of crude protein, acid detergent fiber, and neutral detergent fiber were similar among cultivars. Ground cover increased each year of the study, even though seed production was inhibited. In addition, rust (Puccinia spp.) susceptibility differed among cultivars. Under this management system, which used up to 24‐h grazing periods and at least 8‐cm stubble height, animal preference was not based on endophyte status.

Core Ideas Limestone application reduced ergovaline concentrations by 20 ppb compared with non‐treated control plots. This slight reduction in ergovaline concentrations is not enough to affect toxicosis, but the reduction occurred with a corresponding increase in soil pH, which can improve the growing conditions for pasture legumes and indirectly affect toxicosis. Unlike limestone, other soil amendments, such as N and poultry litter, increase ergovaline concentrations and therefore create a sort of penalty for the producer. Ergovaline is an ergot alkaloid produced by Epichloë coenophiala [(Morgan‐Jones & W. Gams) C.W. Bacon & Schardl], an endophyte in tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] that causes fescue toxicosis. Ergovaline concentrations can be affected by soil nutrients such as N and P. However, its response to limestone has not been documented. This study evaluated the effect of limestone application on ergovaline concentration in established tall fescue. Limestone was surface‐applied in December 2011 on an existing ‘Kentucky 31’ tall fescue (95% infected with E. coenophiala) pasture near Alton, MO. Soils were sampled annually in October by collecting ten 6‐inch cores per plot; cores were divided into three increments: 0 to 1, 1 to 3, and 3 to 6 inches in depth. Whole tillers were harvested spring and autumn from 2012 to 2014 and analyzed for ergovaline concentration. Limestone increased (p < 0.01) soil salt pH [pH(s)] during the 3‐year period, and the greatest increase occurred at the soil surface. The soil pH(s) was 5.6 for the limestone‐treated plots and 5.0 for the non‐treated plots. Limestone application reduced (p < 0.10) ergovaline concentration by 20 ppb compared with non‐treated control plots. An important application of this study is that limestone did not increase ergovaline concentration as other soil nutrients have done, thereby making it possible to improve soil conditions for legume growth and pasture dilution without increasing the potential for fescue toxicosis. Future studies will explore the possibility of a greater reduction in ergovaline concentration with a larger increase in soil pH.

Tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] infected with the endophytic fungus Epichlo coenophiala [(Morgan-Jones and W. Gams) C.W. Bacon and Schardl, comb. nov.] produces ergovaline and other alkaloids responsible for fescue toxicosis, a livestock disorder. Cultivars re-infected with endophytes that do not produce toxic ergot alkaloids, referred to as "novel endophytes," have been used to alleviate the symptoms of fescue toxicosis. This research includes a series of experiments with the overall objective of identifying management practices that reduce fescue toxicosis in order to provide recommendations to Missouri farmers. The fist experiment examined the distribution of ergovaline and total ergot alkaloids throughout the vegetative canopy of tall fescue, and concluded that toxin concentrations are highest in the bottom 5 cm of the plant. The second experiment documented that applying limestone decreased ergovaline concentrations by at least 20 [mu]g kg[superscript -1] dry matter. The third experiment evaluated cattle preference among novel endophyte-infected tall fescue cultivars. This experiment concluded that one cultivar, 'BarOptima,' was grazed first and most frequently.