Tall fescue (Festuca arundinacea Schreb.) has great utility as a low maintenance turfgrass in the northern and transition zone regions of the United States. However, it is difficult to successfully maintain tall fescue of high quality over consecutive summers because of its susceptibility to the fungal pathogen Rhizoctonia solani, which causes the disease brown patch. Not only is brown patch aesthetically unpleasing in a stand of tall fescue but it can also thin out the turf and allow for the encroachment of undesirable weedy species. Cultivar selection, cultural practices, mixing turf species and timing of pesticide applications all can impact the epidemiology of brown patch in tall fescue. Research was conducted in tall fescue to quantify chitinase activity in different cultivars, elucidate the impact of mowing height and nitrogen fertility on brown patch and bermudagrass (Cynodon dactylon L.) encroachment, to evaluate seeding mixtures of tall fescue with hybrid bluegrass (Poa pratensis x Poa arachnifera) on diseases and weeds as well as measuring the impact of the herbicide bispyribac-sodium on brown patch. Chitinase activity was greater in the tall fescue cultivar that was less susceptible to brown patch. In the mowing-fertility studies, cutting tall fescue at 10 cm generally reduced brown patch and bermudagrass encroachment compared to 6 cm. Mixing hybrid bluegrass with tall fescue reduced disease and weed species infestations compared to tall fescue alone. Applying bispyribac-sodium earlier in April resulted in less brown patch and better weed control compared to application in May. Based on this research brown patch severity and subsequent weed species infestations can be reduced by selecting a tall fescue cultivar with a high basal level of chitinase, mowing it at 10 cm and mixing it with a hybrid bluegrass cultivar. / Ph. D.

In terms of acreage, forage is the number one crop in Virginia. The backbone of these forages has long been tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire). Knowledge of the plant species that make up a pasture and the relative amounts of each species present is important for interpreting potential animal performance. It is also important to know the relative amounts and types of weeds present and to monitor for the presence of poisonous plants or noxious weeds. An experiment was conducted in 2003 through 2005 to investigate botanical composition and yield of "Lakota" prairie grass (Bromus catharticus Vahl.), "Kentucky 31" endophyte-infected (KY31 E+), endophyte-free (KY31 E-), and "Quantum" tall fescue (non toxic endophyte infected) under grazing by stocker steers. Forage botanical composition and yield were determined by clipping three 0.25-m2 areas per treatment replicate. Prior to harvesting, the canopy height within each quadrate was measured with a disc meter. In 2005, productive ground cover was assessed using visual evaluation techniques, point quadrat method, and digital imagery quantified with terrestrial remote sensing. Forages were established September 2002 and grazing was initiated in July of 2003. Experimental design was a randomized complete block with four replications. Averaged over the three years the yield of KY31E+ was higher (p<0.05) than all other treatments. Lakota prairie grass had lower (p<0.05) yields than both KY31 E+ and Quantum tall fescue, however no yields did not differ between Lakota prairie grass and KY31 E-. Our results showed a typical forage distribution curve for all the treatments. Early spring, summer, and fall productivity of Lakota prairie grass was less than all the fescues, thus did not extend the grazing season. Forage persistence was greatest for KY31 E+ and Quantum and lowest for Lakota when averaged over all years. Among sampling methods for ground cover, terrestrial remote sensing was the most accurate, compared with visual evaluation and point quadrat methods. For estimates of all yield indirect methods of assessment had high errors; however the plate meter calibrated by sward density seemed the least variable of the methods tested. / Master of Science

Natural soils in the Appalachian coal mining region occur on steep slopes and are often thin, rocky, acidic, and/or infertile. This often makes use of natural topsoil for surface coal mine reclamation impractical. Sandstone (SS) and siltstone (SiS) topsoil substitute materials in mixed and pure treatments were compared to ascertain their effects on soil genesis and tall fescue (Festuca arundinaceae Schrab.) growth in a rock mix study. A second surface amendment experiment with similar objectives was established and contained treatments of sawdust, topsoil, a control, and four rates of sewage sludge. Soil pH, extractable P, and coarse fragment contents decreased at the soil surface from 1982 to 1984. The CEC decreased from 1982 to 1983 due to leaching of cations solubilized from carbonates, but stabilized by 1984. Soil total-N and water availability increased from 1982 to 1984. Particle size distributions changed as sand and >2 mm sized materials weathered into silt and clay sized particles. As sand contents decreased over time, silt contents increased. Morphologically distinct A horizons developed in these soils rapidly and were formed primarily by plant rooting and organic matter additions. Treatment application, topsoil substitute placement, and grading also created morphologically distinct horizons. Fescue biomass production indicates topsoil substitutes support more vigorous vegetative growth than topsoil, especially when topsoils are mixtures of subsoil and A horizons. Biomass production was primarily limited by N, P, and water availability. Blended rock mixes consistently supported higher biomass production than pure SS and SiS treatments. Municipal sewage sludge applied at rates-56 Mg/ha equaled or exceeded inorganic fertilization for establishment and maintenance of tall fescue stands, and did not cause heavy metal phytotoxicity. / M.S.

Fifteen calves of two sires were fed endophyte infected (E + ) fescue seed to quantify differences in susceptibility to fescue toxicosis among sire groups. One of the sires, a Polled Hereford, had a commercial reputation of producing calves with less severe symptoms of tall fescue toxicosis than their contemporaries. The control sire, also a Polled Hereford, had unknown merit with regard to offspring susceptibility to fescue toxicosis. The study was divided into five phases, two in which endophyte-infected fescue seed was included in the diet (phases two and four) and three in which fescue seed was not in the diet (phases one, three, and five). All calves were treated similarly and given the same opportunities for water, shade and socialization. Susceptibility to fescue toxicosis was measured by appetite (amount of feed consumed per day per unit of metabolic body weight), serum prolactin, cholesterol, and alkaline phosphatase concentrations, ability to maintain homeotherny (afternoon minus morning rectal temperature), ability to dissipate core body heat (afternoon minus morning surface temperature), and heat-transfer inefficiency (afternoon rectal minus afternoon surface temperatures). Appetite was decreased by the E + fescue seed, but the sire groups did not differ in their response to or recovery from E + fescue seed. The E + fescue seed caused prolactin to decrease (P < .0001) but the sire groups did not differ in their responses to addition or withdrawal of E + fescue seed from the diet. Cholesterol levels were lower overall (P < .001) when the E+ fescue seed was fed, and the sire groups recovered from the fescue toxicity at different rates (P < .001). Alkaline phosphatase concentrations were lower during the phases when E + fescue seed was fed; calves from the control sire were less resistant to the E + fescue seed effects than the Missouri calves (P < .0001). Ability to maintain homeothermy was reduced by the E + fescue seed, but the reduction did not differ between sire groups. Surface temperature changes and heat-transfer inefficiencies were not indicative of fescue toxicosis in this study. It was concluded that serum cholesterol and serum alkaline phosphatase concentrations may be accurate indicators of differences among paternal half sib groups of cattle in susceptibility to fescue toxicosis. / Master of Science

Use of legumes as an alternative to nitrogen (N) fertilization in pasture management improves forage quality and animal performance and has been suggested to reduce the potential for environmental pollution. "Kentucky 3l" tall fescue fertilized with 160 kg N ha-1 yr-1 (split application) was compared to tall fescue grown with alfalfa or red clover in a 5-yr pasture experiment on a mixed Typic Hapludult. During yr 6, effects of N fertilization or the legume on soil N, forage N concentration, yield, botanical composition, N intake by esophageally fistulated steers grazing the pastures and N utilization by wethers fed the harvested forages were investigated. Soil ammonium was higher (P ≤ .01) in the A and B horizons in the tall fescue-red clover pastures compared to the other treatments and nitrate was lower (P ≤ .05) in the A horizon, but concentrations differed (P ≤ .01) by date. Nitrate in the A horizon averaged 2.65, 1.38 and 2.21 ppm for tall fescue-N, tall fescue-red clover and tall fescue-alfalfa, respectively. In the B horizon, average soil NO3 was .43, .23 and .53 ppm for tall fescueâ N, tall fescue-red clover and tall fescue-alfalfa, respectively. Tall fescue-alfalfa pastures were higher (P ≤ .01) in percentage legume than tall fescue-red clover, overall, but differed by date (P ≤ .01). Alfalfa was generally higher (P ≤ .05) in N concentration than red clover. Total kg N accumulated ha⁻¹ in above-ground herbage was higher (P≤ .05) for the grass-legume mixtures than N-fertilized tall fescue. Esophageally fistulated steers grazing stockpiled tall fescue-alfalfa selected forage higher (P ≤ .05) in N concentration than steers grazing the other pastures. Stockpiled tall fescue-alfalfa fed to wethers in a metabolism trial was higher (P ≤ .01) in N concentration, dry matter digestibility (DMD), apparent N absorption, and N retention than the other treatments. All treatments differed, with wethers fed tall fescue-red clover having the lowest DMD, apparent N absorption and N retention. Wethers fed tall fescue-alfalfa and tall fescue-red clover had higher blood urea N then those fed tall fescue-N. Results of this research demonstrate that soil NO₃ concentrations were low for all three forage treatments and would not contribute to ground water contamination. Legumes supplied adequate N to achieve yields similar to tall fescue fertilized with N and increased N production ha⁻¹ in the above ground biomass. Digestibility and utilization of the N in stockpiled tall fescue were improved by inclusion of alfalfa but not red clover. / Master of Science

Tall fescue (Festuca arundinacea Schreb.) often becomes dormant in the hot summer months. Switchgrass (Panicum virgatum L.) has potential to supplement the limited carrying capacity of tall fescue in mid-summer. The objective of this study was to determine the seasonal dry matter distribution and quality of tall fescue and switchgrass as influenced by different harvest managements. Switchgrass and tall fescue were studied on a fine-loamy, mixed, mesic Ultic Hapludalf of the Duffield soil series at Blacksburg, VA during 1987 and 1988. Normal harvest management included harvests taken from the first growth in spring until mid to late August. Delayed management included harvests taken from regrowth after a hay crop in mid-May for tall fescue and early June for switchgrass until mid to late August. Three and four harvest intensities were imposed on tall fescue and switchgrass, respectively. Plots were harvested in 1989 to determine the accumulative influence of treatments. Yield, crude protein, neutral detergent fiber, and invitro dry matter digestibility were measured for each harvest of both species. Digestible yield and protein were calculated for each harvest. Clipping either switchgrass or tall fescue at any harvest intensity reduced potential yield compared to forage not clipped. Accumulated forage resulted in high yields but unsatisfactory quality. Delayed harvest management resulted in higher total yield than normal harvest management because of high hay yields. This study indicated that considerable overlap of forage production of tall fescue and switch grass occurred in late spring but abundant high quality switchgrass was available in midsummer when available tall fescue was low. Switchgrass warrants consideration in southwest Virginia as a solution to the problem of limited cool-season forage in midsummer. / Master of Science

Les associations symbiotiques entre différentes espèces de champignon du genre Epichloë et des plantes fourragères sont à l’origine de la production de mycotoxines responsables, dans certains pays, de toxicoses du bétail et de pertes économiques. Le développement de d’E. coenophiala dans la fétuque, qui est associé à la production d’ergovaline, est responsable de « fescue foot disease » alors que la présence d’E. festucae var. lolii dans le ray-grass anglais, qui est accompagnée d’une production de lolitrem B, est responsable du « ryegrass staggers » et de la production d’ergovaline, dont les effets toxiques associés à la présence de lolitrème B sont mal documentés. Mon travail de thèse a consisté à explorer les effets de la distribution de différents fourrages de fétuque et ray-grass endophytés toxinogènes produits dans des conditions agricoles françaises, sur la santé et la production animale et les mécanismes d’action de l’ergovaline et du lolitrème B. / The symbiotic associations between different varieties of fungi of the Epichloë kind and forages are responsible for the production of mycotoxins which are responsible of toxicoses in livestock and economic losses in some countries. The development of E. coenophiala in tall fescue, which is associated with the production of ergovaline, is responsible for « fescue foot disease » while the presence of E. festucae var. lolii in ryegrass, which is accompanied by the production of lolitrem B, is responsible for the « ryegrass staggers ». and the production of ergovaline, whose the toxic effects associated in the presence of lolitrem B are poorly documented. My thesis was to explore the effects of the distribution of different toxic forages of endophyte-infected tall fescue or ryegrass produced in French agricultural conditions on health and animal production and the mechanisms of action of ergovaline and lolitrem B.

My objectives were to determine if nutritional benefits occur when animals are offered foods with compounds -- alkaloids, saponins, and tannins - that are potentially complementary. I hypothesized that food intake and digestibility increase when lambs consume plants such as alfalfa ALF that contain saponins or birdsfoot trefoil (BFT) that contain tannins when the basal diet is endophyte-infected tall fescue (TF) or reed canarygrass (RCG) both of which contain alkaloids. I predicted that the nutritional status of lambs would be enhanced if basal diets of alkaloid-containing grasses were supplemented with ALF or BFT. Lambs fed a basal diet of either endophyte-infected TF or RCG ate more food and consequently digested more dry matter, energy and nitrogen when supplemented with ALF or BFT. Lambs ingested more dry matter and digested more nutrients when fed a basal diet of RCG than one of TF, and supplementing with ALF and BFT was more beneficial for lambs fed TF than for lambs fed RCG. Increased intake of digestible nutrients was due to greater intake when lambs were offered more than one food, not due to an increase in digestibility. In pen trials meant to complement the field trials, lambs were offered an alkaloid-containing (either gramine or 5-methoxy-N,N-dimethyltryptamine) total mixed ration and supplemented with a food that contained saponins or tannins. All rations were isocaloric (3.3Mcal/kg) and isonitrogenous (14% CP). Lambs fed a ration with either alkaloid and offered a food containing saponin digested approximately the same amount of dry matter, energy, nitrogen, and NDF as lambs not offered saponin. When lambs were fed a ration with either alkaloid and supplemented with food that contained tannins, tannin consumption adversely affected dry matter, energy, and NDF digestibility, but lambs offered food with tannins increased dry matter intake, and as a result, they digested the same amount of dry matter, energy, and NDF as lambs not offered the food with tannins. Lambs offered tannin digested and retained more nitrogen than lambs not offered tannin. These findings indicate a nutritional advantage for sheep eating mixtures as opposed to monocultures of foods with different profiles of secondary compounds and nutrients.

Burning and grazing are key processes in the natural disturbance regime of the Fescue Prairie. Burning, grazing and their interacting effects on plant species diversity (H¡¯), species richness, and heterogeneity in species composition were studied at two spatial scales for two years in a remnant Fescue Prairie near Saskatoon, Saskatchewan. Cattle distribution in relation to plant communities was also studied. At the plot scale (100 m2), burning increased H¡¯ (P<0.01) (x=1.75) compared to unburned treatments (x=1.54) (S.E.¡À0.058). Burning, grazing, and burning + grazing had no significant effect (P>0.10) on species richness; richness varied between years (P=0.04), averaging 14.2 species m-2 in year one versus 15.8 species m-2 in year two (S.E.¡À 0.65). Spatial heterogeneity (P>0.25; x=46%; S.E.¡À3.0) and temporal heterogeneity in species composition (P>0.21; x=42%; S.E.¡À3.8) were not affected by burning, grazing, or their interaction. Burning + grazing increased tiller densities in <i>Elymus lanceolatus</i> (68%) and those of <i>Festuca hallii</i> (11%) (P<0.001) compared to the control. Burning decreased total aboveground net primary production (ANPP) (P<0.001) (x=305 g m-2) compared to unburned treatments (x=500 g m-2; S.E.¡À30.8). Grazing and burning + grazing had no effect on total ANPP or graminoid ANPP (P¡Ý0.36). At the scale of Kernen Prairie (130 ha), H¡¯ increased between 1996 (P<0.05) (x=1.10) and 2005 (x=1.40; S.E.¡À0.094). Species richness increased from 5.2 species 0.25 m-2 in 1996, to 6.8 species 0.25 m-2 in 2005 (S.E.¡À0.505). Heterogeneity in plant species composition tended to increase after prescribed burning was started in 1986 and after grazing began in 2006. Cattle preferred <i>Bromus inermis-</i> and <i>Poa pratensis-</i>dominated plant communities, areas with intermediate amounts of total aboveground standing crop of plants, and areas in which shrub densities exceeded 16 stems 0.25 m-2. In the short term, burning and environmental conditions had greater effects on species diversity, richness, and heterogeneity in species composition than grazing or the interaction of burning and grazing. Different responses may be expected with different combinations of timing, frequency, and intensity of burning and grazing at different sites under ever changing environmental conditions.

Burning and grazing are key processes in the natural disturbance regime of the Fescue Prairie. Burning, grazing and their interacting effects on plant species diversity (H¡¯), species richness, and heterogeneity in species composition were studied at two spatial scales for two years in a remnant Fescue Prairie near Saskatoon, Saskatchewan. Cattle distribution in relation to plant communities was also studied. At the plot scale (100 m2), burning increased H¡¯ (P<0.01) (x=1.75) compared to unburned treatments (x=1.54) (S.E.¡À0.058). Burning, grazing, and burning + grazing had no significant effect (P>0.10) on species richness; richness varied between years (P=0.04), averaging 14.2 species m-2 in year one versus 15.8 species m-2 in year two (S.E.¡À 0.65). Spatial heterogeneity (P>0.25; x=46%; S.E.¡À3.0) and temporal heterogeneity in species composition (P>0.21; x=42%; S.E.¡À3.8) were not affected by burning, grazing, or their interaction. Burning + grazing increased tiller densities in <i>Elymus lanceolatus</i> (68%) and those of <i>Festuca hallii</i> (11%) (P<0.001) compared to the control. Burning decreased total aboveground net primary production (ANPP) (P<0.001) (x=305 g m-2) compared to unburned treatments (x=500 g m-2; S.E.¡À30.8). Grazing and burning + grazing had no effect on total ANPP or graminoid ANPP (P¡Ý0.36). At the scale of Kernen Prairie (130 ha), H¡¯ increased between 1996 (P<0.05) (x=1.10) and 2005 (x=1.40; S.E.¡À0.094). Species richness increased from 5.2 species 0.25 m-2 in 1996, to 6.8 species 0.25 m-2 in 2005 (S.E.¡À0.505). Heterogeneity in plant species composition tended to increase after prescribed burning was started in 1986 and after grazing began in 2006. Cattle preferred <i>Bromus inermis-</i> and <i>Poa pratensis-</i>dominated plant communities, areas with intermediate amounts of total aboveground standing crop of plants, and areas in which shrub densities exceeded 16 stems 0.25 m-2. In the short term, burning and environmental conditions had greater effects on species diversity, richness, and heterogeneity in species composition than grazing or the interaction of burning and grazing. Different responses may be expected with different combinations of timing, frequency, and intensity of burning and grazing at different sites under ever changing environmental conditions.