For Virginia, the primary forage base is endophyte-infected tall fescue (Schedonorus phoenix (Scop.) Holub). However, the decreased animal performance and disorders caused by the presence of the fungal endophyte Neotyphodium coenophialum reduces its suitability for many forage-livestock producers. The endophyte, which is found in the inter-cellular space of tall fescue tissues, forms a mutalistic relationship with the plant and helps the fescue tolerate drought, insect predation, and grazing pressure. The production of toxic ergot alkaloids by the endophyte is associated with decreased performance of animals that graze endophyte infected tall fescue. The objective of the current experiment was to determine how tall fescue type (endophyte free vs novel endophyte) and orchardgrass-legume (alfalfa vs clover) mixture affect grazing behavior of weaned steers. Forty-eight weaned steers (218 ± 18 kg) were blocked by frame score (medium and large), and randomly assigned within block to four treatments with three replications in a 2x2 factorial design. Each treatment consisted of 2 paddocks with the combination of tall fescue and legume-orchardgrass mixture as follow: alfalfa-orchardgrass mixture (A)/E-, clover-orchardgrass mixture (C)/E- , A/E++ and C/E++. Each group of 4 steers had 24 h access to both tall fescue stand and legume-orchardgrass mixture. Botanical composition of paddocks was determined on d 0, and forage mass, sward height and nutritive value were determined on d 0, 17 and 33. Behavior of steers was scanned every 5 min on d 24 and 25 from 0700 to 1900. The proportion of legumes was higher (P = 0.001) in A paddocks(37 %) compared to C paddocks (6%), while the percent orchardgrass was lower (P = 0.040) in A (33 %) than C (53 %). The proportion of broadleaf and grassy weeds was higher (P = 0.013) in E- paddocks (11 %) as compared with E++ paddocks (3 %). Sward height and herbage mass were similar between treatments during the experiment (P > 0.05). Nutritive value (CP, NDF and ADF) did not differ between fescue paddocks (P > 0.05). However, within mixed swards, CP was higher and NDF was lower in A compared with C (P < 0.05). Acid detergent fiber was (P < 0.05) lower in A than C only on d 0 and 17. Average daily gain did not differ between treatments (P > 0.05). Steers spent higher (P = 0.002) proportion of the daylight time grazing in treatments with C (56 %) as compared with A (50 %), and in treatments (P = 0.023) with E++ (55 %) compared with E- (52 %). Time spent ruminating, idling and lying, as well as steps taken per day, did not differ between treatments (P > 0.05). Regardless of differences in weeds between E- and E++, these results indicate that fescue type affected grazing behavior of calves. Difference between mixed swards in proportion of ground cover with legumes and orchardgrass, as differences in nutritive value between A and C may have affected grazing behavior of calves between mixed swards, instead of a legume species effect within mixtures. / Master of Science

The use of nitrogen (N) fertilizer is generally restricted on mixed species forage systems due to its stimulatory effect on grasses which increases competition with legume species. Reduced legume growth from this competition can compromise forage nutritive value and prospective yields. The controlled-release nature of several enhanced efficiency fertilizer N products holds the potential to improve legume persistence in mixed species pastures while providing supplemental N required by the grass component. The studies contained in this dissertation evaluated the effect of different enhanced efficiency N formulations (ATU, ESN, methylene urea, SuperU, and a 75% ESN: 25% urea blend) and untreated urea on yield, nutritive value, and legume persistence in a ‘Wrangler’ bermudagrass and ‘Durana’ white clover mixture (2014-2016 growing seasons), ‘KY-31’tall fescue and ‘Kenland’ red clover mixture (2015-2016 growing seasons), and ‘KY-31’ stockpiled tall fescue (2015-2017). The three studies were conducted at the University of Kentucky Spindletop Research Farm in Lexington, KY in a randomized complete block design. In the bermudagrass-white clover study, all enhanced efficiency N sources maintained white clover populations similar to the unfertilized grass/clover control, but only ESN caused greater clover composition than standard urea. Total forage yields increased linearly with N rate in all years, but dry weather conditions in the second and third years resulted in lower total yield. Forage nutritive value followed general trends throughout each growing season, but ESN’s ability to maintain clover resulted in higher nutritive value. In the tall fescue-red clover, total forage yields curvilinearly increased with N rate in 2015 but did not vary in 2016. ESN and ESN+urea blend treatments retained clover composition similar to that of the unfertilized control. Stockpiled forage yield increased with higher N rates. Enhanced efficiency N fertilizers with the ability to control N release can enhance forage yield while maintaining clover in mixed species swards.

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 81-88). Also available via the Internet.

Thesis (doctoral)--Universität Leipzig, 1903. / Lebenslauf. Includes bibliographical references.

No description available.

Four berseem clover varieties were planted on three dates (Oct. 2 and 16, Nov. 2) in the fall of 2000. Data for plant heights and yields were obtained during the following winter and spring. Varieties differed widely in their initial stages of growth in terms of green coloration, indicating differences in bacterial nodulation and nitrogen fixation. ‘Tabor’ was a uniform rich green in coloration with vigorous growth, while ‘Saidi’ and ‘Serw 3’ were somewhat green. ‘Joe Burton’ was very reddish in coloration, especially in the later plantings, and no nodules were noted during examination of roots of this variety during the fall of 2000. Forage yields for the most part reflected planting date, with the earlier plantings having the highest yields. One exception was the Oct. 16 planting of ‘Tabor’, which had the highest overall individual yield. Lowest yields were noted with ‘Joe Burton’.

Twenty-nine Rhizobium leguminosarum biovar trifolii strains were tested for acidity tolerance in acidified liquid medium. Only 41\ of the strains grew at pH 4.1. One acid-tolerant strain, USDA 2160, and one acid-sensitive strain, 162-X-103 from Nitragin Co., were inoculated on seeds of 'Nungarin', 'Seaton Park' and 'Clare' subclover cultivars. The inoculated and pelleted seeds were sown in potted Cluff soil with pH 5. 7. Three desiccation levels were imposed by delaying watering for 0, 15 or 30 days. Four gravimetric soil water contents (6.0, 6.6, 10.5 and 12.5\) were maintained under a greenhouse line-source sprinkler system for 7 weeks. The desiccation treatments were more detrimental to the survival of the acid-tolerant Rhizobium strain (USDA 2160) than they were for the acid sensitive strain (162-X-103). Symbiotic effectiveness, measured as shoot dry weight, was higher with strain 162-X- 103 than with strain USDA 2160 and was comparable to the Nfertilized control at the highest water level (12.5 %). At the lower water levels (6.0, 6.6 %) symbiotic N2-fixation was more affected than N-uptake. The Rhizobium strains were able to survive and grow even at the lowest soil water level. The number of rhizobia in the soil and nodulation of the subclover plants had a correlation of 0.56.

The destructive nature of the clover seed chalcid has been known since the latter part of the 19th century. This jet-black Hymenoptera, often called the "chalcis-fly," destroys from 10 to 20 percent of the alfalfa seed in Utah each year. Damage as high as 85 percent has been reported.

One of the limiting factors associated with seed production of alfalfa and certain clovers is a small jet-black wasp commonly known as the clover seed chalcid, Bruchophagus gibbus (Boheman). In alfalfa seed producing areas this insect is often referred to as the alfalfa seed chalcid or the alfalfa seed chalcis-fly. In local areas of Utah, farmers often refer to this insect as simply "the fly."