Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--Columbia University. / Vita. The studies on wheat, barley and alfalfa were published also as Bulletins 502, 512 and 521 of California agricultural experiment station, Berkeley. Bibliography: p. 124.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 23-27).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 83-85).

No description available.

Doctor of Philosophy / Department of Agronomy / Doohong Min / Alfalfa is an important forage legume grown in the central Great Plains. However, producers still lack information about the productivity of alfalfa grown with cool-season grasses and the proper time of the last cut of alfalfa in the fall. Two studies are presented in this dissertation. The first study was to determine during a three-year period (2015-2017) the dry matter yield (DMY) and forage nutritive value of alfalfa-grass mixtures compared to alfalfa and grasses grown in monoculture and to assess the effect of nitrogen fertilizer on the dry matter yield and nutritive value of alfalfa-grass mixtures. During the three-years, the DMY was significantly higher in monoculture alfalfa and alfalfa-grass mixtures than in grass monocultures. No significant differences in DMY between alfalfa monoculture and alfalfa-grass mixtures were found. For all treatments, nitrogen application significantly increased DMY compared to the control. In 2016 and 2017, acid detergent fiber (ADF) and neutral detergent fiber (NDF) in smooth bromegrass and tall fescue were higher than in other treatments. Nitrogen fertilizer application did not affect nutritive values such as crude protein (CP), ADF, NDF, and relative feed value (RFV) in different treatments of the forage species. The second study determined the effect of timing of a fall cut on dry matter yield, nutritive value, and stand persistence of alfalfa in Northeastern Kansas in the United States. The DMY of first cut in 2016 was significantly higher in the Roundup Ready variety of alfalfa than in the low-lignin variety of alfalfa. There were no significant differences in DMY between alfalfa varieties in the remaining seasonal cuttings in 2016 and 2017 and in the annual total yield in both years. The DMY of the last cut in the fall was the highest in 2015, 2016 and 2017 in plots that were harvested on September 30. In 2017 the highest DMY in first cut was found in plots that were cut on October 15 in the previous year. The last harvests of the 2016 season, which were on October 15 and October 30, had the highest nutritive value. Opposite results on October 15 and October 30 were observed in 2017. Alfalfa cut on September 15 and September 30 had a higher stand persistence compared to alfalfa cut on October 15 and October 30. In conclusion, last fall cutting of alfalfa, which could be up to October 15, appeared to be acceptable because it did not affect forage dry matter yield.

Alfalfa plays an important part in Utah's Economy. It is the major forage crop and occupies approximately 40 percent of all irrigated land in the state During the past most of the alfalfa varietal trials have been conducted in Cache Valley, which is not representative of conditions found throughout Utah. In fact, it would be impossible to select any one location for conducting tests where all insect, disease, and climatic conditions would be represented. In view of this it was felt that an attempt should be made to conduct varietal trials at several locations to permit the selection of varieties which would produce higher yields of quality forage.

In 1908, Sackett described for the first time what appeared to be a new bacterial disease of alfalfa in Colorado. To this particular disease he applied the name “stem blight" and attributed the cause to a bacterium, Pseudomonas medicaginis. For some two decades or more Sackett's work on this disease was accepted. During this time stem blight, which was first thought to be indigenous to the western United State, was reported from nine states east of the Rocky Mountains. In 1933, Johnson and Valleau described a disease of alfalfa, characterized by stem lesions very similar in appearance to those of stem blight as described by Sackett. These authors determined the cause of this new disease to be a fungus" Phoma medicaginis Malbr. and Roum., and gave to it the name "black stem". Richards in 1934" in reporting on the resistance of certain alfalfa varieties to stem blight in Utah, states in a foot note that a species of Phoma was isolated with considerable uniformity from bacterial stem blight lesions. This author raises the question as to the possible dual etiology of stem blight in Utah. Research work by Remsberg and Hungerford in Idaho, more definitely suggested this dual etiology of' the stem blight complex. These authors determined the black stem lesions on alfalfa to be caused by Phoma medicaginis, and indicated that the darker lesions caused by this fungus were distinct from the lighter colored lesions characteristic of the bacterial stem blight described by Sackett. Because of the similarity of the late stage of bacterial stem blight to the insipient stage of black stem, much confusion has arisen as to their identity and etiology It has been the policy in Utah during recent years to refer to this wide range of stem lesions as stem blight, recognizing that the exact nature and etiology is not known. This disease complex presents a problem in Utah of major economic importance. It is the purpose of this thesis to bring together the known facts regarding stem blight; to determine the specific etiology of the stem blight lesions on alfalfa as they occur in Utah, and if possible to establish definite criteria by which the components of the stem blight complex might be separated.

Field experiments were conducted to determine the impact of threecornered alfalfa hopper, Spissistilus festinus, (Say), in reproductive growth stage soybeans. High densities of threecornered alfalfa hoppers were examined in field cages to understand feeding on soybean. No significant yield losses were observed from threecornered alfalfa hopper feeding during reproductive growth stages. Sweep net efficiency studies were conducted in order to convert the densities used in field cages to a sweep net threshold. Field experiments were also conducted to determine the impact of threecornered alfalfa hopper injury to seedling cotton. Threecornered alfalfa hopper injury to seedling cotton plants impacts individual plant yield, but further research is needed to understand the ability for undamaged cotton plants to compensate for neighboring damaged plants.