Numerous soil borne pathogens attack alfalfa roots and crowns and reduce stand longevity by predisposing plants to winter injury. Persistence can be improved by the use of cultivars with good disease resistance and by applying phosphorus (P) and potassium (K). The objective of this study was to examine the productivity and quality of alfalfa cultivars differing in disease resistance, under various fertilizer regimes on three different soils. A completely cross-classified factorial experiment in a randomized complete block design (RCBD) was established in 1990 with three rates of P (0, 33, and 66 kg ha$ sp{-1}$), three rates of K (0, 124, and 248 kg ha$ sp{-1}$), and two cultivars ("Apica" and "Oneida VR"). Treatment combinations were established (with 10% timothy, by seed weight) on three soils with distinctive drainage characteristics (referred to as ideal, intermediate and marginal). Disease ratings, stand counts, yields and herbage mineral content were measured in each of two production years. Yields and plant populations were the lowest on the marginal soil, while disease levels were the highest. Fusarium spp. were the most common fungal isolates from diseased roots and crowns at all sites. Apica tended to persist better than Oneida VR and have lower levels of crown and root rot. Neither P nor K had an effect on yield or persistence at the Ideal site, with positive responses noted on yield at the other sites. Potassium improved persistence at the Intermediate site and had variable but positive effects on disease levels. Increased rates of K fertilizer resulted in reduced herbage Ca, Mg, crude protein (CP) and increased herbage K and Acid Detergent Fibre (ADF) levels. Regardless of management, alfalfa production on soils with inadequate drainage remains risky.

The purpose of this project was to evaluate dif1ubenzuron ovicidal effects on adult female alfalfa weevils Hypera postica in the laboratory. There was little relationship of weevil mortality to dosage or length of exposure of the adult to the chemical. An indirect result of dif1ubenzuron was an increase in muscardine fungus (Beauveria Sp.). Other effects of the chemical on the adults were yellow deposits and tissue extending from the tip of the abdomen. The main effect of di1fubenzuron when fed to female alfalfa weevils was on the eggs. The effects were dosage related, especially on eggs viability. The viability was dropped from 99% in the control to 38.9% on the treated insects in ten days using the highest dosage. Another effect of diflubenzuron on alfalfa weevil eggs was on the shape of the eggs. The treated insects laid longer and lighter color eggs.

Typewritten copy / 318 leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Faculty of Agricultural Science, 1958

Thesis (Ph. D. - Soil and Water Science)--University of Arizona, 1986. / Bibliography: leaves 100-104.

Thesis (M.S. - Agronomy)--University of Arizona, 1969. / Includes bibliographical references (leaves 58-65).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 132-141). Also available via the Internet.

Tesis Presentada como Requisito Parcial para Obtener el Titulo de Ingeniero Agronomo, Escuela Superior Politecnica de Chimborazo, Facultad de Recursos Naturales, Ecscuela de Ingenieria Agronomica. / Abstract in Spanish and English.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-85).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1954. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 66-71.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1956. / Typescript. Abstracted in Dissertation abstracts, v. 16 (1956) no. 11, p. 1988-1989. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 151-160).