Master of Science / Department of Agronomy / J. Anita Dille / Kraig Roozeboom / Increasing numbers of herbicide-resistant weed species require alternative methods of weed suppression to be examined. This study quantified the interaction between various cover crop or herbicide systems and horseweed [Conyza canadensis (L.)] growth. Fall cover crops of winter wheat [Triticum aestivum (L.)], winter rye [Secale cereal (L.)], barley [Hordeum vulgare (L.)] and annual ryegrass [Lolium multiflorum (L.)] were seeded in November 2012 and 2013. Spring cover crop of oat [Avena sativa (L.)] was seeded in April 2013 or rye was seeded in March 2014. All cover crops were no-till seeded into grain sorghum stubble [Sorghum bicolor (L.) Moench]. Four herbicide treatments were fall or spring applied, with and without residual. The spring non-residual treatment was also applied to plots of winter rye. Cover crop plots were split and terminated with a roller crimper or glyphosate application prior to soybean [Glycine max (L.) Merr.] planting to determine the effect of termination method on treatment performance. Soybean was planted in June 2013 and May 2014 and mechanically harvested in October of both years. Horseweed density, biomass accumulation, and soybean yield data were quantified. Horseweed height, whole plant seed production, and seed subsamples were recorded in the untreated fallow control, winter wheat, and winter rye plots in 2014. Horseweed suppression by winter rye approached 90%, levels similar to suppression by herbicide systems. In both years, herbicide plots had less than half the horseweed biomass than any of the cover crop systems. In 2013, soybean yields in herbicide plots were at least 1,500 kg ha[superscript]-1, nearly more than double yields in cover crop plots. Soybean yields in 2014 were more consistent across treatments; barley and spring rye plots achieved yields equal to or greater than 2,000 kg ha[superscript]-1. Winter rye and winter wheat reduced horseweed seed production by 60% compared to the untreated fallow control, with no effect on individual seed weight. Seed production varied across plants, with the untreated control producing the greatest number of seeds. Cover crops were successful at reducing horseweed biomass, suppressing horseweed pressure, preserving soybean biomass, and protecting soybean yields when compared to a fallow untreated control.

The United States is the leading producer and exporter of corn and soybeans in the world. The United States exports 20% of the world’s corn and 30% of soybeans in a typical year (USDA, ERS). The U.S., being the top producer and exporter of these commodities, is also confronting major rivals such as Argentina, Brazil, and Ukraine, which are increasing their exports and causing the U.S. to lose some of its market share. In order to stop this decline in market share, the U.S. can adopt and implement different policies to manage resources and employ advanced technology more effectively. In this study, we empirically estimate the export demand function of U.S. corn and soybeans to the top four export destinations: China, Japan, European Union, and Mexico in the current context of energy and agriculture linkages and production of ethanol from corn. A log-linear, panel data equation is used to estimate the U.S. corn and soybeans export demand function. Own price, cross price, income and exchange rate elasticities are estimated econometrically. Data for the U.S. and its top four importer countries were gathered for the 1980-2012 period. A Hausman test implies that a random effects estimator is better for the estimations. Elasticity analysis indicates that U.S. corn demand is elastic to own price, cross price, income and poultry inventory, while inelastic to real exchange rate and pig inventory. The positive cross price elasticity reveals that corn and soybeans are substitutes in these countries. Conversely elasticity analysis for the U.S. soybean demand shows elastic cross price, real exchange rate, and pig and poultry inventory effects, while inelastic own price and income effects. Consequently, for the U.S. to gain more international market share, U.S. corn and soybean producers need to take advantage of their advanced technology and high management skills to increase quality and have more competitive pricing compared to rivals. The U.S. can gain more market share by employing better regulation to increase the quality of products, and provide incentives to U.S. farmers and exporters that could help boost their advantages in a highly competitive international environment. Higher quality and more product differentiation could help in this regard. This could help U.S. farmers increase exports to currently existing foreign destinations and access new markets, to expand market shares.

Master of Science / Department of Agronomy / Phillip W. Stahlman / Kochia [Kochia scoparia (L.) Schrad.] is an invasive weed that is common in cropland, pastures and rangeland, rights-of-way, and disturbed areas throughout the western and northern United States and southern Canada. This species aggressively competes with crops, especially in no-till cropping systems, and has evolved resistance to multiple herbicide modes of action. Thus, it has become highly problematic and is difficult to manage. Roundup Ready 2 Xtend™ (Monsanto Co.) soybeans with resistance to dicamba herbicide are expected to be commercialized in 2016, and will offer a new management practice for controlling kochia and other susceptible broadleaf weeds in soybeans. Objectives of this research were to (1) determine whether greenhouse-grown plants from various kochia populations from the central Great Plains differ in susceptibility to postemergence-applied dicamba; (2) compare preemergence versus postemergence control of kochia with dicamba in a greenhouse environment; and (3) investigate various management practices in a systems approach to control kochia in soybeans. GR[subscript]50 values (dose required to reduce plant biomass by 50%) indicated at least an 8-fold difference among 11 kochia populations in susceptibility to postemergence-applied dicamba. Additionally, dicamba at 210 g ha[superscript]-1 applied preemergence caused 95, 88 and 84% mortality and reduced plant biomass (fresh wt.) of the most susceptible and two least susceptible kochia populations from a previous dicamba dose-response study by 99, 68 and 60%, respectively. In comparison, <10% of kochia plants from those populations died and biomass was reduced only 39, 15 and 7%, respectively, when dicamba was applied postemergence. Field experiments demonstrated that preplant conventional tillage followed by nine different in-crop herbicide treatments, and shallow early-spring tillage followed by preplant herbicides (reduced-till) along with the same in-crop herbicides provided greater kochia control than three no-till systems involving early preplant herbicide treatments followed by the same in-crop herbicides. However, despite greater kochia control with the tillage-based systems in 2013, soybean yields were less compared to the three no-till systems. Consequently, in some years the most effective kochia control practices may not result in the highest soybean yields.

LD2668 .T4 1949 S55 / Master of Science

Genetically Modified Organisms (GMOs) are plants or animals that have been produced using genetic insertion or deletion via technology (also called genetic engineering or GE). Merged DNA from different species creates combinations of plant, animal, bacteria and/or virus genes that cannot occur in nature or in traditional crossbreeding. Our goal was to determine the presence or absence of GMO markers in USDA Organic Certified and in Non-GMO Project food products. We investigated only corn or soy-based products that were purchased from many types of retailers. Our study was limited to products that contained a label for USDA organic certification and/or Non-GMO Verified Project. DNA from each product was extracted, tested for purity, and examined for specific markers denoting the presence of genetic modification. Modified DNA was amplified using PCR techniques and tested against standards on electrophoretic agarose gel. Based on these results, we detected evidence of genetic modification in 75% of soy and 83.3% of corn claiming USDA Organic Certification and 0% of soy and 100% of corn claiming Non-GMO Verified Certification.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 135-140). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 135-140). Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 111-123).

AN ABSTRACT OF THE THESIS OF JESSE MILLER, for the Master of Science degree in PLANT, SOIL, and AGRICULTURAL SYSTEMS, presented on May 13, 2016 at Southern Illinois University Carbondale. TITLE: THE EFFECTS OF STARTER FERTILIZER ON SOYBEAN INFESTED WITH FUSARIUM VIRULIFORME OR RHIZOCTONIA SOLANI MAJOR PROFESSOR: Dr. Jason Bond Fusarium virguliforme (Aoki), the fungus that causes sudden death syndrome of soybeans (SDS), is prevalent in most of the soybean (Glycine max L. Merr.) production regions throughout the United States. Sudden death syndrome management has been limited to cultural practices and host resistance. Rhizoctonia solani (Kühn) is a fungus responsible for pre-emergence and post emergence damping off. Control methods include seed treatments and cultural practices. Several companies have advocated the use of in-furrow starter fertilizers in soybean production. Promoting root growth and emergence are a couple of the alleged benefits. It is unknown if the increased fertility in the root zone may actually increase or decrease the severity of root or seedling diseases. An objective of this study is to determine if the starter fertilizers (2-6-16), (7-12-11), (3-10-13) Nachurs Alpine Solutions™ impacts seedling disease caused by Rhizoctonia solani and soybean yield. A second objective is to determine if starter-fertilizer influences the incidence and severity of SDS and soybean yield. One trial was infested with R. solani at the rate of 0.9 g of inoculum/30.5 centimeters of row. A second trial was infested with F. virguliforme at the rate of 2.25 g/30.5 centimeters of row. Inoculum consisted of sterilized white sorghum inoculated with either pathogen. Plots were 3.04 meters wide by 6.1 meters in length with row spacing of 0.76 meters. Trials took place during the growing season of 2014 and 2015. In 2014, a randomized complete block design consisted of 4 treatments that were replicated 6 times and planted into 4 row plots. Treatments consisted of treated (Metalaxl™, Fluxapyroxad™, Pyraclostrobin™, and Imidacloprid™) or non-treated seed (‘Asgrow 4730’) combined with either fertilizer (2-6-16) or non-fertilizer. Across both trials, there were no seed treatment and fertilizer rate interactions. In the R. solani trial, stand counts were similar between the fertilizer and non-fertilizer treatments. Stand counts were higher when the seed treatment was used. There was no significant difference in soybean yield regardless of treatment. In the F. virguliforme trial, stand counts were reduced in the fertilizer treatment when compared to the non-fertilizer treatment. Foliar symptoms of SDS and soybean yield were not affected by treatment. In 2015, there were changes in treatment structure due to additions of fertilizer treatments 7-12-11 and 3-10-13. Seed treatments and randomized complete block design remained for 2015. Stand counts were higher in plots that received fertilizer treatments in the R. solani trial. Stand counts were lower in R. solani plots with treated seed. Yield was not influenced by seed treatment but was increased by 3-10-13 and 7-12-11 fertilizer treatments. For the F. virguliforme trial, reduced stand counts were found in the plots with seed treatments. Seed treatments did not influence yield. Fertilizer did not impact stand or yield. Foliar symptoms of SDS were not influenced by seed treatment or fertilizer.

Este trabalho trata do avanço do cultivo de soja sobre novas áreas na porção sul do estado do Rio Grande do Sul, onde está localizado o Pampa. O objetivo desta pesquisa é identificar e entender as causas e as consequências do expressivo aumento de áreas plantadas de soja no Pampa gaúcho. Para isso, foram definidos municípios que melhor evidenciam esta recente transformação, além do estabelecimento de conceitos chave para o entendimento deste processo e dos responsáveis por tal. Além disso, foi realizado um breve histórico da presença da soja no Rio Grande do Sul, onde a modernização da agricultura e o surgimento das sementes transgênicas tiveram um importante papel para o avanço deste cultivo pelo estado. Com este panorama é feita uma comparação entre o avanço da soja no norte e sul do estado, pelo qual foi possível constatar que a presença de colonos acostumados com a produção em grande escala de trigo no planalto gaúcho favoreceu a implantação do cultivo antes na porção norte do que na sul. O Pampa esteve, por muito tempo, condicionado a uma série de fatores que impossibilitavam o aumento das áreas de lavoura de soja e, só depois do surgimento e da disseminação do Sistema de Plantio Direto, este quadro se modificou. A partir de algumas teorias foram selecionados alguns atores importantes para o entendimento do que vem acontecendo na região do Pampa e, através de entrevistas com produtores e demais atores, nos municípios selecionados, foram constatados alguns resultados da pesquisa como identificação de grande quantidade de produtores vindos de outras regiões do estado e que as compras de máquinas, implementos e insumos são feitas em municípios vizinhos movimentando a economia de centros já consolidados no setor de serviços. Contudo, este trabalho também traça algumas tendências para as regiões produtoras de soja, por exemplo, a busca por nichos de mercado mais rentáveis, seja com a produção de novos cultivos de grãos ou com a produção de orgânicos. / This work approach the advancement of soybean cultivation into new areas in the southern state of Rio Grande do Sul, where is located the Pampa. The objective of this research is to identify and understand the causes and consequences of the significant increase in areas planted to soybeans in Pampa. For this, we defined municipalities that best show this recent transformation, beyond the establishment of key concepts for the understanding of this process and those responsible for such. In addition, there was a brief history of the presence of soy in Rio Grande do Sul, where the modernization of agriculture and the emergence of transgenic seeds had an important role in the advancement of this growing state. With this scenario a comparison is made between the advance of soybeans in northern and south of the state, by which it was established that the presence of farmers accustomed to large-scale production of wheat in the gaucho upland favored the deployment of cultivation before at the north than in the south. The Pampa, has long been conditioned to a number of factors that made it impossible to increase the soybean crop areas and only after the emergence and spread of Tillage System, this frame could be modified. From some theories some key players were selected to the understanding of what is happening in the Pampa region, and through interviews with producers and other actors, from selected municipalities, were found some search results as the identification of large numbers of producers coming other regions of the state and that purchases of machinery, implements and inputs are made in neighboring municipalities moving the economy centers already established in the service sector. However, this paper also outlines some trends for the soybean growing regions, for example, the search for the most profitable market niches, either by producing new varieties of grain or organic production.