Theses and Dissertations at Montana State University (MSU)
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Item Hybridization and invasiveness in Eurasian watermilfoil (Myriophyllum spicatum): is prioritizing hybrids in management justified?(Montana State University - Bozeman, College of Agriculture, 2021) Hoff, Hannah Katherine; Chairperson, Graduate Committee: Ryan Thum; Ryan A. Thum was a co-author of the article, 'Hybridization and invasiveness in Eurasian watermilfoil (Myriophyllum spicatum): is prioritizing hybrids in management justified?' submitted to the journal 'Invasive plant science and management' which is contained within this thesis.Hybridization can play an important role in the evolution of invasiveness. Eurasian watermilfoil (Myriophyllum spicatum L.) is a widespread aquatic invasive plant species that hybridizes with native northern watermilfoil (Myriophyllum sibiricum Kom.). Previous studies have found mixed evidence for whether hybrid watermilfoil (Myriophyllum spicatum x sibiricum) and pure M. spicatum differ in vegetative growth rate and herbicide response. While several studies have emphasized variation in these traits among M. spicatum x sibiricum genotypes, variation within M. spicatum has not been considered. Therefore, it is unclear how important genetic variation within M. spicatum, versus between M. spicatum and M. spicatum x sibiricum, is in influencing invasive traits and management outcomes. If M. spicatum x sibiricum genotypes are always more invasive than M. spicatum genotypes, simply distinguishing taxa may be sufficient for identifying lake management priorities; however, if significant phenotypic overlap is observed between taxa, distinguishing individual genotypes may be important for tailoring management strategies. We performed replicated trials of a vegetative growth and 2,4-D assay to measure clonal variation in growth rate and herbicide response of M. spicatum and M. spicatum x sibiricum. Our results indicate that M. spicatum x sibiricum exhibits higher average vegetative growth than M. spicatum, whether or not it is treated with 2,4-D. We did not observe interactions between taxon and treatment or between genotype and treatment. Despite differences between M. spicatum and M. spicatum x sibiricum in average vegetative growth, there was substantial overlap between taxa. For example, we found that the fastest-growing genotype of pure M. spicatum did not differ significantly in average growth from the fastest-growing M. spicatum x sibiricum genotype. The potential for overlap between these invasive Myriophyllum taxa suggests that distinguishing and characterizing genotypes may be more informative for management than simply distinguishing between M. spicatum and M. spicatum x sibiricum.Item Integrating DNA fingerprinting of invasive watermilfoil strains into aquatic vegetation monitoring and assessment(Montana State University - Bozeman, College of Agriculture, 2021) Gannon, Kathryn Alta; Chairperson, Graduate Committee: Ryan Thum; Raymond Newman and Ryan Thum were co-authors of the article, 'Integrating DNA fingerprinting of invasive watermilfoil strains into aquatic vegetation monitoring and assessment' submitted to the journal 'Journal of aquatic plant management' which is contained within this thesis.Eurasian watermilfoil (Myriophyllum spicatum L.) and its hybrids with native northern watermilfoil (Myriophyllum spicatum L. x Myriophyllum sibiricum) (invasive watermilfoils) are among the most heavily managed invasive aquatic plants in the United States. Within invasive watermilfoils there are distinct strains which are produced through sexual reproduction and can be maintained indefinitely by clonal propagation. Different strains can differ in their invasiveness (e.g., growth and potential for spread) and response to herbicides. However, strain identification is not routinely implemented as part of management planning or evaluation. In this thesis, we integrated molecular fingerprinting that can distinguish different Eurasian and hybrid watermilfoil strains into aquatic vegetation monitoring in eight Minnesota lakes over the course of three years. We provide proof of concept that by tracking strain incidence over time it is possible 1) to detect changes in strain composition of invasive watermilfoil populations, and 2) to identify priority strains for future growth and herbicide assays. This study demonstrates that integrating genetic fingerprinting into aquatic vegetation management and evaluation holds promise to inform management decisions by identifying those strains that have the most invasive potential. As far as we are aware, this is the first published study to examine the strain composition of invasive watermilfoil populations over time.Item Management options for producers who traditionally plant barley for grain or forage(Montana State University - Bozeman, College of Agriculture, 2007) Boss, Darrin Lewis; Chairperson, Graduate Committee: Philip L. Bruckner; Robert Stougaard (co-chair)The objective of the experiment was to evaluate barley management options by varying seed band width, seeding rates, and harvest endpoint under dryland production conditions in Northern Montana. The experimental design was a randomized complete block with a factorial arrangement and was conducted for three years. Treatments consisted of two cultivars ('Harrington' and 'Haybet'), two band widths (125 mm and 193 mm), and three seeding rates (140, 184 and 226 seeds m-2). Year effects were significant. All established plant populations were lower than planned. Band width was confounded with seeding rate. Established plant populations increased from the narrow to the wide band width, any effect attributed to band width appears to be more what would be expected for increasing the seeding rate. Malt quality was never achieved and no treatment combination aided in moving the quality towards an acceptable malt grade of barley. Feed barley production was greatest in 2001 for the lowest seeding rate where as in 2002 and 2003 no difference existed between seeding rates.Item Bacterial wilt management : a prerequisite for a potato seed certification program in Mali(Montana State University - Bozeman, College of Agriculture, 2007) Thera, Aissata Traore; Chairperson, Graduate Committee: Barry J. Jacobsen; Florence Dunkel (co-chair)Potato is one of the most important cash crops in Mali and has been well adapted to the Malian cropping systems and food habit. Bacterial wilt caused by Ralstonia solanacearum (Smith) Yabuuchi et al., (1995) has become a major problem causing important damage in production. The Race and biovar of the bacterium present in Mali were not known at the start of this thesis research and the objective of this research was to identify the race/biovar and to evaluate integrated control methods with the aim to produce high quality disease free seed potato in Mali. We have initially identified the biovar and Race of R. solanacearum affecting potato in Mali as Race 1 biovar 3. ELISA tests were used on soil and water samples to detect the presence of R. solanacearum. Three detections methods of the bacteria (bacterial streaming test, Agdia immunostrip test and Tetrazolium chloride media) in plant samples were compared; weeds and crops hosting the bacteria as sources of inoculums were identified using Agdia immunostrip test.