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Item Genetic surveys in combination with laboratory studies on growth and response to herbicide can help design, evaluate, and optimize Eurasian watermilfoil management plans(Montana State University - Bozeman, College of Agriculture, 2018) Guastello, Paula Ropp; Chairperson, Graduate Committee: Ryan Thum; Ryan A. Thum was a co-author of the article, 'Mesocosm evaluation of Eurasian and hybrid watermilfoil response to endothall in Jefferson Slough, Montana' in the journal 'Journal of aquatic plant management' which is contained within this thesis.Eurasian watermilfoil (Myriophyllum spicatum) is a top priority for aquatic plant managers in the United States. Dense mats of Eurasian watermilfoil obstruct irrigation and recreational activities, while drastically reducing property values and potentially providing a habitat for disease-carrying mosquitos. Nuisance populations are generally managed through herbicide use. Eurasian watermilfoil is capable of both sexual and clonal reproduction, creating a unique opportunity for adaptation: sexual reproduction generates genetic variation within a population, then fit genotypes can propagate via clonal reproduction. Pure Eurasian watermilfoil is genetically diverse, and additional genotypes result from frequent hybridization with native northern watermilfoil (Myriophyllum sibiricum). Recent studies have shown that genetic variation in Eurasian watermilfoil populations may affect herbicide efficacy in managed populations. Given the variability in herbicide response, I propose conducting site-specific studies to evaluate the response of genotypes in a waterbody to evaluate and optimize management strategies. In my thesis, I evaluated the potential to control nuisance pure and hybrid Eurasian watermilfoil with endothall in a riverine environment (Jefferson Slough, Montana). Molecular genetic surveys indicated that only one genotype of each taxon was present throughout the slough. I first compared vegetative growth and endothall response of the hybrid and Eurasian genotypes in the greenhouse, where I did not identify a difference in endothall sensitivity. Next, I evaluated the efficacy of an operational endothall treatment in Jefferson Slough. Similar to the greenhouse study results, hybrid and Eurasian watermilfoil were reduced to the same average biomass seven weeks after operational endothall treatment. Taken together, the greenhouse and operational field treatment indicate that the genotypes in Jefferson Slough were similarly susceptible to endothall. However, vegetative growth differences may have important management implications over time. In the greenhouse, Jefferson Slough hybrids grew significantly more than Eurasian watermilfoil in the absence of endothall. Additionally, there was a qualitative shift towards higher frequency of hybrids where the taxa intermixed. These results suggest a relatively higher potential for re-growth of hybrids compared to Eurasian watermilfoil following treatment. Jefferson Slough hybrids may require additional treatment to achieve sufficient long-term control. In conclusion, I discuss integration of genetic surveys into management and research priorities.Item Geographical analysis of the distribution and spread of invasive plants in the Gardiner Basin, Montana(Montana State University - Bozeman, College of Letters & Science, 2003) Rens, Emily NicoleItem Quantifying tansy ragwort (Senecio jacobaea) population dynamics and recruitment in northwestern Montana(Montana State University - Bozeman, College of Agriculture, 2003) Trainor, Meghan AnnItem Summer diets of sheep grazing spotted knapweed-infested foothill rangeland in Western Montana(Montana State University - Bozeman, College of Agriculture, 2005) Thrift, Brian Douglas; Chairperson, Graduate Committee: Jeffrey C. Mosley.Spotted knapweed (Centaurea biebersteinii DC.) is a perennial, invasive forb that infests millions of hectares of private and public rangelands in western North America. Previous research indicates that spotted knapweed is nutritious and readily grazed by domestic sheep (Ovis aries), but no studies have investigated prescription grazing of spotted knapweed within different levels of infestation or on a landscape scale. This twoyear study quantified the diets of a ewe-lamb band (n almost equals 800 ewes, 1120 lambs) that prescriptively grazed spotted knapweed-infested foothill rangeland in western Montana. Sheep grazed within light and moderate infestations of spotted knapweed (13% and 36% of vegetative composition, respectively) until perennial grasses were reduced to a 5 to 8- cm residual stubble height. Diets were estimated in mid-June and mid-July by clipping current year's standing crop immediately before and after grazing. Clipped samples were analyzed for CP, NDF, and ADF to estimate nutritive quality. Relative preference indices were calculated to evaluate diet selection by sheep. Sheep ate more spotted knapweed in moderate versus light infestations (64 vs. 26% of their diets, respectively; P<0.01), and spotted knapweed averaged 45% of sheep diets between June and July (P=0.61). Within light infestations, sheep ate fewer graminoids in June than July (17 vs. 55% of their diet, respectively; P<0.01). Sheep diets in moderate infestations averaged 33% graminoids regardless of month (P=0.18). Sheep did not select for graminoids in light infestations in June, but did select for spotted knapweed leaves in moderate infestations during July. Nutritive quality of sheep diets was similar to sheep grazing uninfested rangeland. Relative utilization of graminoids averaged 15%, except under exceptionally hot and dry weather conditions. Relative utilization of spotted knapweed averaged 45%. Previous research suggests that this level of spotted knapweed utilization may render herbicide application uneconomical. My results indicate that sheep can prescriptively graze moderate spotted knapweed infestations in either June or July, but to limit graminoid consumption, light infestations should be grazed in June vs. July.Item Providing supplement, with or without peg, to reduce the effects of cnicin and enhance grazing of spotted knapweed by sheep and cattle(Montana State University - Bozeman, College of Agriculture, 2006) Cheeseman, Melany; Chairperson, Graduate Committee: Bret E. Olson.Spotted knapweed (Centaurea maculosa Lam.), an invasive forb from Eurasia, infests over 1.7 million hectares in Montana and costs millions of dollars in forage losses each year. Some wildlife and livestock graze this species, however, most large herbivores, including cattle and horses, avoid spotted knapweed and prefer native plants. Some herbivores may avoid or reduce their intake of spotted knapweed because the plant contains cnicin. Cnicin is a bitter-tasting sesquiterpene lactone that may cause negative post-ingestive consequences in the rumen. If an appropriate supplement and/or antitoxicant can be identified that will reduce the negative post-ingestive effects of cnicin to rumen microbes, sheep and cattle may consume more spotted knapweed and grazing may help control this invasive species. I determined the effects of cnicin, rates of an anti-toxicant (polyethylene glycol), and a nutrient/energy supplement, with or without polyethylene glycol, on sheep and cattle rumen microbial activity, efficiency, and mass using a modified in vitro system. Sheep and cattle rumen microbes were negatively affected by cnicin. Polyethylene glycol, at the rates provided, had limited effects on sheep and cattle rumen microbial response to spotted knapweed plant parts. The nutrient/energy supplement, with or without polyethylene glycol, enhanced sheep and cattle rumen microbial efficiency. Because the nutrient/energy supplement may reduce some of the negative effects of cnicin on rumen microbes, sheep and cattle may consume more spotted knapweed in the field when provided with the supplement. I hypothesized that providing a nutrient/energy supplement, with or without polyethylene glycol, would increase sheep and cattle intake and time spent consuming spotted knapweed in a drylot, and in the field in July and August. Animal behaviors were recorded by focal animal sampling. Providing a nutrient/energy supplement, with or without polyethylene glycol, did not enhance sheep and cattle intake or time spent consuming spotted knapweed in a drylot, or in the field in July and August. Therefore, supplementing sheep and cattle with the nutrient/energy supplement, with or without polyethylene glycol, provided in these trials, may not be an appropriate method for managing the spread of spotted knapweed.Item The population dynamics of tansy ragwort (Senecio jacobaea) in Northwestern Montana(Montana State University - Bozeman, College of Agriculture, 2006) Bauer, Brad David; Chairperson, Graduate Committee: Bruce D. Maxwell.Following the Little Wolf wildfire of 1994 in northwestern Montana, tansy ragwort (Senecio jacobaea) was classified as a state noxious weed. This project aimed to help prioritize the management of populations of tansy ragwort through an understanding of the biotic and abiotic factors influencing the species. Using field collected data and by constructing a prediction model, we found that the most important variables to predict the presence of tansy ragwort were distance from the main road, slope, cosine of aspect, and several remotely sensed LANDSAT ETM+ bands. Most of the predicted occurrences of tansy ragwort were within the boundary of the wildfire. The life stage and density of tansy ragwort plants in 94 plots in several environments created by the wildfire were used to project the population growth rate after seven to eleven years following the wildfire. Using the relative invasiveness (probability ë > 1.0) of populations to prioritize environments for management, the burned and salvaged logged population had the highest probability of being invasive with probability ë > 1.0 between 0.31 and 0.24. The burned but not logged had a probability ë > 1.0 between 0.20 to 0.10 and the non-burned meadow had a probability ë > 1.0 between 0.01 and 0.00. Additionally, as the native plant populations recovered, the population growth rate and rosette survival declined. Following a field study of the role of slashpiles in the establishment of tansy ragwort we found the highest maximum percent emergence of tansy ragwort seedlings in the low severity burn and non-burned disturbed environment of the slashpiles. The low survival of emerged seedlings and the low projected growth rates for the surviving plants indicated that the dynamics responsible for a large increase in tansy ragwort density did not occur within our slashpiles after two years. With the addition of biological control agents to populations of tansy ragwort, the seed predator fly did not negatively affect the relative invasiveness of tansy ragwort. However, the addition of a foliage herbivore to a limited number of populations reduced the relative invasiveness of these populations.Item The invasion potential and competitive ability of Camelina sativa (L.) Crantz (camelina) in rangeland ecosystems(Montana State University - Bozeman, College of Agriculture, 2010) Davis, Philip Browning; Chairperson, Graduate Committee: Fabian D. Menalled.Camelina sativa (L.) Crantz (large-seeded false-flax) is a recently introduced oilseed crop in Montana and has potential for large scale production for the biofuel market. However, due to weedy characteristics, the invasive potential of this species is of concern. A need exists to create a pre-entry protocol to accurately assess risk to minimize uncertainty inherent in qualitative weed risk assessment approaches. We assessed the probability of C. sativa to invade rangeland ecosystems of southwest Montana to address this concern. The objectives of this study were to 1) quantitatively assess the invasion potential of C. sativa by collecting demographic data over two years and developing a population dynamics model, 2) compare experimental results and modeling outcomes to predictions suggested by a qualitative weed risk assessment system, and 3) assess the impact of growing conditions on the relative competitiveness of C. sativa and Brassica napus (L.) (canola). Objective 1 was carried out in two contrasting rangeland ecosystems to assess the effects of disturbance and seeding season on emergence, survival, and fecundity rates of C. sativa. Population growth (lambda) was forecasted by developing a population dynamics model. Resulting lambda values from simulations using observed data never exceeded 0.03 and the maximum time to extinction was six years. The low lambda values indicate that the threat of invasion by this species in the studied ecosystems is low. Objective 2 compared quantitative results to predictions from the Australian weed risk assessment (WRA) model. In contrast to experimental results, outcomes from the WRA suggested that this species should not be allowed entry into the region. These opposing results highlight the need for a more comprehensive approach to weed risk assessment. Objective 3 was conducted over three trials in two greenhouses. A replacement series design was used to estimate the effects of soil conditions and the presence of an invasive weed, Bromus tectorum (L.) (cheatgrass, downy brome), on the competitive outcomes between C. sativa and canola. Replacement series diagrams determined that competition occurred and that canola was the superior competitor in all treatments, thus providing further evidence that the invasion potential of C. sativa is low.Item Detection of leafy spurge (Euphorbia esula) using affordable high spatial, spectral, and temporal resolution imagery(Montana State University - Bozeman, College of Agriculture, 2010) Jay, Steven Charles; Chairperson, Graduate Committee: Rick L. Lawrence; Kevin S. Repasky (co-chair)Leafy spurge is a designated noxious weed. Accurate mapping and monitoring of this species are needed to understand leafy spurge's extent and spread. Current methods are based on ground crews who survey patches. Development of an affordable technique to map and monitor leafy spurge would contribute to the control of this species. High spatial, temporal, and spectral resolution imagery was used to classify the amount of leafy spurge present with ground and aerial-based imagery. A proof of concept study was performed in 2008 using ground-based images of an area infested with leafy spurge. This proof of concept project guided the development of the methods to be used for the 2009 aerial portion of the study. Thirty-five randomly selected reference points were selected in a range area in southwest Montana. These reference points were ground surveyed to record the density of leafy spurge in a 0.5-m radius area around the reference point. Images were captured approximately 108-m from the study area and classified using random forest classification. Multiple images were collected throughout the summer in order to determine at which time period leafy spurge is most easily detected. A classification using multiple image dates was also performed to determine if a time series of images improves classification. Single date accuracies were highest late in the summer with the highest single date classification achieving 83% accuracy. The multiple date classification significantly increased overall accuracy. Several aerial images were acquired in southwest Montana over the 2009 summer. Fifty randomly selected 2-m x 2-m reference areas were surveyed for percent cover of leafy spurge as well as several other variables. Aerial images were collected at flight elevations between 300-m to 460-m. Classifications were performed using random forest classifier, and both single date and multiple date classifications were performed. Leafy spurge was most accurately detected early and late in the growing season, and significant classification accuracy increases were observed with the multiple date classification. Single date accuracies achieved 90% accuracy in early June, while multiple date classifications achieved over 96% accuracy.