Theses and Dissertations at Montana State University (MSU)
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Item Ventenata (Ventenata dubia) control treatments on the Crow Reservation(Montana State University - Bozeman, College of Agriculture, 2023) Fighter, Zachariah Zachary Zane; Chairperson, Graduate Committee: Jane M. Mangold; Scott Powell (co-chair)Ventenata (Ventenata dubia) is a non-native winter annual grass that has been of increasing concern in southeastern Montana. Research has shown that ventenata can increase rapidly, lower forage production, and reduce biodiversity. This project is located in southeastern Montana, in Bighorn County on the Crow Reservation. Two studies were conducted to understand control options and monitoring of those treatments post-treatment. A field study tested two herbicides and a soil amendment for the management of ventenata. At four sites, indaziflam and imazapic at two water carrier rates and two rates of an organic soil nutrient amendment were tested using a split-plot randomized block design. The water carrier rates were meant to mimic aerial and ground applications. Herbicides were applied using a hand-held boom sprayer pressurized by CO 2. Soil amendment was hand-broadcasted. In late June 2022 (first growing season post-treatment), sampling consisted of randomly placing 3, 20 cm x 50 cm frames in each split-plot and estimating cover by species along with litter and bare ground. Imazapic and indaziflam provided the highest reduction of ventenata, regardless of water carrier rate. Across the four sites, imazapic reduced ventenata cover to <1% while indaziflam reduced cover to 4%, compared to the control which was 38%. The soil amendment reduced ventenata to 25% at two sites, suggesting it may not be as promising of a control method as the herbicides. Application rates for all treatments did not differ, suggesting that aerial application of the herbicides may provide just as good of control as ground application. This is encouraging for the prospect of managing ventenata aerially. At one of the sites, a remote sensing time series study using an Unmanned Aerial Vehicle (UAV) with a multispectral sensor was used to understand differences in the Normalized Difference Vegetation Index (NDVI) between herbicide sprayed and non-sprayed plots. Findings indicate that there is a shift in NDVI in late June where sprayed plots peak in NDVI and remain green longer into the season than non-sprayed plots. This study provides control options that land managers in southeastern Montana can consider using for ventenata management.Item Using genetic and genomic techniques to uncover cryptic diversity for improving aquatic invasive plant management(Montana State University - Bozeman, College of Agriculture, 2021) Chorak, Gregory Michael Thomas; Chairperson, Graduate Committee: Ryan Thum; This is a manuscript style paper that includes co-authored chapters.Genetic diversity can be important at many levels of invasive species management. And, for different questions, it matters at which level we measure diversity to understand its relevance. Some invaders may look similar to other species, so identifying the species to be managed may be difficult without genetic tools. Once the species has been identified, understanding the diversity in that species may be important to identify management units, invasive traits, and the possibility of spread. Finally, understanding how the alleles an individual possesses determine the traits expressed can give managers the tools to control for unwanted traits of an invasive species. In this body of work, I uncover diversity at the species/taxon level, the genotype/clone level, and finally at the gene level in invasive aquatic weed species. At the taxon level, I found that one invasion of aquatic weeds in the northeastern US was actually two or more separate invasions and taxa. At the genotype level, I found that the same genotype responds the same to a common herbicide management regardless of where it is found, and that different genotypes have varying responses to a common herbicide treatment. And, at the gene level, I found that different genotypes with different growth rates have different gene expression in the control and transcriptional response to a common herbicide treatment. At each of these levels, managers have questions and concerns about management decisions. Understanding that there were two unique taxa in what was considered one invasion informed managers that there may be variance in management relevant traits between the two. In the genotype level study, we learned that determining which clones are present in a lake slated for herbicide management may inform which herbicides to use. And, at the gene level, we are starting to understand the molecular process of management relevant phenotypes so that one day managers can screen for molecular markers that will reveal herbicide response of individuals slated for management.Item Management of Kochia (Bassia scoparia) in a time of herbicide resistance(Montana State University - Bozeman, College of Agriculture, 2020) Lim, Charlemagne Ajoc; Chairperson, Graduate Committee: Alan T. Dyer; Alan Dyer and Prashant Jha were co-authors of the article, 'Kochia (Bassia scoparia) growth and fecundity under different crops and weed densities' submitted to the journal 'Weed science journal' which is contained within this dissertation.; Alan Dyer and Prashant Jha were co-authors of the article, 'Survival and reproductive fitness of glyphosate-resistant kochia (Bassia scoparia) in the presence of glyphosate' submitted to the journal 'Weed technology journal' which is contained within this dissertation.; Alan Dyer and Prashant Jha were co-authors of the article, 'Survival, growth and fecundity of Dicamba-resistant kochia (Bassia scoparia) in the absence and presence of Dicamba' submitted to the journal 'Weed technology journal' which is contained within this dissertation.Kochia [Bassia scoparia (L.) A. J. Scott] is one of the most troublesome weeds in the US Great Plains. This is exacerbated by the development of herbicide-resistant kochia populations which necessitates more ecologically driven approaches for its control. This research examined the competitive effects of four crops (sugar beet, soybean, barley and corn) in combination with kochia densities (3, 13, 24, 47, 94 and 188 plants m-2) on kochia development and kochia seed production. Corn had greatest effect in reducing kochia biomass and seed production. Barley had greatest effect in delaying kochia flowering which happened after barley senesced at 113 days after kochia emergence. Soybean and sugar beet had the least effect in reducing kochia biomass and seed production, respectively, relative to fallow. This research also reports the fitness of glyphosate-resistant kochia and dicamba-resistant kochia in the presence and absence of glyphosate and dicamba selection, respectively, under field conditions. Glyphosate-resistant kochia showed limited fitness cost (less seed weight and seed radicle length relative to the susceptible) in the absence of glyphosate selection and reduced reproductive fitness (seed production) in the presence of increasing glyphosate selection. In the absence of dicamba selection, dicamba-resistant kochia showed a fitness cost (reduced growth and seed production relative to the susceptible) associated with dicamba resistance with greater fitness cost observed with increased level of resistance. Dicamba-resistant kochia also showed reduced reproductive fitness (seed production) in the presence of increasing dicamba selection. Overall, this research provides information on the growth and reproductive fitness of glyphosate-resistant kochia and dicamba-resistant kochia in the presence and absence of glyphosate and dicamba selection, respectively. Furthermore, this research provides insights on the competitive abilities of different but financially viable rotational crops for kochia management in Montana.Item Understanding mechanisms of invasion and restoring lands impacted by non-native annual grasses(Montana State University - Bozeman, College of Agriculture, 2020) Majeski, Michelle Lynn; Chairperson, Graduate Committee: Jane M. Mangold; Catherine Zabinski, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Ventenata dubia growth responds to field soil inocolum but not phosphorous and potassium treatments' which is contained within this thesis.; Catherine Zabinski, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Ventenata dubia was associated with perennial grasses, bare ground and soil potassium concentration' which is contained within this thesis.; Stacy C. Simanonok, Zach Miller, Lisa J. Rew and Jane Mangold were co-authors of the article, 'Spring seeding provides a seasonal priority effect for Pseudoroegneria spicata in Bromus tectorum-invaded rangelands' which is contained within this thesis.European settlement and development of rangelands in the western U.S. has led to a shift in vegetation from native species to introduced species, some of which have become weedy and invasive. Effects of invasive plant species can vary but often include replacing native vegetation, altering ecosystems, affecting wildlife that relied on the native plants for food and shelter, and toxicity to livestock. Two introduced annual grasses of concern are Ventenata dubia and Bromus tectorum. These grasses are at different stages in their invasion in the western U.S. Ventenata dubia is a recent invasive species in the past ten years and B. tectorum has been dominant in the Intermountain West since the mid-1900s. Three independent studies were conducted to understand characteristics of V. dubia invasion and to test whether a seasonal priority effect could be shifted to Pseudoroegneria spicata to outcompete B. tectorum in range/pasturelands. A full-factorial design was executed in a greenhouse setting to examine if a plant-soil feedback contributes to V. dubia invasion and if V. dubia preferred specific nutrients for growth. Ventenata dubia biomass, shoot height and number of leaves and tillers (per plant) were higher when grown with field soil inoculum compared to sterilized greenhouse soil. Ventenata dubia growth varied among nutrient treatments, but trended higher with a full nutrient solution. A nested observational study was conducted to examine abiotic and biotic characteristics associated with V. dubia infestations. Ventenata dubia was positively associated with non-native perennial grasses and negatively associated with native perennial grasses, bare ground/rock and soil potassium concentration. A randomized split-plot design was performed in B. tectorum-infested range and pasturelands to test whether timing of herbicide application and seeding of P. spicata could create a seasonal priority effect for P. spicata. Bromus tectorum had lower cover and biomass (per m2) with spring herbicide application. Higher P. spicata density, cover and biomass resulted with spring seeding after B. tectorum was reduced. These studies show that established and seeded native perennial grasses can compete with nonnative, invasive annual grasses. When existing management tools (herbicide and revegetation) are applied in a different way, native perennial grasses benefit.Item Understanding the biology, ecology, and integrated managment of Ventenata dubia(Montana State University - Bozeman, College of Agriculture, 2019) Harvey, Audrey June; Chairperson, Graduate Committee: Jane M. Mangold; Lisa Rew, Timothy Prather and Jane Mangold were co-authors of the article, 'The effects of elevated temperature and CO 2 concentration on seedling growth of Ventenata dubia and Bromus tectorum' submitted to the journal 'Western North American naturalist' which is contained within this thesis.; Lisa Rew, Timothy Prather and Jane Mangold were co-authors of the article, 'Indaziflam provided up to three-years of control for Ventenata dubia in southwestern Montana' submitted to the journal 'Invasive plant science and management' which is contained within this thesis.; Stacy Davis, Lisa Rew, Timothy Prather and Jane Mangold were co-authors of the article, 'Effect of seeding date of Pseudoroegneria spicata (bluebunch wheatgrass) on establishment and subsequent ability to resist invasion by Bromus tectorum (cheatgrass)' submitted to the journal 'Ecological restoration' which is contained within this thesis.Ventenata dubia (Leers) Coss., common name ventenata or African wire grass, is a non-native winter annual grass of increasing concern in western Montana. In North American, V. dubia appeared in the early 1950s; since then it has successfully established in the northeastern and northwestern United States. It is known to invade areas previously inhabited by Bromus tectorum (cheatgrass) and Taeniatherum caput-medusae (medusahead). In the Intermountain Pacific Northwest, V. dubia has caused substantial ecological and economic impacts in perennial grass habitats. Varying disturbance regimes contribute to its rapid expansion over the last decade. Impending climate change threats have the potential to exacerbate the spread of this invasive species. Three independent studies were conducted to explore the biology, ecology, and integrated management of V. dubia populations in Montana to alleviate impacts by this species and other invasive annual grasses. A growth chamber study tested the effects of elevated carbon dioxide and temperature on seedling growth of V. dubia in response to climate change and in competition with B. tectorum. This competition replacement study indicated that at elevated climate conditions V. dubia and B. tectorum grow smaller and competition with V.dubia has the potential to decrease B. tectorum growth. A field-based herbicide efficacy trial utilizing the active ingredient indaziflam compared it to other commonly used herbicides to determine long-term control of V. dubia and potential plant community changes at 8, 11, 20, and 23 months after treatment. Foliar cover, species richness, and functional group biomass were collected. Findings indicated indaziflam can control V. dubia up to three years with positive implications for plant community dynamics. A revegetation study was used to determine the optimum seeding time for perennial grass species, Pseudoroegneria spicata, and the effects seeding time can have with competition dynamics with B. tectorum. A randomized complete block design was established and P. spicata grown for one season prior to Bromus tectorum seeding. After the second growing season, tillers and biomass were collected for both species. Findings indicated priority effects can occur with fall and early spring seeding of P. spicata, with implications for suppression of B. tectorum at earlier seeding dates.Item Restoration of spotted knapweed infested grasslands in Glacier National Park(Montana State University - Bozeman, College of Agriculture, 2003) Stringer, Lewis Tipton; Chairperson, Graduate Committee: Catherine A. ZabinskiThere is an immediate and on-going need in Glacier National Park (GNP), and other public and private lands, to determine effective methods to re-establish and sustain native plant populations following control treatments of Centaurea maculosa. My research was developed in response to GNP concerns regarding annual herbicide treatment of C. maculosa invaded sites. The aim of this study was to determine if herbicide applications, site preparation and revegetation methods would increase the density and percent cover of native species, while reducing spotted knapweed at two sites in and near Glacier National Park. A priori contrast analysis was used to determine differences in treatment effects. The results of my experiment show that spot spray herbicide application reduced C. maculosa cover without significantly reducing existing native forbs. However, a repeat-herbicide application increased exotic graminoid cover. Tillage reduced the density of C. maculosa seedlings, but resulted in an increase in C. maculosa percent cover, and an overall decline in native forbs. Revegetation methods had limited success at increasing native species, and reducing C. maculosa. The only effect was at Swift Current, where the percent cover of native forbs was significantly higher with the planting treatment, and most pronounced in plots with repeat-herbicide application. Additionally, we measured the composition and density of the seed bank in C. maculosa dominated sites using the seedling emergence method. C. maculosa density was 3,900 and 6,714 seeds / m 2 at the two sites, which was 2 and 3 times higher than the sum of all other species. Seed bank composition and density needs to be considered in efforts to restore C. maculosa infested areas.Item Effect of spectral band selection and bandwidth on weed detection in agricultural fields using hyperspectral remote sensing(Montana State University - Bozeman, College of Agriculture, 2017) Tittle, Samuel Bryant; Chairperson, Graduate Committee: Rick L. LawrencePresence of weeds in agricultural fields affects farmers' economic returns by increasing herbicide input. Application of herbicides traditionally consists of uniform application across fields, even though weed locations can be spatially variable within a field. The concept of spot spraying seeks to reduce farmers' costs and chemical inputs to the environment by only applying herbicides to infested areas. Current spot spraying technology relies on broad spectral bands with limited ability to differentiate weed species from crops. Hyperspectral remote sensing (many narrow, contiguous spectral bands) has been shown in previous research to successfully distinguish weeds from other vegetation. Hyperspectral sensor technology, however, might not currently be practical for on-tractor applications. The research objectives were to determine (1) the utility of using a limited number of narrow spectral bands as compared to a full set of hyperspectral bands and (2) the relative accuracy of narrow spectral bands compared to wider spectral bands. Answers to these objectives have the potential for improving on-tractor weed detection sensors. Reference data was provided by field observations of 224 weed infested and 304 uninfested locations within two winter wheat fields in Gallatin County, Montana, USA. Airborne hyperspectral data collected concurrently with the reference data provided 6-nm spectral bands that were used in varying combinations and artificially widened to address the research objectives. Band selection was compared using Euclidean, divergence, transformed divergence, and Jefferies-Matusita signature separability measures. Certain three and four narrow band combinations produced accuracies with no statistical difference from the full set of hyperspectral bands (based on kappa statistic analysis, alpha = 0.05). Bands that were artificially widened to 96 nm also showed no statistically significant difference from the use of 6-nm bands for both all bands and select band combinations. Results indicate the potential for bands that can differentiate weed species from crops and that the narrowest spectral bands available might not be necessary for accurate classification. Further research is needed to determine the robustness of this analysis, including whether a single set of spectral bands can be used effectively across multiple crop/weed systems, or whether band selection is site or system specific.Item Optimizing efficacy of Bromus tectorum (cheatgrass, downy brome) biological contorl in crops and rangelands(Montana State University - Bozeman, College of Agriculture, 2017) Ehlert, Krista Ann; Chairperson, Graduate Committee: Fabian D. Menalled; Jane M. Mangold (co-chair)Management of Bromus tectorum L., an annual grass invasive in western North America, has focused on single and integrated methods across crop and non-crop settings. Extensive literature does not exist on the integration of Pyrenophora semeniperda, a generalist grass pathogen for B. tectorum control, which has been used experimentally with some success to control B. tectorum. However, questions remain about (1) the risk of non-target effects on grassy species, (2) efficacy as part of an integrated management plan, and (3) efficacy under different environmental conditions and on different B. tectorum populations. I sought to answer these questions with three distinct studies. First, I assessed the risk of P. semeniperda on B. tectorum and 15 co-occurring grass species in a greenhouse setting. Pyrenophora semeniperda reduced B. tectorum density by 40% but also negatively affected density of 60% of the non-target species tested, particularly native rangeland grasses. Second, I integrated P. semeniperda as part of a two-year rangeland revegetation management plan that included an herbicide (imazapic), a fungicide seed treatment, and different perennial grass seeding rates. Application of P. semeniperda did not increase inoculum loads above ambient levels, and there was no effect of seeding rate or seed treatment on B. tectorum or seeded perennial grass density or biomass. However, B. tectorum density was reduced by 60% the first year with a single imazapic application. Lastly, I compared the effects of temperature (13°C, 17°C, 21°C, 25°C, 32°C) and B. tectorum populations (range, crop, sub-alpine) on infection and mortality rates caused by P. semeniperda using a temperature gradient table. Infection rates by P. semeniperda peaked at intermediate temperatures (17°C, 21°C, 25°C) for range and sub-alpine populations, but were generally low and not as influenced by temperature in the crop population. Overall, B. tectorum control with P. semeniperda is possible, provided (1) non-target effects are considered, especially for range species, (2) research is conducted to increase P. semeniperda inoculum loads above ambient levels and revegetation is used with other control tactics, and (3) we take into account how distinct B. tectorum populations respond to P. semeniperda.Item How do county extension agents and extension specialists use the demonstration technique for extending weed research findings to farmers in Montana(Montana State University - Bozeman, 1976) Gursoy, Orhan VedatItem An assessment of the use of site-specific weed control for improving prediction-based management decisions and automating on-farm research(Montana State University - Bozeman, College of Agriculture, 2001) Luschei, Edward Charles