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 Impacts of a non-native forb, Alyssum desertorum Stapf., and non-target effects of Indaziflam in the sagebrush steppe of Yellowstone National Park(Montana State University - Bozeman, College of Agriculture, 2021) Meyer-Morey, Jordan; Chairperson, Graduate Committee: Lisa J. RewNon-native plants can reduce biodiversity and disrupt essential ecosystem services and functions. For most non-native plant species however, quantitative evidence of negative effects is lacking, as are fundamental demographic details; such information can inform whether and at what growth stage to implement control. Control strategies can also negatively impact non-target native plant communities; therefore, evaluating the tradeoffs of management and understanding the actual impacts of the invader is essential. I sought to understand the life history, and evaluate the competitiveness and impacts of the non-native annual forb, Alyssum desertorum Stapf., as well as non-target effects of management, across an elevation gradient in a cool, mountain sagebrush (Artemisia tridentata ssp. vaseyana (Rydb.) Beetle) steppe plant community. Seed viability, fecundity, overwintering success, and likelihood of reaching reproductive maturity of A. desertorum all declined as elevation increased; all life stage transition rates were high, suggesting that targeting seed production or fall germination would be the most effective means for control of this species. Replacement series experiments revealed that A. desertorum is a weak competitor with functionally similar species. Additionally, in the field, the presence of A. desertorum did not affect species richness nor Shannon's diversity aboveground or in the soil seedbank, and functionally similar native annual forbs were not displaced in invaded areas. I evaluated the efficacy and non-target effects of the pre-emergent herbicide, indaziflam, in diverse sagebrush steppe with localized infestations of A. desertorum across an elevational gradient. While indaziflam effectively controlled A. desertorum for two years, the richness and diversity of the surrounding community was reduced. Indaziflam inhibited recruitment of forbs, both in the field and in the seedbank. As indaziflam provides residual control of the soil seedbank for up to three years, my results suggest the future community composition may be altered, particularly native annual forb populations. Considering the weak competitive ability of A. desertorum, the species' minimal impacts to richness and diversity, and the negative effects of indaziflam to annual native forb species, I conclude that the non-target effects of indaziflam would outweigh any benefits to controlling A. desertorum in intact sagebrush steppe.Item Restoring semi-arid lands with microtopography(Montana State University - Bozeman, College of Agriculture, 2019) Dillard, Shannon Leigh; Chairperson, Graduate Committee: Anthony HartshornWater is often limiting to plant establishment in semi-arid lands, and this limitation can be especially pronounced in restoration contexts where human legacy impacts and/or non-native plants are present. The application of herbicide and mulch can help retain soil moisture by killing unwanted plant species or lowering evaporative losses, respectively. Creation of microtopography, or soil surface variation, is a third technique that could alleviate growing-season water shortages. Here we report findings from a study that explored the effects of these three techniques combined with broadcast seeding a mix of four native grasses, one native shrub, and one native forb for increasing plant canopy cover and density at three sites in northern Yellowstone National Park. One year after treatment, plant cover in control plots averaged 60%. Across plots treated singly with 1.5% glyphosate herbicide, 3 cm of red cedar mulch, or hand-dug microtopography, only mulch and microtopography increased canopy cover relative to control plots, although the increase consisted mostly of non-native species (>97%). Herbicide, not surprisingly, decreased canopy cover, and that decrease also consisted mostly of non-native species. The herbicide treatment was the most effective in encouraging native species canopy cover and density while simultaneously reducing the same measures of non-native species. Microtopography treatments encouraged growth of all plants (native and non-native), particularly in the micro-lows, but for this to be an effective restoration strategy, non-native species must first be controlled. Although herbicide was quite effective at reducing non-native species populations, particularly at the Cinnabar site, spraying must be timed with the phenology of the existing non-native plant community. We learned that reducing competition with non-native plants does not necessarily encourage native plant growth, which may indicate that growing conditions need to be improved at this site before restoration can be successful. Taken together, our results suggest that soil amendments like microtopography and mulch may have beneficial restoration applications in semi-arid lands but may also show little benefit on a short time-scale in a highly disturbed system. Areas plagued by non-native species invasions and legacy agricultural and grazing impacts are likely to require careful planning of restoration approaches in order to claim long-term success.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 Evaluating non-native annual brome control with herbicides and facilitating Wyoming big sagebrush establishment in degraded drylands(Montana State University - Bozeman, College of Agriculture, 2017) Metier, Emily Pierson; Chairperson, Graduate Committee: Lisa J. Rew; Matt Rinella (co-chair)The degradation of drylands, through resource extraction and non-native annual brome invasion, is a major problem throughout the Intermountain West. Most restoration relies on establishing desired species from seed, but success is limited and establishing Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) is especially failure prone. This study focused on developing methods for controlling annual bromes, specifically cheatgrass (Bromus tectorum L.) and Japanese brome (Bromus japonicus Thunb.), and successfully re-introducing native sagebrush steppe species to degraded drylands. In the greenhouse, I assessed the efficacy of glyphosate and four graminicides (clethodim, sethoxydim, fluazifop, and quizalofop) applied at two rates, to cheatgrass plants of different heights. I also assessed the same five herbicides on three accessions of cheatgrass and Japanese brome. All herbicides reduced cheatgrass biomass, with most effective control on plants less than 11 cm. Overall, glyphosate and sethoxydim treatments were least effective, and quizalofop and fluazifop treatments were most effective. Japanese brome and the disturbed accessions of both species were more susceptible to herbicides than cheatgrass and the undisturbed accessions. My field study targeted the same annual bromes on two Montana coal mines. Four herbicide treatments (control, glyphosate, quizalofop, or glyphosate plus quizalofop) and two seeding treatments (differing in the amount of sagebrush seed) were evaluated for their effectiveness to manage annual bromes and boost seeded species establishment. Half of each herbicide plot was retreated with quizalofop the second year. All herbicide treatments reduced annual brome cover, especially in plots that received glyphosate. Wyoming big sagebrush density and cover of sown species increased in seeded plots with and without herbicides, but there was no difference between seeding treatments. Herbicide effects on seeded species were inconsistent, though generally establishment was greatest in plots receiving glyphosate. Quizalofop retreatment reduced annual brome cover, but did not impact seeded species establishment. These results suggest that targeted herbicide applications can be used to control non-native annual bromes and increase seeded species establishment. Specifically, using glyphosate pre-seeding when plants are small and graminicides post-seeding, can decrease annual brome cover. These treatments can provide a window of opportunity for establishing species from seed, including Wyoming big sagebrush.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 Influence of lodgepole pine spacing intervals and herbicide treatment on soil characteristics(Montana State University - Bozeman, College of Agriculture, 1997) Hagler, Steven EugeneItem Using successional theory to guide restoration of invasive plant dominated rangeland(Montana State University - Bozeman, College of Agriculture, 2003) Anderson, Jennifer Lisa; Chairperson, Graduate Committee: Douglas J. Dollhopf.Item Restoring Russian knapweed-infested riparian areas(Montana State University - Bozeman, College of Agriculture, 2003) Laufenberg, Stephen Michael; Chairperson, Graduate Committee: Roger L. Sheley.