Progress report for GW22-237
Project Information
Montana producers are in a constant balance of managing non-native annual weeds and producing quality forage in high quantities. Ventenata is a non-native annual grass first identified in the United States in 1952 and identified in Montana in the 1990s. As a species with high drought tolerance and low forage quality, it is imperative we find integrated weed management strategies to control this species, while improving forage quality. Our goals are to improve our understanding of ventenata ecology, evaluate integrated weed management practices to control ventenata, increase desired forage and grassland sustainability. We intend to address these goals through two field studies: 1) ventenata and forage response to different growth conditions (current, warmer, warmer + drier) with and without herbicide treatment; and 2) ventenata and forage response to integrated management strategies with herbicides (Axiom, Rejuvra, Rejuvra + Plateau) and fertilizers (N, micronutrient, no fertilizer). Our approach is unique and will add to existing knowledge of how to manage this invasive species. We will share the outcomes of this research with producers, managers, and Montana State University students through several different outreach strategies. We will publish locally and in peer reviewed publications. The findings of this project will provide producers and managers with vital information for controlling ventenata while simultaneously increasing forage quantity and quality using integrated strategies under differing climatic conditions.
The research goals of this project are to evaluate integrated weed management approaches to suppress ventenata and improve quality and quantity of forage by increasing desired grasses. To assess our goals we have three objectives, each with sub-objectives.
The main objectives are:
Objective 1) Quantify ventenata’s competitive ability with other vegetation under different growth conditions (current, warmer, and warmer + drier conditions). These data will allow me to quantify:
1a) the response of ventenata to herbicide (Rejuvra, no spray) under different growth conditions,
1b) if forage and other vegetation are impacted by ventenata and herbicide (Rejuvra, no spray) under different growth conditions, and
1c) if ventenata cycles N more rapidly than cheatgrass and forage species under current conditions.
Objective 2) Evaluate effectiveness of integrated management approaches with herbicides (Axiom, Rejuvra, Rejuvra + Plateau, no spray) and fertilizer (N, micronutrient, no-fertilizer) to control ventenata and improve abundance and quality of desired species. These data will allow me to quantify:
2a) the response of ventenata under different treatment combinations,
2b) if forage and native vegetation are impacted by the treatment combinations, and
2c) if forage quality is impacted by the different treatments.
The educational goals of this project are to further educate Montana producers and managers, the public, and students about the non-native grass ventenata and share outcomes of integrated weed management approaches to suppress ventenata and improve quality and quantity of forage. To assess our goals, we have three objectives.
The main objectives are:
Objective 1) Share our results on the ecology and management of ventenata with producers and managers.
1a) Educate individuals on integrated management strategies effective on ventenata so that they may make informed management decisions for their own properties.
1b) Educate individuals on the identification of ventenata and its ecology under different climates.
Objective 2) Share our results about the quality and quantity of forage following integrated management strategies with producers and managers.
2a) Educate individuals on the outcomes of forage quality tests on ventenata and desired species following management so that they make informed management decisions.
2b) Educate individuals on the changes to forage quantity following management so they may make informed management decisions.
Objective 3) Present research to students at Montana State University enrolled in introductory, intermediate, and advanced plant ecology related courses.
Cooperators
- - Producer
Research
The goals of this project are to evaluate integrated weed management approaches to suppress ventenata and improve quality and quantity of forage by increasing desired grasses. To assess our goals we have three objectives, each with subobjectives.
The main objectives are:
Objective 1) Quantify ventenata’s competitive ability with other vegetation under different growth conditions (current, warmer, and warmer + drier conditions). These data will allow me to quantify:
1a) the response of ventenata to herbicide (Rejuvra, no spray) under different growth conditions,
1b) if forage and other vegetation are impacted by ventenata and herbicide
(Rejuvra, no spray) under different growth conditions, and
1c) if ventenata cycles N more rapidly than cheatgrass and forage species under current conditions.
Objective 2) Evaluate effectiveness of integrated management approaches with herbicides (Axiom, Rejuvra, Rejuvra + Plateau, no spray) and fertilizer (N, micronutrient, no-fertilizer) to control ventenata and improve abundance and quality of desired species. These data will allow me to quantify:
2a) the response of ventenata under different treatment combinations,
2b) if forage and native vegetation are impacted by the treatment combinations, and
2c) if forage quality is impacted by the different treatments.
Methods
Objective 1) was performed on a single site that has a considerable infestation of ventenata. The site has a mix of forage and native grasses (e.g., smooth brome, Kentucky bluegrass, western wheatgrass, and bluebunch wheatgrass) and has not had treatment prior to our own treatments. There was some cheatgrass at the site that was present prior to ventenata invasion. The site is at Amy Cox’s in Gallatin County – see letter of support.
We are evaluating ventenata’s and other species’ response under different climate conditions (current, warmer, warmer + drier) to an herbicide (Rejuvra at 5 oz/acre and no-spray) treatment. These six treatments, 3 climate x 2 herbicides (Figure 1), have been replicated six times totaling 36 plots. We modified current temperatures using open top warming chambers that act as mini greenhouses warming the temperature by ~3.6F (2C), and by adding warming chambers and rainout shelters to partially shield plots (50%) from precipitation to a third of the plots (Figure 2). Soil moisture and temperature is being assessed in each treatment. We established the plots in 2022 prior ventenata germinating and immediately post herbicide application. We assessed the central 1 m2 of each plot, to record cover of each species at the peak of the growing season (July) in 2022 and 2023, will continue in 2024, and additionally assess biomass in 2024. These treatments are novel due to their accounting for different climate treatments simultaneously with herbicide treatments, allowing us to make informed recommendations based on changing climate.
To answer subobjective 1c we will quantify N availability in the rooting zone of ventenata, cheatgrass and dominant forage species (e.g., bluebunch wheatgrass, smooth brome). Nitrate resin strips from Western Agricultural Research will be used and placed in the soil within the rooting zone of each target species and left in for 6-8 weeks. The results will allow us to determine how the different species are cycling N. We will place the strips during the peak growing season (mid-May – mid-July) in both summers (2023-2024), within the control plots (current climate and no-spray).
Objective 2) is being addressed at three locations, west (Sanders County (2)) and east (Cascade County (1)) of the Continental Divide in Montana. The sites in Sanders County are near Hot Springs, MT on collaborating producer Evan Melton’s property, and near Trout Creek, MT on collaborating producer John Josepho’s property, and our site in Cascade County is on collaborating producer Kendra Lane’s property. At each site we established a complete split-plot random block design with herbicide as the main treatment [Rejuvra (5 oz/acre), Rejuvra (5 oz/acre) + Plateau (6 oz/acre), Axiom (flufenacet 4 oz/acre and metribuzin 1 oz/acre), and no spray] and fertilizer as a three-way split treatment (N (40 lb/acre), micronutrients (233 lbs/acre), nothing) (Figure 3). Thus, within each block of four herbicide treatments there are three split plots for the fertilizer, totaling 12 plots per block, and there are 4 blocks (48 plots). Plots were established in August of 2022. Rejuvra and Axiom were applied pre-emergent in August. Plateau was applied when the ventenata emerged in the fall (early October). Micronutrient fertilizer and N fertilizer was spread in August. The herbicide treatment Rejuvra was only approved for use in Montana rangelands in 2020, leaving its impacts on Montana range are understudied especially when used on native dominated sites and in combination with fertilizers. Our micronutrient fertilizer, Edaphix ® is new to the market, and provides a novel strategy to provide perennial grasslands with a fertilizer mix more suitable for their slower growth. By combining the new herbicide and micronutrient products, along with more traditional herbicide treatments (Axiom and Plateau) and N fertilizer, we are creating new integrated weed management strategies that may prove to be useful for Montana producers and managers.
After the establishment of study sites, cover of ventenata was recorded in two 0.75 m2 frames per plot, prior to treatment application. We only sampled ventenata at this time because plots were established late in year due to WSARE funding cycles. In the following two years (2023 and 2024) cover of all species will be sampled at the end of July, with a sub-set of species sampled clipped for biomass, to assess the control of the ventenata and abundance of other vegetation (Objective 2). Percent cover of all species was collected from July 20-27, 2023, with this being the first year of full data collection. Due to increased costs associated with nitrate strips, we decided it was more economical to conduct soil sampling. Soil cores were extracted from each treatment within three blocks at each site in May 2023 and sent to Agvise Laboratories for analysis of soil nitrates, phosphorus, and micronutrients. This allowed us to extract more samples, answer our questions about soil nitrates, and stay within our proposed budget. Biomass samples of ventenata and dominant grass species will be taken to assess forage quality by determining crude protein content and total digestible nutrients (Objective 2c). The samples will be ground using a Wiley mill at Montana State University and analyzed for crude protein content (assessed from N content) and total digestible nutrients (using neutral and acid detergent fiber tests). Forage analysis will allow us to determine if the integrated approaches increase the productivity and quality of forage species.
Analysis
Objective 1) Cover of ventenata, dominant forage grasses, total grasses, species richness, diversity and biomass will be evaluated (response variables) to determine how each is affected by climate and herbicide treatments (fixed variables). We will use generalized linear models with Poisson (richness) and Gaussian (cover, diversity, biomass) distributions, and analysis of variance to determine statistical differences. A post-hoc Dunnett’s test will be conducted to compare the climate and herbicide treatments to the controls (untreated). Dunnett’s test is a pairwise comparison of each treatment to the control, with fewer comparisons than if a full pairwise analysis was done, increasing the statistical power, allowing the researcher to see finer tuned differences between the control and each treatment. This will allow us to see how each treatment impacts the response variables relative to the control. The rate of N cycling will be assessed between ventenata and dominant species using analysis of variance. Data will be checked for model assumptions of heteroscedasticity, normality, and constant variance. If any violations are present, the data will be transformed as necessary.
Preliminary analysis has been completed on the cover of ventenata and all other species richness and diversity for years 1 and 2. Generalized linear models with Poisson (richness) and Gaussian (cover, diversity) distributions were fit, and analysis of variance was used to determine the statistical differences. A post-hoc Dunnett’s test was conducted to determine differences between treatments and control for both years. We found no difference in richness or diversity among treatments within years and between year 1 and year 2 (p>0.83 all). A post-hoc Tukey-Kramer HSD test was conducted to draw comparisons within treatments for each year. We found strong evidence of a decline in ventenata percent cover following herbicide treatment for the non-climate-treated, warming treatment, and warming and drought treatment between 2022 and 2023 (p<0.001 all treatments). However, within 2023 there was weak to moderate evidence of a decrease in ventenata cover within climate treatments when comparing the sprayed and non-sprayed (p<0.07) (Figure 4).
Objective 2) Cover of ventenata, dominant grasses, total grasses, species richness, diversity and biomass will be evaluated (response variables) to determine how each are affected by herbicide and fertilizer treatment as well as site (fixed variables). If site does not differ it will be used as a random effect. We will use generalized linear models with Poisson (richness) and Gaussian (cover, diversity, biomass) distributions, and analysis of variance to determine statistical differences. A post-hoc Tukey HSD test will examine pairwise differences between the treatments. Forage quality among ventenata, cheatgrass, and the dominant species will be assessed using analysis of variance and a post-hoc Tukey HSD test will examine pairwise differences. Data will be checked for model assumptions of heteroscedasticity, normality, and constant variance. If any violations are present, the data will be transformed as necessary.
Objective 1)
To address ventenata’s competitive ability under different growth conditions (current, warmer, warmer and drier), in August of 2022 we established our study site at collaborating producer Amy Cox’s property. Our study is in a complete randomized block design with three climate treatments (control, warmer via open top chamber, warmer and drier via open top chamber and rain out shelter), followed by a split treatment of indaziflam, with six repetitions (36 plots total). We sought to establish our plots in an area with uniform cover of ventenata, but due to the topography and a dense patch of smooth brome, we needed to place six plots 2 m southwest of the others so that the initial cover of ventenata was similar (Figure 1). In July 2022 prior to installing climate treatments and spray, we measured percent cover of all species in the center 1 m² of the plots. We returned to the plots in July 2023 repeated our cover estimates.
Preliminary analysis has been completed on the cover of ventenata and all other species richness and diversity for years 1 and 2. Generalized linear models with Poisson (richness) and Gaussian (cover, diversity) distributions were fit, and analysis of variance was used to determine the statistical differences. A post-hoc Dunnett’s test was conducted to determine differences between treatments and control for both years. We found no difference in richness or diversity among treatments within years and between year 1 and year 2 (p>0.75, all). Ventenata cover was not different among treatment within year 1 (p>0.71), but it was significantly lower in all treatments in year 2 (p<0.01). A post-hoc Tukey-Kramer HSD test was conducted to draw comparisons within treatments for each year. We found strong evidence of a decline in ventenata percent cover following herbicide treatment for the non-climate-treated, warming treatment, and warming and drought treatment between 2022 and 2023 (p<0.001 all treatments). However, within 2023 there was weak to moderate evidence of a decrease in ventenata cover within climate treatments when comparing the sprayed and non-sprayed (p<0.07) (Figure 4).
We will return to the plots in July 2024 to repeat cover sampling, but also collect biomass. Biomass will be analyzed for crude protein content to determine forage quality.
Objective 2)
To evaluate the effectiveness of integrated management with herbicides (Axiom, Rejuvra, Rejuvra + Plateau, no spray) and fertilizer (N, micronutrient, no-fertilizer) to control ventenata and improve abundance and quality of desired species, in August 2022 we established three study sites with two in Sanders County (Melton and Josepho properties) and one in Cascade County (Lane property), on either side of the Continental Divide in Montana. We set up a randomized complete block design with a split plot where herbicide was the main treatment [Rejuvra (5 oz/acre), Rejuvra (5 oz/acre) + Plateau (6 oz/acre), Axiom (flufenacet 4 oz/acre and metribuzin 1 oz/acre), and no spray] and fertilizer as a three-way split treatment (N (40 lb/acre), micronutrients (233 lbs/acre), nothing). Within each block of four herbicide treatments there are three split plots of fertilizer, with 12 plots per block, and 4 blocks (48 plots) (Figure 3). Rejuvra and Axiom were applied pre-emergent in August at the same time as the Micronutrient fertilizer and N fertilizer. Plateau was applied when ventenata was emerged in early October. After the establishment of study sites, cover of ventenata was recorded in two 0.75 m2 frames per plot, prior to treatment application. We only sampled ventenata at this time because plots were established late in year due to WSARE funding cycles. In the following two years (2023 and 2024) cover of all species will be sampled at the end of July, with a sub-set of species sampled clipped for biomass (2024 only), to assess the control of the ventenata and abundance of other vegetation. In May of 2023 soil samples were taken from each treatment combination within three blocks of each site and sent to Agvise Laboratories for analysis of soil pH, salts, nitrate, phosphorous, and micronutrients. Preliminary analysis has not been completed as full species covers for 2023 have not yet been collected by the submission deadline (sampling will occur July 20-28).
Research Outcomes
Objective 1)
Preliminary analysis has been completed on the cover of ventenata and all other species richness and diversity for years 1 and 2. Generalized linear models with Poisson (richness) and Gaussian (cover, diversity) distributions were fit, and analysis of variance was used to determine the statistical differences. A post-hoc Dunnett’s test was conducted to determine differences between treatments and control for both years. We found no difference in richness or diversity among treatments within years and between year 1 and year 2 (p>0.75, all). Ventenata cover was not different among treatment within year 1 (p>0.71), but it was significantly lower in all treatments in year 2 (p<0.01). A post-hoc Tukey-Kramer HSD test was conducted to draw comparisons within treatments for each year. We found strong evidence of a decline in ventenata percent cover following herbicide treatment for the non-climate-treated, warming treatment, and warming and drought treatment between 2022 and 2023 (p<0.001 all treatments). However, within 2023 there was weak to moderate evidence of a decrease in ventenata cover within climate treatments when comparing the sprayed and non-sprayed (p<0.07) (Figure 4). We will return to the plots in July 2024 to repeat cover sampling, but also collect biomass. Biomass will be analyzed for crude protein content to determine forage quality.
The results from this project are preliminary, another full year of data collection is planned before we fully assess the outcomes. The outcomes of this project will elucidate the way a changing climate may impact the spread and density of ventenata, while also impacting its management using indaziflam. This research should continue into the next year so that conclusions can be drawn from multiple years of data.
Objective 2)
For this study, we sampled ventenata in 2022 because plots were established late in year due to WSARE funding cycles, then in the following two years (2023 and 2024) cover of all species will be sampled at the end of July, with a sub-set of species sampled clipped for biomass (2024 only), to assess the control of the ventenata and abundance of other vegetation. Sampling was completed in 2023 from July 20-27. In May of 2023 soil samples were taken from each treatment combination within three blocks of each site and sent to Agvise Laboratories for analysis of soil pH, salts, nitrate, phosphorous, and micronutrients. Preliminary analysis has not been completed as full species covers for 2023 have not yet been collected by the submission deadline.
The results from this project will become clearer following another full year of data collection. The outcomes of this project should provide individuals with ventenata infestations information on integrated management using both herbicides and fertilizers in their fields. Further, this study uses study sites in 3 locations across Montana with varying environmental data, so our outcomes may be applicable to different landowner needs. This research should continue into the next year so that conclusions can be drawn from multiple years of data.
Education and Outreach
Participation Summary:
The educational goals of this project are to further educate Montana producers and managers, the public, and students about the non-native grass ventenata and share outcomes of integrated weed management approaches to suppress ventenata and improve quality and quantity of forage. To assess our goals, we have three objectives.
The main objectives are:
Objective 1) Share our results on the ecology and management of ventenata with producers and managers.
1a) Educate individuals on integrated management strategies effective on ventenata so that they may make informed management decisions for their own properties.
1b) Educate individuals on the identification of ventenata and its ecology under different climates.
Objective 2) Share our results about the quality and quantity of forage following integrated management strategies with producers and managers.
2a) Educate individuals on the outcomes of forage quality tests on ventenata and desired species following management so that they make informed management decisions.
2b) Educate individuals on the changes to forage quantity following management so they may make informed management decisions.
Objective 3) Present research to students at Montana State University enrolled in introductory, intermediate, and advanced plant ecology related courses.
Methods
Objectives 1 & 2 will be addressed through interactions with cooperating producers and managers along with the public which may include other impacted landowners. Interactions that cooperators have with other landowners and land managers are a critical means to circulate the information gained through this project to the most relevant end-users. Advising professor Dr. Jane Mangold is an Extension specialist from Montana State University who will facilitate meetings with Extension agents and county weed coordinators in the different counties. With her, I can join local field days and present my findings at local meetings. Additionally, information will be disseminated through established outreach events such as those sponsored by Montana State University Extension or the Montana Weed Control Association. We will also seek out opportunities in less technical publications such as the Montana State University Extension Lives and Landscapes and Big Sky Small Acres as well as newsletters focused on weed management and conservation such as the Missoula County’s Healthy Acres and Montana Weed Control Association’s Weed Times as well as Dr. Mangold’s Monthly Weed Post. Finally, results of this research will be appropriate for publication in journals such as Invasive Plant Science and Management or Journal of Range Ecology and Management. We will plan at least for one to two peer reviewed publications. We also intend on printing pamphlets to distribute at outreach events that will offer information on my project, ventenata, and integrated weed management. These pamphlets will be written so that they are accessible to anyone who attends an outreach event and will offer direction for if they would like more information from me directly, or through Montana State University Extension resources. We will also utilize digital media to share our project to a wider audience. Details about the project progress and outcomes will be available on social media including: Twitter (MSU Weed Ecology, @MSU_ecology), as part of Dr. Mangold’s Monthly Weed Post (http://msuinvasiveplants.org/extension/monthly_weed_post.html), and our group website (https://www.montana.edu/plantinvasions/). We anticipate reaching a wider audience through social media that may include individuals who wouldn’t have previously known about or attended our outreach events. This way we will be able to interact instantaneously with a broader audience, and potentially attract more individuals to outreach events. During our sampling season of 2022 we met with all cooperating landowners to explain our reasoning with our experiments, offer explanations of the treatments, and describe anticipated results. Interactions have continued into the sampling season of 2023.
Analysis
To determine the effectiveness of our educational outreach programs, we will offer all of those in attendance WSARE approved surveys. We will accompany these surveys with further questions on their understanding of ventenata and integrated weed management so that we can assess attitudes and perspectives of attendees following our presentations. We will also offer collaborating producers and managers a WSARE approved survey at the beginning and end of our study to determine if they are interested in further adoption of the techniques we evaluated on their properties. These surveys will help us determine if our project led to any changes in practices and attitudes. These results will be available in follow-up reports.
The classroom presentations were evaluated through discussion with the classes during and following my presentations. I offered prepared questions at the beginning of the lesson and discussion-oriented questions at the end of the lecture. The discussion engaged students in questions about invasive species, management practices, and ecological implications of management practices. Classes also discussed study design, and how they would conduct a similar study (Would they make any changes? Are there different considerations they would make?). These discussions allow me to gauge if the students understood the presentation but should also allow them the opportunity to think through the concepts they’ve learned and combine them with previous concepts taught in those courses.
To address Objectives 1 & 2, on July 26, 2023, we had a field day with representatives from the Sanders County Weed Board, Montana NRCS, Montana State University extension, and local landowners, where they visited our research site at Evan Melton’s property. At this field day I presented everyone with our research goals, study design, and anticipated results (informational document presented attached). We toured the site and made field observations of treatment effects. We assisted landowners in identifying ventenata, and discussed their options for their own property needs. We were able to discuss as a group the needs of Sanders County with respect to ventenata and display our first year’s results to individuals who are invested in the results of our study.
To address Objective 3, I have presented aspects of my research to a Montana State University class ENSC 410/LRES 510 (Biodiversity Survey methods) and will continue to present to other classes including: ENSC 110 (Introduction to Land Resources and Environmental Sciences) and ENSC 210 (Plants and the Environment). ENSC 410/LRES 510 is a co-convened undergraduate and graduate level course that teaches students strategies used for measuring biodiversity, analysis of biological data, and the importance of studying biodiversity. These projects were used as examples of experimental design strategies within a lecture on imposing treatments on to a landscape. This lecture delved into why I designed the experiments the way I did, how we would sample from our treatment plots, and how one could do a basic statistical analysis on these types of data. This class also requires students conduct a project where they collect their own biodiversity sampling and write a report. In August of 2022 graduate students from the course visited the Amy Cox site (Research Objective 1) to look at the treatments and design. Discussions were held on the objectives and methods of the study, and students were able to examine site up close. Students conducted independent projects at the same site with an emphasis on the same species of interest (Ventenata dubia), however their projects focused on the treatment effect of the Edaphix micronutrient fertilizer from Research Objective 2, that was applied on the same property in a different area from my experiment (but not as part of my project). Students were able to discuss the effects of the product and analyze the richness and diversity following treatment. ENSC 110 and ENSC 210 are undergraduate courses that incorporate an element of guest lecturers who teach about different environmental science and agricultural concepts, along with experimental design. My research would offer these students a look at the use of integrated weed management strategies in grasslands, and how we must consider the response of desired species in these studies, not just the target weed. I could also offer my results to display ecological concepts surrounding plant community response to different climatic conditions and drought. These classes often discuss the basics of experimental design when studying plants, but I could offer detailed explanations of my methods with firsthand pictures and diagrams, and results, so that they could have a more tangible understanding of experimental design. Beyond teaching students, this will also introduce my research to undergraduate students who may have an interest in assisting me through an unpaid internship which will provide them with field work experience.