Progress 10/01/16 to 09/30/17

Outputs
Target Audience:This research aims to advance knowledge in the discipline of weed science, particularly in the sub-disciplines of weed ecology and weed management in agricultural environments. Research is especially focused on addressing weed management problems in vegetable and commodity crops in New Mexico, as well as the invasive plants that threaten sustainble applications of partially treated wastewater in agricultural and rangeland environments. A target audiences for this project include scientists who conduct research on the biology and management of weeds, as well as educators who teach in crop production. The target audience also includes crop producers, land managers and agricultural professionals in the United States Southwest. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Project objective 1: This objective is providing training opportunities for one graduate student and two undergraduate students. Project objective 2: This objective is providing training opportunities for two undergraduate students. Project objective 3: This objective is providing training opportunities for one graduate student and two undergraduate students. How have the results been disseminated to communities of interest?Project objective 1: Results were communicated to farmers and agricutural professionals at the 2017 Field Day held at the New Mexico State University Agricultural Science Center at Los Lunas. Results from previous reporting periods were published in peer-reviewed scientific journals including Weed Science, Rangeland Ecology and Management, Weed Technology Project objective 2: Results were shared with the scientific community at the 57th Annual Meeting of the Weed Science Society of America Project objective 3: Results were communicated to farmers and agricultural professionals at the2017 Field Day held at the New Mexico State University Agricultural Science Center at Los Lunas, as well as the New Mexico Sustainable Agriculture Conference. Results were shared with the scientific community at the 57th Annual Meeting of the Weed Science Society of America, as well as through a peer-revieed article published in Weed Technology. What do you plan to do during the next reporting period to accomplish the goals?Project objective 1: Field experiments on weed management and weed persistence in chile pepper and onion will continue. These field experiments, as well as the associated laboratory studies, will be completed during the next reporting year. Results will be shared with the agricultural community at the New Mexico Sustainable Agriculture Conference. Results will be shared with the scientific community at a professional society meeting. Project objective 2: Laboratory studies on methods for identifying and quantifying mechanical damage to weed seeds will be completed. Data for this study will be analysed. A manuscript from this study will be prepared and submitted to a peer-reviewed scientfic journal. Project objective 3: Results from the stale seedbed study will be communicated through a presentation at a scientfic society conference, as well as through a manuscript submitted to a peer-reviewed journal. New research on Calibrochoa parviflora seedbank management will be initiated. This new research will build on current research described under Project Objective 1.

Impacts
What was accomplished under these goals? Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. New lines of research on weed persistence and interference were initiated during this reporting period. Building on previous research on weed management in New Mexico onion production, one new study pertains to weed management in onions in New Mexico. During a typical summer, New Mexico produces approximately 46% non-storage (fresh market) onions in the United States. Onion production in New Mexico mostly occurs in three contiguous counties in the southern region of the state (Doña Ana County, Luna County, Sierra County). In this region, onion production is challenged by a weed species that is not widely reported in the United States, Calibrachoa parviflora (Juss.) D'Arcy. Although C. parviflora is not considered a primary pest in onion at the national scale, as evidenced by this species' absence in the Pest Management Strategic Plan for Dry Bulb Onion Production in the United States, this weed is reported as a significant barrier sustainable onion production in southern New Mexico. To initiate research that develops ecologically-influenced, yet practical, management solutions for C. parviflora in onion, we established a field study to measure interference and seed production by C. parviflora in fall-seeded onions. This study is located at a university research farm that occurs within Doña Ana County, New Mexico. Using procedures that are customary for onion production in the region, a field was prepared and onion was seeded into raised beds (4 onion rows bed-1) at 2.3 kg ha-1 during Fall 2017. In Spring 2018, the following C. parviflora density treatments will be established in the onion field 0 plants m2, 1 plants m2, 2 plants m2, 4 plants m2, 8 plants m2, 16 plants m2. Weeds other than C. parviflora will be controlled with herbicides and hand hoeing. In summer 2018, the following data will be collected: onion yield, C. parviflora biomass, C. parviflora seed production and C. parviflora seed dormancy characteristics. Calibrachoa parviflora seeds for this study were collected and cleaned during 2017. This study will provide first insights on the economic damage incurred from C. parviflora and will spur the development of ecological strategies for C. parviflora in onion. This study was designed in consultation with onion production experts at NMSU. An additional new line of research was initiated to study a promising, but untested, non-herbicidal technique for weed management in chile pepper: biofumigation with mustard (Brassicaceae family) seed pomace, which is hereafter referred to as "mustard seed meal" and abbreviated "MSM". MSM is known to reduce pathogen propagule densities in soil and plant infections by soil-borne pathogens, and thus, this study features collaborations with a plant pathologist at NMSU. The effects of MSM soil amendments on weed densities, seedbanks and management have yet to studied in the context of chile pepper production. To address this knowledge gap, a field study was initiated to measure MSM effects on weed seed survival, weed seedling densities and hand hoeing requirements in chile production. Materials including MSM, weed seeds and study sites were acquired and prepared in 2017. In Spring 2018, the following three treatments will be implemented at two university research farms prior to chile planting: 1) no MSM, 2) MSM at 2,200 kg ha-1, and 3) MSM at 4,400 kg ha-1. After chile pepper planting, response variables measured will include weed seedling emergence at weekly intervals, rates of survival for seeds buried in mesh bags and hoe time requirements throughout the chile season. Biofumigation properties of MSM are attributed to hydrolysis of glucosinolate compounds and the subsequent release of volatile compounds that are toxic to many plant pathogens and weeds seeds. In order to understand the influence of soil moisture on the hydrolysis of glucosinolates, this project will include a controlled moisture study in the lab. This project will utilize cores comprised of soil, known quantities of weed seeds and MSM. Cores will be subjected to treatment including 1) hydration to specific moisture contents, and 2) saturation for various amounts of time. At time intervals after hydration, glucosinolate concentrations in soil and rates of seed survival will be determined. Glucosinolates will be quantified with high-performance liquid chromatography (HPLC). Preliminary experiments necessary for developing HPLC procedures were conducted in this reporting period. Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks Previous research in this project developed a technique for detecting mechanical damage on Poaceae seeds. Specifically, we distinguished damaged from non-damaged seeds by soaking individual seeds in a resazurin solution that changed light absorbance properties in response to seed coat damage. Such an assay is important because the structural integrity of covering structures is known to be a primary determinant of seed longevity in soil, and thus, instigating superficial damage is considered a possible approach for reducing weed seedbank densities. In this reporting period, the resazurin technique for detecting mechanical damage on Poaceae seeds was studied to better understand its underlying biochemical mechanisms. Results revealed that mechanical damage to seed coats caused the embryo to release hydrogen ions that induce the diagnostic changes in resazurin solution. With this new knowledge on the relationship between seed injury and resazurin properties, we improved the resazurin solution so that the assay now detects mechanical damage on seeds of species in addition to those from the Poaceae plant family. Economically important weeds for which damaged seeds have been distinguished with our assay include Anoda cristata, Ipomoea purpurea, Eragrostis cilianensis, Amaranthus palmeri, Echinochloa crus-galli, Kochia scoparia, Echinochloa colona, Rumex crispus, Setaria viridis. Because many plant families have been successfully assessed with our assay for seed damage, we expect that this seed testing technique will facilitate the development of technologies for injuring weed seeds that are applicable in a wide range of agricultural settings. Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems A stale seedbed is a set of practices that first stimulates weed seed germination through tillage and irrigation and then eliminates subsequent seedlings with non-selective control. A multi-year field study on stale seedbeds for chile pepper production was completed and analyzed in this reporting period. These analyses included comprehensive cost-benefit evaluations that indicated (1) stale seedbeds cost $21 to $33 acre-1 to implement in southern New Mexico, and (2) stale seedbeds reduced hand hoeing expenses in chile pepper by $291 to $462 acre-1. Accordingly, the net effect of stale seedbeds on production expense was a savings of $258 to $440 acre-1. Providing growers information on the effects of stale seedbeds on labor expenses for chile pepper production might promote adoption of such strategies because: 1) costs and availability of labor are primary constraints on chile pepper production in New Mexico, and 2) adoption of an integrated weed management practice is generally influenced by grower perceptions of the practice's economic value in the context of the local cropping system. Stale seedbeds were also found to reduce weed seedling densities in chile pepper during Run 1, but not Run 2. Variability between runs in stale seedbed effects on weed seedling density may have reflected differences in initial seedbank density (Run 1, 4096 ± S.E 653 seeds m-2; Run 2, 1201 ± S.E 187 seeds m-2).

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Hooks, T. N., G. A. Picchioni, B. J. Schutte, M. K. Shukla, D. L. Daniel, J. Ashigh. 2018. Salinity an environmental filter selecting for plant invasiveness? Evidence from the indigeneous Lepidium alyssoides on Chihuahuan desert shrublands. Rangeland Ecology and Management 71:106-114
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Klypina, N., M. Pinch, B. J. Schutte, J. Maruthavanan, T. M. Sterling. 2017. Water-deficit stress tolerance differs between two locoweed genera (Astragalus and Oxytropis) with fungal endophytes. Weed Science 65:626-638
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Landau, C. A., B. J. Schutte, A. O. Mesbah, S. V. Angadi. 2017. Flixweed (Descuraina sophia) shade tolerance and possibilities for flixweed management using rapeseed seeding rate. Weed Technology 31:477-486
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Flores, A. M., M. K. Shukla, B. J. Schutte, G. A. Picchioni, D. L. Daniel. 2017. Physiologic response of six plant species grown in two contrasting soils and irrigated brackish groundwater and RO concentrate. Arid Land Research and Management 31:182-203
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Schutte, B. J. 2017. Measuring interference from mid-season tall morningglory to develop a model for teaching weed seedbank effects on chile pepper. Weed Technology 31:155-164
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Sanchez, A., B. J. Schutte, L. Beck, O. J. Idowu. 2017. Stale seedbed for summer annual weeds in New Mexico chile. Proceedings of the 57th Annual Meeting of the Weed Science Society of America 57:9
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Wood J., Marquez, I., B. J. Schutte. 2017. A non-destructive assay for determining viability of weed seeds. Proceedings of the 57th Annual Meeting of the Weed Science Society of America 57:94

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:This research is directed towards advancing knowledge in the field of weed science, particularly the discliplines of weed ecology and integrated weed management. Thus, a target audience for this project includes scientists who conduct research, teaching and extension activities related to the management and biology of weeds. The target audience also includes crop producers, land managers and agricultural professionals in the United States Southwest. Research is especially focused on addressing the weed management problems that challenge vegetable, forage and commodity production in New Mexico, as well as the invasive plant problems that threaten sustainable applications of partially treated wastewater in agricultural and rangeland environments. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Project objective 1: This project is providing training for two undergraduate students. Project objective 2: This project is providing training two undergraduate students. Project objective 3: This project is providing training for one graduate student and two undergraduate students. How have the results been disseminated to communities of interest?Project objective 1: Results were communicated to farmers and agricultural professionals at the New Mexico Crop Producers Association Annual Conference and the New Mexico Chile Conference and the New Mexico State University Agricultural Experiment Station Chile Pepper Field Day. Results were shared with the scientific community at the 56th Annual Meeting of the Weed Science Society of America, as well as a paper published in Weed Technology. Project objective 2: Results will be shared with the scientific community at the 57th Annual Meeting of the Weed Science Society of America (2017) - abstract submitted. Project objective 3: Results were communicated to farmers and agricultural professionals at the New Mexico Crop Producers Association Annual Conference and the New Mexico Chile Conference and the New Mexico State University Agricultural Experiment Station Chile Pepper Field Day. Results were shared with the scientific community at the 57th Annual Meeting of the Weed Science Society of America (2017) - abstract submitted. What do you plan to do during the next reporting period to accomplish the goals?Project objective 1: Collect weed seedling emergence data from commercial chile pepper fields so that a robust, predictive model for temporal patterns of weed seedling emergence can be made. Project objective 2: Continue laboratory studies that support development of a non-destructive test for weed seed viability. Prepare publication on weed science applications for non-destructive seed viability tests. Project objective 3: Continue to improve understanding of the costs and benefits of stale seedbeds for targeting problematic weeds in New Mexico vegetable production. Specifically, I will complete more robust economic analyses and repeat the field study described above.

Impacts
What was accomplished under these goals? Weeds are ubiquitous crop pests that threaten the gains in productivity necessary to sustain a strong agricultural economy. To insure against weed infestations that cause short-term and long-term reductions in farm profitability, farmers are encouraged to employ a suite of complementary control tactics that each target different stages in the weed life cycle. This Hatch project is advancing adoption and discovery of multi-tactic weed management by: 1) developing readily adoptable techniques for targeting weed seeds in soil (hereafter "soil seedbank"), and 2) producing information that will contribute to the adoption and development of new tactics for targeting soil seedbanks. This Hatch project determined the economic and ecological implications of weeds that escape early-season control in chile pepper production. This information is critical for communicating the importance of full-season weed control programs because farmer adoption of a novel management practice is influenced by perceptions of the practice's economic value. This Hatch project also contributed to the development of a readily adoptable tactic that specifically targets seeds of problematic weeds in New Mexico vegetable production. The tactic was shown to reduce labor expenses for weeding by up to $400 acre-1. This Hatch project was the first to evaluate a new non-destructive test for determining the viability of weed seeds. Although results revealed limitations in the new test, the non-destructive test has promising applications for accelerating the development of control tactics for weed seeds collected by crop harvesting equipment. Further information on the accomplishments of this Hatch project is below. Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico Tall morningglory (Ipomoea purpurea L.) is an annual weed in chile pepper that emerges near the time of crop thinning (9 to 10 weeks after seeding). Previous studies have shown that tall morningglory is not controlled by pendimethalin - a soil-applied herbicide often used in chile pepper. The objective of this study was to determine pendimethalin effects on interference and seed production for tall morningglory infestations that emerge at chile pepper thinning. A field study was conducted at a university research farm near Las Cruces, NM. Chile pepper was grown using practices customary for the region. At 9.5 weeks after seeding, the crop was thinned and treatments were installed. Treatments were factorial combinations of herbicide (pendimethalin-treated [1.6 kg ai ha-1] and untreated) and tall morningglory density (0, 4, 8, 12, 16, 20 plants 10-m row-1). Treatments were arranged in a randomized complete block design with four replications. Experimental units were four raised beds by 10 m and are hereafter referred to as "plots". Throughout the study period, weeds other than tall morningglory were controlled. Data collected at harvest included: tall morningglory seed production, fresh weight of marketable chile peppers and time required for one individual to harvest 10-m of crop row, which was used to calculate the amount harvested in 1 min (i.e., "harvest efficiency"). Results indicated that crop yield was not influenced by tall morningglory density or interactions between tall morningglory density and herbicide treatment. Harvest efficiency was influenced by tall morningglory density but was not influenced by either herbicide treatment or interactions between herbicide treatment and tall morningglory density. In general, each additional tall morningglory plant decreased the amount of chile pepper harvested in 1 min by 9.7 g. Seed production by tall morningglory plants was negatively affected by plant density; however, for each level of plant density pendimethalin did not affect seeds plant-1. Depending on the infestation density, tall morningglory produced 530 to 210 seeds plant-1. These results indicate that mid-season tall morningglory infestations reduce harvest efficiency and produce large amounts of seeds that can contribute to future crop production problems. Pendimethalin does not affect interference and seed production for mid-season tall morningglory infestations. Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks Causal agents of mortality in weed seedbanks can be better understood with non-destructive assays for seed viability. Such assays enable investigations on mechanisms of seed infection by pathogenic microorganisms. In this study, we evaluate a non-destructive method for assessing viability of weed seeds with physiological dormancy. Our method, which was modified from a published study, used a resazurin reagent that was made from resazurin and yeast. In principle, changes in resazurin color caused by respiration in yeast correspond with differences in seed viability because nonviable seeds emit large amounts of solutes that are consumed by yeast. To test this principle, we measured color change in resazurin solutions containing single seeds that were intact, mechanically damaged or subjected to conditions that accelerated aging. Seeds were mechanically damaged by systematically slicing coats (1 incision seed-1). Accelerated aging was accomplished by storing seeds for 80 d under 60% relative humidity, 45 C; conditions created with lithium chloride solutions in air-tight containers. Weed species in this study were common lambsquarters, junglerice, Palmer amaranth and yellow foxtail. Results indicated that intact, damaged and aged seeds of common lambsquarters and Palmer amaranth could not be distinguished with resazurin solution. For junglerice and yellow foxtail, only mechanically damaged seeds caused resazurin solution to change from blue to pink after 3 hr of incubation. These results suggest that resazurin solution can be used to identify mechanically damaged Poaceae seeds. However, the resazurin solution, as evaluated in this study, cannot be used to non-destructively separate viable and nonviable weed seeds. Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems A stale seedbed is a set of practices that first stimulates weed seed germination through tillage and irrigation and then eliminates subsequent seedlings with non-selective control. The overall objective of this study is to develop stale seedbeds that target problematic weeds in chile pepper. Stale seedbed treatments (0, 2 or 3 stale seedbeds) were initiated during summer 2015. Each stale seedbed event consisted of the three sequential steps. First, soil in furrows was tilled to the 10-cm depth. Immediately after tillage, plots were irrigated. Fifteen days after irrigation, emerged seedlings were eliminated with cultivation. Prior to cultivations that eliminated emerged seedlings, weed seedlings were identified and enumerated. Results indicated that stale seedbeds reduced seedbank densities for problematic weeds in chile and reductions in weed seedbank density were similar between the 2 and 3 stale seedbed treatments. In April 2016, chile pepper was seeded into treatment plots. Prior to seeding, a soil-residual herbicide (napropamide at 1.1 kg ai ha-1) was applied to control early-season weeds. Weeds that emerged after crop emergence were controlled with combinations of cultivation, hand hoeing, and post-emergence herbicide for grasses (clethodim at 0.14 kg ai ha-1). Throughout the growing season, weed seedlings were periodically identified, enumerated and removed from permanent quadrats. The time required for one individual to hoe plot sections was determined for each hoeing event. Results indicated that fallow-season stale seedbeds reduced weed densities and hoeing times on specific dates in the chile production season. Across the chile season, stale seedbed-induced reductions in hoeing time were projected to save approximately $400 acre-1.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Flores, A. M., M. K. Shukla, B. J. Schutte, D. L. Daniel, A. L. Ulery, R. St. Hilaire. 2017. Physiologic response of six plant species grown in two contrasting soils and irrigated brackish groundwater and RO concentrate. Arid Land Research and Management in press
• Type: Journal Articles Status: Accepted Year Published: 2017 Citation: Schutte, B. J. 2017. Measuring interference from mid-season tall morningglory to develop a model for teaching weed seedbank effects on chile pepper. Weed Technology in press
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Singla, S., K. Grover, S. V. Angadi, B. J. Schutte, D. VanLeeuwen. 2016. Guar stand establishment, physiology, and yield responses to planting date in southern New Mexico. Agronomy Journal 108:2289-2300
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Schutte, B. J., N. Klypin, M. K. Shukla. 2016. Influence of irrigation timing on disturbance-induced reductions in soil seedbank density. Weed Science 64:613-623
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Flores, A. M., M. K. Shukla, D. Daniel, A. L. Ulery, B. J. Schutte, G. A. Picchioni, S. Fernald. 2016. Evapotranspiration changes with irrigation using saline groundwater and RO concentrate. Journal of Arid Environments 131:35-45
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Flores, A. M., B. J. Schutte, M. K. Shukla, G. A. Picchioni, A. L. Ulery. 2015. Time-integrated measurements of seed germination for salt-tolerant plant species. Seed Science and Technology 43: 541-547
• Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Landau, C. A., B. J. Schutte, A. O. Mesbah, S. V. Angadi. Flixweed (Descuraina sophia) shade tolerance and possibilities for flixweed management using canola seeding rate. submitted to Weed Technology
• Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Hooks, T. N., G. A. Picchioni, B. J. Schutte, M. K. Shukla, D. L. Daniel, J. Ashigh. Salinity an environmental filter selecting for plant invasiveness? Evidence from the indigeneous Lepidium alyssoides on Chihuahuan desert shrublands. submitted to Rangeland Ecology and Management
• Type: Journal Articles Status: Submitted Year Published: 2017 Citation: Omer, M. F., O. J. Idowu, K. Grover, B. J. Schutte, S. M. Sanogo. Evaluating suitability of legume species as cover crops in irrigated arid systems. submitted to Agronomy Journal
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Schutte, B. J. 2016. Model-based software for teaching tall morningglory seedbank density effects on chile pepper production. Proceedings of the 69th Annual Meeting of the Western Society of Weed Science 69:55
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Landau, C. A., B. J. Schutte, S. Angadi, A. Mesbah. 2016. Integrated weed management for conventional canola (Brassica rapa) in eastern New Mexico. Proceedings of the 69th Annual Meeting of the Western Society of Weed Science 69:51
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Schutte, B.J. 2016. Seed production and interference from late-season tall morningglory in chile pepper. Proceedings of the 56th Annual Meeting of the Weed Science Society of America 56:152

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:This research is directed towards advancing knowledge in the weed science discipline, particularly the weed science fields of weed ecology, weed management and integrated pest management. Research is also directed towards crop producers and agricultural professionals in New Mexico, with emphasis on the production of vegetables and forage crops. Finally, research is directed towards land managers who disperse partially treated wastewater in agricultural environments. Changes/Problems:Progress on a component of project 2, the development of non-destructrive tests for weed seed viability, was stalled by the unexpected death of a highly accomplished and highly skilled laborartory research scientists. The work of this talented scientist is now being repeated and will soon move forward. What opportunities for training and professional development has the project provided?Project objective 1: This project is providing training for one graduate student and two undergraduate students. Project objective 2: This project is providing training two undergraduate students. Project objective 3: This project is providing training for one graduate student and three undergraduate students. How have the results been disseminated to communities of interest?Project objective 1: Results were communicated to farmers and agricultural professionals at the New Mexico Chile Conference, the NMSU Chile Pepper Field Day, the NMSU Agricultural Field Day at Los Lunas. Project objective 2: Results were shared with stakeholders at poster presentations at the 68th Annual Meeting of the Western Society of Weed Science and the 54th Annual Meeting of the Weed Science Society of America. Results related to this project were submitted for publication to the journal Weed Science. Project objective 3: Results were shared with stakeholders at the 55th Annual Meeting of the Weed Science Society of America. Results were also communicated to farmers and agricultural professionals at the New Mexico Chile Conference, the NMSU Chile Pepper Field Day, the NMSU Agricultural Field Day at Los Lunas. Furthermore, results were shared with students in weed science and agronomy classes at NMSU. What do you plan to do during the next reporting period to accomplish the goals?Project objective 1: Assist with the publication of studies on Lepidium sp. responses to salinity. Collect Palmer amaranth emergence data from additional sites so that a robust, predictive model for temporal patterns of Palmer amaranth seedling emergence can be made. Project objective 2: Continue laboratory studies that support development of a nondestructive test for weed seed viability. Project objective 3: Continue to improve the model for determining the economic impact of tall morningglory seedbanks by collecting feedback from chile pepper growers. Initiate studies on stale seedbed techniques for weeds in chile pepper.

Impacts
What was accomplished under these goals? Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. Late-season Palmer amaranth (Amaranthus palmeri) seedlings complicate decisions on the optimum time to implement weed control measures in New Mexico crop fields. A study was initiated to develop a robust model capable of predicting temporal patterns of seedling emergence for Palmer amaranth in New Mexico chile fields. Such models require knowledge of the primary environmental drivers of weed seedling emergence under field conditions: soil temperature and soil moisture. Laboratory studies were conducted to determine the temperature below which Palmer amaranth seed germination does not take place (base temperature) and the matric potential below which Palmer amaranth seed germination does not take place (base water potential). Laboratory studies were complemented with field studies that quantified temporal patterns of Palmer amaranth seedling emergence in chile pepper fields. Results from laboratory studies that used two seed accessions from New Mexico indicated that base temperatures for germination were 16 °C (Las Cruces accession) and 18 °C (Los Lunas accession). Base water potentials for germination were -0.35 MPa (Las Cruces accession) and -0.39 MPa (Los Lunas accession). Field data from Las Cruces and Los Lunas indicated that Palmer amaranth seedling emergence in chile fields is biphasic, with a large flush of seedlings emerging in late-April to early-May and another large flush of seedlings emerging in early July. Preliminary modelling suggested that the biphasic pattern of seedling emergence was independent of changes in soil temperature and soil moisture; however, more definitive conclusions require data from additional site-years. A study determined the effects of salinity on germination and growth for three invasive plant species (Lepidium latifolium, Lepidium draba and Lepidium alyssoides). This study was initiated in 2012 and data collection was completed in 2015. Results indicated that significant reductions in plant growth and evapotranspiration (ET) of three L. alyssoides populations were largely independent of the specific isosmotic saline irrigation solution (NaCl, CaCl2, and Na2SO4, each at -0.1 MPa and -0.2 MPa), which indicated that ET and growth responses to salinity solution were controlled by solution osmotic potential. Further, greenhouse study results indicated that these species compartmentalize Na and Cl in leaves that would eventually shed from plants. A NaCl solution at -0.2 MPa had no effect on germination percentages of L. draba and L. latifolium, rather, it merely delayed their mean germination time by a day or less. Under saline conditions, high germinability and vegetative propagule pressure along with high-salt litter deposition are major factors contributing to the invasiveness of these species. Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. A laboratory study that determined the effects of decreasing soil moisture on persistence in weed seedbanks was finalized by conducting statistical analyses. In addition, final statistical analyses were performed for a field study that determined weed seedbank responses to variability in soil disturbance timing with respect to irrigation. These studies (field and laboratory) were combined for a presentation at a scientific meeting and for a manuscript that was submitted to a peer-reviewed journal. Following analyses and combination, these studies indicated that (1) delays in irrigation can reduce the seedbank reduction potentials of soil disturbance events, and (2) irrigation timing effects on disturbed soil seedbanks are likely to occur in all irrigation systems, including those that reduce the amount of water applied to cropland compared to flood irrigation. Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. A field study was repeated to determine pendimethalin effects on interference and seed production for tall morningglory infestations that emerge at chile pepper thinning. Results indicated that crop yield was not influenced by tall morningglory density or interactions between tall morningglory density and herbicide treatment. Harvest efficiency was influenced by tall morningglory density, but, this response variable was not influenced by either herbicide treatment or interactions between herbicide treatment and tall morningglory density. In general, each additional tall morningglory plant decreased the amount of chile pepper harvested in 1 min by 9.7 g. Seed production by individual tall morningglory plants was negatively affected by plant density; however, for each level of plant density pendimethalin did not affect seeds plant-1. These results indicate that pendimethalin does not affect interference and seed production for mid-season tall morningglory infestations in chile pepper. These data were used to develop a user-friendly, model-based software program that allows farmers and agricultural professionals to discover the practical implications of additions to tall morningglory seedbanks. The model is implemented in Microsoft Excel® and is available on the world-wide-web (http://aces.nmsu.edu/faculty/schutte/index.html).

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: Schutte B. J., A. E. Cunningham. 2015. Tall morningglory (Ipomoea purpurea) seedbank density effects on pendimethalin control outcomes. Weed Technology 29:844-853.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Schutte, B. J., L. Lauriault. 2015. Nutritive value of field bindweed (Convolvulus arvensis) roots as a potential livestock feed and the effect of Aceria malherbae on root components. Weed Technology 29:329-334.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Schutte, B.J., N. Klypina. 2015. Influence of irrigation timing on disturbance-induced reductions in soil seedbank density. Proceedings of the 68th Annual Meeting of the Western Society of Weed Science 68:129
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Schutte, B. J., A. E. Cunningham. 2015. Quantifying weed seedbank density effects on pendimethalin control outcomes. Proceedings of the 55th Annual Meeting of the Weed Science of America 55:258
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Schutte, B. J. 2015. Impacts of late-season tall morningglory infestations in chile pepper production. Proceedings of the 55th Annual Meeting of the Weed Science of America 55:36

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: This research is directed towards advancing knowledge in the weed science discipline, particularly the weed science fields of weed ecology, weed management and integrated pest management. Research is also directed towards crop producers and agricultural professionals in New Mexico, with emphasis on the production of vegetables and forage crops. Finally, research is directed towards land managers who disperse partially treated wastewater in agricultural environments. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Project objective 1: This project is providing training for one graduate student and one undergraduate student. Project objective 2: This project is providing training three undergraduate students. Project objective 3: This project is providing training for one graduate student and three undergraduate students. How have the results been disseminated to communities of interest? Project objective 1: Results were shared with stakeholders at a poster presentation at the 59th annual New Mexico Water conference. Results related to this project were submitted for publication to the journal Weed Technology. Project objective 2: Results were shared with stakeholders at poster presentations at the 67th Annual Meeting of the Western Society of Weed Science and the 54th Annual Meeting of the Weed Science Society of America. Project objective 3: Results were shared with stakeholders at poster presentations at the ASA, CSSA, & SSSA International Annual Meeting and the 54th Annual Meeting of the Weed Science Society of America. Results were also communicated to farmers and agricultural professionals at NMSU Chile Pepper Field Day NMSU Onion Field Day. Furthermore, results were shared with students in weed science and agronomy classes at NMSU. Results related to this project were submitted for publication to the journal Weed Technology. What do you plan to do during the next reporting period to accomplish the goals? Project objective 1: Complete and publish studies on the invasive potential of Lepidium alyssoides. Initiate studies comparing weed community composition or wastewater irrigated and groundwater irrigated crop fields. Project objective 2: Complete and publish studies on weed seedbank persistence responses to soil moisture and soil disturbance timing relative to irrigation. Initiate studies to support development of a nondestructive test for weed seed viability. Project objective 3: Repeat studies to determine the functional relationships between population density in tall morningglory seedbanks and time requirements for hoeing and hand harvesting chile pepper. Initiate studies in support of a hydrothermal emergence model for Amaranthus palmeri (Palmer amaranth) in New Mexico.

Impacts
What was accomplished under these goals? Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. A 12-wk greenhouse experiment was completed. This experiment compared salinity effects on the growth of Lepidium alyssoides, a suspected salt-tolerant invasive weed, with salinity effects on the growth of Lepidium draba and Lepidium latifolium, known salt-tolerant invasive weeds, as well as salinity effects on the growth of crop species with different degrees of salt tolerance. Data collected included fresh weights, dry weights, biomass allocation among above-groung and below-ground plant structure, as well as salt and nutrient contents of harvested plant organs. Salt and mineral nutrient analyses are still in progress. This study will determine if Lepidium alyssoides features traits of a halophytic species, and thus, will clarify the habitats susceptible to Lepidium alyssoides invasion. Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. A laboratory study was repeated to determine the effects of decreasing soil moisture on persistence in weed seedbanks. For this experiment, artificial soil seedbanks were maintained for 35 days at the following soil matric potentials: 0 kPa, -30 kPa, -60 kPa, 180 kPa. Weed species studied included Amaranthus palmeri, Echinochloa colona and Setaria pumila, which are common weed species in agricultural fields in New Mexico. Using techniques that monitor activities of anaerobic soil microorganisms, it was determined that soil seedbanks at 0 kPa became anoxic. Despite these potentially harmful conditions, weed seed viability was maintained. Persistence in weed seedbanks decreased with decreasing soil matric potentials from -30 kPa, -60 kPa, 180 kPa. Exit from seedbanks at lower moisture levels was primarily due to germination. These results indicate that weed seeds are capable of persistence in saturated soils, which are prevalent in agricultural systems using flood irrigation technologies. A field experiment was repeated to determine weed seedbank responses to variability in soil disturbance timing with respect to irrigation. Weed species studied included Amaranthus palmeri, Echinochloa colona and Setaria pumila. Treatments included soil disturbance 10, 3 and 0 days prior to flood irrigation. Responses measured included timings and magnitudes of seedling flushes following irrigation and rates of 1-year seedbank persistence. Results from the first run (2013) indicated that seedbank persistence of Amaranthus palmeri and Setaria pumila was reduced in disturbed soil compared to undisturbed soil. For Amaranthus palmeri, delays in irrigation diminished seedbank reduction potentials of soil disturbance events. However for Setaria pumila, delays in irrigation increased seedbank reduction potentials of soil disturbance events. For the second run (2014), seed recovery from soil is currently in process. Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. A field study at two university research farms in southern and central New Mexico was repeated to support development of a bio-economic model for weed seedbank depletion. Because one of the more difficult weeds to control in chile pepper production in New Mexico is tall morningglory (Ipomoea purpurea) and because the soil-applied herbicide pendimethalin is an important component of weed control programs for chile pepper production New Mexico, this study was conducted to determine pendimethalin efficacy responses to increasing population density in tall morningglory seedbanks. Consistent with the first year of the study (2013), pendimethalin control failures generally increased in response to increasing seedbank density. In growth chambers, the likelihood of control failure for each additional seed in the seedbank decreased as pendimethalin application rate increased from 0.5 kg ai ha-1 to 1.6 kg ai ha-1. Although these results indicate that pendimethalin control outcomes in chile pepper production can be improved by reducing population densities in tall morningglory seedbanks, farmer adoption of novel seedbank reduction strategies is likely to require specific information on the consequences of changes in soil seedbank density. Thus, a study was initiated in 2014 to develop functional relationships for the intrinsic connections between population density in tall morningglory seedbanks and time requirements for hoeing and hand harvesting chile pepper. To accomplish this objective, field studies were conducted during 2014 at a university research farm near Las Cruces, NM. Chile peppers were grown using irrigation, soil and pest management practices typical for the region. At 9.5 weeks after seeding, the chile crop was thinned and treatments were installed. Experimental units were four raised beds (1-m row spacing) by 10 m. Within each experimental unit, the two center rows were sown with tall morningglory seeds (approximately 500 seeds 10-m row-1). Prior to burial, tall morningglory seeds were scarified to remove dormancy (pre-burial germination rate = 83%). Prior to tall morningglory emergence, half of the population of experimental units was sprayed with pendimethalin at 1.6 kg ai ha-1. At 45 days after spraying (DAS), tall morningglory population densities were measured immediately prior to determining the time required to hoe 10-m of crop row. At 14 DAS, tall morningglory population density treatments (0, 4, 8, 12, 16, 20 plants 10-m row-1) were established in a randomized complete block design with four replications. Data obtained at harvest (78-81 DAS) included: time required to harvest 10-m of row and chile pepper yield on a fresh weight basis. Results indicated the relationship between time required to hoe 10-m of crop row and tall morningglory population density was not influenced by pendimethalin. Each additional tall morningglory plant increased the time required to hoe 10 m of crop row by 3.6 seconds. Harvest efficiency was influenced by tall morningglory population density treatment, but was not influenced by either herbicide treatment or interactions between herbicide and tall morninnglory population density treatments. Each additional tall morningglory plant decreased the amount of chile pepper harvested in 1 min by 10 g. Combined with knowledge of the percentage of buried seeds that produce seedlings that escape control, the results of this study can be used to communicate specific consequences of changes in population density in tall morningglory seedbanks.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Idowu, O. J., Schutte, B. J., Uchanski, M. E., Grover, K. (2014). Crop performance, weed community and soil changes in an irrigated organic transition field in the southwestern USA. ASA, CSSA, & SSSA International Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Schutte, B. J., Klypina, N. (2014). The effects of decreasing soil moisture on seed mortality of Palmer amaranth (Amaranthus palmeri), junglerice (Echinochloa colona) and yellow foxtail (Setaria pumila). Proceedings of the 67th Annual Meeting of the Western Society of Weed Science
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Cunnigham, A., Schutte, B. J. (2014). Weed seedbank density effects on pendimethalin control outcomes. Proceedings of the 67th Annual Meeting of the Western Society of Weed Science
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Schutte, B. J., Klypina, N., Zamora, V., Cunnigham, A., Ashigh, J. (2014). The effects of delaying irrigation on disturbed soil seedbanks of Palmer amaranth (Amaranthus palmeri), yellow foxtail (Setaria pumila) and junglerice (Echinochloa colona). Proceedings of the 54th Annual Meeting of the Weed Science Society of America
• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Schutte, B. J., Lauriault, L. M. (in press). Nutritive value of field bindweed (Convolvulus arvensis) roots as a potential livestock feed and the effect of Aceria malherbae on root components. To appear in Weed Technology
• Type: Journal Articles Status: Under Review Year Published: 2015 Citation: Schutte, B. J., Cunningham, A. Tall morningglory (Ipomoea purpurea) seedbank density effects on pendimethalin control outcomes. Weed Technology

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: Experimental results were reported in poster presentations at the 64th Annual Meeting of the Western Society of Weed Science and the 53rd Annual Meeting of the Weed Science of America. The Western Society of Weed Science is a non-profit professional society promoting research, education and awareness of weeds throughout the Western United States. The Weed Science Society of America is also a non-profit professional society dedicated to advancing weed science at the US national level. Results were shared with stakeholders at two field days held at the New Mexico State University Agricultural Science Centers at Los Lunas, NM and Tuccumcari, NM. Field-days were attended by agricultural producers and professionals in central and eastern New Mexico. Results were shared with stakeholders in the 2013 Weed Science Field Research Report, New Mexico State University, Department of Entomology, Plant Pathology and Weed Science (EPPWS). This report is publically available at the EPPWS website. Results related to this projected were reported in manuscripts submiited to peer-reviewed scientific journals with international readership. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Project Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. This project is providing training opportunities for one graduate student (MS). Project Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. This project is providing training opportunities for three undergraduate student interns and one graduate student intern. Project Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. This project is providing training opportunities two graduate students (MS). How have the results been disseminated to communities of interest? Project Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. Early results and were shared with stakeholders at a field day held at the NMSU Agricultural Science Center at Tuccumcari. Project Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. Results were reported in poster presentations at the 64th Annual Meeting of the Western Society of Weed Science and the 53rd Annual Meeting of the Weed Science of America. Results related to this project were reported in manuscripts submitted to: American Journal of Plant Sciences (published), Weed Research (published) and Seed Science Research (under review). Project Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. Results were reported in the MS Thesis “Cover Crops for Sustainable Cropping Systems in the Desert Southwest” by Nazar Al-Ibraheemi. Results were shared with stakeholders at a field day held at the NMSU Agricultural Science Center at Los Lunas. Results were shared with stakeholders in the 2013 Weed Science Field Research Report, New Mexico State University, Department of Entomology, Plant Pathology and Weed Science. Results related to this project were reported in a manuscript submitted to Weed Technology (in press). What do you plan to do during the next reporting period to accomplish the goals? Project Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. The greenhouse study will be repeated with consideration of the results presented above. Specifically, a greenhouse study will be conducted to determine salt-induced growth responses for Lepidium latifolium, L. alyssoides, and L. draba. In this experiment growth responses will determined using one salt solution (NaCl) and one population of L. alyssoides. Project Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. Continue data collection and data analysis for 2013 field and laboratory studies on abiotic factors influencing weed seed persistence in agricultural soil seedbank. Repeat 2013 field and laboratory studies on abiotic factors influencing weed seed persistence in agricultural soil seedbank. Present 2013 results at the 65th Annual Meeting of the Western Society of Weed Science and the 54rd Annual Meeting of the Weed Science of America. Project Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. Completion and submission of a manuscript for publication in a peer-reviewed journal. The manuscript will present results related to warm-season cover-crop selection in southern New Mexico. Repeat the experiment on winter cover-crop species selection. Analyze results and prepare manuscript for publication in a peer-reviewed journal. Continue to manage field experiments and to collect data on weed seedbank density and composition under various cover-crop rotations and alfalfa during the 3-yr organic transition period. Repeat the experiment on weed seedbank efficacy on chemical weed control. Analyze results and prepare manuscript for publication in a peer-reviewed journal. Completion of MS student project and thesis. Continue to quantify seedbank dynamics and emergence behaviours for Ipomoea purpurea and Anoda cristata under field conditions.

Impacts
What was accomplished under these goals? Weed infestations in agricultural fields often arise from reserves of viable seeds in soil, which are hereafter referred to as “seedbanks”. The overall goals of this research project is to better understand the ecological factors that accelerate seedbank losses and to develop novel weed management tools that directly target weed seedbanks. Because the number of weed seeds in soil can affect the efficacy of existing control tactics, novel management tools that reduce the number of seeds in soil will improve the efficacy of existing weed control tactics. Objective 1: Determine ecological factors influencing reproduction and spread of weeds in managed ecosystems of New Mexico. 1) Major activities completed: A 12-wk greenhouse study to determine salt-induced growth response in Lepidium alyssoides was completed. The specific objectives of this project were to: 1) determine the effect of population on salt-induced growth responses in L. alyssoides, 2) determine the effect of solution composition on salt-induced growth responses in L. alyssoides, and 3) determine whole plant Na regulation patterns in L. alyssoides. Lepidium alyssoides has been shown to flourish at wastewater application sites in New Mexico and is closely related to noxious and invasive weeds capable of reducing biodiversity in surrounding rangelands. 2) Data collected. Potted plants of L. alyssoides from three different New Mexico populations were each exposed to solutions differing in salt type (NaCl, CaCl2, Na2SO4) and osmotic potential (-0.1 MPa, -0.2 MPa). Growth responses were quantified and shoot and root samples were harvested for chemical composition analysis by a commercial laboratory. 3) Results The electrical conductivity for salt solutions applied to L. alyssoides plants ranged from 1.6 ds/m (water control) to 7.7 ds/m (CaCl2 at -0.2 MPa). Despite irrigation with highly saline solutions, all L. alyssoides plants survived. Root and shoot biomass values for L. alyssoides plants irrigated with salt solutions were significantly less than significance root and shoot biomass values for L. alyssoides plants irrigated with tap water. Population and salt type did not impact salt-induced growth responses in L. alyssoides. However, osmotic potential of the salt solution did impact salt-induced growth responses in L. alyssoides, with the more -0.2 MPa solutions reducing growth more than the -0.1 MPa. 4) Key outcomes These results will guide subsequent studies. Specifically, the results of this experiment indicate that future experiments can focus on one maternal accession and one salt type. Objective 2: Determine environmental and endogenous controls over seed mortality and persistence in soil seedbanks. 1) Major activities completed: A laboratory study was conducted to test the hypothesis that weed seed mortality decreases in response to decreasing soil moisture. A field study was conducted to determine weed seedbank responses to variability in soil disturbance timing with respect to irrigation. 2) Data collected. For the laboratory experiment, Amaranthus palmeri, Echinochloa colona and Setaria pumila seeds were incubated in soil at specific soil moisture levels (flooded, and soil matric potentials of: 0 kPa, -30 kPa, -60 kPa, -180 kPa). For each species, soil moisture level effects on seed mortality were determined separately for germinable and dormant seeds. Weed species used in the laboratory study were also used in the field study. Treatments included soil disturbance 10, 3, or 0 days prior to flood irrigation. Responses measured included timings and magnitudes of seedling flushes following irrigation and rates of 1-year seedbank persistence. 3) Results For the laboratory study, early results indicate that soil moisture level most conducive to seedbank reduction is species-specific; however, flooded soils are universally inhibitive to emergence. Dormant seeds persisted under all moisture conditions. For the field study, results suggest that for weed species with germination stimulated by light, seedling emergence flushes following disturbance were greater for seedbanks disturbed 3 days prior to irrigation compared to seedbanks disturbed 10 days prior to irrigation. Soil disturbance reduced seedbank persistence for A. palmeri and S. glauca, but did not affect seedbank persistence of E. colona. For A. palmeri, seedbanks were reduced to a greater degree when soil was disturbed 0 or 3 days prior to irrigation as compared to when soil was disturbed 10 day prior to irrigation. 4) Key outcomes The laboratory experiment has led to a change in knowledge within the field of weed seed ecology. Previous research suggested that seed mortality was positively influenced by soil moisture, but, the dormancy status of seeds lost under high moisture was not known. The results of this study showed that dormant seeds can persist under high moisture conditions, but that germinable seeds are likely to emerge or perish under high moisture conditions. The field experiment has led to a change in knowledge as it has indicated that A. palmeri seedbanks can be manipulated by adjusting soil disturbance timing with respect to irrigation. If this finding is maintained in further field trials, these results may lead to novel methods for A. palmeri control through soil and irrigation management. Objective 3: Develop management decision tools for depleting weed seedbanks in agroecosystems. 1) Major activities completed: Field studies at two university research farms in southern New Mexico are being conducted to identify cover-crop species and cover-crop rotations suitable for the semi-arid U.S. Southwest. The specific objective for this experiment is to determine the weed suppression abilities of non-conventional, warm-season cover-crop species relative to the conventional, warm-season cover-crop species. In addition, field studies at two university research farms in southern and central New Mexico are being conducted to support the development of a bio-economic model for weed seedbank reduction. The specific objective for this experiment is to quantify the response of pendimethalin efficacy to increasing densities of germinable seeds of Ipomoea purpurea and Setaria pumila. 2) Data collected. For the cover crop experiment, data collected includes cover-crop effects on above-ground weed community composition, biomass and seed production. For the development of a bio-economic model for weed seedbank reduction, data collected includes weed seedbank density effects on the efficacy of chemical weed control tactics employed in chile pepper production. 3) Results For the cover crop experiment, non-conventional species including sesbania and pearl millet suppressed growth and seed output of weeds to the same degree as the conventional sorghum-Sudan grass hybrid. Sesbania did not require inoculant to produce root nodules. For bioeconomic model development, pendimethalin suppressed emergence of I. purpurea and S. pumila. For I. purpurea, the frequency of escape from pendimethalin increased with increasing numbers of germinable seeds in soil seedbanks. For S. pumila, escape from pendimethalin was not associated with the number of germinable S. pumila seeds in soil. 4. Key outcomes. The warm-season cover crop experiment led to a change in knowledge important for advancing sustainable agriculture in southern New Mexico. Because sesbania is capable of nitrogen fixation and because pearl millet can grow well with low nitrogen and water inputs, the non-conventional cover-crop species tested in this study are alternatives to sorghum-Sudangrass hybrids in low-input agricultural systems that utilize cover-crops for weed suppression. The experiment in support of development of a bioeconomic model for weed seedbank reduction led to a change in knowledge as it indicated that germinable seedbank densities impacted pendimethalin control outcomes with respect to I. purpurea but not S. pumila.

Publications

• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Cover Crops for Sustainable Cropping Systems in the Desert Southwest by Nazar Al-Ibraheemi
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Schutte BJ, Tomasek BJ, Davis AS, Andersson L, Benoit DL, Cirujeda A, Dekker J, Forcella F, Gonzalez-Andujar JL, Graziani F, Murdoch AJ, Neve P, Rasmussen IA, Sera B, Salonen J, Tei F, T�rresen KS, Urbano JM. 2013. An investigation to enhance understanding of the stimulation of weed seedling emergence by soil disturbance. Weed Research 54, 112.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Schutte, B. J., S.E. Wortman, J. L. Lindquist, A. S. Davis. 2013. Maternal environment effects on phenolic defenses in Abutilon theophrasti seeds. American Journal of Plant Sciences 4:1127-1133. DOI:10.4236/ajps.2013.45139
• Type: Journal Articles Status: Under Review Year Published: 2014 Citation: Schutte, B. J., A. S. Davis, S. A. Peinado, J. Ashigh. Seed coat thickness data clarifies seed size-seedbank persistence trade-offs in Abutilon theophrasti (Malvaceae). Seed Science Research
• Type: Journal Articles Status: Accepted Year Published: 2014 Citation: Schutte, B. J. and Davis, A. S. Do common waterhemp (Amaranthus rudis) seedling emergence patterns meet criteria for herbicide resistance simulation modeling? Weed Technology
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Schutte, B. J., N. Klypina, M. Shukla. 2013. Soil moisture effects on viability of physically dormant weed seeds. Proceedings of the 64th Annual Meeting of the Western Society of Weed Science 66:45
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Schutte, B. J., S.E. Wortman, J. L. Lindquist, A. S. Davis. 2013. Maternal environment effects on phenolic defenses in Abutilon theophrasti seeds. Proceedings of the 53rd Annual Meeting of the Weed Science of America 53:84
• Type: Other Status: Published Year Published: 2013 Citation: Schroeder, J., Ashigh, J., Schutte, B. 2013. Weed Science Field Research Report. Department of Entomology, Plant Pathology and Weed Science.