Source: MONTANA STATE UNIVERSITY submitted to NRP
ECOLOGICAL MANAGEMENT OF KOCHIA IN IRRIGATED WESTERN CROPPING SYSTEMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1010972
Grant No.
2016-70006-25831
Cumulative Award Amt.
$325,000.00
Proposal No.
2016-07608
Multistate No.
(N/A)
Project Start Date
Sep 1, 2016
Project End Date
Aug 31, 2020
Grant Year
2016
Program Code
[ARDP]- Applied Research and Development Program
Recipient Organization
MONTANA STATE UNIVERSITY
(N/A)
BOZEMAN,MT 59717
Performing Department
Research Centers
Non Technical Summary
This is an Applied Research (single-function) multi-state project that contributes to CPPM focus area 1 - Plant Protection Tactics and Tools. This project includes a lead PI from Montana, two Co-PIs from Wyoming, and one Co-PI from Nebraska, with a total funding request of $325,000 for three years of the project. Stakeholders from across the northern and central Great Plains of the US have identified kochia (Kochia scoparia) as one of the most problematic and economically damaging summer annual weeds. This tumbleweed is currently a threat to sustainable crop production due to a near lack of effective herbicide options, especially in sugar beet-based crop rotations. Widespread resistance to many different herbicides (including glyphosate, PS II inhibitors, ALS inhibitors, and synthetic auxins) has increased the need and the desire for IPM-based solutions for managing this troublesome weed. For this stakeholder-identified research, we propose: 1) quantifying temperature and moisture germination requirements of kochia populations collected from a north-south transect from Montana to Nebraska, and 2) using that information to evaluate the effectiveness of three ecologically-based, IPM strategies, including stale seedbed, cover crops, and diversified crop rotations. We will combine field-validated emergence data, hydrothermal time modeling, and climate data to develop non-herbicidal weed control strategies that have a high likelihood of reducing kochia seed bank and exposure of this species to herbicide treatments, thereby reducing selection for herbicide resistance evolution across the three-state region. Implementation and adoption of these ecologically-based IPM strategies will reduce potential environmental impacts and applicator exposure problems associated with increased pesticide use. Results from this IPM project will be disseminated across geographic boundaries to meet the National IPM Roadmap Goals.
Animal Health Component
70%
Research Effort Categories
Basic
10%
Applied
70%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21623001140100%
Knowledge Area
216 - Integrated Pest Management Systems;

Subject Of Investigation
2300 - Weeds;

Field Of Science
1140 - Weed science;
Goals / Objectives
The long-term goal of this project is to develop ecologically-based, non-herbicidal weed control strategies based on improved understanding of kochia germination ecology in order to mitigate herbicide resistance and develop sustainable IPM practices in diversified cropping systems.In order to accomplish our long-term goal, we propose integrating data from a combination of laboratory and field studies to develop non-herbicide strategies for kochia management. We propose the following specific objectives (SO) for this research project:A. Quantify kochia germination requirements across North-South transect in the region.Using 44 different kochia accessions collected from Northern and Southern locations across the three-state region, we will conduct laboratory studies to:Determine minimum, maximum, and optimal temperature requirements for kochia seed germination.Determine minimum and optimal water requirements for kochia seed germination.Using field sites and natural kochia infestations at four sites (two Northern and two Southern), we will monitor natural kochia emergence patterns.We will develop a hydrothermal time model of kochia emergence from the combined laboratory and field data sets.B. Determine the impact of non-chemical weed management strategies on kochia seedling emergence and seed bank depletion.Using field sites and natural kochia infestations, we will quantify the impact of tillage, irrigation (furrow and sprinkler), and cover crops on kochia emergence patterns.We will combine the hydrothermal time model (SO 1c), climate data, and field-validated emergence data to develop non-herbicide management strategies that have a high likelihood of decreasing the kochia seed bank and reducing herbicide selection across the three-state region.
Project Methods
Effect of temperature and water potential on germination of kochia seed accessions (Specific Objectives 1a, 1c)Fully-matured kochia seeds will be collected from 10 sites each in the fall of 2016 from naturally-infested irrigated agronomic crop production sites near Huntley, MT; Powell and Lingle, WY; and Scottsbluff, NE; representing the North-South transect of this region (N=40). An additional accession will be collected from 4 rangeland sites, one near each location, bringing the total number of accessions to 44 (N=44).The effect of seven thermoperiods (T) and 12 water potentials (ψ) on seed germination of each kochia accession will be studied. The seven thermoperiods will range between: 0/6 and 30/40 C. Each temperature treatment will be cycled on a 14 h day/10 h night cycle. For each kochia accession, 50 seeds will be placed on filter paper in a petri dish and kept at a constant water potential using polyethylene glycol.To quantify the effect of water potential on seed germination, polyethylene glycol (PEG) solution will be used to create solutions with water potentials of 0, -0.03, -0.06, -0.1, -0.3, -0.5, -0.7, -0.9, -1.2, -1.6, -1.8, -2.1, -2.4 MPa. For each water potential, 50 seeds will be placed between two layers of filter papers (Whatman®, Grade 2) in 10-cm-diam petri dishes. Five milliliters of the PEG water potential solution will be added and will be replaced as needed to prevent seed desiccation.For both studies, germinated seed will be counted and removed every 24 h for 15 d or until no further germination occurs for 5 consecutive days. Seed will be considered germinated when the radicle emerges and the tip of the radicle is uncoiled. Any non-germinated seed will be tested for viability using a 1% w/v TZ solution. All experiments will be repeated at least twice, with three to four replicates per treatment in each run. Analysis of seed germination studies will be conducted using nonlinear regression methods. Using this analysis, we can estimate the optimal and minimum thermal and water requirements for kochia germination by calculating the time required to observe 10, 50, and 90% germination (T10, T50, and T90, respectively) of viable kochia seed. This information will also be used to derive base temperatures and water potentials.Effect of irrigation timing, tillage operations, and presence/absence of cover crops on kochia emergence patterns (Specific Objectives 1b, 1c, 2a) Four field sites will be established at Research and Extension Centers located near Huntley, MT; Lingle, WY; Powell, WY; and Scottsbluff, NE. Sites with naturally occurring high density kochia infestations will be selected. Two of the study locations, Huntley and Lingle, will be established under furrow irrigation and two sites, Powell and Scottsbluff, will be established under sprinkler irrigation. Each study location will be repeated for two years, giving a total of 8 site-years. The study design will be a three-factor factorial, arranged as a strip-split-plot randomized complete block, with four replications.Strip-plot factor: presence or absence of a cover crop. In the fall after soil sampling to estimate initial kochia seed bank density, each location will be planted to a winter wheat cover crop or left fallow. Strip-plots will have dimensions of 10 m by 45 m. The cover crop will be removed at different timings corresponding to the normal planting dates of crops, including small grains, sugar beet, corn, and dry bean. The method of cover crop termination is dependent on the split-plot factor, with tillage being used in tillage plots and a non-selective herbicide used in no-tillage plots.Whole-plot factor: irrigation frequency. The purpose of the irrigation factor is to simulate germination of kochia seed in the soil prior to planting a crop. The first irrigation event will occur as soon as allowed by local irrigation districts and will vary between study locations. Irrigation will continue from the first allowable date, up until the end of May when dry beans are normally planted. Irrigation will differ among whole-plots by the number of irrigation events each plot receives. A control treatment will receive no irrigation, the second treatment will receive only a single irrigation, and each subsequent treatment will receive an additional irrigation each at two-week intervals. Rainfall data will be recorded.Split-plot factor: tillage timing. Tillage treatment will be applied at three timings nested within each irrigation treatment: a no-tillage treatment, tillage occurring before the last irrigation event of each irrigation treatment, and tillage occurring after the last irrigation event of each irrigation treatment. In the no-tillage split-plots, cover crops will be terminated on the day of the pre-irrigation tillage treatment using a non-selective herbicide. The pre-irrigation tillage split-plots will be implemented the day before irrigation is planned, while the post-irrigation tillage split-plots will be implemented as soon as the soil is dry enough to allow field operations.Data collection. The efficacy of each treatment will be measured by assessing kochia seedling density throughout the season and by assessing the soil seed bank at the conclusion of each study year in the fall. Soil temperature and moisture readings will be taken at all sites. Weed species density will be assessed by counting each plot prior to the initiation of each post-irrigation tillage treatment. Kochia density will be assessed in each plot on March 30th; April 6th, 13th, 19th, and 27th; and May 20th and a final sampling in July. Within each split-plot, two sub-samples will be taken using a 1 m2 quadrat. Sampling locations will be fixed within each split-plot. Soil moisture and temperature data will be taken. The soil seed bank will be assessed each fall using an exhaustive germination method.Statistical analysis. A mixed model ANOVA will be used, considering site location, study year, and block as random effects. Cover crop presence or absence, irrigation treatment, and tillage will be considered fixed effects, with tillage nested within irrigation. Response variables will include weed density and the net change in the soil seed bank.Hydrothermal time germination models for kochia accessions (Specific Objectives 1c, 2b)Hydrothermal time models will be used to model germination of kochia seed from field studies, using information from the laboratory studies. Analyses of seed germination rates across temperatures and water potentials will be conducted according to the hydrothermal time model: θHT = θT* θH [1]where θHT is the hydrothermal time constant, or the independent variable used to predict seed germination. θT is a measure of growing degree days and θH is the measure of soil water potential. This model has been shown to adequately describe germination curves over a wide range of suboptimal T and ψ values. Base temperature (Tb) and water potential (ψb) values will be experimentally derived from the thermoperiod and water potential studies and validated in field emergence studies.Ultimately, for each location, the percentage cumulative germination will be plotted against θHT and modeled using a modified Weibull function of the form: Y = d {1 - exp[-k (θHT - a )c]} [2]where Y is the percent cumulative germination at hydrothermal time (θHT), d is the maximum germination percentage, k is the rate of increase, a is the lag phase before start of germination, and c is a shape parameter. The parameters k, a, and c will be estimated by nonlinear regression procedure in R.Developing non-herbicide management strategies for kochia across a three-state region (Specific Objective 2b)After a hydrothermal time germination model for kochia has been developed and validated, we will use that model to predict kochia emergence for various sites across the region using historical weather records.

Progress 09/01/16 to 08/31/20

Outputs
Target Audience:The target audience(s) comprised of local and regional growers across the three state western region (MT, WY, NE), extension agents, crop consultants, industry representatives, commodity groups (Montana Wheat and Barley Committee, Western Sugar Cooperative, Wyoming Sugar, Nebraska Bean Growers Association), agronomists and extension specialists, and regional/national weed science researchers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two graduate students (one of each at MSU and University of Wyoming) have been trained through this project. This research will serve as one of the disseration projects for the PhD graduate student at Montana State University (now at Iowa State University). In addition, four undergraduate students were trained across the four sites in 2019. During this reporting period PIs have conducted meetings todiscuss the project flow, field site selection, data collection and data analysis. A meeting in the Fall of 2019 was conducted for final data anaylysis and presentation of results and development of hydrothermal modelto predict kochia emergence across the threestate region.This grant will enhance our collaborative opportunities at regional and national levels with the ultimate goal to manage herbicide resistance and maintain the sustaibability of current and future weed management technologies.A PD workshop presentation was delivered by Dr. Jha as Western IPM-Hour presentation. October 14, 2020. Participants 60. How have the results been disseminated to communities of interest?The PI and Co-PIs conducted workshops, plot demonstrations, field days and CCA tours in the the three-state region (MT, WY, NE) during 2019-2020 to train and educate the Ag Professionals and growers on implementation of sustainable, ecologically based weed management programs to manage herbicide resistance in cropping systems of the US Great Plains. We made growers and commodity groups aware of the outcomes and impacts of this integrated project during the 2019/2020 field days, extension presentations, and the CCA tours across MT, WY, and NE region. This project will surely have a positive impact on adoption of ecologically based, IWM strategies for multiple herbicide-resistant kochia mangement across the northwestern region of the US. What do you plan to do during the next reporting period to accomplish the goals?This is the final report

Impacts
What was accomplished under these goals? Objective A 1-3. Data for the water potential experiments were analyzed in R statistical software using a time-event, two-parameter log-logistic model. Germination rate (1/t50) and base water potential (Ψb50) were calculated from the estimated parameter (t50) values. A mixed-effects model was used to test the effect of treatments between northern (Huntley, MT and Powell, WY) and southern region (Lingle, WY and Scottsbluff, NE) of the US Great Plains. Based on the results, we concluded that 1) kochia can germinate over a wide range of water potential (as low as -1.65 MPa); 2) moisture requirement for kochia germination did not differ between northern and southern region; 3) changes in moisture requirement may not explain differential kochia emergence patterns across the North-South transect. Data from temperature experiment were also analyzed in R statistical software using a time-event, three-parameter log-logistic model. Germination rate (1/t50) and optimum temperature (to) were calculated from the estimated parameter (t50) values. A mixed-effects model was used to test the temperature requirements for germination of northern and southern kochia accessions. Results of this experiment revealed that at optimal temperatures, thermal requirements for kochia germination did not differ between northern and southern region. However, at sub-optimal temperatures (4 to 12 C), kochia from northern region took less time to achieve 50% germination and had higher cumulative germination than kochia from southern region. This indicates that changes in thermal requirements could possibly explain differential kochia emergence patterns across the N-S transect. Therefore, a stale seed bed approach may be more effective in the southern region of the U.S. Great Plains to stimulate kochia germination early in the spring and exhaust the seed bank using tillage or non-selective herbicides prior to late-planted crops such as dry bean (planted in early June) grown in rotation with sugar beet (planted in mid-April). Based on the parameter estimates derived from the laboratory experiments, a hydrothermal time model for kochia germination was developed that will be validated with the field emergence data. Results will be published in peer-reviewed journal and extension publications. Objective B 1-2. Field experiments were conducted in 2017-2018 and repeated in 2018-2019 at four sites in MT, WY, and NE (north-south transect) to quantify the effect of cover crop, irrigation, and tillage on emergence patterns of kochia, with an ultimate goal to exhaust the kochia seed bank. A total of 44 kochia accessions were collected in 2016 from northern (Huntley, MT; Powell, WY) and southern (Lingle, WY; Scottsbluff, NE) regions, 11 accessions from each of the four locations. These 11 accessions were grown in bulk on edges of the experimental field at each location for seed production in 2017. Fully-mature seeds were cleaned and a known quantity of seeds were uniformly broadcasted in each plot in the fall of 2017. A strip-split-split plot design was used. Strip-plot factor included winter wheat cover crop vs. no cover crop. Split-plot factor included five irrigation treatments ranging from no irrigation to four irrigations, with timings depending on each irrigation district. Split-split-plot factor consisted of no tillage, tillage (to a depth of 10 cm) before irrigation, and tillage after irrigation. Emerged kochia seedlings were counted and removed from two permanent 1 m2 quadrats placed at the center of each plot at a biweekly interval. Data were analyzed using a generalized linear mixed effects model to with cover crop, irrigation, and tillage as fixed effects. Data from one northern (MT) and one southern (NE) location are presented. Winter wheat used as a cover crop did not influence kochia emergence patterns. Irrigation and tillage treatments did not influence kochia emergence at the MT site. In contrast, irrigation and tillage treatments significantly improved kochia emergence from the seed bank at the NE site. Kochia emergence increased with an increase in the number of irrigations; plots that received three irrigations had 80% compared to 60% emergence in plots that received no irrigation. Similarly, tillage after irrigation had a higher kochia emergence (80%) compared to no tillage or tillage before irrigation (60% emergence). These results also indicate that a stale seed bed approach may be more effective in the southern region to stimulate kochia emergence early in the spring with irrigation and a subsequent tillage to exhaust the seed bank prior to late-planted crops such as dry bean (planted in early June) grown in rotation with sugar beet (planted in mid-April). The region-specific hydrothermal models for predicting kochia emergence in the field is being validated. The model to determine the impact of these ecological tactics in reducing the risk of resistance evolution in kochia is also being developed. Results will be published in peer-reviewed journal and extension articles.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Elizabeth G Mosqueda, Charlemagne A Lim, Gustavo M Sbatella, Prashant Jha, Nevin C Lawrence, Andrew R Kniss. 2020. Effect of crop canopy and herbicide application on kochia (Bassia scoparia) density and seed production. Weed Sci 68:278-284
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Kumar V, P Jha, M Jugulam, R Yadav, PW Stahlman. 2019. Herbicide-Resistant Kochia (Bassia scoparia) in North America: A Review. Weed Science, 67(1), 4-15. doi:10.1017/wsc.2018.72
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yadav R, Jha P, Kniss AR, Lawrence NC, Sbatella GM. 2020. Ecological management of kochia in irrigated Western cropping systems. Proc. Weed Sci. Soc. Am. 276
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., V. Kumar, C. A. Lim, R. Yadav, S. Leland, J. Anjani. 2019. Herbicide Resistance in Montana: Current Status and Future Directions. Proc. Weed Sci. Soc. Am. 69.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., A. Kniss, N. C. Lawrence, R. Yadav. 2019. Ecological Strategies to Manage Herbicide-Resistant Kochia Seed Bank in Irrigated Cropping Systems of the US Great Plains. Proc. Weed Sci. Soc. Am. 347.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yadav R., P. Jha, A. Kniss, N. C. Lawrence, G. M. Sbatella. 2019. Regional Differences in Kochia Germination from the US Great Plains: Effect of Water Potential. Proc. Weed Sci. Soc. Am. 358.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., A. Kniss, N. C. Lawrence, R. Yadav, C. A. Lim. 2019. Ecological Strategies to Manage Herbicide-Resistant Kochia Seed Bank in the Western US. Proc. West. Soc. Weed Sci. 57
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yadav R., P. Jha, A. Kniss, N. C. Lawrence, G. M. Sbatella. 2019. Regional Differences in Kochia Germination from the US Great Plains: Effect of Temperature. Proc. West. Soc. Weed Sci. 97.


Progress 09/01/18 to 08/31/19

Outputs
Target Audience:The target audience(s) comprised of local and regional growers across the three state western region (MT, WY, NE), University extension agents, crop consultants, industry representatives, commodity groups (Western Sugar Cooperative, Montana Wheat and Barley Committee, Nebraska Bean Growers Association), agronomists and weed extension specialists, and regional/national weed science researchers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two graduate students (one each at Montana State University and University of Wyoming) have been trained through this project. This research will serve as one of the dissertation projects for the PhD graduate student at Montana State University (now at Iowa State University). In addition, four undergraduate students were trained across the four sites in 2019. During this reporting period, PIs have conducted two meetings (one in the summer and one in the fall of 2018) to discuss the project flow, field site selection, data collection, and data analysis. Another meeting in the fall of 2019 will be conducted for final data analysis and presentation of results and development of hydrothermal model to predict kochia emergence across the three-state region. Recommendations for adoption of ecological strategies to deplete kochia seed banks in irrigated western cropping systems will be developed. Results were presented by the PIs and the graduate student at winter grower meetings, commodity group meetings (2018/2019) and regional and national weed science conferences. This grant will enhance our collaborative opportunities at regional and national levels with the ultimate goal to manage herbicide resistance and maintain the sustainability of current and future weed management technologies. How have the results been disseminated to communities of interest?The PI and Co-PIs conducted workshops, plot demonstrations, field days, and CCA tours in the three-state region (MT-WY-NE) during 2018-2019 to train and educate the Ag professionals and growers on implementation of sustainable, ecologically based weed management programs to manage herbicide resistance in cropping systems of the US Great Plains. We made growers and commodity groups aware of the outcomes and impacts of this integrated project during the 2018/2019 field days, extension presentations, and CCA tours across MT, WY, and NE region. This project will surely have a positive impact on adoption of ecologically based, IWM strategies for multiple herbicide-resistant kochia management across the northwestern region of the US. What do you plan to do during the next reporting period to accomplish the goals?Data from water potential and temperature experiments (Objective 1c) have been analyzed and interpreted. However, two-year field emergence data from all locations are currently being analyzed. Both data set will be combined together once the analysis is complete and will be used to develop a hydrothermal model. The results will be submitted with the final report. A hydrothermal model based on two-year of laboratory and field emergence data (Objective 2b) will be used to predict kochia emergence patterns across North-South transact. By using these data along with inferences from the specific objective 2a, we will be able to develop and recommend site-specific management strategies to best manage kochia across the three-state region. This will allow timely submission of results of data and models for publication in late 2019. Climate data (temperature and precipitation) will be assembled and processed in fall 2019, and predictive modeling of kochia emergence based on our hydrothermal time model and historical records among and within regions will be conducted in 2019/2020. This will allow recommendations to be made at grower meetings beginning in the winter extension season of 2019/2020.The results will be disseminated to a diverse group of stakeholders to enhance adoption of these IWM programs. A final report will be submitted in 2020.

Impacts
What was accomplished under these goals? Objective 1a: A second-run of water potential and temperature experiment was conducted in the fall 2018 using the same methodology as for the first run. Data for the water potential experiments were analyzed in R statistical software using a time-event, two-parameter log-logistic model. Germination rate (1/t50) and base water potential (Ψb50) were calculated from the estimated parameter (t50) values. A mixed-effects model was used to test the effect of treatments between northern and southern region. Based on the results, we concluded that 1) kochia can germinate over a wide range of water potential (as low as -1.65 MPa); 2) moisture requirement for kochia germination did not differ between northern and southern region; 3) changes in moisture requirement may not explain differential kochia emergence patterns across the North-South transect. Findings of this experiment were presented at Weed Science Society of America' 59th annual meeting held at New Orleans, LA during February 11-14, 2019. Data from temperature experiment were also analyzed in R statistical software using a time-event, three-parameter log-logistic model. Germination rate (1/t50) and optimum temperature (to) were calculated from the estimated parameter (t50) values. A mixed-effects model was used to test the temperature requirements for germination of northern and southern kochia accessions. Results of this experiment revealed that at optimal temperatures, thermal requirements for kochia germination did not differ between northern and southern region. However, at sub-optimal temperatures, kochia from northern region took less time to achieve 50% germination and had higher cumulative germination than kochia from southern region. This indicates that changes in thermal requirements could possibly explain differential kochia emergence patterns across the N-S transect. These results were presented at Western Society of Weed Science 72nd annual meeting held at Denver, CO during March 11-14, 2019. Objective 1b: The second-year of field experiment was started with planting of winter wheat as a cover crop in October 2018. Plots were uniformly infested with known amount of kochia seeds before planting cover crop. The 2019 field layout and treatment plan were similar to those of 2018. In Montana study location, kochia started emerging in first week of April 2019. Subsequent emergence flushes were counted biweekly until there was no further germination for two weeks. Soil moisture and temperature readings were also recorded from each plot using a Stevens Portable Hydra Data Reader on daily basis. Two-year field emergence data from all study locations are currently being analyzed and results will be submitted with the final report. Objective 2a: Field experiments were repeated in 2018-2019 at all study locations to evaluate the impact of tillage, irrigation, and cover crop on kochia emergence patterns. Winter wheat was planted in cover crop treatments in fall 2018. Cover crop was terminated in 2019 with a rototiller to a depth of 5-7 cm in tillage plots, and with glyphosate at 1260 g ae ha-1 in no-till plots. A linear-move irrigation system was used to irrigate irrigation plots. Rain gauges were also installed in each replication to measure precipitation and to insure proper adjustments for the irrigation treatments. At the end of study period (July 2019), soil samples were collected. Soil sampling was done using a 5-cm diameter 'soil core sampler' at a depth of 10 cm, 5 samples per plot. These samples are currently being processed to determine the impact of ecological strategies on kochia seedbank depletion. Data from the field experiments from all locations (MT, WY, and NE) are being analyzed and will be submitted with the final report.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Citation: Kumar V, Jha P, Dille A, Stahlman PW (2018) Emergence dynamics of kochia (Kochia scoparia) populations from the US Great Plains: A multi-site-year study. Weed Sci 66:25-35
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Kumar V, Jha P, Jugulam M, Yadav R, Stahlman PW (2019) Herbicide-Resistant Kochia (Bassia scoparia) in North America: A Review. Weed Science, 67(1), 4-15
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Kumar V, Engel RP, Currie R, Jha P, Stahlman PW, Thompson C (2019) Dicamba-resistant kochia (Bassia scoparia) in Kansas: characterization and management with fall- or spring-applied PRE herbicides. Weed Technol. 33: 342-348
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., V. Kumar, C. A. Lim, R. Yadav, S. Leland, J. Anjani. 2019. Herbicide Resistance in Montana: Current Status and Future Directions. Proc. Weed Sci. Soc. Am. 69.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., A. Kniss, N. C. Lawrence, R. Yadav. 2019. Ecological Strategies to Manage Herbicide-Resistant Kochia Seed Bank in Irrigated Cropping Systems of the US Great Plains. Proc. Weed Sci. Soc. Am. 347.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yadav R., P. Jha, A. Kniss, N. C. Lawrence, G. M. Sbatella. 2019. Regional Differences in Kochia Germination from the US Great Plains: Effect of Water Potential. Proc. Weed Sci. Soc. Am. 358.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jha P., A. Kniss, N. C. Lawrence, R. Yadav, C. A. Lim. 2019. Ecological Strategies to Manage Herbicide-Resistant Kochia Seed Bank in the Western US. Proc. West. Soc. Weed Sci. 57.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yadav R., P. Jha, A. Kniss, N. C. Lawrence, G. M. Sbatella. 2019. Regional Differences in Kochia Germination from the US Great Plains: Effect of Temperature. Proc. West. Soc. Weed Sci. 97.


Progress 09/01/17 to 08/31/18

Outputs
Target Audience:The target audience(s) comprised of local and regional growers across the three state western region (MT, WY, NE), University extension agents, crop consultants, industry representatives, commodity groups (Western Sugar Cooperative, Montana Wheat and Barley Committee, Nebraska Bean Growers Association), agronomists and weed extension specialists, and regional/national weed science researchers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?As listed in the "Products" section, this project provided oppurtunities to present (oral/poster presentation) the Yr-1 results and approaches for ecological management of kochia in irrigated western cropping systems, with emphasis on herbicide resistance mitigation to a diverse group of audience at the Weed Science Society of America and Western Weed Science Society annual meetings held in 2018.Graduate students were involved in these meetings and presentation of the results. Apart from other training and outreach programs listed below, an integrated weed management (IWM) workshop was organized by the PIs during February 2018 at MSU-SARC, Huntley, MT to further engage/train Ag professionals, mostly crop consultants, Ag retailers, industry reps, and University extension agents/field agronomists. The Yr-1 results and implications of this project were dessiminated to these stakeholders. How have the results been disseminated to communities of interest?The PI and Co-PIs conducted workshops, plot demonstartions, field days, and CCA tours in the three-state region (MT-WY-NE) to train and educate the Ag professionals and growers on implementation of sustainable, ecologically based weed management programs to manage herbicide resistance in cropping systems of the US Great Plains. Extension and outreach activities (presentations) are listed below: Utilizing crop rotation diversity to mitigate herbicide-resistant weed seed banks. Simplot Grower Meeting. Powell, WY, February 27, 2018 An IWM approach to herbicide resistance management in irrigated cropping systems of NGP. Winfield Solutions Agronomy Meeting. Billings, MT, February 21, 2018 Effect of crop rotation, tillage, and herbicide diversity on evolution of herbicide resistance in kochia: Results from a four-year multi-location study. Herbicide Resistance Workshop, Powell, WY, December 12, 2017 Status of herbicide resistance in Montana and ecological weed management strategies. CCA Field Day, Southern Agricultural Research Center, Huntley, MT, August 8, 2017. Herbicide resistance management in the US Great Plains. CHS Grower Meeting, Malta, MT, Jan 9, 2017 Ecological strategies to manage kochia seed banks in sugar beet-based rotations. UNL Field day, Scottsbluff, NE, July, 2018 What do you plan to do during the next reporting period to accomplish the goals?Research and extension activities will be continued in 2018-2019 to fulfill the objectives as proposed in the research goals (A and B) of the project. All experimental procedures for the field trials will be repeated in fall of 2018 through summer 2019, the schedule of events will remain the same as for the first year.Initial validation of the germination model with the field emergence data will begin in fall 2018, and a final model development and validation by fall of 2019 after the final year of field data collection. This will allow timely submission of results of data and models for publication in late 2019. Climate data (temperature and precipitation) will be assembled and processed in fall 2018, and predictive modeling of kochia emergence based on our hydrothermal time model and historical records among and within regions will be conducted in 2019. This will allow recommendations to be made at grower meetings beginning in the winter extension season of 2019/2020.The results will be dessiminated to a diverse group of stakeholders to enhance adoption of these IWM programs.

Impacts
What was accomplished under these goals? Objective A-1: To determine minimum, maximum and optimal temperature and moisture requirement for 44 kochia accessions, two separate experiments were conducted in fall 2017. Temperature experiment was conducted on a thermogradient table with temperatures ranging from 0/6 to 30/40 C at the University of Wyoming. This experiment will be repeated in the fall of 2018. Data from both runs will be presented in Weed Science Society annual meetings in spring 2019. Final results from this experiment will be submitted in 2019. To determine moisture requirement of 44 kochia accessions, an experiment was conducted at MSU-SARC in fall 2017. We used polyethylene glycol 8000 to create water potential (Ψ) treatments that ranged from 0 to -2.4 MPa. All the treatments were arranged in a randomized complete block design with four replication in the incubator set at a constant temperature of 24 C. We analyzed germination count data using a time-event, 3-parameter log-logistic model and calculated the time taken for median germination (T50), optimum water potential (Ψ0), and base water potential (Ψb). Data from 16 accessions (4 accessions from each location Huntley, MT; Powell and Lingle, WY; and Scottsbluff, NE) were presented at the 71st annual meeting (March 12-15, 2018) of the Western Society of Weed Science, Anaheim, CA. No differences in 1/T50 were evident between the accessions at no water stress; however, at medium- to high- level of water stress, accessions from Huntley and Powell showed higher germination rates compared to Lingle and Scottsbluff. Similarly, accessions from Huntley and Powell had lower Ψb(50) (base water potential) compared to Lingle and Scottsbluff. These results indicate that kochia from northern states are more tolerant to water stress than kochia from southern states of the US Great Plains. Data from rest of the kochia accessions will be analyzed in fall 2018. The hydrothermal model will be developed in the fall 2018 and final results will be submitted in 2019. Objective A-2/B1: Kochia accessions that were collected in fall 2016 were planted near to the experimental fields in April 2017 for seed production. Seeds from each location were harvested, cleaned, and a known amount (g) of seeds were uniformly broadcasted in each plot in the fall of 2017. Prior to kochia infestation, soil samples were collected to determine the initial soil seed bank. Field studies were laid out in fall 2017 at Huntley, MT; Scottsbluff, NE; and Lingle, WY in a strip-split-plot randomized complete block design. Winter wheat was planted in the cover crop treatments. Tillage, irrigation, and cover crop termination treatments were applied in the following spring and summer of 2018. In the northern part of the region (Huntley, MT), kochia started emerging in the second week of April 2018. Kochia emergence count was started in the third week of April and continued at 2-weeks interval until first week of July (with no further emergence for 10 days). Emerged seedlings were counted using two 0.5 m2 permanent quadrats in each plot. Daily soil moisture and temperature readings from each plot were recorded using Stevens Portable Hydra Data Reader. Tillage treatments were applied using a roto-tiller to a depth of 5 to 7 cm. The cover crop in no-tillage treatments was terminated by spraying glyphosate (1260 g ae ha-1) with AMS. Irrigation treatments (Liner/Furrow) were applied at each site as per the local irrigation districts. The linear system was set up to deliver 2 cm of water in each plot. Rain gauges were installed in each replication to measure rainfall throughout the study period. To determine the residual soil seed bank, soil samples were collected in August 2018. Sampling was done using a 5-cm diam soil core sampler at a depth of 10 cm and 5 sub-samples per plot. Sub-samples within each plot were combined together and stored in a freezer to break seed dormancy. These samples will be used for exhaustive germination in a greenhouse. All the data from the first year of the field study will be analyzed in fall 2018 and results will be submitted in in 2019. The second year of the field study at each location will be initiated in October 2018 without any changes to the protocol.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Kumar V, Jha P, Dille A, Stahlman PW (2018) Emergence dynamics of kochia (Kochia scoparia) populations from the US Great Plains: A multi-site-year study. Weed Sci 66:25-35
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Kumar V, Jha P (2017) Effect of temperature on germination characteristics of glyphosate-resistant and glyphosate-susceptible kochia (Kochia scoparia). Weed Sci 65:361-370
  • Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Kumar V, Jha P, Jugulam M, Yadav R, Stahlman PW (2018) Herbicide-resistant kochia (Bassia scoparia) in North America: A review. Weed Sci (in press)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Jha P, Kniss A, Sbatella GM, Lawrence NC, Yadav R (2018) Ecological approaches to manage kochia seed bank in irrigated western cropping systems. Proc Weed Sci Soc Am 297
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Lim CA, Mosqueda EG, Jha P, Kniss A, Sbatella GM, Lawrence NC (2018) Optimizing crop rotations to best utilize crop canopy effects on kochia seed bank reduction: A multi-site-year study. Proc Weed Sci Soc Am 27
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Jha P, Kniss A, Lawrence NC, Sbatella GM, Yadav R, Lim CA (2018) Ecological management of kochia in irrigated western cropping systems: Approaches and path forward. Proc Western Soc Weed Sci 56
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Yadav R, Jha P, Sbatella GM, Lawrence NC (2018) Effect of water potential on germination of kochia (Kochia scoparia) accessions from the US Great Plains. Proc Western Soc Weed Sci 91


Progress 09/01/16 to 08/31/17

Outputs
Target Audience:The target audience(s) comprised of local and regional growers across the three state western region (MT, WY, NE), extension agents, crop consultants, industry representatives, commodity groups (Montana Wheat and Barley Committee, Western Sugar Cooperative, Wyoming Sugar, Nebraska Bean Growers Association), agronomists and extension specialists, and regional/national weed science researchers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two graduate students (one each at Montana State University and University of Wyoming) have been hired in spring 2017 and are currently involved in this project. This research will serve as one of the dessertation projects for the PhD graduate student at Montana State University. In addition, three undergraduate students are involved across the four sites. During this reporting period, PIs have conducted two meetings (one in spring and one in summer of 2017) to discuss the project flow, data collection, and field site selection. Another meeting in the fall of 2017 will be conducted for data analysis to fullfill Objective A, subjectives 1 and 3. Results from this objective will be presented by the PIs at winter grower meetings, commodity group meetings, (2017/2018) and regional and national weed science conferences. We made growers and commodity groups aware of this project during the 2017 field days, extension presentations, and CCA tours across MT, WY, and NE region. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?By the next reporting period (Auguest 2018), we hope to accomplish Objective A, subobjective 1, 3 for all 44 kochia accessions based on the germination studies. Field studies to fullfill objective A, subobjective 2 and objective B, subobjective 1 will be established and in-field emergence data collection for year 1 will be in progress. The field study (year 1) will be demonstrated at field days and CCA tours at MSU, UWY, and UNL and practical implications of kochia emergence dynamics and ecological management strategies will be presented.

Impacts
What was accomplished under these goals? Fully-matured kochia seeds were collected from 10 sites each in the fall of 2016 from naturally-infested agronomic crop production sites near Huntley, MT; Powell and Lingle, WY; and Scottsbluff, NE; representing the North-South transect of this region (N=40). An additional accession was collected from 4 rangeland sites, one near each location, bringing the total number of accessions to 44 (N=44). Individual inflorescence were hand-harvested and dried at room temperature. Seeds were separated by gently hand-rubbing the inflorescence; debris was removed from the seed with a series of standard sieves and air cleaning. Fully-intact seeds were selected and stored at 5 C until the beginning of the germination experiments to fullfill Objective A, subobjectives 1 and 3. Germination experiments to study the effect of temperature and water potential (Objective A, subobjective 1) has been initiated (summer of 2017) and currently in progress. In the temperature experiment using a thermogradient plate at UWY, seven thermoperiods are currently being used, ranging from 0/6 to 30/40 C. To quantify the effect of water potential on kochia seed germination (study conducted at MSU), polyethylene glycol (PEG) solution is being used to create solutions with water potentials of 0, -0.03, -0.06, -0.1, -0.3, -0.5, -0.7, -0.9, -1.2, -1.6, -1.8, -2.1, -2.4 MPa. For both temperature and water potential studies, germinated seed is counted and removed every 24 h for 15 d or until no further germination occurs for 5 consecutive days. The experiments will be repeated. Preliminary data analysis from the germination experiments will be conducted. Analysis of seed germination studies will be conducted using appropriate nonlinear regression models. Using this analysis, we will estimate the minimum, optimal and maximum thermal and water requirements for kochia germination by calculating the time required to observe 10, 50, and 90% germination (T10, T50, and T90, respectively) of viable kochia seed. This information will be used to inform regional management recommendations (if differences between accessions follow geographical patterns) and also to derive base temperature and water potential in the hydrothermal time germination models to fullfill Objective A, subobjective 3. To fullfill Objective A-subobjective 2 and Objective B-subobjective 1, kochia from 11 accessions collected per site are currently being grown (starting April 2017) at each experimental site for bulk seed production. Seeds will be uniformly broadcasted at the test site in the fall of 2017.The experimental plots at Huntley, Powell, Lingle, and Scottsbluff have already been established (laid out). Two of the study locations, Huntley and Lingle, will be under furrow irrigation and two sites, Powell and Scottsbluff, will be under sprinkler irrigation in order to be representative of the crop production practices utilized across the region. The winter wheat cover crop plots will be planted in the fall 2017 and all other treatments will be applied in 2018 (first year of the field study).

Publications