WEED CONTROL STRATEGIES FOR NORTH DAKOTA AND THE NORTHERN GREAT PLAINS

• Sponsoring Institution: State Agricultural Experiment Station
• Project Status: TERMINATED
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 0223935
• Project No.: ND06349
• Project Start Date: Oct 1, 2010
• Project End Date: Sep 30, 2015

Project Director
Jenks, BR.

Recipient Organization
NORTH DAKOTA STATE UNIV
(N/A)
FARGO,ND 58105

Performing Department
North Central Research Extension Center

Non Technical Summary
Weeds generally are considered one of the greatest problems in crop production. Changes in weed species, weed densities, and weed resistance to herbicides have made weed control more challenging. These changes are especially important for crops that do not compete well with weeds such as lentil, chickpea, and flax. About 85 percent of all pesticides used in North Dakota are herbicides. However, the major herbicide manufacturers focus most of their resources on major crops such as corn, soybean, and wheat. Minor crops in North Dakota such as canola, safflower, dry pea, lentil, chickpea, and flax receive much less attention and thus have few registered herbicides. The State of North Dakota has appropriated money to fund research that will lead to new product registrations in minor crops. Herbicide efficacy and crop tolerance data gathered by this project will help register new weed control products. New herbicide registrations will provide growers with more choices to solve weed control issues in minor crops. Many ND growers have adopted variations of direct seeding or no-till. As growers moved away from tillage, winter annual weeds that typically were controlled by tillage now need to be controlled through the use of herbicides or cultural methods. This research may provide growers with options to control winter annual weeds more effectively through fall applications. This will lead to cleaner fields in the spring and ultimately higher yields, crop quality, and profitability. Dry pea, lentil, and chickpea acres have increased significantly over the past decade. However, grower surveys still say that weed control remains their top priority. Growers want herbicide options that control weeds effectively without causing crop injury. The most effective herbicides we currently have or will have in the near future are influenced by soil and environmental conditions. It is important to understand these conditions to maximize weed control and crop safety. The objectives of this project will address ways to maximize weed control through fall and spring applications as well as determining crop sensitivity to commonly used herbicides.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
213	2410	1140	25%
213	5220	1140	50%
711	2410	1140	25%

Knowledge Area
711 - Ensure Food Products Free of Harmful Chemicals, Including Residues from Agricultural and Other Sources; 213 - Weeds Affecting Plants;

Subject Of Investigation
2410 - Cross-commodity research--multiple crops; 5220 - Pesticides;

Field Of Science
1140 - Weed science;

Keywords

weed control

no-till

minor crop

winter annual

summer annual

cultivar sensitivity

differential tolerance

ppo inhibitor

Goals / Objectives
Objective 1: Investigate new herbicides in minor crops to fill existing weed control gaps. Although minor crop acreage has increased over the past decade, the process for herbicide registration in minor crops moves very slowly and has not filled weed control gaps that exist across the northern plains. Crop protection product manufacturers base their registration priorities on crops with the largest number of acres. Many North Dakota crops do not fall into the major crop category, so registration of herbicides for these crops is much lower on the priority list. Research is needed to document that a product is safe on a given crop and that it can provide better weed control than currently labeled herbicides. Some new active ingredients have become available in recent years. These materials are available for universities to conduct research to determine how they may fit production practices in minor crops. The specific agronomic and economic strengths and weaknesses of each product need to be identified. This research can lead to herbicide registrations in minor crops to help growers control problem weeds. Objective 2: Determine the effectiveness of fall-applied herbicides for winter annual and summer annual weed control. A shift to winter annual weeds has been observed in recent years. Winter annual weeds have increased because more farmers are using no-till systems as well as growing more minor broadleaf crops where effective herbicides are not available. Tank mixing a soil residual herbicide with glyphosate in the fall may provide better control of winter annuals and give growers application flexibility. Removing fall emerging weeds would result in fewer weeds to control in the spring, likely increasing the effectiveness of the spring burndown. Effective fall weed control would also preserve precious water resources and would allow soils to warm up faster in the spring. Objective 3: Determine if pulse crop cultivars differ in their sensitivity to PPO-inhibitors. Dry pea, lentil, and chickpea production are hampered by the lack of herbicides to control weeds. North Dakota farmers have listed weeds as their number one problem and top research priority. Three herbicides that can now be used for certain pulse crops include sulfentrazone, flumioxazin, and saflufenacil. Each herbicide differs slightly in spectrum of weeds controlled. Some crop injury has been observed in certain soils and environmental conditions. Pulse growers have questioned whether pulses differ (green vs. yellow pea, green vs. red lentil, kabuli vs. desi chickpea, etc.) in their sensitivity to these herbicides. Differential tolerance among soybean and dry bean cultivars has been reported for sulfentrazone and flumioxazin. Given this evidence of differential sensitivity, it is possible that pulse crop cultivars also may respond differently to these herbicides. This project will evaluate pulse crop cultivar sensitivity to PPO inhibitors through field and laboratory studies.

Project Methods
Objective 1: Investigate new herbicides in minor crops to fill existing weed control gaps. We will conduct field studies to optimize herbicide use patterns (timing, rate, adjuvant) for controlling weeds in minor crops such as pea, lentil, chickpea, canola, flax, dry bean, safflower, and sunflower. A standard experiment will consist of 3 by 9 m plots arranged in a randomized complete block design with three or four replications. All data will be subjected to analysis of variance. Treatments will be applied with either a tractor-mounted or bicycle sprayer. If a new product is found to be safe on a specific crop and adequately controls a problem weed, we will consult with commodity groups to determine if registration should be pursued. Products that exhibit good safety will be submitted to IR-4 for residue studies and development of tolerance petitions. Objective 2: Determine the effectiveness of fall-applied herbicides for winter annual and summer annual weed control. We will conduct field studies that target problem winter and summer annual weeds. Fall and spring applications of various soil residual herbicides will be evaluated. These studies will be conducted over multiple years to verify consistency of results. A standard experiment will consist of 3 by 9 m plots arranged in a randomized complete block design with three or four replications. Objective 3: Determine if pulse crop cultivars differ in their sensitivity to PPO-inhibitors. Field and laboratory studies will be conducted to determine if pulse crop cultivars respond differently to PPO inhibitors sulfentrazone, flumioxazin, and saflufenacil. At least two cultivars from different market classes will be selected for dry pea, lentil, and chickpea. The field experiment statistical design will be a split plot arrangement in a randomized complete block design with four replications. Cultivar will be the whole plot and herbicide concentration the sub-plot. Each treatment will be evaluated visually for crop tolerance and crop height will be measured twice during the season. Crop yield and test weight will be determined following harvest with a small-plot combine. In the laboratory, seeds will be surface-sterilized in a 5 percent sodium hypochlorite solution, rinsed, and dried at room temperature. Seeds will be imbibed in distilled water spiked with herbicide at various concentrations. Four imbibed seeds will be transferred to the upper trough of individual seed germination pouches that contain 40 ml of the appropriate herbicide solution in the lower reservoir of the pouch. Soil potting mix will be placed over the top of the seeds to simulate soils conditions and prevent seeds from drying out. The pouches will be placed in the darkened growth chamber for four days after which hypocotyls and root lengths will be measured. Variables will include cultivar and herbicide concentration. The study will be a completely randomized design with four replications, and the study will be conducted two times. All data will be subjected to analysis of variance.

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

Outputs
Target Audience:The primary target audience includes farmers, retailers, agronomists, and crop consultants. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has provided opportunities to attend and share information at North Central and Western Weed Science Society meetings, as well as regional meetings. How have the results been disseminated to communities of interest?Information has been dissemminated through local, regional, and national meetings as well as by website, magazines, and newsletters. The main focus audience includes farmers, agronomists, crop consultants, retailers, and university extension. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Several studies were conducted to address information gaps for optimal herbicide application timing, weed resistance, and crop tolerance to herbicides. A study was conducted to evaluate alternative herbicides for controlling emerged kochia that may be glyphosate-resistant in a spring burndown. Herbicide treatments were applied May 21 to 0.5- to 4-inch kochia with about 50 plants/ft2. All treatments were applied with recommended adjuvants to enhance foliar control. Glyphosate provided poor kochia control. Saflufenacil, paraquat, and any sulfentrazone product provided fair to good kochia control, which is in contrast to the 2013-14 studies where these treatments provided good to excellent kochia control. Cold temps in 2015 may have contributed to lower control in 2015. Herbicides with longer residual such as sulfentrazone provided better long-term control. A study was conducted to evaluate Group 1-resistant wild oat control in Liberty Link canola with glufosinate and clethodim. All treatments were applied to 4- to 5-leaf canola and 4-leaf wild oat. All treatments provided excellent wild oat control. Tank mixing glufosinate and clethodim has provided good grass control in previous studies and may help manage Group 1-resistance. Some green foxtail populations across North Dakota are known to be resistant to Group 1 herbicides like fenoxaprop, clodinafop, and pinoxaden. A study was conducted to evaluate barley tolerance to soil-applied preemergence herbicides for foxtail control. This study was conducted in 2012, 2014, and 2015. All treatments were applied preemergence (after barley was planted). In 2012, metolachlor, flucarbazone, and flumioxazin caused early moderate crop injury; however, the crop generally recovered by mid-July. Pyroxasulfone, acetochlor, and pendimethalin caused minimal crop injury in 2012. In contrast, pyroxasulfone and acetochlor caused slight to moderate crop injury in 2014. Flucarbazone and pendimethalin caused only slight crop injury in 2014. Flumioxazin caused moderate crop injury both years. Metolachlor and dimethenamid caused severe injury in 2014. Despite crop injury in 2012, there was minimal effect on crop yield. In 2014, only metolachlor and dimethenamid reduced barley yield. In 2015, all treatments (except pendimethalin) caused moderate crop injury (22-40%) soon after crop emergence. However, the injury subsided to 5-18% by mid-July. Only acetochlor, metolachlor, flumioxazin, and dimethenamid reduced tended to reduce yield slightly in 2015. A study was conducted to evaluate dry pea tolerance to sulfentrazone and saflufenacil applied alone or in a tank mix at different rates. All treatments were applied preemergence. Sulfentrazone at 3 oz and saflufenacil at 1 oz were considered as the 1X rates. Sulfentrazone at 3 oz + saflufenacil at 2 oz caused 10% injury or less. Rates up to sulfentrazone 6 oz + saflufenacil 4 oz caused 10-20% injury. Saflufenacil applied alone at 6 oz caused up to 21% injury and was the only treatment that caused a yield reduction. These results are very similar to the same study conducted in 2014. A study was conducted to evaluate foxtail control and dry pea/lentil tolerance to labeled and non-labeled herbicides. All treatments were applied preemergence in a no-till field. Pyroxasulfone, metolachlor, dimethenamid, and metribuzin caused slight to moderate lentil and dry pea injury (1-21%). Flumioxazin & pyroxasulfone caused up to 22% dry pea injury. Sulfentrazone & metolachlor caused up to 62% early-season lentil injury, but recovered over time. Despite the early season visual crop injury, the crops recovered over time and there were no yield differences between treated and untreated. A study was conducted to determine if six lentil cultivars differ in tolerance to 1X and 2X rates (140/280 g ai/ha) of sulfentrazone. Moderate to severe injury was observed in the early season evaluations. Lentil plants recovered somewhat over time, but still slight to moderate injury was visible at the late season evaluation. Early season visual injury ranged from 15-65% and 30-98% at sites 1 and 2, respectively. Late season injury ranged from 0-75% and 40-98% at sites 1 and 2, respectively. Greater injury at site 2 is likely a result of higher soil pH and lower organic matter.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Jenks, B. M., E. Davis, T. D. Walter, and G. P. Willoughby. 2014. Desiccant Effect on Canola Seed Moisture, Yield, and Quality. American Soc. Agron. Proc., Long Beach, CA. Oct 31-Nov 6.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Jenks, B. M. 2014. Options for controlling glyphosate-resistant kochia preplant. North Central Weed Sci. Soc. Proc., Minneapolis, MN. Dec 1-4.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Jenks, B. M. 2015. Preemergence weed control alternatives in barley. Western Soc. Weed Sci. Proc. Portland, OR. Mar 9-12.

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

Outputs
Target Audience: The primary target audience includes farmers, retailers, agronomists, and crop consultants. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project has provided opportunities to attend and share information at North Central and Western Weed Science Society meetings, Weed Resistance Summit in Washington, DC, as well as regional meetings. How have the results been disseminated to communities of interest? Information has been dissemminated through local, regional, and national meetings as well as by website, magazines, and newsletters. The main focus audienceincludes farmers, agronomists, crop consultants, retailers, and university extension. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Several studies were conducted to address information gaps for optimal herbicide application timing, weed resistance, and crop tolerance to herbicides.A study was conducted to evaluate alternative herbicides for controlling emerged kochia that may be glyphosate-resistant in a spring burndown. Herbicide treatments were applied June 5 to 0.5- to 4-inch kochia with about 12 plants/ft2. All treatments were applied with recommended adjuvants to enhance foliar control. Glyphosate provided poor kochia control while saflufenacil and any sulfentrazone product provided good to excellent kochia control. Paraquat provided good kochia control as well. Herbicides with longer residual such as sulfentrazone provided better long-term control. In a separate study, herbicides were evaluated for controlling emerged glyphosate-resistant kochia in a spring burndown using soybean herbicides. Glyphosate + pyroxasulfone provided poor kochia control. Kochia control was greater where metribuzin was applied at 0.5 lb compared to 0.25 lb/A. Saflufenacil & dimethenamid tended to provide slightly better kochia control than saflufenacil alone. Treatments containing sulfentrazone provided excellent kochia control. Flumioxazin & pyroxasulfone was not as effective as the sulfentrazone treatments. Fluthiacet provided poor kochia control.A study was conducted to evaluate Group 1-resistant wild oat control in Liberty Link canola with glufosinate and clethodim. All treatments were applied to cotyledon- to 3-leaf canola and 3-leaf wild oat. All treatments provided excellent wild oat control. Tank mixing glufosinate and clethodim has provided good grass control in previous studies and may help manage Group 1-resistance.Some green foxtail populations across North Dakota are known to be resistant to Group 1 herbicides like fenoxaprop, clodinafop, and pinoxaden. A study was conducted to evaluate barley tolerance to soil-applied preemergence herbicides for foxtail control. This study was conducted in 2012 and 2014. All treatments were applied preemergence (after barley was planted). In 2012, metolachlor, flucarbazone, and flumioxazin caused early moderate crop injury; however, the crop generally recovered by mid-July. Pyroxasulfone, acetochlor, and pendimethalin caused minimal crop injury in 2012. In contrast, pyroxasulfone and acetochlor caused slight to moderate crop injury in 2014. Flucarbazone and pendimethalin caused only slight crop injury in 2014. Flumioxazin caused moderate crop injury both years. Metolachlor and dimethenamid caused severe injury in 2014. Despite crop injury in 2012, there was minimal effect on crop yield. In 2014, only metolachlor and dimethenamid reduced barley yield.A study was conducted to evaluate dry pea tolerance to sulfentrazone and saflufenacil applied alone or in a tank mix at different rates. All treatments were applied preemergence. Sulfentrazone at 3 oz and saflufenacil at 1 oz were considered as the 1X rates. Sulfentrazone at 3 oz + saflufenacil at 2 oz caused 10% injury or less. Rates up to sulfentrazone 6 oz + saflufenacil 4 oz caused 10-20% injury. Saflufenacil applied alone at 6 oz caused up to 26% injury and was the only treatment that caused a yield reduction.A study was conducted to evaluate foxtail control and dry pea/lentil tolerance to labeled and non-labeled herbicides. All treatments were applied preemergence in a conventional-till field. Pyroxasulfone, sulfentrazone & metolachlor, metolachlor, dimethenamid, and metribuzin caused slight to moderate lentil injury, but only slight dry pea injury. Flumioxazin & pyroxasulfone caused moderate dry pea injury. Despite the early season visual crop injury, the crops recovered over time and there were no yield differences between treated and untreated.A study was conducted to determine if six lentil cultivars differ in tolerance to 1X and 2X rates of sulfentrazone. Moderate to severe injury was observed in the early season evaluations. Lentil plants recovered somewhat over time, but still slight to moderate injury was visible at the late season evaluation. At site 1, yield was reduced 0-16% and 0-42% for the 1X and 2X rates, respectively. At site 2, yield was reduced 6-31% and 45-84% for the 1X and 2X rates, respectively. Greater injury at site 2 is likely a result of higher soil pH and lower organic matter. There were injury and yield differences between varieties, but they were not always consistent across locations.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Jenks, B. M., T. D. Walter, and G. P. Willoughby. 2014. Foxtail barley control in wheat. Western Soc. Weed Sci. Proc., Colorado Springs, CO. Mar 10-13.

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

Outputs
Target Audience: The primary target audience includes farmers, retailers, agronomists,and crop consultants. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The project has provided opportunities to attend and share information at North Central and WesternWeed Science meetings, Weed Resistance Summit in Washington, DC, as well as regional meetings. How have the results been disseminated to communities of interest? Information has been dissemminated through local, regional, and national meetings as well as by website, magazines, and newsletters. The main focus audience is farmers, agronomists, crop consultants, retailers, and university extension. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Several studies were conducted to address information gaps for optimal herbicide application timing, weed resistance, and crop tolerance to herbicides. A study was conducted to evaluate false chamomile control with fall vs. spring-applied herbicides. Glyphosate applied alone in the fall (Oct 1) or spring (May 29) provided 60-68% chamomile control on July 26. Tank mixing glyphosate with linuron and metribuzin increased control slightly (74-75%). Treatments containing glyphosate+flumioxazin provided excellent long-term control (93-97%). A study was conducted to evaluate fall- or spring-applied herbicides for foxtail barley control. Fall treatments were applied October 1, 2012 to 3- to 6-inch foxtail barley. A blanket glyphosate application was made over the entire study on May 29, 2013. Postemergence treatments were applied June 27, 2013. Glyphosate and propoxycarbazone applied in the fall provided good foxtail barley suppression (65-81%) at the June 1 evaluation. Fall treatments followed by spring treatments containing propoxycarbazone provided excellent foxtail barley control (99%). A study was conducted to evaluate alternatives to glyphosate for glyphosate-resistant kochia control. No crop was planted due to wet soil conditions. All treatments were applied June 18 to 1.5-4 inch kochia. Paraquat+NIS, sulfentrazone+carfentrazone+MSO, and sulfentrazone+saflufenacil+MSO+AMS provided 92-98% kochia control 7 WAT, which was 20-40% more than glyphosate+AMS, saflufenacil+MSO+AMS, glufosinate+AMS, and sulfentrazone+metribuzin. A study was conducted to evaluate foxtail control and dry pea/lentil tolerance to labeled and non-labeled herbicides. All treatments were applied preemergence in a no-till field. Pyroxasulfone, sulfentrazone+metolachlor, metolachlor, dimethenamid, pendimethalin, and flumioxazin+pyroxasulfone caused moderate to severe lentil injury, but only slight to moderate dry pea injury. Pendimethalin and metolachlor generally provided good yellow foxtail control, while the other treatments provided only fair control. A study was conducted to evaluate foxtail control with labeled and non-labeled herbicides. All treatments were applied June 24 to 4-leaf wheat and 1-4 leaf foxtail. None of the treatments caused crop injury. Mesosulfuron+propoxycarbazone tank mixed with bromoxynil+pyrasulfatole provided poor yellow foxtail control, while mesosulfuron+propoxycarbazone tank mixed with thifensulfuron+tribenuron provided good yellow foxtail control (89%). Historically, we haven’t seen this level of enhanced foxtail control with mesosulfuron+propoxycarbazone tank mixed with thifensulfuron+tribenuron. Normally, we have seen only 5-15% higher control with this tank mix over mesosulfuron+propoxycarbazone alone. Thiencarbazone, bromoxynil+pyrasulfatole+thiencarbazone, and bromoxynil+pyrasulfatole+fenoxaprop provided excellent yellow foxtail control. A study was conducted to evaluate ACCase-resistant wild oat control with glufosinate and clethodim in Liberty Link canola. Glufosinate provided fair-good wild oat control alone, but provided excellent control when tank mixed with clethodim.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Jenks, B. M., T. D. Walter, and G. P. Willoughby. 2013. Effect of Pre-Harvest Desiccants on Canola Yield and Seed Quality. Western Soc. Weed Sci. Proc., San Diego, CA. Mar 11-14. Jenks, B. M. and T. D. Walter. 2012. Long-term yellow toadflax control in rangeland with aminocylopyrachlor. North Central Soc. Weed Sci. Proc., St. Louis, MO. Dec 10-13.

Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Obj. 1. Evaluate the impact of herbicide application timing on wild oat and foxtail control in spring wheat. Flucarbazone, pyroxsulam&flor&flur, and thiencarbazone&brom&pyra were applied at 2-leaf, 3-leaf, or 4-leaf wheat. Obj. 2. Evaluate barley tolerance to non-labeled preemergence herbicides. If resistance to Group 1 herbicides continues to increase, we will need alternative herbicides to control grassy weeds in barley. Obj. 3. Determine if foxtail control with flucarbazone, pyroxsulam&flor&flur, and mesosulfuron&propoxycarbazone will increase when tank mixed with tribenuron or tribenuron&thifensulfuron. Obj. 4. Evaluate foxtail barley control with a glyphosate burndown compared to glyphosate tank mixed with propoxycarbazone or flucarbazone and then followed postemergence by thiencarbazone&brom&pyra, mesosulfuron&propoxycarbazone, or flucarbazone. Obj. 5. Evaluate Group 1-resistant wild oat and foxtail control with the Group 2 herbicides, mesosulfuron&propoxycarbazone and thiencarbazone&brom&pyra. Obj. 6. Evaluate DPX-MAT28 (aminocyclopyrachlor) for yellow toadflax control in rangeland compared to picloram. Treatments were applied to 10 by 30 ft plots with a hand boom using standard small plot procedures. Treatments were applied at the vegetative stage (Jul 25), flowering stage (Sep 11), and in late fall (Oct 16) of 2008. No other treatments have been applied. Treatments were evaluated for percent visual control in 2009, 2010, 2011, and 2012. Weed density was recorded prior to application in 2008 and each year after. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Obj. 1. All treatments provided 91% or more wild oat control. Pyroxsulam&flor&flur and thiencarbazone&brom&pyra were slightly more effective applied at the later stage, while flucarbazone was generally consistent across timings. Flucarbazone provided good to excellent foxtail control at all stages, but was slightly more effective applied at the two later stages. Pyroxsulam&flor&flur provided poor foxtail control at the 2-leaf wheat stage, but good to excellent control at later stages. Obj. 2. S-metolachlor, flucarbazone, and flumioxazin caused slight to moderate crop injury on June 5 and June 25. However, by July 11 very little barley injury was visible. Pyroxasulfone, acetochlor (microencapsulated), and pendimethalin caused minimal injury. Despite early injury, there were no yield differences between treatments. Obj. 3. Tank mixing tribenuron or tribenuron&thifensulfuron increased foxtail control only 5-9% with flucarbazone, 2-4% with pyroxsulam&flor&flur, and 9-12% with mesosulfuron&propoxycarbazone. In 2011, green foxtail control was increased 6-14% with the same treatments. In 2010, yellow foxtail control with flucarbazone was increased 14-16%, but control with pyroxsulam&flor&flur and mesosulfuron&propoxycarbazone was not increased. Obj. 4. The glyphosate burndown alone provided about 68% foxtail barley control at the final evaluation on July 12. Foxtail barley control with thiencarbazone&brom&pyra applied POST was about 14-18% higher than the glyphosate burndown alone. Applying propoxycarbazone preplant or postemergence with thiencarbazone&brom&pyra resulted in about 21-25% higher foxtail barley control compared to the glyphosate burndown alone. Flucarbazone applied POST or following flucarbazone PRE improved foxtail barley control about 11-17% above the glyphosate burndown alone. Obj. 5. Mesosulfuron&propoxycarbazone and fenoxaprop&brom&pyra provided poor foxtail control (32-59%) regardless of tank mix partner or adjuvant used. Thiencarbazone&brom&pyra provided 82% foxtail control. All mesosulfuron&propoxycarbazone and thiencarbazone&brom&pyra treatments provided ≥97%wild oat control, whereas fenoxaprop&brom&pyra provided only 47% wild oat control due to ACCase resistance. Obj. 6. Picloram (2 pt/A) provided 23-60% yellow toadflax (YT) visual control in 2009, but decreased to 0-3% in 2012. Picloram reduced YT density 6-55% in 2009, but density increased in 2010, 2011, and 2012. DPX-MAT28 at 1.5 oz ai/A provided 90-95% YT visual control in 2009, but decreased to 22-32% in 2012. YT density was reduced 84-98% in 2009; however, density increased from 0.2-1.0 plants per sq ft in 2009 to 4.6-6.9 plants in 2012. DPX-MAT28 at 3 oz ai/A provided 98-100% visual control and reduced density 100% in 2009 and 2010. Plants began to appear again in 2011 with 0-0.3 plants per sq ft, and increased to 0-1.8 plants in 2012. DPX-MAT28 at 2 oz ai/A plus chlorsulfuron at 0.75 oz ai provided 99-100% YT visual control in 2009, but decreased to 69-84% in 2012. YT density was reduced 99% in 2009; however, density increased from 0-0.1 plants per sq ft in 2009 to 0.6-1.8 plants in 2012. Grass injury was 6% or less.

Publications

• Jenks, B. M. 2012. Yellow toadflax control in rangeland with DPX-MAT28. West. Soc. Weed Sci. Proc. Reno, NV. March 12-15.
• Mack, J. R. Zollinger, B. M. Jenks, P. W. Stahlman, S. Tan, L. Charvat, and S. Fitterer. 2012. Clearfield sunflower tolerance to pyroxasulfone. West. Soc. Weed Sci. Proc. Reno, NV. March 12-15.
• Jenks, B. M. and G. P. Willoughby. 2012. Broadleaf and grass control with sulfentrazone and metolachlor. West. Soc. Weed Sci. Proc. Reno, NV. March 12-15.

Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: Objective 1. Studies were conducted in 2010 and 2011 to determine if saflufenacil will antagonize glyphosate activity on Canada thistle (CT). In 2010, saflufenacil was applied at 25 g/ha tank mixed with glyphosate at 420 g ae/ha. Treatments were applied to 5- and 15-cm CT. In 2011, different rates of glyphosate were tank mixed with saflufenacil (25 g/ha) to determine if higher glyphosate rates would overcome the antagonism. Glyphosate was applied at 420, 630, and 840 g ae/ha with and without saflufenacil at 25 g/ha. Treatments were applied to 5-15 cm Canada thistle. Objective 2: A study was initiated to determine if a higher lentil seeding rate would help offset yield loss due to herbicide injury. Lentil was planted at 129 or 194 plants/m2. Various herbicides were applied preemergence (June 1) after planting on May 26. Treatments were evaluated for visual injury and yield. Objective 3. A study was conducted to evaluate canola desiccation with saflufenacil (25 and 50 g/ha) and flumioxazin (72 g/ha) compared to diquat (420 g/ha). Other treatments included glyphosate alone at 840 g/ha, saflufenacil + glyphosate (25 g + 840 g/ha), an untreated straight cut, and a swathed treatment. Desiccation treatments were applied with a tractor sprayer on when at least 60% of the seeds had started to turn color. Reglone was applied at 187 L/ha with XR8001 nozzles at 276 kPa travelling 2.4 kph. All other desiccation treatments were applied at 94 L/ha using the same nozzles at 4.8 kph. The swath treatment was swathed the same day as application of desiccation treatments. Four equally-spaced sticky cards (15 by 30 cm) were placed under the canopy in each plot just prior to the desiccant application to estimate seed loss due to shattering. Treatments were evaluated for percent pod and stem desiccation at 3, 6, 9, and 14 days after treatment. Seed moisture at harvest was estimated using a hand-held moisture tester. Yield and test weight were estimated from harvesting the middle 1.3 m of each plot with a small plot combine. Seed samples were evaluated for green count, damage, and overall grade by ADM (Velva, ND). Objective 4. A study was initiated to evaluate DPX-MAT28 (aminocyclopyrachlor ) for long-term yellow toadflax control in rangeland compared to picloram. DPX-MAT28 was applied at 105 or 210 g/ha or at 140 g/ha tank mixed with chlorsulfuron at 53 g/ha. Picloram was applied at 560 g/ha. Treatments were applied at vegetative stage, flowering, and late fall. Treatments were applied in 2008 and evaluated in 2009, 2010, and 2011. Toadflax density was measured before application in 2008 and again each year after. Objective 5. A study was initiated to evaluate barley variety sensitivity to imazamox carryover from the previous year. In 2010, imazamox was applied postemergence to Clearfield lentil at 18, 26, 35, 53, and 70 g/ha. Tradition, Celebration, Pinnacle, and Conlon were planted in 2011 into the treated blocks. Each variety was evaluated for visual injury, height, yield, test weight, and percent plump and thin. All imazamox rates were compared to an untreated check. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Obj. 1: In 2010, saflufenacil + glyphosate applied to 5 cm weeds provided only 38% Canada thistle (CT) control compared to 74% with glyphosate alone 60 days after treatment. Saflufenacil + glyphosate applied to 15 cm weeds provided 62% CT control compared to 85% with glyphosate alone. In 2011, Canada thistle treated with just glyphosate provided more consistent control over time. Increasing the glyphosate rate from 420 to 840 fl oz did increase Canada thistle control, but not to the level of glyphosate applied alone. It should be noted that we have not observed antagonism from saflufenacil + glyphosate on annual weeds. Obj. 2: All treatments caused slight to moderate lentil injury at the July evaluation; however, in most treatments, the lentils generally overcame initial injury. In early August, there were no differences in height between treatments. There were no yield differences between treatments; however, wet soil conditions in some areas contributed to yield variability (high CV). Lentil yields were higher where seeded at 194 plants/m2 compared to 129 plants/m2. There tended to be slightly less visible injury (3-8%) with the higher seeding rate. Obj. 3. Diquat provided faster canola pod desiccation after 3 and 6 days after treatment (DAT); however, saflufenacil at 50 g and saflufenacil (25 g) + glyphosate (840 g) provided similar pod desiccation after 9 and 14 DAT. All treatments provided complete pod desiccation at 14 DAT, except for the untreated (93%). Diquat provided faster stem desiccation at 3, 6, and 9 DAT; however, treatments containing glyphosate provided more stem desiccation than diquat at 14 DAT. All other treatments provided less stem desiccation than diquat. Very little seed was lost due to shattering with any treatment (≤73 kg/ha). The untreated straight cut had harvest seed moisture of 9.3%. Treatments containing glyphosate lowered seed moisture to about 6.5%, diquat at 7.0%, saflufenacil alone at 7.5%, flumioxazin at 8.1%. There were no significant differences in canola yield between treatments. Canola swathed or desiccated with diquat had slightly higher test weight compared to other treatments. The swathed treatment had slightly higher green count (2.4%) compared to diquat (0.5%) and to the other treatments (0-0.2%). Obj. 4. Picloram provided poor toadflax control at any stage. DPX-MAT28 provided excellent control after 1 year with any rate. However, after 2 years, control with the 105 g rate dropped off significantly, while the 210 g rate still maintained excellent control. Toadflax control with DPX-MAT28 + chlorsulfuron was 8-13% lower than with 210 g. No treatment caused more than 6% grass injury. After 3 years, the 210 g rate is still providing ≥95% control at any stage, while the 140 g rate + chlorsulfuron provided 76-89% control. Obj. 5. No visible barley injury was observed with any imazamox rate. There were no differences between treatments for height, yield, test weight, or percent plump and thin. Excessive rainfall flooded out the Conlon block, so no data is available for Conlon. This study was also conducted by Vision Research (Berthold, ND) with similar results.

Publications

• Hoefing, J. L, B. M. Jenks, and G. P. Willoughby. 2011. Effect of saflufenacil and flumioxazin applied pre-harvest on canola yield and seed quality. West. Soc. Weed Sci. Proc. Spokane, WA. March 7-10.
• Jenks, B. M., J. L. Hoefing, and G. P. Willoughby. 2011. Dry pea and chickpea tolerance to saflufenacil tank mixed with other PPO inhibitors. West. Soc. Weed Sci. Proc. Spokane, WA. March 7-10.