Brief Summary of Minutes of Annual Meeting

Judit Barroso, Chair, called the meeting to order at 3:00 pm. Attendance sheet was passed and attendees introduced themselves.

Presentation from Bill Whitacre (Policy Advisor for Western Governors’ Association):

The meeting was initiated with an update from Bill Whitacre. Major topics addressed included:

• Biosecurity & Invasive Species Initiative
  • Launched in July – ends in June
  • Workshops – website (westgov.org) – initiative page
  • Webinars
  • Initiative Deliverables
    • Cheatgrass/Invasive annual grasses
    • Grazing practices
    • Biocontrol
  • Invasive Species Data Mobilization Campaign
    • Improve invasive species occurrence data

Update from Mike Harrington (Director of Western Association of Agricultural Experiment Station Directors, Colorado State University):

The next update was from Mike Harrington. He provided a Multistate Committee Update.

• Multistate Committee Update
  • NIFA in the Federal Budget – President’s budget cuts 22 programs
  • Changes in AFRI Programs – new programs focus on collaborations, RFA will soon be available for Sustainable Ag Systems Program
  • New initiatives – single request 200 M increase in NIFA budget
• Impact Reporting
  • Output vs. Impacts
  • What is an impact statement? = So what? Who cares?

Update on seeding direction study:

Unfortunately, Andrew Kniss could not attend the meeting due to his Presidential responsibilities. Judit will contact him in there is an update further than what we discussed in the meeting.

• What we learned
  • An effect was not observed with brome
  • Carol aw something with ryegrass
  • Andrew, Joan, and Judit lost trials
• Now what? Publish something in Weed Tech Notes?

Discussion of feral rye collections:

• Not much done. Seems to be a low priority
• Phil will talk to Todd Gaines about his possible involvement
• New collection this spring?
• Do we need funding in order to increase prioritization? CPPM?

WERA-77 Priority Discussion:

• What are our priorities?
  • Need individual’s to lead projects that they are passionate about
  • Do we need a social media platform for our group?
  • Misha will incorporate these ideas in the 2020 meeting so look for her emails!

Other business:

The 2020 meeting will take place on Monday, March 2, 2020 in Maui, Hawaii. Time TBD, but likely at the same 3 PM time.

Misha Manuchehri will be collecting the state reports (due 6 weeks from the meeting).

Selection of new secretary/chair elect:

Vipan Kumar volunteered to be the new secretary/chair elect for next year. All the meeting participants agreed. Consequently, next year (2020) Misha Manuchehri will organize and conduct the meeting and Vipan Kumar will take notes and file the annual report.

The meeting adjourned at 4:30 pm.

IDAHO REPORT

Joan Campbell, Principle Researcher; Traci Rauch, Senior Research Specialist; and Don Morishita, Extension Weed Scientist.

Plant Science Department, University of Idaho, 875 Perimeter Dr. MS 2333, Moscow, ID 83844-2333; 208-885-7730; jcampbel@uidaho.edu

Objective 1. Results. Using GPS, Italian ryegrass seed was collected in the same locations as in a 2006/2007 herbicide-resistant survey. Italian ryegrass samples were collected in 2017 and 2018. Samples not collected due to the cropping rotation (3 year) will be collected in 2019. Currently, 94 samples have been collected. Seed was collected by hand in the center of the infestation in each field. Seeds from each sample along with a known susceptible biotype are screened in the greenhouse against herbicides used in our area to control Italian ryegrass. Untreated plants are included from each sample. For 2017, no resistant samples were found for Zidua, Dual Magnum, Outlook or glyphosate. Axiom resistance is very low but screening for the group 15 herbicides is still incomplete at this point. Axial XL resistance is near 50% while PowerFlex and Osprey resistance is widespread (<90%). The non-selective group 1 herbicides with resistance includes:  Shadow (clethodim) (10%)< Poast (60%)<Assure II (80%).

Objective 1. Outcomes/Impacts. Identifying Italian ryegrass changes in herbicide resistance overtime aids growers in understanding how their weed control management practices, including tillage and crop and herbicide rotation, have altered the makeup of the population.

Objective 2. Results. In winter wheat, Italian ryegrass control with Anthem Flex at the highest rate applied preplant was similar to preplant Anthem Flex followed by spring applied Anthem Flex. A winter wheat/Italian ryegrass control study evaluated Zidua and Anthem Flex at the highest labeled rates with the following application times:  pre-fertilization (shank applied dry fertilizer), post fertilization, postplant no germination and postplant germinated wheat. Italian ryegrass control was improved with Anthem Flex versus Zidua at all timings due to a higher rate of pyroxasulfone. Axiom did not control Italian ryegrass and is most likely due to a resistant population. This study is being repeated in 2019. Rattail fescue was controlled 89 to 98% with Axiom, Zidua, and Anthem applied postplant preemergence in the fall alone or in combination with spring applied PowerFlex, Maverick and Everest. PowerFlex and Maverick alone only suppressed rattail fescue, while Everest controlled rattail fescue 90%. This study will be repeated in 2019. Downy brome was controlled 91% or greater with Zidua, Anthem Flex and Axiom alone or combined with Osprey Xtra. Osprey Xtra alone did not control downy brome. Downy brome was controlled 91% or better with Axiom, Zidua, and Anthem applied postplant preemergence in the fall alone or in combination with spring applied PowerFlex, Maverick and Everest. Everest alone did not control downy brome (78%). In the greenhouse, Italian ryegrass was planted into dry conditions and sprayed with Zidua. Pots were irrigated with 0.3 inch of rainfall at 0, 8,15, 22,29, 36, and 43 DAT. Pots with untreated plants were included. The study is arranged as a randomized complete block with 4 replications. It is currently ongoing and plant emergence, height and biomass will be measured.

Objective 2. Outcomes/Impacts: Zidua (group 15) was registered for annual grass control, including Italian ryegrass and rattail fescue, in winter and spring wheat in spring 2014. Zidua registration has aided in control of group 1 and 2 resistant Italian ryegrass. Very few herbicides control rattail fescue. Zidua and Anthem treatments controlled rattail fescue 89-97% in 2018.Winter wheat yield was not reduced by Zidua when 0.5 inch of sprinkler irrigation was applied immediately after planting and spraying on the same day (worst-case scenario). Wheat had minimal injury in 11 conventional-tilled (chisel plowed/field cultivated) sites and in seven direct-seed locations. U of I studies were instrumental in implementing Zidua label changes including an increased use rate and a preplant application time in winter wheat. These label changes have aided growers by giving them more options to improve weed efficacy. Anthem Flex also was registered in wheat fall 2014. Our Anthem Flex studies were useful to FMC when drafting rates and timings for their label. This information will help growers use these products safely and effectively to control grass weeds with minimal crop injury. These registrations provide needed tools to help control herbicide resistant weeds, especially Italian ryegrass.

Objective 3. Results: A field trial was established at UI research farms near Moscow and Genesee to examine tillage effects on rattail fescue. Winter wheat was direct-seeded in fall 2013. The rotation is winter wheat- spring wheat- spring chickpea. Tillage initiated in the fall 2014 included fall disc or chisel plow followed by spring field cultivation. A no-tillage treatment is included as a control. Heavy harrow replaced disc in year 2 and 3. The tillage was performed all 3 years, 2 years or 1 year for a total of 7 tillage regimes. Spring chickpea was seeded in 2016. Rattail fescue populations were low in the chickpea year of the tillage comparison study. The weed was found only in no-till and the one year of chisel plow. Tillage treatments were applied and winter wheat was planted fall 2016 for the third year of the study. Winter wheat yield was confounded by standing water at Moscow and rodent damage at Genesee. This is currently being repeated.

Objective 3. Outcomes/Impacts: Knowledge of cultural controls, crop rotation and tillage is limited for rattail fescue control. Current information is speculative at best. Herbicide usage is the only known research-based tool for rattail fescue control. Tillage is important but research on how invasive and how often is unknown. This data will help growers take an integrated weed management approach to reducing rattail fescue and increasing crop yield.

Objective 4. Results: Two new broadleaf weed control herbicides in winter wheat were evaluated. Talinor (bicyclopyrone/bromoxynil) was combined with grass herbicides that require a fertilizer adjuvant. The Talinor label currently does not allow applications with ammonium sulfate (AMS), a fertilizer. Talinor combined with PowerFlex or Osprey plus UAN (fertilizer) did not reduced grain yield or test weight compared to PowerFlex or Osprey alone plus UAN. Talinor was also combined with foliar fungicides to evaluate wheat tolerance. No visual injury or yield and test weight reduction were found with Tilt, Priaxor, Quilt Xcel, Nexicor, Approach and Trivapro. In winter wheat, Quelex (halauxifen/florasulam) alone or combined with Huskie, Talinor, and Starane Ultra controlled mayweed chamomile 95 to 96% which was similar to WideMatch or Starane Flex alone (91&94%). In spring wheat, Quelex alone controlled common lambsquarters 86% which was similar to Huskie and WideMatch combined with Affinity Broadspec and Affinity TankMix (99%). A new postemergence grass herbicide, Osprey Xtra (mesosulfuron/ thiencarbazone) controlled rattail fescue (86-96%) better than Everest (20%) and Osprey (61%). Osprey controlled downy brome better than Osprey Xtra. Studies in 2019 will continue to evaluate these new herbicides for weed control efficacy.

Objective 4. Outcomes/Impacts: Examining tolerance and efficacy of newly registered and soon-to-be registered herbicides is critical to the development of unbiased information on the use of these products by Idaho wheat growers. Evaluating combinations of fungicides with herbicides for crop response and weed control is also important. This data assists in timely federal registration of new compounds. Herbicides with new and different modes of action are necessary to reduce or stop the development of herbicide resistant weeds. Talinor and Quelex may be options for possible control of herbicide resistant broadleaf weeds.

Objective 5. Results: Suspected-resistant weed seed samples collected from research plots and submitted by growers, fieldmen, and industry representatives were screened in the greenhouse. The weed seed samples were sprayed with herbicides at twice the labeled rate. Susceptible plants were included to verify spray coverage and rate. Seeds were counted at planting with preemergence herbicides and plants counted at emergence with postemergence herbicides. Untreated plants were included from each sample. Resistance was evaluated on plant survival and vigor compared to the untreated. Two interrupted windgrass seed samples were treated with five herbicides. No sample was resistant to Shadow (clethodim) or glyphosate. Samples were resistant to PowerFlex, Osprey, and Everest (group 2). Three downy brome seed samples were screened with six herbicides. No sample was resistant to Shadow or glyphosate Samples were resistant to PowerFlex, Beyond, Olympus, and Maverick (group 2). A mayweed chamomile seed sample was treated with six herbicides. The sample was resistant to Affinity BroadSpec and Ally Xtra (group 2). It was not resistant to Huskie, Lorox, Talinor and WideMatch. A common lambsquarters seed sample was treated with five herbicides. The sample was susceptible to all herbicides (Pursuit, Spartan, Valor, Sharpen, and metribuzin).

Objective 5. Outcomes/Impacts: Screening weed seed samples enables growers to combat herbicide resistance by adjusting their weed control approach so that it includes rotating chemicals, changing crop rotations, and implementing other cultural practices.

Objective 6. Results: Project personnel participated in cereal schools in north Idaho in January. Research information was presented at the Western Society of Weed Science meeting in March. Cereal research was also presented at field days in June and July.

Objective 6. Outcomes/Impacts: Information presented at cereal schools, field tours, and extension meetings will aid growers in making the best economic and ecological decisions for weed control in their wheat production systems.

KANSAS REPORT

Vipan Kumar, Weed Scientist

Kansas State University, Agricultural Research Center, Hays, KS 67601. vkumar@ksu.edu

Research:

Downy brome control in CoAxium™ winter wheat. Field experiment was conducted at Kansas State University Agricultural Research Center near Hays, KS to evaluate Aggressor herbicide for downy brome control in CoAxium™ winter wheat. CoAXium™ wheat is a new herbicide-resistant (non GMO) wheat technology that contains the AXigen™ trait for resistance to the ACCase (Group 1) class of herbicides. Aggressor is the herbicide labeled for use on CoAXium wheat and contains the active ingredient quizalofop-p-ethyl. POST treatments of Aggressor were applied in fall (Nov 6, 2017) and spring (Mar 28, 2018) using a CO₂-operated backpack sprayer calibrated to deliver 14 GPA at 40 psi. All Aggressor treatments were applied with NIS adjuvant. Field site was uniformly infested with natural population of downy brome. Downy brome plants were at 3 to 4-lf stage at fall application timing and 2 to 3 tiller stage at spring application timing. No visible injury to winter wheat was observed with any of the fall or spring applied Aggressor treatments. Aggressor applied at 8 to 10 fl oz/a in fall provided an excellent, season-long control (96% prior to wheat harvest) of downy brome. Control with Aggressor (8 fl oz/a) applied in spring was slightly lower than fall application timing, and did not exceed 91% at final rating. Lower control observed with spring application of Aggressor was possibly due to presence of some dormant seedlings of downy brome at spring timing. Fall treatments of Aggressor (8 or 10 fl oz/a) showed slight increase in wheat yields compared with spring application timings.    

Downy brome control in Clearfield^® winter wheat. A field study was conducted at Kansas State University Agricultural Research Center near Hays, KS to evaluate PRE alone, POST alone and PRE followed by (fb) POST herbicide treatments for downy brome control in Clearfield^® winter wheat. PRE alone programs included Zidua (pyroxasulfone) at 3 oz/a, Olympus (propoxycarbazone-sodium) at 0.6 oz/a, and AnthemFlex (pyroxasulfone + carfentrazone) at 3 fl oz/a; POST alone treatments were Powerflex HL (pyroxsulam) at 2 oz/a and Beyond (imazamox) at 5 fl oz/a; PRE fb POST treatments were Zidua (1.5 oz/a) fb Beyond (5 fl oz/a), Olympus (0.6 oz/a) fb Beyond (5 fl oz/a), and AnthemFlex (3 fl oz/a) fb Beyond (5 fl oz/a). All PRE treatments were applied on Sep 29, 2017 and POST treatments were applied on Mar 28, 2018 using a CO₂-operated backpack sprayer equipped with four nozzle tips and calibrated to deliver 14 GPA at 40 psi. Data on percent downy brome control were collected on biweekly interval after POST applications. The study site had uniform, natural population of downy brome. POST applications of Beyond herbicide was made by using NIS adjuvant. All PRE alone and PRE fb POST treatments provided effective control (91 to 99%) of downy brome at final rating (prior to wheat harvest). Downy brome control with POST alone treatments was moderate and did not exceed 83% at final rating. No significant differences in wheat yields were observed among these herbicide programs.

Response of Kansas feral rye populations to Beyond and Aggressor. Feral rye is a problematic winter annual grass weed species in Kansas winter wheat production. A random collections of feral rye seeds were initiated in summer 2018 from wheat fields in central Kansas. Seeds of nine feral rye populations were randomly collected with GPS coordinates at the time of wheat harvest. Greenhouse experiments were conducted at Kansas State University Agricultural Research Center near Hays, KS to determine the response of those populations to Aggressor (quizalofop-p-ethyl) and Beyond (imazamox) herbicides. Seedlings of population were grown in 4- by 4-in plastic pots containing commercial potting mixture. At 3- to 4-lf stages, feral rye seedlings were separately treated with various doses (ranging from 0.25X to 4X) of Aggressor (1X = 8 fl oz/a) and Beyond (1X = 5 fl oz/a) in cabinet spray chamber. NIS and MSO adjuvants were included with Aggressor and Beyond herbicide doses as per each label guidelines. Percent visual control of those treated seedlings were assessed at 7, 14, and 21 days after treatment (DAT). For majority of the feral rye populations tested, control with Beyond herbicide was inconsistent. Percent control ratings for feral rye at 21 DAT of Beyond at field-use rate (1X=5 fl oz/a) ranged from 75 to 80 % for those nine populations. In contrast, the Aggressor provided effective control (95 to 100%) of all nine feral rye populations even at half of the labeled-use rate (4 fl oz/a) 21 DAT. Control ratings of all nine populations were consistent with the shoot dry weight reductions with various Beyond and Aggressor herbicide rates tested.  

Impact Statement:

Information obtained from these research projects was delivered to Kansas wheat growers through a variety of presentations and popular press articles on K-State Agronomy Extension e-update (https://webapp.agron.ksu.edu/agr_social/). Results were also shared with wheat growers, county ag agents and crop consultants through Weed Schools conducted across western Kansas.

OKLAHOMA REPORT

Misha Manuchehri, Extension Weed Specialist, Department of Plant and Soil Sciences, Oklahoma State University, 371 Agricultural Hall, Stillwater, OK 74078. 405-744-9588. misha.manuchehri@okstate.edu

Identification and Management of ACCase Resistant Italian Ryegrass

Axial XL resistant Italian ryegrass biotypes are suspected in Oklahoma; however, only plants with an increased tolerance have been identified in greenhouse screenings. The use of group 15 herbicides may improve the control of these difficult-to-manage plants. Several studies were conducted throughout Oklahoma throughout the 2016-17, 2017-18, and 2018-19 seasons to evaluate the use of Zidua (pyroxasulfone), Anthem Flex (pyroxasulfone + carfentrazone), and Axiom (flufenacet+metribuzin) to control Italian ryegrass. Control was at least 95% for all treatments that included pyroxasulfone DPRE or VEPOST or pinoxaden VEPOST. Similar control was achieved with pyroxasulfone + carfentrazone and flufenacet + metribuzin. Timely rains and proper herbicide to soil contact contributed to the success of these treatments. A study evaluating the impact of residue on performance of these group 15 herbicides is currently being carried out.

IMPACTS

Growers in Oklahoma battling Italian ryegrass can receive nearly season long control of the weed with DPRE applications of Zidua, Anthem Flex, or Axiom as long as products have been adequately incorporated with rainfall.

Horseweed Management in Winter Wheat

Traditional broadleaf postemergence herbicide treatments vs. those containing Quelex (florasulam + halauxifen), Sentrallas (thifensulfuron methyl + fluroxypyr), and Talinor (bicyclopyrone + bromoxynil) were compared when applied to multiple growth stages of horseweed (5, 10, and 15 cm) throughout Oklahoma during the 2016-17 and 2017-18 field seasons. Across all site years, halauxifen + florasulam achieved greater than 90% control with the exception of two treatments at Altus in 2018 and one treatment at Ponca City in 2018. Thifensulfuron + fluroxypyr + dicamba achieved greater than 90% control at all site years except at Ponca City in 2017. Halauxifen + florasulam and thifensulfuron + fluroxypyr were both effective at controlling a wide range of horseweed rosette sizes across all locations while control with other treatments varied depending on presence of herbicide resistance, weed size at time of application, and tank mix partner. Finally, no visual crop injury was observed following any treatment.

IMPACTS

Halauxifen + florasulam and thifensulfuron + fluroxypyr are both effective at controlling a wide range of horseweed rosette sizes across Oklahoma. Successful horseweed control in winter wheat aids in ease of harvest, increased grain quality, and suitable planting conditions for double crops.

Rescuegrass Management in Winter Wheat

Rescuegrass is one of the most challenging winter annual weeds to manage in Oklahoma. There are few herbicides labeled for rescuegrass control in winter wheat and for the ones that are labelled, control is often inconsistent. To evaluate herbicide systems for rescuegrass management, several trials were conducted throughout Oklahoma during the 2017-18 and 2018-19 field seasons. At both Altus and Yukon, rescuegrass control was the highest following fall postemergence applications of imazamox. At Altus, imazamox + AMS + NIS or MSO controlled rescuegrass 93 to 96%. At Yukon, imazamox + AMS + MSO achieved 69% control while imazamox + AMS + NIS controlled rescuegrass 56%. All other treatments at Yukon performed poorly as a six inch rain event followed PRE treatments and control with pyroxsulam was low (<10%). Conversely, at Altus, PRE treatments of glyphosate alone or glyphosate + flucarbazone-sodium or propoxycarbazone-sodium achieved 64 to 69% control. Preemergence treatments of glyphosate alone or glyphosate + flucarbazone-sodium or propoxycarbazone-sodium + pyroxsulam achieved 80 to 84% control.

CoAXium Systems for Management of Feral Rye and Rescuegrass

Applications of Aggressor herbicide + NIS, COC, MSO, and/or AMS were applied to feral rye in the fall and/or spring of the 2017-18 and 2018-19 field seasons. Fall treatments alone and a fall treatment followed by a spring treatment achieved the highest levels of control (nearly 100%); however, all treatments controlled these plants at a greater level than other, existing herbicide options. Still, in Oklahoma, the primary recommendation to manage these weeds is to rotate out of winter wheat or delay planting if rescuegrass is the target weed species.

IMPACTS

The cost of successfully managing feral rye and rescuegrass with herbicides in Oklahoma is typically not worth the investment. If primary weed species include feral rye or rescuegrass, rotation out of a winter cereal is highly recommended. Tillage or glyphosate burndown follow by a delayed planting date also can be a successful strategy in managing rescuegrass populations.

OREGON REPORT

Judit Barroso, Weed Scientist.

Crop and Soil Science Department, Columbia Basin Agricultural Research Center, Oregon State University. (541)2784394. judit.barroso@oregonstate.edu

Research:

Weed responses to fallow management in Pacific Northwest dryland cropping systems: A two-year rotation of summer fallow (SF)/winter wheat (WW) is the most common cropping system in low precipitation areas of the U.S. Pacific Northwest (PNW). In SF, multiple tillage operations are used to manage weeds and maximize soil water storage and potential WW yield. Reduced tillage fallow (RTF) is an alternative to SF that leaves>30% of the previous crop’s residue on the surface. A four-year (2014–18) field study was conducted to evaluate the influence of SF and RTF on weed species density, cover and composition in dryland WW; determine if changes in these weed infestation attributes have any influence on crop density and yield; and evaluate economic costs of each type of fallow management. The experimental design was randomized complete block with four replications where each phase of SF/WW and RTF/WW rotations was present every year. Individual plots of WW were divided into a weedy sub-plot with no weed control, general area with chemical weed control, and weed-free sub-plot where weeds were manually removed. Infestations of annual grass and other weeds in weedy sub-plots increased throughout the study. Grass weed cover, consisting mainly of downy brome (Bromus tectorum L.), and total weed cover were significantly lower in WW following RTF than following SF in all years except 2018. Densities of grass and total weeds were similar in both fallow managements indicating that weed plants were larger in WW following SF than following RTF due to earlier or faster emergence. Grass cover differences were not found in general areas likely because of a reduced seedbank. When weeds were present, mean yield of WW was higher following RTF than SF indicating that weeds were less competitive in RTF.

Impact Statement: Reduced tillage fallow could improve weed management in fallow/WW cropping systems of the PNW compared to SF/WW, particularly if the most problematic species are grasses.

Effect of cropping system intensification on weeds in the semi-arid region of inland Pacific Northwest: Downy brome (Bromus tectorum L.) is a problematic weed for the conventional fallow/winter wheat (F/W) production system in the low precipitation-region (<350mm yr−1) of the Pacific Northwest. A 4-yr field experiment was conducted to determine if incorporating spring barley (B, Hordeum vulgare L.) or spring carinata (C, Brassica carinata A. Braun) into 3-yr crop rotations with W would benefit weed management. The experimental design was a split-plot with four replications where each phase was present every year for the following rotations: 1) F/W, 2) F/W/B, and 3) F/W/C. Reduced tillage, consisting of a single undercutting operation with a wide-blade sweep, and herbicides were used to control weeds during the fallow period. The seeded plots were subdivided in three different weed management areas: a weed-free area where weeds were pulled by hand, a weedy area with no weed control and a general area where weeds were chemically controlled. Weed density and cover per species and W yield were evaluated in each rotation. Grass cover and density after one and two complete cropping cycles were significantly higher in F/W than in F/W/B and F/W/C. Reduction in density and cover of total weeds was found after two cycles. However, differences in community biodiversity were only found between F/W, and F/W/B or F/W/C in 2017. Winter wheat plots of F/W had more downy brome than F/ W/B or F/W/C indicating the greater capacity of the latter to control this weed. In 2018, the 3-yr rotation with barley had greater winter wheat grain yield compared with F/W when weeds were not present though weeds were more competitive in F/W/B.

Impact Statement: Intensifying the F/W cropping system into a 3-yr crop rotation of W followed by spring barley or spring carinata may reduce weed infestations of winter annual grasses that are difficult to control in W and the most competitive due to larger similarities in their life cycle with this crop.

Downy brome (Bromus tectorum) and rattail fescue (Vulpia myuros) control with Osprey Extra in winter wheat. A field study was conducted at the OSU Columbia Basin Ag Research Center near Pendleton, OR to test the efficacy and tolerance of Osprey Xtra in combination with other herbicides on winter wheat for control of downy brome (Bromus tectorum) and rattail fescue (Vulpia myuros). Osprey Xtra is a Group 2 herbicide (ALS inhibitors) containing mesosulfuron-methyl, thiencarbazone-methyl and mefenpyr-diethyl. Crop damage was low for all treatments at all evaluation times. The Zidua (Fall pre-emerge) + Osprey Xtra (Spring) treatment had the best downy brome control (93%), followed closely by Axiom (Fall pre-emerge) + Osprey Xtra (Spring) (86%). Axiom (Fall pre-emerge) showed the least downy brome control of all treatments. There was no significant difference among treatments for rattail fescue, with Zidua (Fall pre-emerge) and Zidua (Fall pre-emerge) + Osprey Xtra (Spring) showing the best control (69%). Zidua (Fall pre-emerge) + Osprey Xtra (Spring) (92 bu/A) was the only treatment to have a significant difference in yield with the untreated plots (34 bu/A). However, all treatments had at least double the amount of yield compared to the control plots.

Impact Statement: Collaborating with the industry to understand how new herbicides work in the different regions is critical to provide growers with unbiased information. Growers are normally very interested in new products that can help them with the day-to-day problem of resistant weeds.

UTAH REPORT

Earl Creech, Extension Agronomist; Corey Ransom, Extension Weed Scientist; Steve Young, Weed Scientist.

Plants, Soils & Climate Department, Utah State University, 4820 Old Main, Logan, UT 84322; 435-797-0139; steve.young@usu.edu

Research:

Kochia-cover crop study – Year 2 (2019)

The objective of this study is to evaluate the influence of cover crops, and planting dates and rates on kochia populations in wheat fields of Utah and southern Idaho. Similar to Year 1 (2018), planting dates and rates will be assessed as secondary tactics (e.g., early or late season plantings – avoidance, size advantage; high rates – resource use, competitive advantage) against kochia in combination with cover crops as a primary tactic.

Wheat allelopathy study – Year 1 (2019)

Many plants are reported to naturally produce secondary compounds that can have a deleterious effect on neighboring vegetation, also known as allelopathy. While not lethal, this allelopathic effect by a plant can also provide a competitive advantage against weed species. Unknown is to what extent allelopathy in wheat prohibits species of weeds. Therefore, our hypothesis is that wheat cultivars from the Pacific Northwest will stop weed species seed from germinating. The objective is to determine the allelopathic effect of several wheat cultivars on the growth and development of weed seed.

Extension:

Kochia-cover crop study – Year 2 (2019)

Similar to Year 1 (2018), specific methods for disseminating results will include: 1) establishing research at university field sites, 2) conducting field days in partnership with local growers, crop advisors and seed dealers (Utah Seed), 3) updating county educators, regional specialists, and private crop advisors at in-service meetings, 4) uploading findings on university extension and private organization websites, 5) presenting findings at local and regional meetings and conferences, 6) announcing project findings in local newsletters, newspapers for growers, and during statewide and regional speaking engagements, and 7) integrating research findings into course teachings that target next generation ag-professionals.

Impacts:

Kochia-cover crop study – Year 2 (2019)

Outcomes: Growers will benefit from our project through increased understanding and directly implementable results. A survey will be administered at the in-service meetings to determine what changes have occurred in awareness, knowledge, attitude, or skills related to learning and resulting actions, if any.

WASHINGTON REPORT

Drew J. Lyon, Extension Weed Scientist; Rachel J. Zuger, Research Technician; Ian C. Burke, Weed Scientist.

Crop and Soil Sciences Department, Washington State University, Pullman, WA 99164-6420; 509-335-2961. drew.lyon@wsu.edu

Research:

Evaluation of Aggressor herbicide for the control of feral rye in the CoAXium wheat production system. The CoAXium™ wheat production system was recently developed by the Colorado Wheat Research Foundation, Inc., Limagrain Cereal Seeds, LLC and Albaugh, LLC. AXigen™ is the non-GMO trait in wheat that confers tolerance to the ACCase inhibitor (Group 1) herbicide Aggressor™ (quizalofop-P-ethyl). The AXigen trait will be made available to both private and public breeders and was one of the reasons we were interested in evaluating the system. Aggressor is labelled to control annual grassy weeds, such as downy brome, jointed goatgrass and feral rye that are problematic in the low to intermediate rainfall zones of eastern WA. On October 17th, the trial area was direct-seeded with a John Deere 9400 hoe drill with openers on a 7-inch spacing and a planting depth of 2.0 inches. The area was seeded at the rate of 120 lb/A, 107 lbs CoAxium winter wheat plus 13 lbs cereal rye. The ground was fertilized with 100 lb N per acre from dry urea on March 21, 2018. The soil at this site is a Palouse silt loam with 4.2% organic matter and a pH of 5.0. Early postemergence treatments were applied on April 11th. At the time of application, wheat was at the 2-tiller stage and was 7 inches tall. Cereal rye had one node and was 14 inches tall, which is larger than the 1- to 4-inch height prescribed on the label. Late postemergence treatments were applied on May 4th. At the time of application, wheat had one node and was 14 inches tall. Cereal rye had 3 nodes and was 22 inches tall. Both applications were made with a CO2-powered backpack sprayer set to deliver 15 gpa at 47 psi at 2.3 mph. The Aggressor label only allows applications to be made on 1- to 4-inch tall cereal rye, hence our applications were made outside the label guidelines. Despite the late applications, early spring applications of Aggressor were highly effective for cereal rye control. There were no significant differences among the three rates evaluated, and no differences seen between NIS and MSO. The late spring application was also highly effective. Only Aggressor treatments applied at 8.0 or 10.0 fl oz/A and tank mixed with 1.0% MSO had a few plants that escaped control. There were no significant differences in yield among the Aggressor treatments and the mean was 86 bu/A. The yield in the nontreated check plots was 85 bu/A with 15% foreign material as cereal rye. Aggressor appears to be highly effective for the control of cereal or feral rye in the high rainfall zone. It will be important to evaluate the CoAXium wheat production system in the intermediate to low rainfall zones under more stressful environmental conditions.

Control of Bromus spp. (Bromus tectorum L. and Bromus sterilis L.) in Winter Wheat. Downy brome (Bromus tectorum) continues to be a problematic and widespread weed in inland PNW wheat-fallow rotations. Acetolactate synthase inhibitor resistance continues to spread, and there are very few herbicide options remaining. Sterile brome (Bromus sterilis) is another bromegrass invading wheat fields in intermediate and low rainfall zones. Our objective was to identify one or more herbicide treatments with different herbicide modes of action for management of downy brome and sterile brome. Two winter wheat studies were conducted in the intermediate to low rainfall (< 17” rainfall annually) area in 2018 at Ewan and Anatone, WA. Visual control was assessed for both sites. The combination of both a fall applied delayed-PRE and a spring applied POST herbicide treatment did not impact the efficiency of Bromus spp. control at either site. All delayed-PRE treatments, except propozycarbazone and sulfosulfuron + metribuzin, controlled the Bromus spp. with greater than 65% control compared to the nontreated control. Yield for both sites was combined and increases in yield were observed for pyroxasulfone + metribuzin (780 kg ha^-1), pyroxasulfone + diclofop (850 kg ha^-1), pyroxasulfone + metribuzin + diclofop (840 kg ha^-1), diclofop (770 kg ha^-1), and metribuzin + diclofop (770 kg ha^-1). The nontreated control yielded 640 kg ha^-1. Pyroxasulfone, with and without either metribuzin of diclofop, appears to be an effective PRE herbicide for both Bromus tectorm and Bromus sterilis when applied delayed-PRE.

Impact Statement: Grower and industry awareness of herbicide resistance continued to increase in 2018 through a variety of presentations and articles in the popular press and through Timely Topic posts and podcast episodes on the Wheat and Small Grains Website (smallgrains.wsu.edu). Wheat growers were provided with a new decision tool to help them make more informed decisions on herbicide use for the control of troublesome weeds. Growers were also provided with efficacy and crop safety information for newer herbicide products in wheat.

Peer Review Publications:

Barroso J, Gourlie J, Lutcher L, Mingyang L, Mallory-Smith C. 2018. Identification of glyphosate resistance in Salsola tragus in Northeastern Oregon. Pest Management Science 74:1089-1093.

Lawrence NC, Hauvermale AL, Burke IC. 2018. Downy Brome (Bromus tectorum) vernalization: variation and genetic controls. Weed Sci. 66:310-316.

Lyon DJ, Swanson ME, Young FL, Coffey T. 2018. Jointed goatgrass biomass and spikelet production increases in no-till winter wheat. Crop Forage Turfgrass Manage. doi:10.2134/cftm2018.04.0031.

Mallory-Smith C, Kniss AR, Lyon DJ, Zemetra RS. 2018. Jointed goatgrass (Aegilops cylindrica): A review. Weed Sci. 66:562-573.

Reardon CL, Wuest SB, Melle CJ, Klein AM, Williams JD, McCallum J, Barroso J, Long DS. 2019. Soil enzyme activity under minimum and conventional tillage wheat-fallow cropping systems. Soil Science Society of American Journal (Accepted (01/15/2019), In Press).

San Martin C, Long D, Gourlie JA, Barroso J. 2018. Suppression of downy brome by reduced tillage fallow in dryland winter wheat. PloS One 13(9):1-17.

San Martín C, Lyon DJ, Gourlie J, Wetzel HC, Barroso J. 2018. Weed control with bicyclopyrone + bromoxynil in wheat. Crop Forage Turfgrass Manage. 4:180011. doi:10.2134/cftm2018.02.0011.

San Martín C, Long D, Gourlie JA, Barroso J. 2019. Spring crops in three year rotations reduce weed pressure in winter wheat. Field Crops Research 233, 12-20.

Spring, JF, Thorne ME, Burke IC, Lyon DJ. 2018. Rush skeletonweed (Chondrilla juncea) control in Pacific Northwest winter wheat. Weed Technol. 32:360-363.

Walsh MJ, Broster JC, Schwartz-Lazaro LM, Norsworthy JK, Davis AS, Tidemann BD, Beckie HJ, Lyon DJ, Soni N, Neve P, Bagavathiannan MV. 2018. Opportunities and challenges for harvest weed seed control in global cropping systems. Pest Manag. Sci. 74:2235-2245.

Extension Publications:

Hauvermale AL, Race KN, Lawrence NC, Koby L, Lyon DJ, Burke IC. 2018. A mayweed chamomile growing degree day model for the Inland Pacific Northwest. (FS306E).

Lyon DJ, Ball DA, Hulting AG. 2018. Rattail fescue: Biology and management in Pacific Northwest wheat cropping systems. (PNW613).

Lyon DJ, Burke IC, Campbell JM. 2018. Integrated management of mustard species in wheat production systems. (PNW703).

Manuchehri MR, Ogden G. 2018. Herbicide Programs for Italian Ryegrass Control in Oklahoma Winter Wheat, PSS-2791.

Manuchehri MR. 2018. Herbicide Mixing Order. Oklahoma State University, PSS-2789.

Manuchehri MR, Adcock M, Arnall DB. 2018. Rainfastness for Fallow and In-Season Winter Wheat Herbicides that have Postemergence Activity, L-468.

Manuchehri MR, Arnall DB. 2018. How Does Soil pH Impact Herbicides. Oklahoma State University, PSS-2778.

Peterson D, Kumar V. 2018. CoAXium Wheat and Aggressor Herbicide for Grass Weed Control. Kansas State University, eUpdate. Issue 719. November 7, 2018.

Conference Presentations:

Childers JT, Manuchehri MR, Kumar V, Liu R, Crose JA. 2019. Non-tolerant Wheat Response to Simulated Drift of Quizalofop-P-ethyl in Central Oklahoma. Proc. West. Soc. Weed Sci. 72:24 (in press).

Liu R, Kumar V, Lambert T, and Manuchehri MR. 2019. Response of Kansas Feral Rye Populations to Imazamox and Quizalofop-P-ethyl. Proc. West. Soc. Weed Sci. 72:119 (in press).

Ogden, G. K., M. R. Manuchehri, A. C. Hixson, K. E. Cole, J. A. Crose. 2018. The Development and Management of ACCase Resistant Italian Ryegrass in Oklahoma. Western Soc. Weed Sci. 71:35.

Crose, J. A., M. R. Manuchehri, K. E. Cole, R. Rupp, B. Lindenmayer, and D. Cummings. 2018. Horseweed Management in Oklahoma Winter Wheat. Western Soc. Weed Sci. 71:34.

Manuchehri, M. R., G. Strickland, K. E. Cole, J. A. Crose. 2018. Rescuegrass Management in Oklahoma Winter Wheat. Western Soc. Weed Sci. 71:32.

Manuchehri, M. R., J. A. Crose, K.E. Cole, R.N. Rupp, B. Lindenmayer, D.C. Cummings. 2018. Horseweed Management in Oklahoma Winter Wheat. Weed Sci. Soc. Am. Abs. 58:38.

Rauch T, Campbell J.  2018.  Rattail fescue and downy brome control in winter wheat with mesosulfuron plus thiencarbazone.  Western Society of Weed Science Proceedings 71:17.

Wuest SB, Barroso J. 2019. Is volunteer wheat a serious weed in annual winter wheat production? Proceedings of the WSWS Annual Meeting. Denver, CO. Abstract.