Brief Summary of Minutes of Annual Meeting

The annual meeting of the WERA077 Managing Invasive Weeds in Wheat working group was held in conjunction with the Western Society of Weed Science annual meeting on March 14, 2013 (02:00 PM to 07:00 PM) at Catamaran Hotel, San Diego, CA. Joe Armstrong officiated as Chair and called the meeting to order at 2:00 pm. Fabian Menalled acted as Vice-Chair/Secretary. Donn Thill, the WERA077 Administrative Advisor, opened the meeting with a summary of the current status of the WERA077 working group. Thill informed that the WERA077 project will expire in September 2014, expressed concerns about the functionality of this working group, and provided inputs on approaches to improve its efficiency. Thill indicated that a new proposal should be submitted before January 2014. Finally, Thill informed that due to budget sequester, NIFA expects a 5% cut for FY2103. However, these cuts may not impact already funded projects. During the discussion, the working group evaluated the benefits and costs of continuing to meet. It was decided to continue functioning as a working group and a writing committee composed by Menalled, Kniss, and Lyon, with advice from Thill, will submit a new proposal. Along with this discussion, a conversation was held on approaches to increase attendance to the working group meeting and participation of other states, particularly those who share common agronomic interests such as Nebraska, Kansas, Texas, North and South Dakota. In addition, it was mentioned that an invitation should be extended to anyone interested in weed management in small grains, including anyone from private industry. It was mentioned that including a tour or a special guest presentations could increase the participation to this working group. During the general discussion, participants discussed results of the projects at their respective states (see Accomplishments Section). A general discussion was held regarding the extent and impact of herbicide resistance in the region, with special emphasis on kochia and feral rye. In this regard, the possibility of organizing a symposium and/or inviting a sociologist or an epidemiologist was discussed. As part of discussion, the working group evaluated the possibility of submitting a collaborative proposal to AFRI but no formal decision was made as there is no current call for proposal that will fit the interests of the group. Finally, the group evaluated a time for next year's WERA077 meeting. To avoid conflicts, it was decided to meet on the Thursday afternoon at the conclusion of the 2014 WSWS meetings. The meeting room should be reserved in December, as this is the time frame when Phil Banks is reserving meeting space for the upcoming WSWS meetings. An election was held for Vice-Chair/Secretary for 2014-2015. Don Morishita was nominated and voted unanimously as Vice-Chair/Secretary. Menalled will move into the Chair role for 2014.

Colorado. Submitted by Phil Westra Jointed Goatgrass. A MS graduate student is finishing a 2 year biotech risk assessment program to evaluate gene flow between winter wheat and jointed goatgrass. BC1 hybrid plants were planted in the field in the fall of 2010 and 2011 and a high level of jointed goatgrass was interspersed with these hybrid plants to serve as pollen donors to force the hybrid crosses back toward the jointed goatgrass genotype. Fertility of these field crosses was very low, typically less than 1% of resulting florets produced viable seed. The level of fertility varied by BC1 plant used in these studies. GISH genome staining has been developed to track chromosome segment movement where crossing did occur among these plants. This technique is being used to better understand the amount of DNA exchange that occurs when hybridization occurs between winter wheat and jointed goatgrass. Based on the preliminary results of these studies, it appears that the frequency of this DNA exchange is very low. Kochia. Kochia is a major summer annual weed of both wheat and the fallow fields that often are utilized to conserve moisture in the Great Plains. The 2007 documentation of glyphosate resistance in KS kochia led to a research project at CSU in which a MS student used molecular techniques to determine the mechanism of glyphosate resistance in kochia. This issue is exacerbated by the tumble weed nature of kochia in which wind-blown plants distribute their seeds over long distances. We found no mutation at the Proline 106 position in the EPSPS gene, thus ruling this out as a possible mechanism of the observed resistance. However, using qPCR, we were able to show that significant amplification of the EPSPS gene occurs in all glyphosate resistance plants tested to date from a wide geographic range. This increase in gene copy number ranges from 3 to 9 additional copies, all of which confer resistance to glyphosate applied at the recommended field rate. Some plants survive up to 6 lb ae/acre of glyphosate. New research is focused on alternative control of glyphosate resistant kochia. Feral Rye. Feral rye is a winter annual grass weed of wheat that closely mirrors the life cycle of winter wheat. Imazamox has been labeled for suppression of feral rye because field-level control has been variable. Feral rye field samples of seed were collected from 71 locations in eastern Colorado in July of 2012, around the time of wheat harvest. Threshed seed were planted in the greenhouse and all accessions were sprayed with 3, 6, and 12 fluid ounces of imazamox + 1% v/v MSO. Virtually no accessions were controlled at the 3 oz rate (which is ½ the labeled field rate), while many were controlled at the 6 oz rate. However, multiple accessions survived the 12 oz rate (2 X) and continued to grow in spite of being temporarily damaged. ALS enzyme assays are being run on these potentially resistant accessions to determine if point source mutations have now conferred imazamox resistance in select feral rye populations. Idaho. Submitted by Don Morishita In 2012, 17 grass weed control studies were conducted in Idaho. Fourteen of the studies in northern Idaho included seven trials for Italian ryegrass control, 2 rattail fescue studies, 3 downy brome studies and 3 wild oat studies. In southern Idaho, three wild oat studies were conducted. Italian ryegrass was controlled best with a combination of flufenacet + metribuzin applied preemergence followed by pinoxaden or pyroxsulam or mesosulfuron. Pyroxasulfone applied preplant or preemergence provided 70 to 80% Italian ryegrass control, but pyroxasulfone did not satisfactorily control downy brome. Pyroxsulam and propoxycarbazone controlled downy brome 85%. Rattail fescue was controlled 95% with pyroxasulfone or flufenacet + metribuzin applied preemergence and followed by flucarbazone applied postemergence. In southern Idaho, wild oat was effectively controlled with pinoxaden and fenoxaprop applied in combination with several broadleaf herbicides. Montana. Submitted by Fabian Menalled Our research focused on several areas related to weed biology, ecology, and management. Among them: Effect of height and seeding rate on spring wheat-wild oat (Avena fatua) interactions. Increasing crop competitive ability through seeding rate and crop size provides a means to diversify weed management. However, few studies have assessed the integrated effects of these two practices and the evidence for linking taller varieties with improved weed management are confounded by inter-variety morphological differences. A field experiment was conducted near Bozeman, MT to investigate the impacts of seeding rate and height of three hard red spring wheat varieties on crop-wild oat interactions. Within each variety, crop height (tall or semi-dwarf) was determined by one to two genes. Spring wheat was planted at high (337 plants/m squared) or low (202 plants/m squared) seeding rates into wild oat-infested or weed-free plots. Each treatment was replicated four times in a completely randomized design. Data were collected on grain yield, weed density, biomass, and seed production. Effects of wild oat on spring wheat yields depended on an interaction between crop height and seeding rate. At low seeding rates, semi-dwarf lines had greater yields than tall lines in weed-free controls but yields were similar in weedy plots. At high seeding rates, weeds-free yields and weed impacts on yields were similar between tall and semi-dwarf lines. While increasing seeding rate decreased weed per capita biomass, canopy height did not impact weed growth. Both seeding rate and crop height had independent effects on weed seed production. Increasing seeding rate and crop height reduced weed seed production by approximately 30% and 20%, respectively. Increasing seeding rate had the largest and most consistent effects on weed growth and seed production and taller wheat lines may be useful as part of a long-term integrated wild oat management program that should be used in combination with high seeding rates. Effectiveness of newly developed herbicides for weed control in Montanas agriculture. Every year, new herbicides and re-formulations of existing products are released into the market. As part of a service to Montana agricultural producers and in close collaboration with the Industry, we conducted herbicide screening trials to assess the effectiveness of these products under a range of environmental and crop conditions representative of Montanas agriculture. This study is being developed with the help of Mr. Edward S. Davis, Weed Research Associate, MSU. Oregon. Submitted by Daniel Ball, Andrew Hulting, and Carol Mallory-Smith A statewide effort focusing on evaluation of newer herbicide products for management of invasive weeds in wheat based cropping system was undertaken in 2011-2012. Studies in western Oregon focus on grass control in winter and spring wheat. Control of Italian ryegrass, California brome, downy brome and rattail fescue in winter wheat are being evaluated with a range of preemergence, early postemergence and postemergence applications of herbicides in several studies. A number of winter wheat studies have been initiated to compare Italian ryegrass and rattail fescue control between preemergence and early postemergence applications of Axiom and preemergence applications of pyroxasulfone (Zidua). Rattail fescue, California brome and downy brome control in winter wheat are being evaluated with fall versus spring timing applications of herbicides. Results indicate that applying postemergence herbicides such as PowerFlex, Goldsky and Osprey to winter wheat by approximately the end of November provide the best control of these weedy grass species compared to a spring application in most western Oregon production systems (in the absence of a preemergence application of Axiom). Studies also were established through cooperation with wheat growers in commercial production fields where populations of suspected multiple resistant (Group 1 and/or 2 and/or 15) Italian ryegrass populations are present to evaluate herbicide combinations for the management of these difficult to control biotypes. A preemergence or early postemergence application of pyroxasulfone (Zidua) or Axiom followed by a spring application of PowerFlex provided the best control of these Italian ryegrass populations in all of the studies. Postemergence applications alone did not provide significant control of these Italian ryegrass populations. Trials in eastern Oregon focused on improving effectiveness of downy brome control with preemergence applications of PrePare, Axiom, Far-Go, or pyroxasulfone (Zidua) compared to commercial standard treatments. Because of the current, heavy reliance on Group 2 (sulfonylurea and imidazolinone) herbicides for downy brome control, information on effectiveness of herbicides with differing modes of action will facilitate future resistance management strategies. Another trial was conducted under eastern Oregon conditions to evaluate PowerFlex effectiveness for control of rattail fescue. Results of this study indicate only a moderate level of efficacy for rattail fescue suppression. Other trials were conducted in eastern Oregon to evaluate new herbicide combinations for broadleaf weed control in direct-seeded winter and spring wheat. Huskie herbicide continues to exhibit excellent activity on key broadleaf weeds in wheat including prickly lettuce, Russian thistle, and tumble pigweed. Trial results from 2011-12 and earlier eastern Oregon weed control trials are available on-line at http://oregonstate.edu/weeds/. Dr. Dan Ball will be retiring from his position based in Pendleton, OR, in November of 2013. A replacement for this weed science position in eastern OR will be sought. During 2011-12, weed management Extension presentations were made to wheat producers in many OR locations including Forest Grove, Albany, Salem, Mt. Angel, Corvallis, Klamath Falls, Pendleton, Condon, Hood River, LaGrande, and Walla Walla, WA, among other locations throughout Oregon and the PNW. Topics covered included precision application of herbicides for weed management, herbicide resistance management, herbicide mode of action, Russian thistle control, carryover potential for Beyond herbicide in wheat, and Italian ryegrass, rattail fescue and downy brome control in winter and spring wheat. Formal field tours or research results were conducted with industry groups and growers at the Columbia Basin Ag Research Center in Pendleton, the Hyslop Ag Research Farm near Corvallis and in Washington County. A. Hulting and D. Ball continue to serve as Associate Editors for the PNW Weed Management Handbook and edit and update several wheat-related weed management chapters in the handbook on a yearly basis: http://pnwhandbooks.org/weed/. Relation to Other Research: Cooperative projects between researchers at Washington State University, University of Idaho, and OSUs Columbia Basin Agricultural Research Center have recently investigated the influence of rainfall zone and preplant tillage on Beyond herbicide persistence in an array of PNW dryland agroclimatic zones. The eastern Oregon weed science team continues to cooperate with the OSU wheat breeding program to identify 2-gene winter wheat lines with improved tolerance to Beyond herbicide treatments. Two-gene Clearfield varieties have dramatically improved herbicide tolerance which will allow for improved weed control treatments for weed species such as feral rye. Surveys funded, in part, by the Oregon Wheat Commission and the Agricultural Research Foundation of jointed goatgrass and wheat X jointed goatgrass hybrids present in wheat fields across eastern Oregon are ongoing. These surveys will be used to help inform management decisions to maintain the utility of the Clearfield production system across the state. The statewide program also continues to work with a variety of university and industry collaborators to identify herbicide resistant weed species in a range of cropping systems and to improve management of these biotypes in many crops, including wheat. Washington. Submitted by Ian C. Burke and Drew J. Lyon Control of rattail fescue in no-till winter wheat. The efficacy of Axiom and Zidua herbicides for the control of rattail fescue was evaluated in two separate studies near Pullman. The study evaluating Axiom was conducted over three years, while the study evaluating Zidua was conducted over two years. In both studies, the use of a PRE herbicide was superior to a POST herbicide when used alone. Postemergence applications generally did not provide adequate control of rattail fescue. Axiom at 10 oz per acre and Zidua at a minimum rate of 1.68 oz per acre provided effective control of rattail fescue. Only a marginal benefit was seen by using a sequential POST application following a PRE application. There was no significant difference when comparing early POST and late POST applications. Control of Italian ryegrass in no-till winter wheat with Axiom. A trail was conducted near Pullman, WA during the 2011-2012 growing season to assess Axiom herbicide systems for control of Italian ryegrass. This study was designed to compare various POST herbicides, POST herbicides in combination, Axiom applied PRE, and Axiom PRE followed by different POST herbicide combinations. The results of this study are difficult to interpret as treatments that provided a high level of control were often inconsistent. When a single herbicide was used, regardless of application timing, control ranged from 62-79%. When two herbicides were used either in a tank mix or sequentially, control ranged from 64-89%. When a PRE herbicide was followed by a POST herbicide containing two products in a tank mix, control ranged from 70-86%. Yield loss due to prickly lettuce in winter and spring wheat. Two studies were conducted to address yield loss in spring wheat caused by prickly lettuce. The first trial was in winter wheat, while the second trial was in spring wheat. Both trials were conducted in Pullman. Prickly lettuce failed to cause any measurable yield loss in winter wheat. The cool wet spring likely contributed to increased competitiveness of winter wheat. The variety Xerpha was used in the winter wheat trial, and it appears to be a very competitive wheat variety. The spring wheat trial was successful. The variety was Louise, and it was planted on April 20, 2010. A natural prickly lettuce population was allowed to establish. The initial density of prickly lettuce on the site ranged from 20 to 202 plants/m squared. On May 20, 2010, each 30 ft by 7 ft plot was divided in half. One half was left nontreated, and the other half was treated with Huskie herbicide. Spring wheat is sensitive to prickly lettuce infestations. Density-dependent yield loss was not significant. Biomass-dependent yield loss was significant. For every gram increase in prickly lettuce biomass, yield loss increased 0.29 bushels. Prickly lettuce cross resistance to ALS-inhibiting herbicides. Since the introduction of ALS inhibitor herbicides in the 1980s, the frequency of herbicide-resistance (R) species to those herbicides has become greater than any other herbicide class. It is known that one or more amino acid substitutions in the ALS protein are sufficient to convert an herbicide-susceptible (S) weed to an R one. Twenty previously collected Eastern Washington prickly lettuce biotypes with known ALS herbicide resistance were studied. Biotypes were grown in a greenhouse and sprayed with various ALS inhibiting herbicides to determine resistance. Cross resistance is not predictable yet, but imazapyr, and the new ALS-inhibiting herbicide, florasulam controlled all the biotypes, even the ALS-resistant ones. Peak (prosulfuron) and Amber (triasulfuron) also controlled a number of biotypes that are known to be ALS-resistant. When we put this information together with the mutation causing the resistance, we can test unknown biotypes and predict cross resistance. Studies initiated in fall of 2012. Several field studies were initiated in the fall of 2012. These included a study on downy brome control with Axiom, rattail fescue control with Everest 2.0, rattail fescue control with Anthem, Italian ryegrass control with pyroxysulfone, and screening of two-gene Clearfield wheat varieties for tolerance to Beyond herbicide. Wyoming. Submitted by Andrew Kniss In 2012, research was conducted for management of glyphosate-resistant kochia in wheat-fallow systems, and downy brome in winter wheat. A variety of herbicide options were identified for kochia control in wheat and fallow. Glyphosate-resistant kochia can be effectively and economically managed in this system. In winter wheat, preemergence applications of propoxycarbazone provided greater than 90% control, compared to less than 60% control with fall or spring postemergence treatments. This is the second year in a row that preemergence applications showed promise for downy brome control in winter wheat. Severe drought limited crop yields in all trials. Less than 6 inches of precipitation was received at the Lingle experiment station in the 2012 calendar year.

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