Progress 10/01/07 to 09/30/13
Outputs
Target Audience: Target audiences received information from field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains and oilseed crops. Main objectives included maximizing control of wild oat, foxtail species, and winter annual brome species; identification and management of resistant biotypes; control of kochia and other broadleaf weeds; maintaining herbicide efficacy while minimizing drift; and identification and development of weed control strategies in oilseed and alternative crops. Target audiences included undergraduate students, graduate students, crop consultants and agronomists, county extension agents, peer institution researchers, industry representatives, professional society memberships, field day participants, popular press/advertising writers, and growers. Information was used in several venues to educate clients for more appropriate decision making. Research results were used in classroom type settings for instruction aid. Information was used to provide tangible examples related to discussion topics. Field examples also were used to construct learning exercises to refine diagnostic skills. Classroom and consulting interactions directly reached more than 1200 individuals annually. Changes/Problems: Research direction responded to EPA scrutiny of spray drift. Spray droplet size can greatly affect drift potential with larger droplets not moving as far from point of source. However, limited information was available to demonstrate the result of extremely large droplet sizes on herbicide efficacy. Conversely, more information was needed on the impact of sublethal glyphosate exposure to sensitive crops. What opportunities for training and professional development has the project provided? A workshop was presented for about 240 consultants and industry professionals annually in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. Schedule of special topics is identified each year with presentation responsibilities distributed among the researchers. Other research discussion sessions or workshops addressed various topics and reached a total of about 250 individuals annually. Field demonstration days are held at several Research and Extension Centers across North Dakota. Information was presented at four to five field days each year with attendance ranging from 40 to 150 individuals at each location each year. These discussions are part distribution of research results and part training examples. Participation in other events such as Western Crop Scout School, North Dakota Ag Association, county Crop Improvement Boards, and Zero Tillage Conferences extended training opportunities occasionally through the duration of this project. Sessions included information on weed biology and ecology, chemical and non-chemical weed control, weed resistance, and herbicide symptomology and damage to crops. How have the results been disseminated to communities of interest? The data of nonconfidential work are included in a database available to researchers and the public for review and query. This database is directly used by 10 individuals to assist research development, but a web framework has made the information available to anyone on the internet (http://www.ag.ndsu.edu/weeds/nd-weed-control-research). The database covers North Dakota field research spanning approximately 35 years. Research reports are prepared for cooperators and industry partners. Web access to these reports has allowed broader access to weed science research in North Dakota with questions about information in the reports coming from across the United States and Canada. Research is published in graduate student theses and professional society journals. Journals included Weed Technology, Weed Science, American Society of Testing Materials, HortTechnology, and Korean Journal of Turfgrass. In addition, abstracts have been published through the Weed Science Society of America, North Central Weed Science Society, American Society of Agronomy, and the Australian Summer Grains Conference. Many presentations, volunteered and requested, have disseminated results to growers, consultants, industry representatives, and peer academicians. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Impact Information to improve control of yellow foxtail with flucarbazone (Everest) by adding the broadleaf herbicide tribenuron (Express) is implemented by 30% of wheat producers. Control also can be improved with addition of nitrogen source. These strategies are especially useful for areas with ACCase-resistant wild oat where yellow foxtail also is present because flucarbazone is an ALS-inhibiting herbicide, therefore effective against ACCase-resistant wild oat, but is not exceptional for yellow foxtail control. Addition of tribenuron or nitrogen can improve yellow foxtail control with flucarbazone by as much as 20%. Incorporation of soil-applied herbicides in North Dakota cereals could prevent $350 million in lost revenue annually. This originates from less weed competition early in the season, but also weed biotypes with resistance to herbicides ban be very difficult to control with postemergence strategies alone. In addition to pre- and postemergence herbicide application, postharvest control of weeds such as kochia with paraquat can eliminate the production of thousands of weed seeds per plant and millions of seeds per acre. Damage to crops because of herbicide drift is leading the EPA to encourage larger spray droplet sizes. This potential was confirmed with simulated drift of less than 1% of a field Roundup rate causing 15% wheat yield loss. However, experiments have indicated decreased weed control (as much as 50 percentage point decrease depending on the species) with increasing droplet size. Diminished control was not corrected with encapsulation or polymer adjuvant systems. Research supports proactive regulation of drift management to preclude establishment of highly restrictive buffer zones that could reduce harvestable acreage by 10%. Objective 1. Maximize grass weed control in cereal crops PRE triallate provided greater than 90% control of wild oat. Pyroxasulfone gave 77 and 82% control depending on rate, but flucarbazone only provided 60% control. Clodinafop appied post emergence (POST) provided 96% control. Postemergence ALS-inhibiting herbicides gave 68 to 80% control of wild oat except for imazamethabenz at 43%, while ACCase-inhibiting herbicides provided 82 to 99% control. Clodinafop gave less control than other ACCase inhibitors. Flucarbazone at 0.32 oz ai/A was critical to achieve better than 85% control of a resistant wild oat biotype. If 0.32 oz/A flucarbazone was split between PRE and POST, control dropped to 62%. Other single ingredient products gave 62% control or less. Adding pinoxaden or fenoxaprop to flucarbazone tended to increase control (91 and 88%, respectively). But pinoxaden plus fenoxaprop gave only 30% control. Pyroxasulfone did not cause visible or physiological injury to cereal crops except oat. Pyroxasulfone at 2.8 oz/A was needed to reach 80% control of foxtail. At a second location, pyroxasulfone at 1.8 oz/A gave 75 to 80% weed control but 2.8 oz/A provided 97% weed control. Inclusion of tribenuron tended to improve consistency and control of yellow foxtail with ALS inhibitors, at least 5 points, especially for propoxycarbazone and mesosulfuron (20 to 30 point increase). Best control of foxtail barley was achieved when glyphosate, which killed existing plants, was tank-mixed with an herbicide having soil residual activity, such as propoxycarbazone, sulfosuluron, or pyroxasulfone (85 to 95% control). Propoxycarbazone or imazapic gave 40 to 70% control of foxtail barley. Treatments that included Propoxycarbazone PRE to downy brome emergence provided at least 92% control of downy brome. When propoxycarbazone was included POST, even at greater rate, control was less than 70% at the end of the season. Propoxycarbazone was more effective than flucarbazone as a PRE herbicide. Objective 2. Identify herbicides with potential for use in camelina and flax Tembotrione and topramezone caused as much as 40% injury to flax, expressed as chlorosis, stunting, and leaf deformity. Previous observations that flax may be tolerant of these new products were identified with less herbicide. Field use rates appropriate for weed control will carry exceptional risk of crop injury. There appears to be too much injury potential for either product to be a viable weed control option for flax. Florasulam previously did not cause substantial injury to flax and would be useful to control pigweed species. Postemergence application to flax that was 15 to 25 cm tall resulted in 29% injury. Addition of MCPA increased injury to almost 40%. While postemergence application is not recommended, additional work with preemergence application of florasulam and similar herbicides will continue. Kochia control in field pea is difficult. Fluthiacet applied at four rates and two adjuvants caused 40 to 75% injury to field pea while the registered herbicide bentazon caused only 3% injury. Injury with fluthiacet was greater when MSO was the adjuvant compared with NIS; however, none of the fluthiacet treatments would be commercially acceptable because of injury. Objective 3. Evaluate pre/postharvest desiccation Visible desiccation of sunflower underestimates the actual moisture content. Paraquat was very effective at desiccating leaf tissue. However, stalk desiccation after paraquat was low compared with saflufenacil. Flumioxazin produced less desiccation than saflufenacil when each was applied alone, and the effect took longer to develop with flumioxazin than saflufenacil. Glyphosate tended to temper the effect of saflufenacil, but the response of the combination typically was better than glyphosate alone. Use of herbicide has resulted in earlier harvest by 5 to 14 days. Glyphsate alone was slow to desiccate legume crops, less than 75% for lentil and chickling vetch. In contrast, flumioxazin provided 97 and 88% visible desiccation, respectively. Inclusion of glyphosate with flumioxazin did not improve desiccation. F7121 was slower to elicit symptoms and did not reach the level of desiccation expressed by flumioxazin. Only postharvest treatments with paraquat provided 94% or better control of kochia. Combinations with paraquat provided similar control to paraquat alone with slight differences in growth from the base of kochia plants. Saflufenacil and dicamba or bromoxynil and pyrasulfotole plus fluroxypyr gave similar control of about 85% and other treatments gave 76% control or less. Postharvest control of glyphosate-resistant kochia should include paraquat for optimal activity with translocating tankmix partner to help inhibit growth from meristems at the base of the plant. Added objective. Evaluate spray droplet size for herbicide efficacy For each 2,4-D formulation, medium spray quality gave the best control of amaranth and buckwheat. At times the difference was more than 35 percentage points between medium and coarser spray qualities. Thifensulfuron showed the same effect. Fenoxaprop control of wild oat decreased about 10 percentage points with droplet ranges larger than medium. The effect was more dramatic for clopyralid and fluroxypyr control of wild mustard, 98% with medium compared with 40 to 50% control with coarser spray qualities. Glyphosate at 0.75 oz/A, 4 to 6% of a field rate, killed nearly all wheat vegetation. Even one-third that much provided 73% injury to wheat and resulted in nearly 80% yield loss. Visible injury was barely perceivable with glyphosate at 0.05 to 0.1 oz/A, 2 to 5% injury. Injury manifested as slight stunting but chlorosis was not apparent. Glyphosate at these rates, less than 1% of a field use rate, still caused about 15% yield loss. Although this was not statistically significant, the numerical difference and strength of the trend in yield loss with such low glyphosate rates warrants concern and refined investigation to the non-identified loss potential at field margins bordering glyphosate-resistant crops.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Ostlie MH, Howatt KA (2013) Downy brome (Bromus tectorum) competition and control in no-till spring wheat. Weed Technol. 27:502-509
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Zollinger RK, Howatt KA, Bernards ML, Peterson DE, Young BG (2012) Acidic ammonium sulfate replacement adjuvants. Amer. Soc. Test. Mater. doi: 10.1520/STP104566
- Type:
Other
Status:
Published
Year Published:
2013
Citation:
Zollinger R, Howatt K (2013) Does acidic AMS replacement adjuvants condition water? Abstract 135 in Proceedings of Western Soc. Weed Sci., vol. 66, San Diego, CA. http://wssaabstracts.com/public/18/abstract-135.html. Accessed August 2, 2013
Howatt KA et al. (2013) 47 contributions In 2012 North Dakota Weed Control Research. Weed Research Projects, Department of Plant Sciences, North Dakota State University, Fargo, ND 58105-5051
- Type:
Other
Status:
Published
Year Published:
2012
Citation:
Fillmore AN, Howatt KA (2012) Wheat response to glyphosate drift or contamination. Proceedings of the North Central Weed Sci. Soc. Ann. Mtg. 67:17. http://www.ncwss.org/proceed/NCWSS-2012-Proceedings.pdf. Accessed February 1, 2013
Howatt KA, Fillmore AN (2012) Glyphosate-resistant kochia confirmation in North Dakota. Proceedings of the North Central Weed Sci. Soc. Ann. Mtg. 67:85. http://www.ncwss.org/proceed/NCWSS-2012-Proceedings.pdf. Accessed February 1, 2013
Li D, Gao Y, Howatt K (2012) Crabgrass control using pre-emergence herbicides applied in tankmix with humic substances. Proceedings of Amer. Soc. Agron., Crop Sci., and Soil Sci. Ann. Mtg. http://scisoc.confex.com/scisoc/2012am/webprogram/Paper71582.html. Accessed February 1, 2013
|
Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Outputs were primarily related to conducting and analyzing field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains. Main objectives include maximizing control of wild oat, foxtail species, and winter annual brome species; identification and management of resistant biotypes; control of kochia and other broadleaf weeds; maintaining herbicide efficacy while minimizing drift; and identification and development of weed control strategies in oilseed and alternative crops. This information was used in several venues to educate clients for more appropriate decision making. Research results are used in classroom type settings for instruction aid. Information is used to provide tangible examples related to discussion topics. Field examples also are used to construct learning exercises to refine diagnostic skills. Classroom and consulting interactions reached more than 200 individuals. A workshop was presented for about 240 consultants and industry professionals in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. Eight other research discussion sessions or workshops addressed various topics and reached a total of about 250 individuals. Personal consultation on sunflower desiccation, weed control in cereals, spray quality effects on herbicide efficacy, and other topics benefited over 200 individuals. Interviews were provided for 6 articles that appeared in popular press and trade magazines. These publications, mostly directed at small grain and sunflower producers, reach thousands of individuals. Research results were published in electronic format and made available on the internet, also a book form was distributed to about 30 cooperators. A database of much of this information continues to be updated with new North Dakota weed research. This database is directly used by 10 individuals to assist research development, but a web framework is under construction that would make the information available to anyone on the internet.  PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Saflufenacil provided 76% control of alfalfa 4 WAT in the fall, but the crown tissue still appeared green and healthy. 2,4-D plus clopyralid or dicamba provided 84% control. 2,4-D ester was better amine. Spring evaluation of treatments applied in the fall indicated that ester or amine formulations of 2,4-D provided similar control at 99% which was better than other treatments. Florasulam previously did not cause substantial injury to flax and would be useful to control pigweed species. Postemergence application to flax that was 15 to 25 cm tall resulted in 29% injury. Addition of MCPA increased injury to almost 40%. While postemergence application is not recommended, additional work with preemergence application of florasulam and similar herbicides will continue. Kochia control in field pea is difficult. Fluthiacet applied at four rates and two adjuvants caused 40 to 75% injury to field pea while the registered herbicide bentazon caused only 3% injury. Injury with fluthiacet was greater when MSO was the adjuvant compared with NIS; however, none of the fluthiacet treatments would be commercially acceptable because of injury. Kochia collected in North Dakota with resistance to glyphosate was confirmed in the greenhouse. Field characterization of control with herbicides used in cereals was conducted at one if these sample sites. While most treatments provided 90% control of kochia or better 4 weeks after treatment, kochia plants remained in most plots and produced biomass nearing 2 m in height by the end of the season. Barley in some plots was completely overtaken was not harvestable. Crop competition seemed to be important in limiting recovery of kochia and will be investigated further. Kochia remaining after cereal harvest produced regrowth even in dry environment. Paraquat plus atrazine or linuron provided rapid desiccation of vegetation. Seed production was not quantified but treatments with paraquat visibly reduced seed production of kochia regrowth compared with treatments containing plant growth regulator herbicides even though general control rating was similar among treatments at 82 to 85% control of kochia. Increased planting area to glyphosate-resistant crops has increased the risk of glyphosate drift or sprayer contamination to cereal crops. Low dose exposure at the four-leaf stage of wheat causing 20% visible injury results in 68% less yield than untreated wheat. The same exposure at flag leaf emergence causes 30% less yield. Glyphosate at 7 g ae/ha (1/100th standard field rate) did not cause visible injury or less yield. Whole field responses to glyphosate could be caused by sprayer contamination or misapplication. Information to improve control of yellow foxtail with flucarbazone by adding the broadleaf herbicide tribenuron is implemented by 30 to 40% of wheat producers. This is especially useful for areas with ACCase-resistant wild oat and yellow foxtail in the same field. Identification of kochia with resistance to glyphosate at 8x field rate in North Dakota is quickly altering general weed control practices. We expect high adoption of preemergence options and an increase of control in waste areas.
Publications
- Hall, A.E. 2012. H13 efficacy as a spring cereal crop herbicide. M.S. thesis. North Dakota State Univ., Fargo. 63 p.
- Hall, A.E., and Howatt, K.A. 2012. Preemergence herbicide evaluation in spring wheat. WSSA Title and Abstract System. Weed Sci. Soc. Amer. http://wssaabstracts.com/public/9/abstract-266.html (accessed 18 Dec. 2012).
- Howatt, K.A., and Lukach, J.R. 2012. Herbicide efficacy with coarser spray quality. WSSA Title and Abstract System. Weed Sci. Soc. Amer. http://wssaabstracts.com/public/9/abstract-361.html (accessed 18 Dec. 2012).
- Zollinger, R.K., Howatt, K.A., Bernards, M.L., Peterson, D.E., and Young, B.G. 2012. Acidic ammonium sulfate replacement adjuvants. Amer. Soc. Test. Mater. doi: 10.1520/STP104566.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Outputs were primarily related to conducting and analyzing field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains. Main objectives include maximizing control of wild oat, foxtail species, and winter annual brome species; identification and management of resistant biotypes; characterization of broadleaf herbicide antagonism of grass weed control; control of broadleaf weeds; maintaining herbicide efficacy while minimizing drift; and identification and development of weed control strategies in oilseed and alternative crops. This information was used in several venues to educate students and clients for more appropriate decision making. Research results are used in the traditional classroom for student instruction. Information is used to provide tangible examples for students related to discussion topics. Field examples also are used to construct classroom learning exercises and exam problems to refine students' diagnostic skills. A workshop was presented for about 225 consultants and industry professionals in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. Seven other research discussion sessions or workshops addressed various topics and reached a total of about 650 individuals. Public Field Days at five Research Extension Centers across North Dakota provided opportunity to reach over 600 individuals with research results of downy brome and cereal grain weed control and answer questions or acknowledge needs for future work. Results of specific experiments were presented at professional meetings as well: North Central Weed Science Society, Western Society of Weed Science, and National Sunflower Association. Summary of sunflower desiccation with chemicals was discussed with the National Sunflower Association and discussion of future direction for weed control in sunflower led to broad screening of mutation lines. Personal consultation on sunflower desiccation, weed control in cereals, spray quality effects on herbicide efficacy, and other topics benefited over 300 individuals. Interviews were provided for 9 articles that appeared in popular press and trade magazines. These publications, mostly directed at small grain and sunflower producers, reach thousands of individuals. Research results were published in electronic format and made available on the internet, also a book form was distributed to about 30 cooperators. A database of much of this information continues to be updated with new North Dakota weed research. This database is directly used by 10 individuals to assist research development, but a web framework is under construction that would make the information available to anyone on the internet. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Average values for control across species with auxinic herbicides declined from 45 to 50% with fine and medium spray quality to 20 to 25% control with extremely coarse spray quality. The deposition aid AG02013 did not consistently affect weed control with herbicides. Saflufenacil provided 76% control of alfalfa 4 WAT, but the crown tissue still appeared green and healthy. 2,4-D plus clopyralid or dicamba provided 84% control. 2,4-D ester was better than amine. Thifensulfuron and tribenuron applied to SU-canola caused substantial injury at 1 to 4 times field rate, resulting in 19 to 35% chlorosis. Field rate of thifensulfuron and tribenuron gave broadleaf weed control similar to glyphosate and better than imazamox or glufosinate. Glyphosate or imazamox provided better foxtail control (90%) than clethodim or glufosinate (70%). Chlorosis was observed for IMI-sunflower lines treated with imazamox. Injury increased as tribenuron rate increased with imazamox. The CLHA-sunflower were more susceptible (at least 90%) to tribenuron than the CL-sunflower, and injury to either sunflower type included necrosis. However, tribenuron did improve control of Canada thistle with imazamox. Wheat injury with PRE herbicides was not evident until July 18. At this evaluation, only flumioxazin and pyroxasulfone caused injury (4%). Averaged across weeds, flumioxazin and pyroxasulfone provided 93% control. Flumioxazin alone gave 85% broadleaf control, and foxtail control was 57%. Other herbicides gave 30 to 60% control. The new herbicide 20211 provided excellent control of grass and broadleaf weeds. Propoxycarbazone and mesosulfuron gave 55% control or less of yellow foxtail, while 20211 or the fenoxaprop premix provided 90% control or better. All herbicides gave 93 to 95% control of wild oat and 99% control of broadleaf weeds. Flucarbazone at 0.32 oz ai/A was critical to achieve better than 85% control of a resistant wild oat biotype. If 0.32 oz/A flucarbazone was split between PRE and POST, control dropped to 62%. Flucarbazone at 0.42 oz/A provided the same control whether split or applied all POST. Other single single ingredient products gave 62% control or less. Adding pinoxaden or fenoxaprop to flucarbazone tended to increase control (91 and 88%, respectively). But pinoxaden plus fenoxaprop gave only 30% control. A growth stimulant may encourage more rapid symptom progression and stabilize herbicide activity under environmental stress. Control of yellow foxtail with flucarbazone was enhanced with HM1045 or Ascend from 40% alone to 53 and 63%, respectively. With pinoxaden, only Ascend had beneficial influence on herbicidal activity, although all hormone products tended to improve foxtail control. We are helping producers and land managers understand the proper spray quality, or droplet size, for specific herbicide application. An inappropriate spray quality can reduce weed control by 50%. NDSU research has demonstrated the benefit of including soil-applied herbicides in weed control programs for wheat. In North Dakota cereals, the improved weed control results in greater yield and could prevent $350 million in lost revenue annually.
Publications
- Stahlman, P. W., K. A. Howatt, B. M. Jenks, and M. J. Moechnig. 2010. Saflufenacil: A new preharvest desiccant of sunflower. In Proceedings of the 1st Australian Summer Grains Conference, Gold Coast, Australia. (Eds B. George-Jaeggli and D. J. Jordan). (Grains Research and Development Corp.). http://www.grdc.com.au/uploads/documents/2010ASGCEditedPapersPDF/Stah lman_Saflufenacil_ededit_paper.pdf. Accessed January 11, 2012.
- Xie, L., D. Li, W. Fang, and K. Howatt. 2011. Urea ammonium nitrate additive and raking improved mesotrione efficacy on creeping bentgrass. HortTechnology 21:1-5.
- Hall, A. E. and K. A. Howatt. 2011. Tribenuron enhanced control of yellow foxtail (Setaria pumila) with flucarbazone. Pages 87-88 in Proceedings of Western Soc. Weed Sci., vol. 64, Spokane, WA. http://www.wsweedscience.org/Proceedings%20Archive/2011.pdf. Accessed January 11, 2012.
- Howatt, K. A. 2011. Attempts to overcome poor herbicide efficacy from large spray droplets. Page 95 in Proceedings of Western Soc. Weed Sci., vol.64, Spokane, WA. http://www.wsweedscience.org/Proceedings%20Archive/2011.pdf. Accessed January 11, 2012.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Outputs were primarily related to conducting and analyzing field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains. Main objectives include maximizing control of wild oat, foxtail species, and winter annual brome species; identification and management of resistant biotypes; characterization of broadleaf herbicide antagonism of grass weed control; control of broadleaf weeds; maintaining herbicide efficacy while minimizing drift; and identification and development of weed control strategies in oilseed and alternative crops. This information was used in several venues to educate students and clients for more appropriate decision making. Research results are used in the traditional classroom for student instruction. Information is used to provide tangible examples for students related to discussion topics. Field examples also are used to construct classroom learning exercises and exam problems to refine students' diagnostic skills. Interactions with students on campus include coordination of the Crop and Weed Sciences major, advising undergraduate and graduate students, co-advising the Agronomy Club, and serving as faculty mentor for a residence hall. Classroom and advising interactions reach more than 250 individuals. A workshop was presented for about 225 consultants and industry professionals in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. Seven other research discussion sessions or workshops addressed various topics and reached a total of about 650 individuals. Public Field Days at six Research and Extension Centers across North Dakota provided opportunity to reach over 650 individuals with research results of downy brome and cereal grain weed control and answer questions or acknowledge needs for future work. Results of specific experiments were presented at professional meetings as well: Western Society of Weed Science and National Sunflower Association. Summary of sunflower desiccation with chemicals was discussed with the National Sunflower Association and discussion of future direction for weed control in sunflower led to broad screening of mutation lines. Personal consultation on sunflower desiccation, weed control in cereals, spray quality effects on herbicide efficacy, and other topics benefited over 300 individuals. Interviews were provided for 12 articles that appeared in popular press and trade magazines. These publications, mostly directed at small grain and sunflower producers, reach thousands of individuals. Research results were published in book form and distributed to about 500 individuals. A database of much of this information continues to be updated with new North Dakota weed research. This database is directly used by 10 individuals to assist research development, but a web framework is under construction that would make the information available to anyone on the internet. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Best control of foxtail barley was achieved when glyphosate, which killed existing plants, was tank-mixed with an herbicide having soil residual activity, such as propoxycarbazone, sulfosuluron, or pyroxasulfone (85 to 95% control). Propoxycarbazone or imazapic gave 40 to 70% control of foxtail barley. Soil-applied pyroxasulfone at 1.8 oz ai/A provided greater than 90% control of wild mustard and redroot pigweed and 86% control of yellow foxtail. Flucarbazone gave 81 to 89% control, but flumioxazin activity did not reach 80%. In general, pyroxasulfone weed control resulted in more wheat yield than other treatments. Saflufenacil, up to 2.8 oz ai/A, did not cause wheat injury. POST herbicide application is needed for maximum weed control, but residual activity from 0.26 oz/A saflufenacil improved grain yield by 28%. Control of yellow foxtail (70 to 90%) was provided by all saflufenacil rates. Redroot pigweed was controlled nearly 80% with 0.72 oz/A saflufenacil. Substantial wheat injury was observed with dicamba. This injury increased with increasing rate when applied early (5 to 15%) but was consistent when applied late (10 to 12%). Dicamba plus 2,4-D caused the most injury to wheat (24% post jointing). BAS810 also caused injury that lasted through the season. Dicamba plus 2,4-D applied to 5 leaf wheat resulted in 30% less wheat yield. Inclusion of tribenuron tended to improve consistency and control of yellow foxtail with ALS inhibitors at least 5 points, especially for propoxycarbazone and mesosulfuron (20 to 30 point increase). In this study, foxtail control with tribenuron alone was atypical and near 80%. For each 2,4-D formulation, medium spray quality gave the best control of amaranth and buckwheat. At times the difference was more than 35 percentage points between medium and coarser spray qualities. Thifensulfuron showed the same effect. Fenoxaprop control of wild oat decreased about 10 percentage points with droplet ranges larger than medium. The effect was more dramatic for clopyralid and fluroxypyr control of wild mustard, 98% with medium compared with 40 to 50% control with coarser spray qualities. Imazamox caused transient mottled chlorosis of sunflower leaf tissue. Wild buckwheat control with imazamox was substantially better with MSO (93%) than with NIS (71%). This also improved control of yellow foxtail, resulting in 10 percentage points advantage over clethodim. Commercial imidazolinone-resistant sunflower was less tolerant of imazamox than CLHA sunflower. Tribenuron caused excessive damage (80%) to CLHA sunflower but did not kill more than a couple plants. The best full-season weed control was obtained with sulfentrazone followed by 0.75 oz/A imazamox, resulting in 1760 lb/A sunflower seed yield. Incorporation of soil-applied herbicides in North Dakota cereals could prevent $350 million in lost revenue annually. More aggressive weed control programs proven in sunflower by NDSU scientists improve weed control by 10 to 25% and would increase annual North Dakota receipts by up to $25 million. Non-discriminately increasing spray droplet size to reduce drift would reduce weed control by 10 to 50%.
Publications
- Howatt, K. A., and R. Luciano. 2010. DRT implications for weed control. Proc. Western Soc. Weed Sci. 63:76.
- Luciano, R., and Howatt, K. A. 2010. Downy brome response to soil applied herbicides. Proc. Western Soc. Weed Sci. 63:24-25.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Outputs were primarily related to conducting and analyzing field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains. Main objectives include maximizing control of wild oat, foxtail species, and winter annual brome species; identification and management of herbicide resistant biotypes; characterization of broadleaf herbicide antagonism of grass weed control; control of broadleaf weeds; maintaining herbicide efficacy while minimizing drift; and identification and development of weed control strategies in small grains, legume, and oilseed crops. This information was used in several venues to educate students and clients for more appropriate decision making. Research results are used in the traditional classroom for student instruction. Information is used to provide tangible examples for students related to discussion topics. Field examples also are used to construct classroom learning exercises and exam problems to refine students' diagnostic skills. Interactions with students on campus include coordination of the Crop and Weed Sciences major, advising undergraduate and graduate students, co-advising the Agronomy Club, and serving as faculty mentor for a residence hall. Classroom and advising interactions reach more than 250 individuals. A workshop was presented for about 225 consultants and industry professionals in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. Five other research discussion sessions or workshops addressed various topics and reached a total of about 300 individuals. Public Field Days at six Research and Extension Centers across North Dakota provided opportunity to reach over 500 individuals with research results of downy brome and cereal grain weed control and answer questions or acknowledge needs for future work. Results of specific experiments were presented at professional meetings as well: Western Society of Weed Science, North Central Weed Science Society, and National Sunflower Association. Summary of sunflower desiccation with chemicals was discussed with the National Sunflower Association and similar presentation addressing production and quality issues was presented at a Canadian sunflower production meeting. Personal consultation on sunflower desiccation, weed control in cereals, and other topics benefited over 200 individuals. Research results are published in book form and distributed to about 500 individuals. A database of much of this information continues to be updated with new North Dakota weed research. This database is directly used by 10 individuals to assist research development, but a web framework is under construction that would make the information available to anyone on the internet. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Damage to crops because of herbicide drift is leading the EPA to encourage larger spray-droplet sizes. Several experiments have indicated decreased weed control (as much as 50 percentage point decrease depending on the species) with increasing droplet size. Diminished weed control was not corrected with encapsulation or polymer adjuvant systems. Research supports proactive regulation of drift management to preclude establishment of highly restrictive buffer zones that could reduce harvestable acreage by 40%. Development and spread of weeds with resistance to herbicides is a concerning issue. 2009 was the third year of a rotation to evaluate five herbicide sequence programs. In 2008, a few wild oat survivors were observed. In 2009, several treatments did not control wild oat. Two of these treatments (74 and 79% control) were continuous fenoxaprop. Control with clethodim also was less than expected at 81 to 87% control. This study has demonstrated how quickly concerns of resistance can develop. Difenzoquat has been the standard rescue treatment for wild oat resistance. However, new wheat varieties have not been tested for tolerance to difenzoquat. Severe and lasting injury (as much as 80% leaf damage, stunting, and developmental delay) to 'Alsen' wheat with difenzoquat was observed. Alsen is not included as a recommended cultivar on the product label, but it had not demonstrated injury. Use on some of the recent introductions involves risk of injury and economic loss. A new herbicide offers control of resistant wild oat biotypes and did not cause injury to wheat. The herbicide at 1.4 oz/A provided 93, 87, and 96% control of wild oat, wild buckwheat, and wild mustard, respectively. Another option to manage resistance is further development of soil-applied products. The flumioxazin label requires 30 d between application and wheat seeding. Data from several experiments have demonstrated the viability of a shorter period. A shorter period between application and seeding would extend the soil-residual benefits further into the season. Additional development of the application method could stabilize activity on wild oat. A second soil-herbicide option is not currently registered but shows promise for wild oat and other weeds. Pyroxasulfone did not cause visible or physiological injury to cereal crops except oat. Pyroxasulfone at 2.8 oz/A was needed to reach 80% control of foxtail. Wild mustard exhibited slight response to proxasulfone. Common lambsquarters and smartweed were adequately controlled but POST treatments would be necessary to maximize weed control. At a second location, pyroxasulfone at 1.8 oz/A gave 75 to 80% weed control but 2.8 oz/A provided 97% weed control. New herbicide options are sought in other crops as well. Tembotrione and topramezone caused as much as 40% injury to flax, expressed as chlorosis, stunting, and leaf deformity. Previous observations that flax may be tolerant of these new products were identified with less herbicide. Field use rates appropriate for weed control will carry exceptional risk of crop injury. There appears to be too much injury potential for either product to be a viable weed control option for flax.
Publications
- Hanson, L. K. 2009. Pyroxsulam efficacy to wild oat (Avena fatua L.) and yellow foxtail [Setaria glauca (L.) BEAUV.] as influenced by application timing or adjuvants. M.S. thesis. North Dakota State Univ., Fargo. 61 p.
- Hanson, L. K. and K. A. Howatt. 2008. Does pyroxsulam control ALS-resistant wild oat [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Howatt, K. A., B. M. Jenks, P. W. Stahlman, and M. Moechnig. 2008. Potential of saflufenacil for preharvest desiccation of sunflower. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Howatt, K. A., R. Roach, and J. Harrington. 2008. Saflufenacil use preemergence in wheat. Proc. Western Soc. Weed Sci. 62:59-60.
- Kazmierczak, A. J. 2008. Propoxycarbazone for grass weed control and injury to subsequent crops by soil residues. M.S. thesis. North Dakota State Univ., Fargo. 46 p.
- Ostlie, M. H. 2008. Downy brome competition and evaluation of herbicidal control for no-till hard red spring wheat. M.S. thesis. North Dakota State Univ., Fargo. 59 p.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Outputs were primarily related to conducting and analyzing field and greenhouse experiments for the purpose of gaining knowledge and improving understanding of weed management in cereal grains. Main objectives include maximizing control of wild oat, foxtail species, and winter annual brome species; characterization of broadleaf herbicide antagonism of grass weed control; control of broadleaf weeds; and identification and development of weed control strategies in legume and oilseed crops. This information was used in several venues to educate students and clients for more appropriate decision making. A workshop was presented for consultants and industry professionals in conjunction with other North Dakota State University weed science researchers. Each researcher prepared a discussion of important and relevant findings in project activities. This project leader also facilitated the presentation and discussion of three graduate students' projects results pertaining to new weed concerns for North Dakota. Two of the students work was on downy brome. Downy brome is a rising problem in North Dakota and generated substantial interest among attendees. An invited article on downy brome identification and control was prepared for Duck's Unlimited agronomic newsletter, and a presentation and identification clinic was prepared for a special meeting in Emmonds county that focused on downy brome issues. Public Field Days at six Research and Extension Centers across North Dakota provided opportunity to reach over 500 individuals with research results of downy brome and cereal grain weed control and answer questions or acknowledge needs for future work. Results of specific experiments were presented at professional meetings as well: Western Society of Weed Science, North Central Weed Science Society, and National Sunflower Association. Summary of sunflower desiccation with chemicals was requested at the summer meeting of the National Sunflower Association in Rapid City, SD. A similar presentation addressing production and quality issues was requested for a Canadian sunflower production meeting. Personal consultation on sunflower desiccation, weed control in cereals, and other topics benefited over 200 individuals. Research results also are used in the traditional classroom for student instruction. Information is used to provide tangible examples for students related to discussion topics. Field examples also are used to construct classroom learning exercises and exam problems to refine students' diagnostic skills. Interactions with students on campus include coordination of the Crop and Weed Sciences major, advising undergraduate and graduate students, co-advising the Agronomy Club, and serving as faculty mentor for a residence hall. Serving as mentor has allowed promotion of Plant Sciences to students in diverse programs. This role has included academic advising and registration, career counseling, professional programs on plant topics, and social programs for student well-being. It has given the opportunity to introduce agriculture to students who would not have considered careers in agriculture-related fields. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Saflufenacil applied preemergence (PRE) in wheat did not injure wheat, but poor control of emerged weeds was common among studies. Glyphosate alone was slow to kill weeds but curly dock did not recover. Glyphosate plus saflufenacil or carfentrazone provided 93 to 97% control of curly dock on 6/20, but control was less than 80% on 7/14. PRE triallate provided greater than 90% control of wild oat. Pyroxasulfone gave 77 and 82% control depending on rate, but flucarbazone only provided 60% control. Clodinafop appied post emergence (POST) provided 96% control. Wheat population generally was greater with clodinafop than herbicides applied to the soil, indicating that herbicide residues may cause more damage to wheat than initial competition with weeds. Less than 3 oz/A pyroxasulfone did not result in visible reduction of wild oat growth. From 3 to 6 oz/A pyroxasulfone, wild oat control increased from 78 to 90%. Pyroxasulfone at rates up to 6 oz/A did not cause visible injury to wheat in several studies. Pyroxasulfone appears to be a viable weed control option for wheat. PRE flucarbazone had a minor effect on wild oat. On 6/20, PRE flucarbazone appeared to result in less control with POST flucarbazone than POST only, but control was at least 87%. Control between other POST herbicide pairs was similar with and without PRE flucarbazone. By 7/2, control with POST flucarbazone was not affected by PRE flucarbazone, but tralkoxydim was 10 percentage points less when PRE flucarbazone was included compared with tralkoxydim alone. ALS-inhibiting herbicides gave 68 to 80% control of wild oat except for imazamethabenz at 43%, while ACCase-inhibiting herbicides provided 82 to 91% control. Clodinafop gave less control than other ACCase inhibitors. By 7/2, the wild oat fenoxaprop rate maintained 94% control, similar to pinoxaden and tralkoxydim. Difenzoquat gave 82% control. Flucarbazone gave 70% control of yellow foxtail. Other herbicides provided 83 to 88% control. Pinoxaden plus florasulam and MCPA provided 97% control on 7/18. Flucarbazone, fenoxaprop, and pinoxaden plus clopyralid and fluroxypyr with MCPA gave less control at 87 to 91%, but only two of these treatments resulted in less yield compared with nontreated wheat. Visible desiccation of sunflower underestimates the actual moisture content. Paraquat was very effective at desiccating leaf tissue. However, stalk desiccation after paraquat was low compared with saflufenacil. Flumioxazin produced less desiccation than saflufenacil when each was applied alone, and the effect took longer to develop with flumioxazin than saflufenacil. Glyphosate tended to temper the effect of saflufenacil, but the response of the combination typically was better than glyphosate alone. Use of herbicide has resulted in earlier harvest by 5 to 14 days. Glyphsate alone was slow to desiccate legume crops, less than 75% for lentil and chickling vetch. In contrast, flumioxazin provided 97 and 88% visible desiccation, respectively. Inclusion of glyphosate with flumioxazin did not improve desiccation. F7121 was slower to elicit symptoms and did not reach the level of desiccation expressed by flumioxazin.
Publications
- Howatt, K.A. 2008. Investigation of sunflower response to BAS800H as a preharvest desiccant. Proc. Western Soc. Weed Sci. 61:56.
- Kazmierczak, A.J., and Howatt, K.A. 2008. Herbicide solution pH effect on control of downy brome and wild oat. Proc. Western Soc. Weed Sci. 61:18.
- Kazmierczak, A.J., and Howatt, K.A. 2008. Adjuvant class screening with propoxycarbazone for control of downy brome. Proc. Western Soc. Weed Sci. 61:18.
- Ostlie, M.H. and Howatt, K.A. 2008. Deposition adjuvants for enhancing wild oat and downy brome control. Proc. Western Soc. Weed Sci. 61:83.
- Ostlie, M.H. and Howatt, K.A. 2008. Downy brome control with herbicides in no-till hard red spring wheat. Proc. Western Soc. Weed Sci. 61:44.
- Howatt, K., Jenks, B., Stahlman, P., and Moechnig, M. 2008. Effect of preharvest herbicides on sunflower. Online http:www.sunflowernsa/research/default.aspcontentID=70.
- Hanson, L.K. and Howatt, K.A. 2007. Pyroxsulam efficacy to wild oat influenced by application timing or adjuvants. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Howatt, K.A. 2007. Scouringrush control with herbicides. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Kazmierczak, A.J. and Howatt, K.A. 2007. Adjuvant class screening with propoxycarbazone for control of downy brome. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Kazmierczak, A.J. and Howatt, K.A. Howatt. 2007. Herbicide solution pH effect on control of downy brome and wild oat. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Kazmierczak, A.J. and Howatt, K.A. 2007. Propoxycarbazone injury to subsequent crops by soil residues. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Ostlie, M.H. and Howatt, K.A. 2007. Deposition adjuvants for enhancing wild oat and downy brome control. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Zollinger, R.K., Howatt, K.A., and Jenks, B.M. 2007. Tolerance of several crops to KIH-485. [CD-ROM Computer File]. North Central Weed Sci. Soc., Champaign, IL.
- Ostlie, M.H. and Howatt, K.A. 2008. Winter annual brome control in no-till spring and winter wheat. Ducks Unlimited Agronomy Newsletter 8(2):2-3. Online http://www.ducks.org/Page2816.aspx.
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