Progress 05/01/09 to 04/30/14
Outputs
Target Audience: We reached mint and alfalfa seed producers in the United States by means of reports at annual meetings of the WA State Mint Commission, WA State Alfalfa Seed Commission, and the Mint Industry Research Council, and publications and reports on research to various vegetable grower organizations and extension conferences. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Annual reports at grower meetings, extension conferences, and publications in trade journals What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Tall hedge mustard is difficult to control in mintbit in a field trial, clomazone and paraquat tank mixes provided season long control while maintaining peppermint oil yield. Rattail fescue, another problem weed in mint was controlled well by sequential applications of paraquat in tank mixes with residual herbicides pyroxasulfone and terbacil. Larvae of Tyta luctuosa, a field bindweed biocontrol agent, were released in a vineyard and adult moths recovered in pheromone traps later in the season. This indicates that the biocontrol agent successfully completed its life cycle. Managing weeds in alfalfa seed production is important in orderto obtain high yields and quality seed. In a trial on an established commercial alfalfa seed field, catchweed bedstraw was controlled well with tank mixes of carfentrazone with theresidual herbicides flumioxazin, sulfentrazone, or pyroxasulfone + flumioxazin. Imazamox suppressed catchweed bedstraw but allowed some plants to escape and produce seed. Glyphosate use is restricted to prebloom applications in glyphosate resistant alfalfa seed production fields. Glyphosate applied at 1 to 3% bloom slightly reduced seed yields of alfalfa and seed yields declined greatly as glyphosate applications were delayed until full bloom or early seed pod development. This research identified preemergence and postemergence applied herbicides for selective control of catchweed bedstraw and identified critical stages of alfalfa growth in which glyphosate can be safely applied in alfalfa seed production. These findings were utilized by alfalfa seed producers to improve weed management and provide growers with options for managing difficult to control weeds.
Publications
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: Mint and alfalfa seed producers in the United States. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Presentations, reports, and posters at various mint and alfalfa commodity meetings What do you plan to do during the next reporting period to accomplish the goals? Continue expanding the research on the current goals and submit grant proposals to the WA Mint Commission to fund the research. Cooperate with WSU researchers in getting weed control materials registered for use.
Impacts
What was accomplished under these goals?
Tall hedge mustard is difficult to control in mint;in a field trial, clomazone and paraquat tank mixes provided season long control while maintaining peppermint oil yield. Rattail fescue, another problem weed in mint was well controlled by sequential applications of paraquat in tank mixes with the residual herbicides pyroxasulfone and terbacil. Larva of Tyta luctuosa, a field bindweed biocontrol agent, were released in a vineyard and adult moths recovered in pheromone traps later in the season. This indicates the biocontrol agent successfully completed its life cycle. Managing weeds in alfalfa seed production is important in order to obtain high yields and quality seed. In a trial on an established commercial alfalfa seed field, catchweed bedstraw was controlled well with tank mixes of carfentrazone with residual herbicides flumioxazin, sulfentrazone, or pyroxasulfone + flumioxazin. Imazamox suppressed catchweed bedstraw but allowed some plants to escape and produce seed. Glyphosate use is restricted to prebloom applications in glyphosate resistant alfalfa seed production fields. Glyphosate applied at 1 to 3% bloom slightly reduced seed yields of alfalfa and seed yields declined greatly as glyphosate applications were delayed until full bloom or early seed pod development. Uncontrolled weeds lower mint oil yield and quality and cost growersapproximately $2.5 million annually in the U.S. This research identified several effective strategies to control tall hedge mustard and rattail fescue in mint production. A biocontrol agent of field bindweed may reduce the impact of this weed on mint production, once widely established. Improved weed management practices could lead to lower inputs and reduce mint oil yield and quality losses due to escaped weeds. Weeds present in alfalfa seed production reduce seed yield and quality, and the life of the alfalfa stand. This research identified preemergence and postemergence applied herbicides for selective control of catchweed bedstraw and identified critical stages of alfalfa growth in which glyphosate can be safely applied in alfalfa seed production. These findings can be utilized by alfalfa seed producers to improve weed management and provide growers with options for managing difficult to control weeds.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Johnson, D., R. Baker, and R. A. Boydston. 2013. Field evaluation of mint mutant and hybrid lines for resistance to Verticillium wilt and yield. Crop Protection 43:1-6.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Boydston, R. and R. Baker. Weed Research in Mint in Mint Industry Research Council 2012 Research Reports, Las Vegas, NV. 24 pp. Jan. 2013.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Managing weeds in alfalfa seed production is important in order to obtain high yields and quality seed. In a trial on an established commercial alfalfa seed field, catchweed bedstraw was controlled most completely by preemergence treatments (PRE) of flumioxazin, sulfentrazone, pyroxasulfone + flumioxazin, and ethofumesate applied Feb. 23, 2012 soon after burning of field crop residues. Three standard PRE herbicides labeled in alfalfa seed failed to control catchweed bedstraw. Flumioxazin and sulfentrazone did not injure alfalfa seed crop whereas ethofumesate injured alfalfa 22% in April. Flumioxazin also controlled prickly lettuce and mayweed chamomile well. Applying herbicides in early December resulted in failure to control all weeds. In a second field trial on fall-planted alfalfa seed, prickly lettuce control was greater than 90% with flumioxazin, diuron, and flumioxazin + pyroxasulfone, whereas six other herbicide treatments failed to adequately control the weed. Alfalfa seed yield was not reduced by any of the herbicide treatments. Weeds resistant to terbacil, the most widely used herbicide in mint production, are becoming more prevalent in Washington State. Metribuzin resistant redroot pigweed and common lambsquarters biotypes from Washington were cross resistant to terbacil. Bromoxynil and bentazon at normal use rates controlled all common lambsquarters resistant to terbacil. Bromoxynil controlled all pigweed biotypes resistant to terbacil. Bentazon controlled 11 of 14 terbacil resistant pigweed biotypes similar to the susceptible control biotype, but only partially controlled three other resistant pigweed biotypes. Rattail fescue is becoming increasingly prevalent in the Yakima Valley of Washington and is difficult to control in mint production. Sequential applications of pyroxasulfone and terbacil provided the best control of rattail fescue in native spearmint. Preemergence applied sulfentrazone, flumioxazin, oxyfluorfen controlled catchweed bedstraw well in native spearmint. PARTICIPANTS: Ray Baker, Tech III, Washington State University provided technical assistance for peppermint studies. Chon Rivera, Tech II, Washington State University provided technical assistance for alfalfa research. TARGET AUDIENCES: Mint and alfalfa seed producers in the United States. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Weeds present in alfalfa seed production reduce seed yield and quality, and the life of the alfalfa stand. This research identified preemergence and postemergence applied herbicides for selective control of catchweed bedstraw and prickly lettuce in alfalfa seed production. These findings can be utilized by alfalfa seed producers to improve weed management and provide growers with options for managing difficult to control weeds. Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research identified cross resistance in weed biotypes resistant to terbacil and metribuzin, the most commonly used herbicides in mint and potato production, respectively. Growers can utilize this information to control and delay development of terbacil resistant weeds by rotating or tank mixing herbicides with other mode of actions in mint. Improved weed management practices could lead to lower inputs and reduce mint oil yield and quality losses due to escape weeds.
Publications
- Boydston, R. and R. Baker. Weed Research in Mint in Mint Industry Research Council 2011 Research Reports, Las Vegas, NV. 24 pp. Jan. 2012.
- Boydston, R. Weed Management in Alfalfa Seed Production. Proc. 2012 Winter Alfalfa Seed School Conference. Las Vegas, NV. 23 pp. Jan. 2012.
- Johnson, D., R. Baker, and R. A. Boydston. 2013. Field evaluation of mint mutant and hybrid linesfor resistance to Verticillium wilt and yield. Crop Protection 43:1-6.
- Lange, B. M., S. S. Mahmoud, M. R. Wildung, G. W. Turner, E. M. Davis, I. Lange, R. C. Baker, R. A. Boydston, and R. B. Croteau. 2012. Improving peppermint essential oil yield and composition by metabolic engineering. Proc. Natl. Acad. Sci. 108:16944-16949.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Managing weeds in alfalfa seed production is important to obtain high yields and quality seed. In field trials, annual sowthistle was controlled most completely by preemergence (PRE) treatments of flumioxazin, hexazinone plus diuron, and flumioxazin plus pyroxasulfone. Sulfentrazone controlled sowthistle fairly well in May, but control decreased by late July. Chloransulam, pyraflufen-ethyl, asulam, and asulam plus imazamox applied postemergence controlled annual sowthistle from 86 to 99%. Imazamox applied alone tended to be less effective on sowthistle, averaging 73% control. In a second field trial, prickly lettuce control was greater than 90% with all flumioxazin, hexazinone plus diuron, saflufenacil, indaziflam, and flumioxazin plus pyroxasulfone. Sulfentrazone and pyroxasulfone applied alone did not control prickly lettuce season long. Alfalfa seed yield was not reduced by any of the herbicide treatments. Weeds resistant to terbacil, the most widely used herbicide in mint production, are becoming more prevalent in Washington State. Nine of 22 pigweed biotypes collected from Washington mint fields were resistant to terbacil. All terbacil resistant biotypes were also resistant to metribuzin. Dose response analysis in based on I90 values (dose required to provide 90% control) indicated that 3.4 to 17.3 times as much herbicide would be required to provide 90% control the resistant biotypes compared to the susceptible control. Eight of 25 common lambsquarters biotypes collected from potato fields in Washington State were resistant to metribuzin and were cross resistant to terbacil. PARTICIPANTS: R.W. Boydston, PI, USDA,ARS, Prosser, WA; Ray Baker, Tech III, Washington State University, provided technical assistance for peppermint studies. Chon Rivera, Tech II, Washington State University, provided technical assistance for alfalfa research. Dr. Doug Walsh, entomologist, Washington State University, collaborated on alfalfa research. TARGET AUDIENCES: Mint and alfalfa producers in the United States. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Weeds present in newly seeded alfalfa reduce hay yield and quality, and the life of the alfalfa stand. This research identified preemergence and postemergence applied herbicides for selective control of annual sowthistle and prickly lettuce in alfalfa seed production. These findings can be utilized by alfalfa seed producers to improve weed management and provide growers with options for managing difficult to control weeds. Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research identified weed biotypes resistant to terbacil, the most commonly used herbicide in mint production. Growers can utilize this information to control and delay development of terbacil resistant weeds by rotating or tank mixing herbicides with other mode of actions in mint. Improved weed management practices could lead to lower inputs and reduce mint oil yield and quality losses due to escape weeds.
Publications
- No publications reported this period
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Mayweed chamomile is a common weed escape in alfalfa seed production. In field trials, mayweed chamomile was controlled 95% or more by preemergence application of flumioxazin, sulfentrazone, saflufenacil, indaziflam, and metribuzin. Pyroxasulfone applied preemergence only partially controlled mayweed chamomile. Chloransulam and asulam applied postemergence to mayweed chamomile controlled the weed greater than 95%. Alfalfa seed yield was not impacted by any of the herbicide treatments. Preemergence herbicides applied in February and March are often dissipated by June and allow broadleaf weeds to infest double-cut mint in the second cutting. In the third year of field trials, sulfentrazone applied immediately following peppermint and spearmint harvest and prior to mint regrowth, controlled redroot pigweed without significant crop injury or mint oil yield loss. PARTICIPANTS: Ray Baker, Tech III, Washington State University provided technical assistance for peppermint studies. Chon Rivera, Tech II, Washington State University provided technical assistance for alfalfa research. Dr. Doug Walsh, entomologist, Washington State University collaborated on alfalfa research. Washington Mint Commission provided grant funds. Mint Industry Research Council provided grant funds. TARGET AUDIENCES: Mint and alfalfa producers in the United States. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Weeds present in newly seeded alfalfa reduce hay yield and quality, and the life of the alfalfa stand. This research identified preemergence and postemergence applied herbicides for selective control of mayweed chamomile in alfalfa seed production. These findings can be utilized by alfalfa seed producers to improve weed management and provide growers with options for managing difficult to control weeds. Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research identified new weed control methods in mint that could reduce mint oil yield and quality losses due to escape weeds.
Publications
- Boydston, R. and R. Baker. 2010. Weed Research in Mint in Mint Industry Research Council 2009 Research Reports, Las Vegas, NV. 65 pp. Jan.
- Boydston, R. 2010. Weed Management in Alfalfa Seed Production. Proceedings 2009 Winter Alfalfa Seed School Conference. Las Vegas, NV. 23 pp. Jan.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Pre-emergence herbicides applied in February and March are often dissipated by June and allow broadleaf weeds to infest double-cut mint in the second cutting. In the second year of field trials, sulfentrazone applied immediately following peppermint and spearmint harvest, and prior to mint regrowth, controlled redroot pigweed without significant crop injury or mint oil yield loss. Clopyralid and MCPB are labeled for perennial broadleaf weed control in mint, but can result in crop injury. Clopyralid applied at two rates and timings to peppermint reduced nodes per stem and stem length, but not oil yield, whereas MCPB did not significantly injure mint or reduce oil yield. Catchweed bedstraw is a common weed escape in alfalfa seed production. Pre-emergence control of catchweed bedstraw was excellent with diuron, flumioxazin, terbacil, hexazinone, metribuzin, and norflurazon, which are labeled for use in alfalfa seed production. Pendimethalin failed to control catchweed bedstraw. Field burning of alfalfa seed crop residues destroyed >99% of prickly lettuce and mayweed chamomile seed, and 95% of Western salsify seed placed on the soil surface. Field burning and spring tillage resulted in the lowest number of Western salsify seedlings in an alfalfa seed crop compared to mowing and no burning, which resulted in high numbers of salsify. PARTICIPANTS: R.A. Boydston, Weed Scientist, USDA, ARS, Prosser WA; Ray Baker, Tech III, Washington State University, provided technical assistance for peppermint studies. Chon Rivera, Tech II, Washington State University, provided technical assistance for alfalfa research. Dr. Doug Walsh, entomologist, Washington State University, collaborated on alfalfa research. TARGET AUDIENCES: Mint and alfalfa growers in irrigated areas of WA State. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research identified new weed control methods in mint that could reduce mint oil yield and quality losses due to escaped weeds. Weeds present in newly seeded alfalfa reduce hay yield and quality, and the life of the alfalfa stand. This research identified herbicides for selective control of catchweed bedstraw in alfalfa seed production. The research also documented weed control benefits of field burning and spring tillage for managing alfalfa crop residues. These findings can be utilized by alfalfa seed producers to improve weed management and provide growers with options for managing alfalfa crop residues other than through field burning.
Publications
- Boydston, R. and R. Baker. Weed Research in Mint in Mint Industry Research Council 2008 Research Reports, Maui, HI. 23 pp. Jan. 2009.
- Boydston, R. Alfalfa forage and seed crop tolerance to flumioxazin. WSSA Abstracts, 2009 Meeting of WSSA. Abstract #509. 2009. http://www.wssa.net/Meetings/WSSAAbstracts/abstractsearch.php
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Fall applications of 2,4DB, fluroxypyr, and bromoxynil controlled several winter annual weeds well without injuring peppermint. A dormant application of paraquat following fall-applied herbicides improved winter annual weed control. Broadleaf weeds are difficult to control in the second cutting of peppermint, when preemergence herbicides applied in early spring have dissipated. Sulfentrazone, flumioxazin, and carfentrazone applied immediately following peppermint and spearmint harvest and prior to mint regrowth controlled redroot pigweed without significant crop injury. Peppermint hay and oil yield was not reduced by the herbicide treatments tested. Weed control is an important component of producing high quality and high yielding alfalfa seed. February dormant applications of flumioxazin plus paraquat to alfalfa planted the previous fall inhibited early growth and forage yields of the first cutting of alfalfa in 1 of 2 years. Alfalfa forage yield of the second cutting was not reduced by flumioxazin. Established alfalfa treated with flumioxazin in February produced seed yields similar to treating with other currently registered preemergence herbicides or paraquat alone. Forage yield of established alfalfa treated with flumioxazin in February was similar to that treated with currently registered herbicides. PARTICIPANTS: R.A. Boydston, Weed Scientist, USDA,ARS, Ray Baker, Agr. Tech. III, Washington State University provided technical assistance for peppermint studies. Chon Rivera, Agr. Tech II, Washington State University provided technical assistance for alfalfa research. Dr. Doug Walsh, Agrichemical & Environmental Education Specialist & Associate Entomologist, Washington State University and Dr. Troy Peters, Extension Irrigation Specialist, Washington State University collaborated on mint and alfalfa research. TARGET AUDIENCES: Mint and alfalfa producers in the United States. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research contributes to improved weed control in mint and reduces the chance of crop injury from herbicides. Weeds present in newly seeded alfalfa reduce hay yield and quality, and the life of the alfalfa stand. This research determined the tolerance of newly seeded alfalfa and established alfalfa to flumioxazin, a new herbicide for broadleaf weed control in alfalfa, which could improve control of prickly lettuce, common grounsel, and nightshade in alfalfa and improve yield and quality of the harvested hay. The data was used to support registration of flumioxazin alfalfa.
Publications
- Boydston, R. and R. Baker. 2008. Weed Research in Mint Industry Research Council 2007 Research Reports, Las Vegas, NV. 23 pp.
- Boydston, R. 2008. Weed Research in Alfalfa Seed Production. Proceedings 2008 Winter Alfalfa Seed School Conference. Reno, NV. pp.47-60.
- Boydston, R. 2008. Weed management research in alfalfa seed production in Washington State. Proc. 2008 Calif. Alfalfa and Forage Symposium and Western Seed Conference, San Diego, CA, 2-4 Dec. On CD. UC Cooperative Extension, Plant Sciences Department, University of California, Davis, CA 95616. http://alfalfa.ucdavis.edu.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Broadleaf weeds are difficult to control in the second cutting of peppermint, when preemergence herbicides applied in early spring have dissipated. Sulfentrazone and flumioxazin applied at reduced rates immediately following peppermint harvest and prior to peppermint regrowth controlled redroot pigweed without significant crop injury. Carfentrazone also controlled redroot pigweed if applied one week after emergence of the weed. Peppermint hay and oil yield was not reduced by the herbicide treatments tested. Alfalfa seeded in mid August or early September was more tolerant to dormant applications of flumioxazin plus paraquat than alfalfa seeded in late September. Although alfalfa seeded in late September was less tolerant of flumioxazin plus paraquat applications, the alfalfa recovered well after the first cutting of hay. Flumioxazin slightly lowered hay yields from the first cutting of hay following applications in February or June among all three alfalfa planting dates.
PARTICIPANTS: Ray Baker, Tech III, Washington State University provided technical assistance for peppermint studies. Dallas Spellman, Associate in Research, Washington State University provided technical assistance for alfalfa research. Dr. Doug Walsh, entomologist, Washington State University and Dr. Troy Peters, agricultural engineer, Washington State University collaborated on mint research.
TARGET AUDIENCES: Mint and alfalfa producers in the United States.
Impacts
Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research will contribute to improved weed control in double cut mint and reduce the chance of crop injury from herbicides. Weeds present in newly seeded alfalfa reduce hay yield and quality, and the life of the alfalfa stand. This research determined the tolerance of newly seeded alfalfa to flumioxazin, a promising herbicide for broadleaf weed control in alfalfa, which could improve control of prickly lettuce and nightshade in alfalfa and improve yield and quality of the harvested hay. The data can be used to support registration of flumioxazin in newly seeded alfalfa.
Publications
- Boydston, R.A. and R. Baker. 2007. Weed Research in Mint. Proc. Wash. State Mint Growers Winter Conf., Pasco, WA, pp 51-54. http://www.ars.usda.gov/research/projects/projects.htm?ACCN_NO=407883 &showpars=true
- Boydston, R. A. and D. Walsh. 2007. Prickly lettuce control in alfalfa seed production. West. Soc. of Weed Sci. Res. Prog. Report. pp. 70-71. http://www.ars.usda.gov/research/publications/Publications.htm?seq_no _115=208113
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Progress 01/01/06 to 12/31/06
Outputs
Carfentrazone applied preemergence on a sandy loam soil at rates of 0.016 lb ai/a or greater to carrots, and at rates of 0.032 lb ai/a to sugar beets and onions, injured and reduced crop stand and yield, whereas peas and snap beans were not injured. Carfentrazone was previously reported to have little or no soil residual activity. Peppermint and native spearmint were injured by postemergence applications of carfentrazone and pyraflufen-ethyl, but mint recovered and oil yield was not reduced. Imazamox at 0.03 lb ai/a plus bentazon at 1 lb ai/a, bentazon at 1 lb ai/a, and cloransulam at 0.0156 lb ai/a controlled hairy nightshade in lima beans with minimal crop injury. Fomesafen from 0.125 to 0.25 lb ai/a controlled broadleaf weeds well, but injured lima beans and greatly reduced yield.
Impacts
Over 70,000 acres of pea, snap bean, onion, sugar beets, and carrots are grown in Washington State. Characterization of carfentrazone residual herbicidal activity will allow producers to safely use carfentrazone while preventing damage to numerous vegetable crops grown on mineral soils in the western United States. Uncontrolled weeds lower mint oil yield and quality and cost growers some $2.5 million annually in the U.S. This research will contribute to improved weed control in mint and reduce the chance of crop injury from herbicides. Crop losses due to uncontrolled weeds in lima beans range from $75 to $150/acre and this research identified three promising treatments for postemergence broadleaf weed control in lima beans which could eliminate crop losses due to weeds.
Publications
- Boydston, R. A. and R. Parker. 2006. Crop response to carfentrazone applied preemergence. Western Soc. of Weed Science Res. Prog. Report. pp. 41-42.
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Progress 01/01/05 to 12/31/05
Outputs
Tolerance of peppermint, scotch spearmint, and native spearmint to five auxin inhibitor herbicides was determined in green house and field trials. Oil yield of peppermint was reduced more by dicamba than native or scotch spearmint. Scotch spearmint was the least tolerant to fluroxypyr. Native spearmint was the least tolerant to clopyralid. All three mint types exhibited poor tolerance to triclopyr and diflufenzopyr plus dicamba. MCPB was the least injurious to all mint types of the auxin inhibitor herbicides tested. Carfentrazone applied preemergence to a sandy soil injured sugar beets, broccoli, cabbage, onions, and lettuce and severely reduced stand counts of all crops. Carfentrazone was previously reported to have little or no soil residual activity on crops or weeds.
Impacts
Uncontrolled weeds lower mint oil yield and quality in approximately 30,000 acres of mint grown in Washington State. This research will contribute to the registration of fluroxypyr and MCPB in mint, which are currently IR-4 registration projects. These herbicides will improve control of kochia, prickly lettuce, western salsify, and field bindweed in mint production. Knowledge of carfentrazone soil activity will prevent damage to numerous vegetable crops grown on mineral soils in the western United States.
Publications
- Boydston, R.A. and R. Baker. 2005. Weed Research in Mint. Proc. Washington State Mint Growers Winter Conference, Pasco, WA, pp 14-37. Dec.
- Boydston, R. A. and R. Baker. 2005. Weed Control Research in Mint Industry Research Council 2005 Research Reports, Las Vegas, NV. 21 pp. Jan.
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Progress 01/01/04 to 12/31/04
Outputs
Flumioxazin applied to native spearmint as a liquid spray solution immediately after first cutting injured spearmint 91% at eight days after treatment and 31% at four weeks after treatment. Flumioxazin applied on fertilizer granules at the same rate and timing did not injure native spearmint or peppermint, but pigweed control was marginal. Low rates of sulfentrazone at 0.016 to 0.0312 lb ai/a and mesotrione at 0.032 lb ai/a applied postemergence to peppermint and native spearmint selectively controlled redroot pigweed. Dicamba, paraquat, and triclopyr applied postemergence in green house trials controlled white cockle. In field trials, dicamba applied to peppermint and native spearmint as dormant or early postemergence applications injured mint, but yield was not reduced at 0.25 lb ae/a rate. Scotch spearmint was less tolerant to fluroxypyr than peppermint and native spearmint were in previous trials. Tolerance of Scotch spearmint to fluroxypyr was greater with
dormant or early postemergence applications.
Impacts
Uncontrolled weeds lower mint oil yield and quality in approximately 30,000 acres of mint grown in Washington State. Registration of two new herbicides, fluroxypyr and MCPB that are selective in peppermint and spearmint will improve control of kochia, prickly lettuce, and field bindweed.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Sulfentrazone at 0.19 lb ai/a (active ingredient/a) or flumioxazin at 0.125 lb ai/a applied to dormant peppermint in February did not cause injury to peppermint and increased peppermint oil yield compared to weedy checks. Tank mixing both herbicides with paraquat at 0.5 lb ai/a increased control of winter annual weeds present at the time of herbicide application. Mesotrione or MCPA applied to emerged peppermint caused unacceptable crop injury. Dormant applications of fluroxypyr at 0.125 or 0.25 lb ae/a (acid equivalent/A) in peppermint controlled common groundsel and prickly lettuce well without injury to peppermint. MCPB applied at 0.5 to 1 lb ae/a in May suppressed field bindweed in Scotch spearmint and increased oil yield compared to nontreated plots infested with field bindweed. Western salsify seed buried in nylon bags 2 cm deep in soil in peppermint was short-lived with only 5 % and 1 % of seed intact after 6 and 12 months, respectively. All herbicides that are
registered for use in spearmint or peppermint applied at normal use rates had no effect on predatory mite populations in native spearmint. Pea tolerance to flumioxazin and sulfentrazone applied preemergence was evaluated in the second year of field trials on a sand soil with 0.4% organic matter near Paterson, WA. Pea emergence injury was minimal with most herbicide treatments and was greatest with flumioxazin at 0.06 lb ai/a, flumioxazin tank mixed with metolachlor or pendimethalin, and sulfentrazone tank mixed with metolachlor. Both herbicides caused stunted pea growth and leaf necrosis at higher rates. Pea yield ranged from a low of 0.2 T/a for flumioxazin plus metolachlor applied at 0.047 + 1 lb ai/a, respectively to a high of 2.9 T/a in nontreated checks. No treatments of flumioxazin or sulfentrazone applied alone reduced pea yield while most treatments containing tank mixes of either herbicide with metolachlor reduced pea yield. Control of redroot pigweed, common lambsquarters,
and hairy nightshade was excellent with all herbicide treatments. Based on injury ratings, stand counts, and pea yield, flumioxazin applied preemergence appeared safe on peas when applied alone at 0.03 to 0.047 lb ai/a. Sulfentrazone applied preemergence at 0.094 or 0.125 lb ai/a was also safe on peas and maintained yields equal to hand-weeded checks.
Impacts
Uncontrolled weeds lower mint oil yield and quality in approximately 30,000 acres of mint grown in Washington State. Registration of two new herbicides, clomazone and sulfentrazone, that are selective in peppermint and spearmint will improve control of herbicide tolerant and resistant weeds. Nightshade berries can contaminate processing peas reducing quality and increasing processing costs. Nightshade berries are similar in color, density, and size to peas, making them difficult to separate from peas during processing and contain toxic alkaloids. Nightshade control in peas is erratic with currently labeled herbicides. Registration of sulfentrazone or flumioxazin in peas could improve nightshade control, improve the quality and quantity of peas harvested, and reduce processing costs.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
Pea tolerance to flumioxazin and sulfentrazone was evaluated in field trials on a sand soil with 0.5% organic matter. Pea emergence was delayed and stand counts were reduced with most herbicide treatments. Tank mixes of flumioxazin or sulfentrazone with metolachlor delayed pea emergence and injured peas more than tank mixes with pendimethalin. Both herbicides caused stunted growth and leaf necrosis. Pea injury increased as herbicide rate increased for both flumioxazin and sulfentrazone. Pea yield ranged from a low of 1.1 T/a for sulfentrazone applied at 0.38 lb ai/a to a high of 3.7 T/a for sulfentrazone applied at 0.125 lb ai/a. Hand-weeded checks average 3.4 T/a. No treatments containing flumioxazin reduced pea yield while all treatments containing sulfentrazone above 0.125 lb ai/a reduced pea yield. Control of redroot pigweed, common lambsquarters, and hairy nightshade was excellent with all herbicide treatments. Based on injury ratings, stand counts, and pea
yield, flumioxazin applied preemergence appeared safe on peas when applied alone at 0.03 to 0.047 lb ai/a or when applied at 0.03 with pendimethalin. Sulfentrazone applied PRE at 0.094 or 0.125 lb ai/a was also safe on peas and maintained yields equal to hand-weeded checks. Sulfentrazone or flumioxazin split applied in the fall and spring to dormant mint were safe on native spearmint and peppermint and controlled most winter and summer annual weeds well. Mesotrione and sulfosulfuron applied to dormant or emerged native spearmint caused considerable crop injury. Dormant applications of sulfentrazone and clomazone controlled kochia and redroot pigweed in peppermint equal to or better than pendimethalin. MCPB applied twice at 0.5 lb ae/a in May and July suppressed field bindweed in Scotch spearmint and increased oil yield from the second harvest. Western salsify seed buried in nylon bags 2 cm deep in soil in peppermint was short-lived with only 5 % and 1 % of seed intact after 6 and 12
months, respectively. Western salsify emergence from an October planting peaked in November with a second smaller peak in May. Western salsify was controlled in greenhouse trials with clopyralid, flumioxazin, sulfentrazone, and oxyfluorfen applied at various growth stages.
Impacts
Nightshade berries can contaminate processing peas reducing quality and increasing processing costs. Nightshade berries are similar in color, density, and size to peas, making them difficult to separate from peas during processing and contain toxic alkaloids. Nightshade control in peas is erratic with currently labeled herbicides. Registration of sulfentrazone or flumioxazin in peas could improve nightshade control, improve the quality and quantity of peas harvested, and reduce processing costs. Uncontrolled weeds such as kochia and salsify lower mint oil yield and quality in the 30,000 acres of mint grown in Washington State. Registration of two new herbicides, clomazone, flumioxazin and sulfentrazone, that are selective in peppermint and spearmint will improve control of herbicide tolerant and resistant weeds.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Western salsify (Tragopogon dubius) was controlled in greenhouse trials with preemergence flumioxazin, sulfentrazone, terbacil and oxyfluorfen. Sulfentrazone and flumioxazin applied preemergence in fall or spring were safe on native spearmint and peppermint, whereas halosulfuron and pyrithiobac caused considerable injury. Sulfentrazone suppressed yellow nutsedge (Cyperus esculentus) in peppermint. Fluroxypyr, pyrithiobac, and 2,4-DB applied postemergence suppressed field bindweed (Convolvulus arvensis) growth, but did not reduce the number of field bindweed in native spearmint. Fluroxypyr injured native spearmint as rate increased from 0.06 to 0.25 lb ai/a. Sulfentrazone, two formulations of pendimethalin, and terbacil controlled annual weeds well with minimal injury to newly planted peppermint. Flumioxazin applied preemergence at 0.047 and 0.094 lb ai/a slightly injured newly planted peppermint but controlled annual weeds well. Oxyfluorfen applied to carrot seed crop
controlled common groundsel (Senecio vulgaris) well. Spring application of oxyfluorfen to larger carrots was less injurious than fall applications to carrots in the three-leaf stage. Oxyfluorfen did not affect the germination of the carrot seed harvested.
Impacts
Uncontrolled weeds such as salsify lower mint oil yield and quality in the 30,000 acres of mint grown in Washington State. Registration of two new herbicides, flumioxazin and sulfentrazone, that are selective in peppermint and spearmint will improve control of herbicide tolerant and resistant weeds. A special local needs label for oxyfluorfen for use in carrot seed in Washington State is being prepared and could improve control of common groundsel and other weeds that are not currently controlled well in 2000 acres of carrot seed production.
Publications
- Boydston, R., R. Baker, and L. Birch. 2001. Weed Research in Mint in Washington State. Proc. First Annual Tri-State Mint Convention, Spokane, WA. Jan. 2001.
- Boydston, R. Baker, and L. Birch. 2001. Weed Research in Mint in Washington State. Proc. Mint Industry Research Council, Las Vegas, NV. Jan. 2001.
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Progress 01/01/00 to 12/31/00
Outputs
Oxyfluorfen applied to 20-25 cm tall seed carrots in early April caused visual injury on carrots that worsened as herbicide rate increased from 0.3-0.6 kg ai/ha. Injury was greatest approximately 1 month after application but no injury was evident on carrots by mid June and plants produced seed. Oxyfluorfen applied in October to 1.5 inch tall seed carrots injured carrots from 22-47% but did not decrease carrot stand. Oxyfluorfen controlled ladysthumb and suppressed common groundsel better than linuron. Oxyfluorfen failed to control cudweed and horseweed. Oxyfluorfen applied in October to 5-13 cm tall seed parsley injured parsley from 37-73%. Oxyfluorfen applied following linuron suppressed common groundsel better than oxyfluorfen alone. Studies are in progress to further evaluate oxyfluorfen for weed control in carrot and parsley grown for seed. Sulfentrazone applied to dormant spearmint at 0.3 and 0.4 kg ai/ha in combinations with clomazone at 0.14 kg ai/ha reduced
growth of native spearmint in late March compared to sulfentrazone at 0.14 kg ai/ha with clomazone. Spearmint injury was transient and spearmint oil and hay yield from herbicide- treated plots were not different than the nontreated, weed free check. Fluroxypyr applied from 0.07-0.4 kg ai/a to 5, 10 & 15 cm tall spearmint injured spearmint, but injury was transient and less severe at the 0.07 and 0.14 kg ai/ha rates. Spearmint bloom in late June was delayed by fluroxypyr applied at 0.3 and 0.4 kg ai/ha. Spearmint hay and oil yield decreased with increasing fluroxypyr rate. Fluroxypyr may be utilized for control of kochia, catchweed bedstraw, and field bindweed if adequate mint tolerance can be demonstrated. Flumioxazin applied preemergence to spearmint at 0.14 and 0.3 kg ai/ha slightly reduced early spring growth of spearmint, but by late April growth was normal and spearmint hay and oil yields from flumioxazin treated plots were similar to weed free checks. Azafenidin and fluthiamide
applied preemergence to spearmint caused unacceptable crop injury. A 0.46 kg ai/gal formulation of pendimethalin injured spearmint less than the standard 0.4 kg ai/gal formulation of pendimethalin (Prowl). Applying pendimethalin to emerged spearmint increased injury to spearmint compared to a preemergence application. Azafenidin applied preemergence to newly planted peppermint at 0.14 and 0.3 kg ai/ha delayed peppermint emergence and reduced mint growth the entire season. Sulfentrazone applied preemergence at 0.2 kg ai/ha to newly planted peppermint slightly stunted peppermint growth early in the season, but growth appeared normal the remainder of the season. Sulfentrazone suppressed yellow nutsedge from 80 to 94% and controlled common lambsquarters, common groundsel, redroot pigweed, and barnyard grass well. Pyrithiobac applied early postemergence at 0.03, 0.07, and 0.1 kg ai/ha to native spearmint caused minor chlorosis, but injury was transient. Pyrithiobac applied postemergence at
0.06 kg ai/ha to peppermint stunted field bindweed growth and bloom and stunted peppermint growth slightly.
Impacts
Oxyfluorfen could improve control of common groundsel (Senecio vulgaris) and other weeds that are not currently controlled well by herbicides labeled for use in carrot seed production. Carrot seed is produced on about 800 ha in Washington State and uncontrolled weeds decrease carrot seed yield and contaminate the seed crop, lowering the value of the seed. Uncontrolled weeds in mint lower oil yield and quality. New herbicides that are selective in peppermint and spearmint can be utilized to improve control of herbicide tolerant and resistant weeds. New herbicides with shorter soil residuals can reduce potential for herbicide carryover in crop rotations and increase flexibility in crop rotations.
Publications
- No publications reported this period
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