Progress 10/01/05 to 09/30/11
Outputs
OUTPUTS: Activities under this project included conducting over 400 field trials plus several greenhouse trials, analyzing and summarizing the data, and presenting the data in various formats. The field research conducted under this project was utilized for at least 30 field days conducted to disseminate new information on weed management to agronomic crop producers, extension agents, consultants,N.C. Department of Transportation personnel, and agrichemical industry personnel. Five in-field training programs utilizing the field research were held specifically for extension personnel, three for Dept. of Transportation personnel, and numerous other training programs for industry personnel and consultants. The research was an integral part of the degree programs for five graduate students who completed their programs during this period and two additional students who are still in the program. In addition to field days and training programs, information from this work was disseminated to growers via over 80 grower meetings and written recommendations. Information was also disseminated to the scientific community through publications and presentations at scientific meetings. PARTICIPANTS: Bacheler, J. (N. C. State Univ.) Beam, J. (formerly with N.C.State Univ.) Burke, I. (Washington State Univ.) Burton, J. (N. C. State Univ.) Burton, M. (formerly with N. C. State Univ.) Chahal, G. (N. C. State Univ.) Chandi, A. (former graduate student) Collins, G. (Univ. Georgia) Culpepper, A. (Univ. Georgia) Duffie, W. (formerly Univ. Georgia) Edmisten, K. (N. C. State Univ.) Everman, W. (N. C. State Univ.) Faircloth, J. (formerly Virginia Tech) Fisher, L. (N. C. State Univ.) Flanders, J. (Univ. Georgia) Gardner, A. (formerly graduate student) Grey, T. (Univ. Georgia) Hoyle, S. (N. C. State Univ.) Jordan, D. (N. C. State Univ.) Jost, P. (formerly Univ. Georgia) Kichler, J. (Univ. Georgia) Lanier, J. (formerly with N. C. State Univ.) MacRae, A. (Univ. Florida) Main, C. (Univ. Tennessee) Marshall, M. (Clemson Univ.) Milla-Lewis, S. (N. C. State Univ.) Nichols, R. (Cotton Incorp.) Parker, R. (former graduate student) Patterson, M. (Auburn Univ.) Pegram, T. (formerly with N. C. State Univ.) Prostko, E. (Univ. Georgia) Roberts, P. (Univ. Georgia) Sammons, D. (Monsanto) Seagroves. R. (N. C. State Univ.) Sosnoskie, L. (Univ. Georgia) Spears, J. (N. C. State Univ.) Steckel, L. (Univ. Tennessee) Stewart, A. (formerly with Louisiana State Univ.) Vencill, W. (Univ. Georgia) Wallace, R. (former graduate student) Webster, T. (USDA) Whitaker, J. (former graduate student) Wilcut, J. (N. C. State Univ.) Wilson, D. (former graduate student) TARGET AUDIENCES: Target audience for most of the work was North Carolina cotton, corn, soybean, and wheat growers and those who advise growers, such as extension agents, consultants, and dealers/distributors. Numerous training programs and educational meetings were held to disiminate information. Audience for wildflower research was N. C. Department of Transportation. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
At the initiation of this project, methyl bromide was widely used by the N.C. Dept. Transportation (NCDOT) to fumigate wildflower beds along roadsides. With the phase-out of methyl bromide, alternatives to control weeds were needed. Extensive research was conducted to determine what herbicides could be effectively used on more than 20 species of wildflowers. The results of multi-year testing were compiled for NCDOT vegetation managers, in-field training was held, and a set of recommendations printed along with identifying features of the various wildflower species. As a result of this work, herbicides are now used on the majority of the roadside wildflower plantings. Weed control costs are less than 5% of methyl bromide fumigation. Glyphosate-resistant Palmer amaranth was discovered in North Carolina about the time of initiation of this project. Although not in the original objectives, development of management programs for this weed fit in well with the original objectives. Knowledge gained from working with the resistant weed was presented in several peer-reviewed journal papers, many presentations at scientific conferences, and educational programs for grower clientele using printed recommendations in extension publications, meetings,etc. As a result of the research and outreach, along with the crisis caused by the resistant weed, over 90% of the state's cotton growers are following at least some of the recomended resistance management practices. Research showed the feasibilty of narrow-row cotton, along with good weed management systems and positive net returns. However, the expense of new harvesting equipment kept most growers from adopting the technology. To the contrary, research developing management systems in glufosinate-tolerant cotton was not only productive in terms of building a data base, publicatons, etc., but 35% of the cotton in the state is now planted to glufosinate-tolerant cultivars, largely as a result of this research showing alternative ways to manage resistant Palmer amaranth in cotton.
Publications
- No publications reported this period
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Activities under this project included conducting 72 field trials plus several greenhouse trials, analyzing and summarizing the data, and presenting the data in various formats. The field research conducted under this project was utilized for 8 field days conducted to disseminate new information on weed management to agronomic crop producers, extension agents, consultants, and agrichemical industry personnel. Two in-field training programs utilizing the field research were held specifically for extension personnel, and numerous other training programs for industry personnel and consultants. The research was an integral part of the degree programs for one graduate student who is nearing program completion. In addition to field days and training programs, information from this work was disseminated to growers via 27 grower meetings and various written recommendations. Information was also disseminated to the scientific community through publications and presentations at scientific meetings. PARTICIPANTS: Faculty and graduate students cooperating from N. C. State University: G.S. Chahal, A. Chandi, K.M. Edmisten, P.M. Eure, D.L. Jordan, Faculty and graduate students cooperating from University of Georgia: A.S. Culpepper, J.M. Kichler, E. Protsko, L.M. Snoskie, T.M. Webster. Faculty from other universities: M.W. Marshall (Clemson), L.E. Steckel (Univ. Tenn.). Partner organizations: Cotton Incorporated, North Carolina Cotton Producers Assoc., North Carolina Small Grain Growers Assoc.; Training opportunities: One graduate student directly involved with project has multiple opportunities to attend professional meetings and present papers; 8 field days were held for growers, extension personnel, and industry to showcase the work; over 30 grower educational meetings were held to update growers on new recommendations coming from the work. TARGET AUDIENCES: Cotton, soybean, small grain growers; county extension personnel; agrichemical industry personnel; graduate students. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Glyphosate-resistant Palmer amaranth was discovered in North Carolina about the time of initiation of this project. Although not in the original objectives, development of management programs for this weed fit in well with the original objectives. Knowledge gained from working with the resistant weed was presented in several peer-reviewed journal papers, many presentations at scientific conferences, and educational programs for grower clientele using printed recommendations in extension publications, meetings,etc. As a result of the research and outreach, along with the crisis caused by the resistant weed, over 90% of the state's cotton growers are following at least some of the recomended resistance management practices. Research developing management systems in glufosinate-tolerant cotton was not only productive in terms of building a data base, publicatons, etc., but 35% of the cotton in the state is now planted to glufosinate-tolerant cultivars, largely as a result of this research showing alternative ways to manage resistant Palmer amaranth in cotton.
Publications
- Culpepper, A. S., A. C. York, P. Roberts, and J. R. Whitaker. 2009. Weed control and crop response to glufosinate applied to PHY 485 WRF cotton. Weed Technol. 23:356-362.
- Everman, W. J., S. B. Clewis, A. C. York, and J. W. Wilcut. 2009. Weed control and yield with flumioxazin, fomesafen, and S-metochlor systems for glufosinate-resistant cotton residual weed management. Weed Technol. 23:391-397.
- Everman, W. J., C. R. Mayhew, J. D. Burton, A. C. York, and J. W. Wilcut. 2009. Absorption, translocation, and metabolism of 14C-glufosinate in glufosinate-resistant corn, goosegrass (Eleusine indica), large crabgrass (Digitaria sanguinalis), and sicklepod (Senna obtusifolia). Weed Sci. 57:1-5.
- Johnson, B., B. Young, J. Matthews, P. Marquardt, C. Slack, K. Bradley, A. York, S. Culpepper, A. Hager, K. Al-Khatib, L. Steckel, M. Moechnig, M. Loux, M. Bernards, and R. Smeda. 2010. Weed control in dicamba-resistant soybean. Online. Crop Management doi:10.1094/CM-2010-0920-01-RS.
- Sosnoskie, L. M., A. S. Culpepper, A. C. York, J. B. Beam, and A. W. MacRae. 2009. Sequential applications for mesosulfuron and nitrogen needed in wheat. Weed Technol. 23:404-407.
- Whitaker, J. R., A. C. York, D. L. Jordan, and A. S. Culpepper. 2010. Palmer amaranth (Amaranthus palmeri) control in soybean with glyphosate and conventional herbicide systems. Weed Technol. 24:403-410.
- Whitaker, J. R., A. C. York, D. L. Jordan, and A. S. Culpepper. 2011. Weed management with glyphosate- and glufosinate-based systems in PHY 485 WRF cotton. Weed Technol. (in press; accepted 10-4-2010).
- Culpepper, A. S., T. M. Webster, L. M. Sosnoskie, and A. C. York. 2010. Glyphosate-resistant Palmer amaranth n the United States. P. 195-212. In V. K. Nandula, ed. Glyphosate Resistance in Crops and Weeds. John Wiley & Sons.
- Chandi, A., D. J. Jordan, J. Burton, A. York, and S. Clewis. 2009. Phenotypic expression of selected Palmer amaranth biotypes resistant to glyphosate. Proc. South. Weed Sci. Soc. 62:213 and WSSA Abstracts 2009, No. 233. (Joint meeting of WSSA and SWSS).
- Chandi, A., D. Jordan, J. Burton, A. York, J. Spears, S. Milla-Lewis, S. Culpepper, B. Vencil, and J. Whitaker. 2010. Relative interference of eight populations of Palmer amaranth with selected crops. Weed Sci. Soc. Amer. Abstracts P A-95. Available online at https://srm.conference-services.net/reports/template/onetextabstract. smlxsl=template/onetestabstract.xsl&conferenceID=1756&abstractID=344 178.
- Chandi, A., D. Jordan, J. Burton, A. York, J. Whitaker, and S. Culpepper. 2010. Efficacy of selected herbicides on eight Palmer amaranth populations. Proc. South. Weed Sci. Soc. 63:82.
- Chandi, A., D. Jordan, J. Burton, A. York, J. Spears, S. Milla-Lewis, S. Culpepper, B. Vencil, and J. Whitaker. 2010. Relative interference of eight populations of Palmer amaranth with selected crops. Weed Sci. Soc. Amer. Abstracts P A-95. Available online at https://srm.conference-services.net/reports/template/onetextabstract. smlxsl=template/onetestabstract.xsl&conferenceID=1756&abstractID=344 178.
- Chandi, A., D. Jordan, J. Burton, A. York, J. Whitaker, and S. Culpepper. 2010. Efficacy of selected herbicides on eight Palmer amaranth populations. Proc. South. Weed Sci. Soc. 63:82.
- Chandi, A., D. L. Jordan, A. C. York, J. D. Burton, and B. R. Lassiter. 2010. Management of ALS-resistant common ragweed in corn, cotton, peanut, and soybean. Proc. South. Weed Sci. Soc. 63:242.
- Chandi, A., A. C. York, and D. L. Jordan. 2009. Documentation of ACCase and ALS resistant Italian ryegrass biotypes in North Carolina. Proc. South. Weed Sci. Soc. 62:209 and WSSA Abstracts 2009, No. 229. (Joint meeting of WSSA and SWSS).
- Culpepper, A. S., J. Kichler, L. Sosnoskie, A. York, D. Sammons, and B. Nichols. 2010. Integrating cover crop residue and moldboard plowing into glyphosate-resistant Palmer amaranth management programs. Proc. 2010 Beltwide Cotton Conf., page 1531. Available online at http://www.cotton.org/beltwide/proceedings/2005-2010/index.htm.
- Culpeper, A. S., A. C. York, and J. M. Kichler. 2009. Impact of tillage on managing glyphosate-resistant Palmer amaranth in cotton. Proc. 2009 Beltwide Cotton Conf. p. 1343.
- Culpepper, A. S., A. C. York, and M. W. Marshall. 2009. Glyphosate-resistant Palmer amaranth in the Southeast. (Symposium paper). Proc. South. Weed Sci. Soc. 62:371 and WSSA Abstracts 2009, No. 364. (Joint meeting of WSSA and SWSS).
- Culpepper, S., A. York, and L. Sosnoskie. 2010. Controlling glyphosate-resistant Palmer amaranth prior to planting cotton. Weed Sci. Soc. Amer. Abstracts P A-8. Available online at https://srm.conference-rervices. net/reports/template/onetextabstract. smlxsl=template/onetestabstract.xsl&conferenceID=17568&abstractID=34 3849.
- Eure, P. M., D. L. Jordan, L. R. Fisher, G. S. Chahal, J. S. Bacheler, R. Seagroves, J. Hinton, and A. C. York. 2010. Influence of premix timing on efficacy of herbicides. Proc. South. Weed Sci. Soc. 63:105.
- Kilcher, J. M., A. S. Culpepper, A. C. York, and L. M. Sosnoskie. 2009. Managing glyphosate-resistant Palmer amaranth in conservation tillage. Proc. 2009 Beltwide Cotton Conf. p. 1344-1345.
- Seagroves, R. W., J. D. Hinton, D. L. Jordan, and A. C. York. 2010. Weed control with glufosinate in corn, cotton, and soybean in North Carolina. Proc. South. Weed Sci. Soc. 63:82.
- Sosnoskie, L., J. Whitaker, J. M. Kichler, A. S. Culpepper, and A. C. York. 2010. Cotton and Palmer amaranth response to Milo-Pro applied at-plant and Post. Proc. 2010 Beltwide Cotton Conf., page 1537. Available online at http://www.cotton.org/beltwide/proceedings/2005-2010/index.htm
- Starke, A., S. Hoyle, R. Richardson, A. York, M. Burton, and D. Jordan. 2009. Emergence patterns of Palmer amaranth, apple of Peru, eastern blacknightshade, and cutleaf groundcherry in row crops. Proc. South. Weed Sci. Soc. 62:33 and WSSA Abstracts 2009, No. 38. (Joint meeting of WSSA and SWSS).
- Wallace, R., L. M. Sosnoskie, A. S. Culpepper, A. York, K. L. Edmisten, M. Patterson, M. A. Jones, G. Cloud, L. Crooks, J. Pierson, and M. Rinehardt. 2009. Weed management and crop tolerance in Glytol and Glytol + LibertyLink cotton in the southeast US. Proc. 2009 Beltwide Cotton Conf. p. 1355-1356.
- Whitaker, J. R. and A. C. York. 2009. Evaluation of preemergence herbicides for control of glyphosate-resistant Palmer amaranth in cotton. Proc. South. Weed Sci. Soc. 62:83 and WSSA Abstracts 2009, No. 91. (Joint meeting of WSSA and SWSS).
- Whitaker, J. R., A. C. York, and A. S. Culpepper. 2009. Weed control and cotton tolerance with glufosinate in Widestrike cotton. Proc. 2009 Beltwide Cotton Conf. p. 1328-1329.
- York, A. C. 2009. Pigweed update for the Southeast. Proc. 2009 Beltwide Cotton Conf. p. 1542.
- York, A. C. and A. S. Culpepper. 2009. Practicing herbicide resistance management. (Symposium paper). Proc. South. Weed Sci. Soc. 62:378 and WSSA Abstracts 2009, No. 370. (Joint meeting of WSSA and SWSS).
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Research focused heavily on management systems for glyphosate-resistant Palmer amaranth in cotton and soybean. In soybean, good control of resistant Palmer amaranth required a preplant or preemergence residual herbicide followed by another herbicide mixed with glyphosate applied POST. The most effective soil-applied herbicides included flumioxazin, flumioxazin plus chlorimuron, flumioxazin plus chlorimuron plus thifensulfuron, fomesafen, fomesafen plus s-metolachlor, alachlor, sulfentrazone plus metribuzin, sulfentrazone plus cloransulam, and metribuzin plus chlorimuron. Both fomesafen and thifensulfuron mixed with glyphosate postemergence were effective when following a residual preemergence herbicide. Effective control in cotton required a preplant or preemergence herbicide, followed by glyphosate plus either s-metolachlor or pyrithiobac tank mix postemergence, and a residual lay-by application such as diuron or flumioxazin mixed with glyphosate or MSMA. An encapsulate formulation of acetochlor applied postemergence with glyphosate was found to have crop tolerance and weed control similar to that with metolachlor. Several experiments focused on weed control and crop tolerance with glufosinate applied to Phytogen varieties with the Widestrike trait. Some injury, usually minor, was noted with glufosinate applied to these varieties. Mixing s-metolachlor with glufosinate usually increased injury whereas there was little increase in injury with pyrithiobac added to glufosinate. Ammonium sulfate added to glufosinate increased injury but had no impact on yield or quality. Various insecticides mixed with glufosinate also had no impact on yield or quality. Glufosinate-based systems were effective in cotton if applications were timely. Best control in these systems was obtained with a residual preemergence herbicide, a glufosinate plus metolachlor or pyrithiobac tank mix postemergence, and a residual lay-by herbicide. Glyphosate-resistant Italian ryegrass was detected in two counties in the southwestern part of the state. Under greenhouse conditions,eight times more glyphosate was required to kill these biotypes as opposed to susceptible biotypes. Multiple resistance to diclofop, penoxaden, and mesosulfuron was confirmed in Italian ryegrass. Flufenacet plus metribuzin was the only registered option that provided control. Combinations of flumioxazin plus chlorimuron plus thifensulforon plus crop oil or flumixazin plus cloransulam plus crop oil effectively conrolled glyphosate-resistant horseweed as a burndown application under no-till conditions. PARTICIPANTS: PARTICIPANTS: Individuals at North Carolina State University: Alan C. York, principal investigator; Jared R. Whitaker, graduate student; Wesley J. Everman, graduate student; David L. Jordan, collaborator; James Burton, collaborator; Individuals at University of Georgia: A. Stanley Culpepper, collaborator; Lynn M. Sosnoskie, collaborator. Partner organizations: North Carolina Cotton Growers Association; Cotton Incorporated; North Carolna Soybean Producers Association; North Carolina Small Grain Growers Association. TARGET AUDIENCES: Growers, industry personnel, extension agents, and graduate students. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Glyphosate-resistant Palmer amaranth and horseweed have become serious problems in North Carolina, and glyphosate-resistant ryegrass has the potential to become a serious problem. Ryegrass resistant to ACCase inhibitors has long been a problem, and now ALS resistance is becoming a serious problem. Research on management systems for these problems has been very helpful in formulating management recomendations. The research has been incorporated into educational programs for growers and other clientele. This research was instrumental in training graduate students. Additionally, results from these research were used in field days and in-class training for extension agents, growers, and industry personnel.
Publications
- Everman, W. J., S. B. Clewis, A. C. York, and J. W. Wilcut. 2009. Weed control and yield with flumoxazin, fomesafen, and S-metolachlor systems for glufosinate-resistant cotton residual weed control. Weed Technol. 23:391-397.
- Everman, W. J., C. R. Mayhew, J. B. Burton, A. C. York, and J. W. Wilcut. 2009. Absorption, translocation, and metabolism of 14C-glufosinate-resistant corn, goosegrass (Eleusine indica), large crabgrass (Digitaria sanguinalis), and sicklepod (Senna obtusifolia). Weed Sci. 57:1-5.
- Everman, W. J., W. E. Thomas, J. B . Burton, A. C. York, and J. W. Wilcut. 2009. Absorption, translocation, and metabolism of glufosinate in transgenic and nontransgenic cotton, Palmer amaranth (Amaranthus palmeri), and pitted morningglory (Ipomoea lacunosa). Weed Sci. 57:357-361.
- Sosnoskie, L. M., A. S. Culpepper, A. C. York, J. B. Beam, and A W. MacRae. 2009. Sequential applications for mesosulfuron and nitrogen needed in wheat. Weed Technol. 23:404-407.
- Culpepper, A. S., A. C. York, P. Roberts, and J. R. Whitaker. 2009. Weed control and crop response to glufosinate applied to 'PHY 485' cotton. Weed Technol. 23:356-362.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Research conducted in 2008 focused heavily on management systems for glyphosate-resistant Palmer amaranth in cotton and soybean. In soybean, good control of resistant Palmer amaranth required a preplant or preemergence residual herbicide followed by another herbicide mixed with glyphosate applied POST. The most effective soil-applied herbicides included flumioxazin, flumioxazin plus chlorimuron, flumioxazin plus chlorimuron plus thifensulfuron, fomesafen, fomesafen plus s-metolachlor, alachlor, sulfentrazone plus metribuzin, sulfentrazone plus cloransulam, and metribuzin plus chlorimuron. Both fomesafen and thifensulfuron mixed with glyphosate postemergence were effective when following a residual preemergence herbicide. Similar results were noted in no-till and conventional tillage. In cotton, one-, two-, and three-way combinations of fluometuron, MSMA, and pyrithiobac were not adequately effective. Effective control in cotton required a preplant or preemergence herbicide, followed by glyphosate plus either s-metolachlor or pyrithiobac tank mix postemergence, and a residual lay-by application such as diuron or flumioxazin mixed with glyphosate or MSMA. Several experiments focused on weed control and crop tolerance with glufosinate applied to Phytogen varieties with the Widestrike trait. Some injury, usually minor, was noted with glufosinate applied to these varieties. Mixing s-metolachlor with glufosinate usually increased injury whereas there was little increase in injury with pyrithiobac added to glufosinate. Ammonium sulfate added to glufosinate increased injury but had no impact on yield or quality. Various insecticides mixed with glufosinate also had no impact on yield or quality. Glufosinate-based systems were effective in cotton if applications were timely. Best control in these systems was obtained with a residual preemergence herbicide, a glufosinate plus metolachlor or pyrithiobac tank mix postemergence, and a residual lay-by herbicide. Glyphosate-resistant horseweed was best controlled with preplant burndown applications of glyphosate plus flumioxazin plus either 2,4-D or dicamba. Tank mixtures of glyphosate plus glufosinate were found to be antagonistic on Palmer amaranth, common lambsquarters, and annual grass species but not morningglory species. A number of experiments were completed to determine tolerance of 20 or more wildflower species to various herbicides applied preplant incorporated, preemergence, or postemergence. This work was conducted in an effort to find alternatives to fumigants for weed control in roadside wildflower plantings. Several species were found to have adequate tolerance to certain herbicides. PARTICIPANTS: Individuals: Alan C. York, principal investigator; Jared R. Whitaker, graduate student; David G. Wilson, Jr., graduate student; David L. Jordan, collaborator; James Burton, collaborator; Michael Burton, collaborator. Partner organizations: North Carolina COtton Growers Association; Cotton Incorporated; North Carolna Soybean Producers Association; North Carolina Department of Transportation. Training: This research was instrumental in training the above graduate students. Additionally, several field days and in-class training sessions were held to train extension agents, growers, industry personnel, and N. C. Department of Transportation personnel. TARGET AUDIENCES: The primary audience was row crop producers in North Carolina. Secondary audiences were extension agents and representatives of various agribusinesses operating in North Carolina. PROJECT MODIFICATIONS: No major changes.
Impacts
Glyphosate-resistant Palmer amaranth and horseweed have become serious problems in North Carolina. Research on management systems for these problems have been very helpful in formulating management recomendations. The research has been incorporated into educational programs. Research on wildflowers resulted in development of a decision aid to assist Department of Transportation employees in selecting apppropriate herbicides for wildflower plantings. The work also was instrumental in supporting a Section 24c registration for mesotrione in tolerant species.
Publications
- Culpepper, A. S., J. R. Whitaker, A. W. MacRae, and A. C. York. 2008. Distribution of glyphosate-resistant Palmer amaranth (Amaranthus palmerii) in Georgia and North Carolina during 2005 and 2006. J. Cotton Sci. 12:306-310.
- Everman, W. J., C. R. Mayhew, J. D. Burton, A. C. York, and J. W. Wilcut. 2009. Absorption, translocation, and metabolism of 14C-glufosinate in glufosinate-resistant corn, goosegrass (Eleusine indica), large crabgrass (Digitaria sanguinalis), and sicklepod (Senna obtusifolia). Weed Sci.57:1-5.
- Wilson, D. G., Jr., A. C. York, and K. L. Edmisten. 2007. Narrow-row cotton response to mepiquat chloride. J Cotton Sci. 11:177-185.
- Wilson, D. G., Jr., A. C. York, and D. L. Jordan. 2007. Effect of row spacing on weed management in glufosinate-resistant cotton. Weed Technol. 21:489-495.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Research was conducted in 2006-07 to determine distribution of glyphosate-resistant Palmer amaranth in North Carolina and develop management systems in cotton and soybean. Palmer amaranth seed were collected from 290 fields in 29 eastern North Carolina counties and their response to glyphosate was determined. Resistant biotypes were found in 48 of the fields scattered over 11 counties. The level of resistance ranged from 3 to 22 X. Acceptable control in soybean required both an effective preemergence herbicide plus a non-glyphosate postemergence herbicide. In cotton, acceptable control was achieved with flumioxazin preplant or fomesafen preemergence followed by metolachlor plus glyphosate postemergence followed by diuron plus MSMA postemergence-directed. Several studies focused on Palmer amaranth control and tolerance of Widestrike Roundup Ready Flex cotton to glufosinate applied postemergence. Good control of Palmer amaranth was obtained in systems with an effective
preemergence herbicide followed by multiple glufosinate applications. Timeliness of glufosinate application was critical. Some cotton injury was noted with glufosinate, but yields were not adversely impacted. Other studies focused on the effect of residual herbicides and timing of initial glufosinate application on control of annual grasses, Amaranthus species, Ipomoea species, and common lambsquarters in Liberty Link cotton. Greater control of grasses and Amaranthus was noted when preemergence herbicides were included. With preemergence herbicides and timely application of glufosinate, excellent weed control was obtained. Separate studies focused on annual grass control in Liberty Link cotton with glufosinate in combination with postemergence graminicides. Severe antagonism on grasses was noted with mixtures of glufosinate and clethodim, fluazifop, quizalofop, or sethoxydim. Antagonism was not alleviated by increasing the graminicide rate by 50% or by adding ammonium sulfate.
Antagonism was not observed when graminicides were applied 3 or more days before glufosinate or 5 or more days after glufosinate. Work on the potential for fluometuron, diuron, and prometryn applied to cotton to carry over to peanuts and tobacco was completed. Neither fluometuron preemergence nor diuron or prometryn postemergence-directed on cotton adversely affected peanut or tobacco the following year. These residual herbicides will aid in herbicide resistance management. Results of this research have been incorporated into Extension recommendations and have been shared at various field days and grower meetings.
PARTICIPANTS: Individuals: Alan C. York, principal investigator; Andrew P. Gardner, graduate student; Jared R. Whitaker, graduate student; David L. Jordan, collaborator; David W. Monks, collaborator. Partner organizations: North Carolina Cotton Growers Association; Cotton Incorporated; North Carolina Soybean Producers Association. Training: This research was instrumental in training the above graduate students. Additionally, several field days were held to train extension agents, growers, and industry representatives.
TARGET AUDIENCES: The primary audience was row crop producers in North Carolina. Secondary audiences were extension agents and representatives of various agribusinesses operating in North Carolina.
PROJECT MODIFICATIONS: No major changes in approach.
Impacts
The distribution of glyphosate-resistant Palmer amaranth was greater than anticipated, and the findings have captured the attention of growers. That, along with the findings in the management studies, have been used to encourage growers to more proactively manage weeds with emphasis on resistance management. Liberty Link cotton is curently not widely grown in North Carolina, but with new Liberty Link varieties better adapted to the state and increasing glyphosate resistance, there is likely to be more interest in Liberty Link cotton. The results from these trials will aid in formulating management recommendations. The research on flumeturon, diuron, and prometryn carryover potential will give growers greater confidence in using these materials as part of a resistance management program in cotton without fear of adversely affecting peanut and tobacco rotated with cotton.
Publications
- Fisher, L. R., A. C. York, and D. L. Jordan. 2007. Flue-cured tobacco and peanut response to diuron, fluometuron, and prometryn applied to a preceding cotton crop. J. Cotton Sci. 11:168-176.
- Gardner, A. P., A. C. York, D. L. Jordan, and D. W. Monks. 2006. Glufosinate antagonizes postemergence graminicides applied to annual grasses and johnsongrass. J. Cotton Sci. 10:319-327.
- Gardner, A. P., A. C. York, D. L. Jordan, and D. W. Monks. 2006. Management of annual grasses and Amaranthus spp. in glufosinate-resistant cotton. J. Cotton Sci. 10:328-338.
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Progress 10/01/05 to 09/30/06
Outputs
Doveweed is becoming more common in transgenic cotton. Experiments were conducte to determine effect of temperature and seed burial depth on doveweed germination and emergence. Germination peaked at 28 C. No germination was observed at 38 C constant temperature or at alternating temperatures of 20/10 and 25/15 C. Light did not enhance germination. Greatest emergence occurred form 0 to 1 cm, with a reduction in emergence as depth increased to 4 cm. No emergence occurred at 6 cm or deeper. Field studies evaluated weed control in glyphosate-resistant corn treated with glyphosate or nicosulfuron plus atrazine POST at thre application timings with and without alachlor plus atrazine PRE. Most weeds were controlled equally well by all treatments. Sicklepod and tall morningglory control decreased with delayed POST application. Corn yield was similar with glyphosate and nicosulfuron plus atrazine. Yield was unaffected by POST herbicide application timing in the presence of PRE
herbicide, but yield decreased as POST application was delayed in the absence of PRE herbicide. Glyphosate-resistant Palmer amaranth was found in North Carolina in 2005. Research in 2006 focused on screening 300 fields for resistance. Resistance was found over a wide area in eastern North Carolina. Field research was initiated to develop management systems. In glyphosate-resistant cotton, best control was obtained with a program consisting of pendimethalin plus fomesafen PRE, glyphosate plus pyrithiobac or s-metolachlor POST, and diuron plus MSMA POST-directed.
Impacts
Research on doveweed seedbank dynamics, specifically effect of temperature on germination and emergence depth, will aid in deveoping tools and strategies for managing this increasingly common pest in glyphosate-resistant cotton. Research on management systems in glyphosate-resistant corn, specifically on timing of POST application and the role of PRE herbicides, will help growers avoid yield loss due to early season competition and better manage weeds in this system. Glyphosate-resistant corn is rapidly increasing in acreage. Glyphosate-resistant Palmer amaranth is a very serious problem for cotton producers. Research on management systems will help growers avoid yield loss and delay resistance development in areas currently not infested.
Publications
- Burke, I. C., J. D. Burton, A. C. York, J. Cranmer, and J. W. Wilcut. 2006. Mechanism of resistance to clethodim in a johnsongrass (Sorghum halepnese) biotype. Weed Sci. 54:401-406.
- Culpepper, A. S., T. L. Grey, W. K. Vencill, J. M. Kichler, T. M. Webster, S. M. Brown, A. C. York, J. W. Davis, and W. W. Hanna. 2006. Glyphosate-resistant Palmer amaranth (Amaranthus palmeri) confirmed in Georgia. Weed Sci. 54:620-626.
- Parker, R. G., A. C. York, and D. L. Jordan. 2006. Weed control in glyphosate-resistant corn as affected by preemergence herbicide and timing of postemergence herbicide application. Weed Technol. 20:564-570.
- Wilson, D. G., Jr., M. G. Burton, J. F. Spears, and A. C. york. 2006. Doveweed (Murdania nudiflora) germination and emergence as affected by temperature and seed burial depth. Weed Sci. 54:1000-1003.
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