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Funded Project |
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Funding Program:
Regional IPM Grants (S-RIPM) |
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Project Title:
Integrated methods for sustainable control of glyphosate-resistant horseweed (Conyza canadensis) and other problematic winter weeds |
Project Directors (PDs):
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Lead State: NC Lead Organization: North Carolina State University |
| Research Funding: $80,000 |
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Start Date: Jul-01-2006 End Date: Jun-30-2008 |
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Pests Involved: horseweed |
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Area of Emphasis: glyphosate resistance |
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Summary:
Glyphosate-resistant horseweed is a major threat to efficient crop production in the United States. The acreage infested continues to increase as horseweed produces wind-disseminated seed, is self-fertile, has no fitness penalty for glyphosate resistance, and heterozygous individuals survive recommended glyphosate rates. In addition, cropping production changes from conventional tillage towards no-till favor establishment of horseweed and winter seasonal weed species, and the widespread adoption of glyphosate-resistant crop technology has dramatically increased selection pressure for glyphosate resistance among weeds. Continued reliance on herbicides as the predominant control method will only increase the prevalence of herbicide-resistant biotypes in the United States as specific horseweed biotypes have already evolved resistance to at least six herbicide modes-of-action. In North Carolina, horseweed and winter weeds have been observed as greater problems following a no-till corn crop than other crops or conventional-tillage corn. Previous research has documented the relationship of tillage or the presence of cover crops to weed establishment, but the effects of crop architecture have not been adequately described. The proposed research will measure the spatial and temporal relationship of horseweed and other winter weeds to rotational crop species with and without the presence of a winter cover crop and with and without tillage. Results will directly improve the current best management practices for corn, soybean, cotton, and peanut production in the southeastern United States. In addition, this research will provide benefits for horseweed and winter weed management in conventional and organic crops in other regions of the United States.
Objectives: 1. Evaluate the effect of various crop canopy heights and time of crop maturity/senescence on horseweed and winter annual and biennial weed germination, establishment, and growth. Planned accomplishments: a) Determine the effect of crop canopy (development, maturity, and senescence) on temporal relationship with horseweed germination and establishment in corn, cotton, peanut, and soybean. b) Determine the crops that suppress or facilitate horseweed germination and establishment. Objective 2. Evaluate the effects of fall tillage and use of a winter cover crop on horseweed and winter weed germination and establishment. Planned accomplishments: a) Determine horseweed establishment under conventional tillage and no-tillage production systems. b) Determine horseweed establishment and growth in the presence or absence of a winter cover crop. c) Identify any interactions between rotational crop, cover crop, and tillage that may maximize horseweed and winter weed control. Objective 3. Disseminate research findings. Planned accomplishments: a) Present research findings at the Weed Science Society of America, the Southern Weed Science Society, and/or the American Society of Agronomy. b) Publish research findings in Weed Technology. c) Present updated extension recommendations to clientele through commodity and agricultural consultant meetings, and extension publications. d) Conduct field research at university research stations that host field days including the Cotton, Peanut, and Grain Field Days. |
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Final Report: |
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Results From report submitted by the PI to USDA CRIS report system PROGRESS: 2006/07 TO 2009/06 OUTPUTS: Experiments were initiated on November 1, 2006 at the Upper Coastal Plain Research Station near Rocky Mount and at the Peanut Border Belt Research Station near Lewiston-Woodville, North Carolina. Plots were arranged and respective tillage operations were performed along with wheat planted as the cover crop. The experimental design was a randomized complete block with a factorial treatment arrangement of four crops (corn, cotton, peanuts, and soybeans), two tillage production systems (no-till and conventional tillage), and three cover crop options (no cover crop, wheat cover crop, blank cover planting) for a total of 24 treatments replicated four times. Winter weed counts were taken on a biweekly interval schedule from November 1, 2006 until corn planting in mid-April. All weeds in a meter by meter square were counted in each plot for a total of 96 counts per biweekly schedule. Each weed count location was mapped with GPS to assure that location was counted at each interval. Data collected included weed number, densities, and size either by leaf or height by species for each plot. Corn variety DKC 69-71 RR2/YGCR was planted at both locations. A commercial standard preemergence herbicide was applied to all corn plots. Cotton variety ST 4554 B2RF was planted at both locations and a commercial standard preemergence herbicide was applied to all cotton plots. Peanut variety VA 98-R and soybean variety AG 6702 RR were planted at both locations with a commercial standard preemergence herbicide applied to all peanut and soybean plots. Crop production systems including fertilization, planting, and general (non-weed) pest management will be managed according to North Carolina Cooperative Extension Service recommendations with corn planted in 36-inch rows at a seeding density of 2 seed/ft of row, cotton in 36-inch rows at 4 seed/ft of row, peanuts in 36-inch rows at 4 seed/ft of row, and soybeans in 18 cm rows at 2 seed/ft of row. These row spacings and plant populations are in accordance with state extension recommendations. All plots were maintained weed-free for the duration of the summer. The same experimental procedures were used in each study during year 2. Two graduate research assistants and two undergraduate participated in this project and received valuable experience in field crop production. This experiment generated two years of data across two sites. Data was collected on the response of 12 weed species to two cultivation methods and three cover crop practices. A total of 1,496 complete data sets were generated. PARTICIPANTS: North Carolina State Univ. and North Carolina Department of Agriculture personnel participated in this projected. Major personnel included Rob Richardson, John Wilcut, Alan York, David Jordan, Scott Clewis, Rory Roten, and Sarah True (graduate student). Various undergraduate and graduate students participated in this research. Richardson managed the whole project while Wilcut, York, and Jordan provided guidance and technical expertise on specific weed management and agronomic practices. True, Roten, and Clewis supervised day to day activities. TARGET AUDIENCES: All producers of cotton, corn, soybean, and peanut in the southeastern U.S. Individuals in occupations that service these commodity producers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period. IMPACT: 2006/07 TO 2009/06 The treatment structure of this research generated 1,496 data sets (weed species x date x trial location x year). Based upon the data generated in this project, commodity specialists will update recommendations for agricultural crop production in North Carolina and the Southeast to improve management of horseweed and winter annual weed species. These trials generated a huge amount of crucial information to document that weed responses will be species specific to agronomic practices and the specific crop in production. This knowledge will push behavioral changes to weed species-crop specific management. For instance, when summarized across crop and site, neither tillage nor cover crop practice had a significant influence on horseweed densities. However, cut-leaf evening primrose densities were greatest in no-till and wheat cover crop treatments. Annual ryegrass densities were also greatest in no-till, but were lower where wheat cover was planted than where no cover crop was used. Similarly, time of emergence differed by species and the effect of standing crop differed by species. Thus, specific agronomic practices must be selected for the specific crop and the specific weed species present to provide the greatest impact. Two graduate research assistants and two undergraduate participated learned through this project. One of the graduate students is now in a faculty position at a major land grant university and the other is employed by a major agricultural company. PUBLICATIONS (not previously reported): 2006/07 TO 2009/06 No publications reported this period |
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Outcomes N/A |
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Impacts From report submitted by the PI to USDA CRIS report system The treatment structure of this research generated 1,496 data sets (weed species x date x trial location x year). Based upon the data generated in this project, commodity specialists will update recommendations for agricultural crop production in North Carolina and the Southeast to improve management of horseweed and winter annual weed species. These trials generated a huge amount of crucial information to document that weed responses will be species specific to agronomic practices and the specific crop in production. This knowledge will push behavioral changes to weed species-crop specific management. For instance, when summarized across crop and site, neither tillage nor cover crop practice had a significant influence on horseweed densities. However, cut-leaf evening primrose densities were greatest in no-till and wheat cover crop treatments. Annual ryegrass densities were also greatest in no-till, but were lower where wheat cover was planted than where no cover crop was used. Similarly, time of emergence differed by species and the effect of standing crop differed by species. Thus, specific agronomic practices must be selected for the specific crop and the specific weed species present to provide the greatest impact. Two graduate research assistants and two undergraduate participated learned through this project. One of the graduate students is now in a faculty position at a major land grant university and the other is employed by a major agricultural company. |
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