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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICALLY AND ECOLOGICALLY BASED KNOWLEDGE FOR INTEGRATED WEED MANAGEMENT SYSTEMS

Location: Global Change and Photosynthesis Research Unit

2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
Weed infestations are ranked as the greatest problem for growers, causing crop yield losses (estimated at 10% in the United States), and impacting grower profitability by decreasing harvest efficiency and grain quality. The annual economic impact of weeds in U.S. agriculture has been estimated in the billions of dollars, with more than $1 billion spent on herbicides in soybean crop systems alone. In the U.S. Corn Belt, over 95% of the acreage is treated annually with herbicides, with such dependence attributed largely to reliability, cost-effectiveness and energy efficiency of herbicides. Reliance on herbicide use not only presents a risk to environmental quality, but the consequent development of resistant or tolerant weed populations reduces the efficacy of future herbicide use. Escape of herbicide-resistant weed biotypes poses a further threat to other ecosystems. There is clearly a need for alternative weed management strategies that integrate effective and sustainable chemical, biological, cultural, and mechanical practices. Understanding the optimization and use of multiple mortality- and fitness-reducing events will facilitate development of integrated weed management systems. There is a need to determine the suitability of safer herbicides, especially for minor crops that provide insufficient economic incentive for the private sector owing to limited acreage. Research is needed to reduce dependency on existing herbicides, including more efficient use combined effectively with increased use of biologically based weed management methods. A broad range of weed species needs to be examined in crop systems, with particular focus on identifying common underlying mechanisms that can be enhanced or exploited for broader weed management strategies.

The biology and ecology of invasive weeds must be investigated in order to understand.
1)the context and processes in which they negatively affect food production and ecosystem function, and.
2)the adaptive mechanisms that allow these species to succeed. Increased research is needed on the biology and population dynamics of weeds, weed propagules, and their interactions with other ecosystem biota in response to newly developed crop and soil management systems. Interactions between crops and weeds are species-specific, and the significance of weed competition on growth, development, yield, and quality, of many vegetable crops in particular, is largely unknown. Understanding the comprehensive impact of weed species in vegetable crops is critical, given the limited options available for managing weeds in these systems, and will require some application of the larger knowledge base for weeds in field corn and soybean crops. New research is needed to understand mechanisms that regulate the processes of weed seed bank dynamics, including the role of natural microbial populations, knowledge of annual rates of weed seed removal in different cropping systems, effects of different crop habitats and weed seed density on seed predator feeding behavior, influence of soil bioperturbation on weed seed apparency to predators, and methods for rapidly characterizing the extent of seed predation in contrasting cropping systems.

The project has three main objectives:.
1)gain knowledge of the ecology of important weeds in vegetable and agronomic crops to understand the fundamental principles that affect weed emergence, growth, interference, seed production, and crop yield and quality,.
2)investigate biotic and abiotic factors linked to natural mechanisms that regulate weed seed and seedling survival in soil ecosystems, and.
3)identify effective combinations of weed management components through application of both new and existing knowledge and technology that exploit useful plant, natural enemies, and environmental interactions. The major objectives of this project are intended to be addressed over long term (20 years) and will be achieved by addressing more specific short term (5 years) specific aims that are progressively built upon an increasing database of knowledge and technology development. The overall benefit will be long term, sustainable weed management based on the use of underlying biological and ecological principles that govern agroecosystem processes, leading to adaptable and site specific practices. Attaining these objectives will:.
1)improve our understanding of fundamental biological and ecological factors that regulate weed invasion,.
2)identify the potential for weed seed bank management with increased knowledge of seed predation ecology and specific microorganism-weed target relationships that can be enhanced by modifying seed bank factors, and.
3)determine effectiveness of combining new and existing knowledge and technologies for weed management that exploit useful interactions and emphasizes integrated non-chemical and chemical methods in crop systems to minimize harmful effects of herbicide input into the environment. Knowledge of key environmental and biological factors and how these might be modified for weed management is anticipated.

This program falls within Component VII (Weed Biology and Ecology), Component VIII (Chemical Control of Weeds), Component IX (Biological Control of Weeds), and Component X (Weed Management Systems) of NP 304. The project is also tied to NP 302 (Plant Biological and Molecular Processes) Components IIb (Plant Tolerance to Environmental Stresses) and IIIc (Biological Interactions that Reduce Environmental Pollution). A minor component of this project, which partly addresses this ARS unit’s NP202 (Soil Resource Management) research goals, is to evaluate the environmental consequences of herbicide use, especially in vulnerable areas often used for vegetable crops.

The agronomic and vegetable crop industry of the Corn Belt will be included in the research process, informed of research results. Weed scientists, plant biologists, microbiologists, and ecologists will benefit from a more developed knowledge base; data and technology transfer from this project will assist other scientists working in related areas. The vegetable industry will benefit from this research, including vegetable processors (e.g. Midwest Food Processors Association, Inc.), growers (of all farm sizes), regulatory agencies (e.g. Environmental Protection Agency), service providers (e.g. university extension and crop consultants), and herbicide manufacturers. Customers of the agronomic crop research include commodity groups (e.g. Illinois Soybean Program Operating Board) and farm operations seeking reduced-input approaches (typically small farms or specialty markets such as organic). The general public expecting safe and economical food and fiber will also benefit.


2.List by year the currently approved milestones (indicators of research progress)
Aim 1.1 Williams - 12 months - Continue ragweed and millet studies in sweet corn. Collect kernel data for whole plots. 24 month - Complete 1st sweet corn studies. Analyze data and report. 36 months - Initiate more interference studies in sweet corn. 48 months - Continue interference studies. 60 months - Report results. Determine critical knowledge gaps, develop follow-up experiments. Aim 2.1 Chee-Sanford - 12 months - Continue microbial identification. Initiate soil core studies. Evaluate seed exudates for further studies. 24 months - Continue microbial identification. Continuie seed burial studies. Develop internal database. 36 months - Continue microbial identification. Continue seed burial studies. 48 months - Continue microbial identification. Continue seed burial studies. 60 months - Extend seed burial studies. Report results. Identify gaps and develop follow-up experiments. Aim 2.2 Davis - 12 months. Initiate seed predation study. 24 months - Continue seed predation studies. 36 months - Continue studies and modeling. 48 months - Continue studies and modeling. 60 months - Report results. Aim 3.1 Davis - 12 months - Initiate year 1 cover crop treatments. 24 months - Initiate year 2 cover crop treatments. 36 months - Continue cover crop studies. 48 months - Continue cover crop studies. 60 months - Report results. Aim 3.2 Sims - 24 months - Initiate N-status studies. 36 months - Initiate ALS-inhibitor studies. 48 months - Report resutls. Publications, presentations, and database entries of results will occur as significant outcomes arise.


4a.List the single most significant research accomplishment during FY 2006.
Cover crop residue management. Despite severe moisture stress, soybeans planted directly into rolled rye residues, with no primary tillage and no other form of weed control, yielded 40 bushels per acre, compared to surrounding conventional soybean fields that yielded 50 bushels per acre. This may be an attractive option for organic producers, as it greatly limits the number of trips through the field, and hence limits fuel and labor costs, without substantial crop yield losses to weed pressure. The experiment will be repeated twice more to determine the importance of interannual variations in weather on outcomes. The outcome of this accomplishment addresses NP 304 Component X (Weed Management Systems).


4b.List other significant research accomplishment(s), if any.
Weed interference and sweet corn ear and quality traits. Improvements in weed management systems in crop production rely on detailed understanding of how the crop is negatively affected by weed interference. For many horticultural crops, weed interference has the potential to influence several crop quality traits besides yield. Studies were conducted over four site-years to quantify relationships between giant ragweed density and sweet corn yield and ear traits. Many ear traits responsible for crop quality were affected by weed interference. This research impacts future studies of weed-sweet corn interactions, because selection of crop response variables will often need to consider traits beyond mass of ears. This work addresses NP 304 Component VII (Weed Biology and Ecology) and NP 302 Component IIb (Plant Tolerance to Environmental Stresses).

Significance of planting date on crop/weed interactions. The critical period for weed control (CPWC) identifies the phase of the crop growth cycle when weed interference results in unacceptable yield losses. The period in which crop planting occurs can span several months, especially for vegetable crops grown in the U.S. Planting date has potential to influence CPWC, because weed community composition and environmental conditions regulating plant growth change over time. Field studies in sweet corn demonstrated the significance planting date has on CPWC. Two planting dates separated by six weeks revealed a crop highly susceptible to weed interference when planted early (maximum yield loss of 85%), relative to a late planting date with considerable crop tolerance (maximum yield loss of 15%). This research is likely to impact weed management in corn production, especially sweet corn, by facilitating the use of crop-weed ecology information to optimize weed management systems. This work addresses NP 304 Component VII (Weed Biology and Ecology) and Component X (Weed Management). Fundamental knowledge of weed/carrot interactions and alternatives to handweeding in carrots. Weed management in domestic carrot production is characterized by high yield loss potential, few herbicides, and heavy reliance on handweeding. Weed management systems in carrot could be improved with an understanding of the specific conditions resulting in crop yield loss and weed fecundity. Significant weed management guidelines such as economic thresholds and critical times for removal of volunteer potato, the most troublesome weed in carrot, were determined in field studies. Weed height served as a good predictor of timing weed management tactics. In addition, weed fecundity was high even before the crop suffered yield losses, underscoring the importance of targeting multiple stages of the weed life cycle. Additional studies conducted over 4 site-years demonstrated that specific rates of prometryn or ethofumesate were safe on carrot and controlled volunteer potato similar to handweeding. This impact of this research is.
1)this research is the first to document fundamental knowledge of carrot/weed ecology that could be used to guide new weed management systems in the crop,.
2)new tools have been identified for weed management systems in carrot that could help modernize domestic carrot production,.
3)handweeding expenses would be eliminated or reduced greatly if prometryn and ethofumesate were registered for use in carrot. This work addresses NP 304 Component X (Weed Management Systems).

Cross-sensitivity in corn to multiple postemergence herbicides. Many herbicides registered or being considered for use in sweet corn lack selectivity in certain hybrids. Previous research found associations, hereafter called ‘cross-sensitivity’, between crop response to nicosulfuron and mesotrione. Studies were conducted to determine if there was a common genetic basis for cross-sensitivity to these and other herbicides. Results indicate a single recessive gene conditioned sensitivity to four ALS-inhibiting herbicides (foramsulfuron, nicosulfuron, primisulfuron, and rimsulfuron), an HPPD-inhibiting herbicide (mesotrione), a growth regulator herbicide combination (dicamba+diflufenzopyr), and a PPO-inhibiting herbicide (carfentrazone). This research was the first to provide evidence that a single recessive gene conditions sensitivity to herbicides with unique modes of action in corn, leading to a novel hypothesis for eliminating herbicide-sensitive hybrids in breeding programs. Given the ubiquitous production of corn in the U.S., advancement in this field has broad, large-scale impact.This work addresses NP 304 Component VIII (Chemical Control of Weeds).


4c.List significant activities that support special target populations.
None


4d.Progress report.
A headquarter-funded postdoctoral research associate was hired in May 2006 to conduct studies in a new area focused primarily on characterizing chemical exudates from weed seeds and to investigate these compounds for their role in weed ecology and microbial relationships with weed seeds.


5.Describe the major accomplishments to date and their predicted or actual impact.
CRIS project 3611-22000-018-00D is in its second year.

Cover crop residue management (NP 304 Component X Weed Management Systems). Despite severe moisture stress, soybeans planted directly into rolled rye residues, with no primary tillage and no other form of weed control, yielded 40 bushels per acre, compared to surrounding conventional soybean fields that yielded 50 bushels per acre. This may be an attractive option for organic producers, as it greatly limits the number of trips through the field, and hence limits fuel and labor costs, without substantial crop yield losses to weed pressure. Weed interference and sweet corn ear and quality traits, and significance of planting date (NP 304 Component VII Weed Biology and Ecology and Component X Weed Management; NP 302 Component IIb Plant Tolerance to Environmental Stresses). In studies conducted over four site-years to quantify relationships between giant ragweed density and sweet corn yield and ear traits, many ear traits responsible for crop quality, besides yield, were affected by weed interference. This research impacts future studies of weed-sweet corn interactions, because selection of crop response variables will often need to consider traits beyond mass of ears. Planting date has potential to influence the critical period for weed control (CPWC), which identifies the phase of the crop growth cycle when weed interference results in unacceptable yield losses. Field studies in sweet corn demonstrated the significance planting date has on CPWC. Two planting dates separated by six weeks revealed a crop highly susceptible to weed interference when planted early (maximum yield loss of 85%), relative to a late planting date with considerable crop tolerance (maximum yield loss of 15%). This research is likely to impact weed management in corn production, especially sweet corn, by facilitating the use of crop-weed ecology information to optimize weed management systems. Chemical exudates from weed seeds and effects on microbial populations (NP 304 Component VII Weed Biology and Ecology; NP 302 Plant Biological and Molecular Processes). Seed bank dynamics involving weed seeds and natural soil microbial populations have not been well-investigated. Seed decay is an important process affecting seed fate, and intrinsic mechanisms to protect seeds against microbial antagonism can contribute to seed bank longevity. This work is the first to investigate the role of seed-produced chemicals as antimicrobial compounds. This work will further knowledge concerning plant natural products and their potential use, and development of strategies to modify natural processes that may enhance weed management. Fundamental knowledge of weed/carrot interactions and alternatives to handweeding in carrots (NP 304 Component X (Weed Management Systems). Weed management in domestic carrot production is characterized by high yield loss potential, few herbicides, and heavy reliance on handweeding. Significant weed management guidelines such as economic thresholds and critical times for removal of volunteer potato, the most troublesome weed in carrot, were determined in field studies. Weed fecundity was high even before the crop suffered yield losses, underscoring the importance of targeting multiple stages of the weed life cycle. Specific rates of prometryn or ethofumesate were safe on carrot and controlled volunteer potato similar to handweeding. This impact of this research is.
1)this research is the first to document fundamental knowledge of carrot/weed ecology that could be used to guide new weed management systems in the crop,.
2)new tools have been identified for weed management systems in carrot that could help modernize domestic carrot production,.
3)handweeding expenses would be eliminated or reduced greatly if prometryn and ethofumesate were registered for use in carrot. Cross-sensitivity in corn to multiple postemergence herbicides (NP 304 Component VIII Chemical Control of Weeds). Many herbicides registered or being considered for use in sweet corn lack selectivity in certain hybrids. Previous research found associations, hereafter called ‘cross-sensitivity’, between crop response to nicosulfuron and mesotrione. Studies were conducted to determine if there was a common genetic basis for cross-sensitivity to these and other herbicides. Results indicate a single recessive gene conditioned sensitivity to four ALS-inhibiting herbicides (foramsulfuron, nicosulfuron, primisulfuron, and rimsulfuron), an HPPD-inhibiting herbicide (mesotrione), a growth regulator herbicide combination (dicamba+diflufenzopyr), and a PPO-inhibiting herbicide (carfentrazone). This research was the first to provide evidence that a single recessive gene conditions sensitivity to herbicides with unique modes of action in corn, leading to a novel hypothesis for eliminating herbicide-sensitive hybrids in breeding programs. Given the ubiquitous production of corn in the U.S., advancement in this field has broad, large-scale impact.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Published results and presentations at scientific meetings in FY06 that report on the biology and ecology of weeds, weed-crop interactions, herbicide effectiveness and variety tolerance, resistance mechanisms, and seed bank microbial ecology are available to industry and scientists across a broad range of disciplines. Our research has been highlighted in popular press releases that are accessible by the general public. The anticipated products of the overall project is intended to fill gaps in the database, include fundamental knowledge regarding plant biology, plant ecology, microbial function and ecology, seed bank ecology, seed biology, and a more thorough understanding of the physical, chemical, and biological factors affecting weed development and spread. These products will form a basis of knowledge and will more initially benefit researchers interested in developing more efficient and effective weed management technology. We will also provide data on improved herbicide use in vegetable crops and evaluate integrated chemical and non-chemical weed control strategies. These latter technologies will have a more immediate benefit to growers, as well as to industry and the scientific community. The constraints to effective application of the knowledge gained from this project to development of new integrated weed management systems lies in the challenge of understanding the complexities associated with crop and natural area systems. By gaining a more thorough knowledge of the fundamental mechanisms that affect weed growth and survival, we can begin to develop integrated strategies for weed management that incorporate effective combinations of both chemical and biologically-based factors.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Williams, M.M. II. 2005. Weeds of sweet corn and their impact on yield traits. Midwest Food Processors Association 78th Processing Crops Conference Proceedings, St. Paul, MN. (invited presentation)

Davis, A. S. 2006. Integrated weed management for organic field crops. Illinois Organic Production Conference. January 12, 2006 (invited presentation)

Davis, A. S. 2006. Integrated weed management for organic field crops. The New Agriculture Network. Vol 3. No. 3, May 10, 2006. http://ipm.msu.edu/new-ag.htm

Suszkiw, J. 2006. Unearthing new clues to controlling weeds. Agricultural Research. May 2006. p. 20-21.

Suszkiw, J. 2006. Seed-rotting microbes sought to battle weeds. ARS News Service. May 2006. http://www.ars.usda.gov/is/pr/2006/060510.htm

Vance, J. 2006. Managing for profit: Using nature to fight weeds. Brownfields AgNews Network. May 8, 2006. http://www.brownfieldnetwork.com (Invited podcast interview).

Williams, M.M. II. 2006. Cross-sensitivity of sweet corn to postemergence herbicides. Illinois Specialty Crop Conference and Trade Show, Springfield, IL. (invited presentation)

Williams, M.M. II. 2006. Weed control, wild proso millet, and more. Ontario Fruit and Vegetable Convention. Brock University, St. Catherines, Ontario, Canada. (invited presentation)


Review Publications
Davis, A.S., Cardina, J., Forcella, F., Johnson, G.A., Kegode, G., Lindquist, J., Luschei, E.C., Renner, K.A., Sprague, C.L., Williams, M. 2005. Environmental factors affecting seed persistence of 13 annual weeds across the U.S. corn belt. Weed Science. 53(6):860-868.

Williams, M., Pataky, J.K., Nordby, J.N., Riechers, D.E., Sprague, C.L., Masiunas, J.B. 2005. Cross-sensitivity in sweet corn to nicosulfuron and mesotrione applied postemergence. Hortscience. 40(6):1801-1805.

Williams, M., Boydston, R.A. 2005. Alternative to handweeding volunteer potato (Solanum tuberosum)in carrot (Daucus carota). Weed Technology. 19(4):1050-1055.

Davis, A.S., Anderson, K.I., Hallett, S.G., Renner, K.A. 2006. Weed seed mortality in soils with contrasting agricultural histories. Weed Science. 54(2):291-297.

Chee Sanford, J.C., Holman, T.J., Connor, L.M., Williams, M., Davis, A.S., Sims, G.K. 2005. Microbial interactions with weed seeds [abstract]. North Central Weed Science Society. 60:16.

Davis, A.S., Anderson, K.I., Hallett, S.G., Renner, K.A. 2005. Weed seed mortality in soils with contrasting agricultural histories [abstract]. North Central Weed Science Society Meeting. 60(1):64.

Williams, M., Boydston, R.A.,. 2005. Sweet corn cultivar influences biologically effective herbicide dose [abstract]. North Central Weed Science Society US Proceedings. 60(1):28.

Williams, M., Frihauf, J.C. 2005. Planting date influences critical period for weed control in sweet corn [abstract]. Weed Science Society of America Meeting Abstracts. 46:219.

Ortiz Ribbing, L.M., Williams, M. 2006. Potential of Phomopsis amaranthicola and Microsphaeropsis amaranthi, as bioherbicides for several weedy amaranthus species. Crop Protection. 25(1):39-46.

Chee Sanford, J.C., Williams, M., Davis, A.S., Sims, G.K. 2006. Do microbes influence seed bank dynamics? Weed Science. 54(3):575-587.

Cupples, A.M., Shaffer, E.A., Chee Sanford, J.C., Sims, G.K. 2006. DNA buoyant density shifts during 15N DNA stable isotope probing. Microbiological Research. 161. Available: http://www.sciencedirect.com.

Davis, A.S. 2006. When does it make sense to target the weed seedbank? Weed Science. 54(3):558-565.

Williams, M., Boydston, R.A. 2006. Volunteer potato(Solanum tuberosum l.) interference in carrot. Weed Science. 54(1):94-99.

Chee Sanford, J.C., Sanford, R.A., Loffler, F.E., Thomas, S.H., Sims, G.K. 2006. Investigating anaerobic microbial processes in agricultural soils using Anaeromyxobacter dehalogenans as a cosmopolitan model [abstract]. International Society for Microbial Ecology. 11:2025.

Davis, A.S., Landis, D.A., Schemske, D.W., Evans, J.A. 2006. Matrix population models to inform A. petiolata biocontrol agent selection [abstract]. Weed Science Society of America Meeting. 45:36.

Fu, X., Williams, M.M.II, Chee-Sanford, J.C. 2006. Soil seed bank synamics of giant ragweed (Ambrosia trifida l.) and the role of soil fungi in seed decay processes [abstract]. Association for Tripical Biology and Conservation. Available: http://atbc.xtbtg.ac.cn.

Last Modified: 9/2/2014
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