Source: AGRICULTURAL RESEARCH SERVICE submitted to
INTEGRATED MANAGEMENT AND ECOLOGY OF WEED POPULATIONS IN THE SOUTHEASTERN COASTAL PLAIN
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0403800
Grant No.
(N/A)
Project No.
6602-22000-032-00D
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2000
Project End Date
Sep 30, 2005
Grant Year
(N/A)
Project Director
JOHNSON W C
Recipient Organization
AGRICULTURAL RESEARCH SERVICE
(N/A)
TIFTON,GA 31793
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
35%
Research Effort Categories
Basic
40%
Applied
35%
Developmental
25%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2131420114010%
2131421114010%
2131429114010%
2131461114010%
2131480114010%
2131710114010%
2131830114030%
2132300114010%
Goals / Objectives
Develop integrated weed management systems with emphasis on reducing herbicide use, improving crop production efficiency, reducing vulnerability to weed establishment, and minimizing weed propagule production. Conduct basic research in weed-crop ecology by correlating environmental factors with weed emergence, evaluating shifts in weed composition in reduced tillage cropping systems, and determining the effect of weed management practices on the soil seedbank. Evaluate alternative methods for managing weeds in vegetable crops without methyl bromide fumigation by assessing the efficacy of new technologies in vegetable crops to replace methyl bromide and integrating alternatives to methyl bromide fumigation into vegetable crop production systems.
Project Methods
The majority of the research is in field plots. The research will devise new crop production practices that improve the crop's ability to compete with weeds. Innovative crop production practices that offer potential include crop planting dates, narrow row patterns, conservation tillage, mechanical barriers with thin-film plastic mulch, alternative mulching materials, and stale seedbed weed control. This research also involves in-depth study of new herbicide technologies, which are still a critical component of crop production in the southeastern Coastal Plain. Cover crops will be evaluated for their weed control benefits in conservation tillage systems, including small grains and clovers. Recently renovated greenhouse facilities will be fully utilized for evaluating weed species composition and weed seed survivability from varous soil seedbanks. Weed emergence patterns in the field will be correlated with environmental factors, particularly temperature. Growth chambers and thermal gradient germination tables will be used to evaluate base temperatures for weed germination. Base temperature data will be used in conjunction with field emergence patterns to develop predictive weed emergence models. Alternatives to methyl bromide fumigation for weed control vary from short-term replacements, such as metham, to more permanent long-term solutions such as solarization, mulching, and cultural weed control methods. All aspects will be given equal research effort. Most of the research will be in-field studies, but some will be conducted in the recently renovated greenhouses.

Progress 10/01/00 to 09/30/05

Outputs
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? What does it matter? Cotton, peanut, and vegetable are important crops in the southeastern coastal plain. Sustainability of these systems is currently challenged by the increasing costs of crop production inputs while crop prices remain stagnant or decline. We are studying cost-effective systems of weed management with less dependence on herbicides. Integrated weed management systems are being developed and implemented using knowledge of weed control (e.g. modified cultural practices, alternative tillage methods, computer decision support systems) and weed biology (e.g. weed propagule ecology, weed seed germination patterns). Production costs for weed control are a major input for producers in the southeastern coastal plain. Acreages of cotton, peanut, and vegetable crops within this area have always fluctuated due to environmental conditions and economic constraints. However, these commodities consistently account for a significant proportion of the total agricultural value in the region. Weed management in peanut and vegetable crops is difficult and costly, with herbicides (including methyl bromide fumigation for vegetables) being the primary component of most weed management systems. Therefore, farmers are spending more for herbicides, while weeds are still causing major losses. Clearly, the state of weed management has not improved in recent years, despite new herbicide developments. Effective integration of cultural weed controls, alternative tillage systems, and current weed control practices will result in improved weed management and lower unit production costs in agronomic and vegetable crops in the southeastern coastal plain. This project directly addresses high research priorities in ARS National Programs 304 (Crop Protection and Quarantine) and 308 (Methyl Bromide Alternatives) in the pest management discipline: current integrated weed management technology is inadequate to assure effective, safe, and economical weed control, agroecosystem productivity, and environmental quality. 2. List the milestones (indicators of progress) from your Project Plan. Year 1 (FY 2001) 1. Developed herbicide and fumigant application technology, including modified implements and drip-irrigation injection. 2. Conducted herbicide and fumigant efficacy trials, particularly on perennial nutsedges. 3. Conducted field and greenhouse trials on crop tolerance to new herbicide technologies. 4. Incorporated results into integrated crop management systems and transferred the information to stakeholders through programs held in conjunction with the Cooperative Extension Service. Year 2 (FY 2002) 1. Surveyed the region on troublesome weeds (such as tropical spiderwort) , their distribution, and estimates of losses incurred. 2. Conducted research on germination, seed production, seed survival, and temperature requirements for germination, and unique aspects of the ecology of troublesome weeds, such as the perennial nutsedges and tropical spiderwort. 3. Conducted multidisciplinary trials on interactions among weeds (particularly winter annuals/biennials and volunteer crops that are alternate hosts of tomato spotted wilt virus), insects vectors (thrips), and diseases (spotted wilt, stem rot, root-not nematodes). 4. Incorporated results into expert systems (HADSS) for peanut and cotton, for improved cost-effective management of weeds and other pest complexes. Year 3 (FY 2003) 1. Developed and refined fumigant application technology, including drip- irrigation injection and modified tillage equipment used to apply fumigants. 2. Conducted herbicide and fumigant efficacy trials to control perennial nutsedges, with and without thin-film polyethylene mulch. 3. Conducted field and greenhouse trials on crop tolerance to herbicides that may replace methyl bromide for perennial nutsedge control. 4. Validated results using long-term large-scale research trials on sustainable vegetable crop production and incorporated the results into recommended vegetable crop production systems in collaboration with the Cooperative Extension Service. Year 4 (FY 2004) 1. Conducted basic crop production research on modified cultural practices for weed control (modified row patterns, alternative mulching materials, stale seedbed techniques). 2. Conducted competition and interference studies with relevant weeds (Texas panicum, yellow nutsedge, tropical spiderwort) and crops (peanut, cotton). 3. Conducted basic research on weed management systems in organic peanut production using row patterns, cultivation, propane flaming, and herbicides approved for use in organic systems. 4. Validated results using long-term large-scale research trials on sustainable crop production and integrated weed management, using on-farm demonstrations in collaboration with the Cooperative Extension Service. Year 5 (FY 2005) 1. Developed herbicide and fumigant application technology. 2. Conducted herbicide and fumigant efficacy trials, particularly on perennial nutsedges. 3. Conducted field and greenhouse trials on crop tolerance to new herbicide technologies. 4. Conducted basic crop production research on modified cultural practices for weed control (modified row patterns, planting dates, cover crops, mulching materials, stale seedbed techniques). 3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met, substantially met, or not met. If not met, why. 1. Develop herbicide and fumigant application technology. Future studies will build upon these research results, especially with application of herbicides through drip irrigation in vegetable crop production systems. Milestone Fully Met 2. Conduct herbicide and fumigant efficacy trials, particularly on perennial nutsedges. Due to complexity of the ecology of perennial nutsedges and tropical spiderwort (a newly emerging noxious weed), this is a continual area of research. Milestone Substantially Met 3. Conduct field and greenhouse trials on crop tolerance to new herbicide technologies. Due to the diversity in vegetable and agronomic crops served by this project, this is an area of continual research. Milestone Substantially Met 4. Conduct basic crop production research on modified cultural practices for weed control (modified row patterns, mulches, stale seedbed techniques). This milestone will be expanded to include cover crops, smother crops, and living mulches for weed control in organic crop production systems. Milestone Substantially Met 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? This is the final report for this CRIS project and currently we are awaiting approval of a new CRIS project. 4a What was the single most significant accomplishment this past year? Early planted cotton minimizes tropical spiderwort competition. Tropical spiderwort has become the most troublesome weed of cotton production in Georgia due to its tolerance of glyphosate, the region-wide planting of glyphosate-tolerant cotton cultivars (>90%), and resulting increases in the cost of overall weed management. Research from the Crop Protection and Management Research Unit located at the Coastal Plain Experiment Station in Tifton, GA indicates that cotton has a significant competitive advantage over weeds if it is planted early in the growing season because it establishes prior to the bulk of tropical spiderwort emergence in June and July. In contrast, late-planted cotton growth coincides with tropical spiderwort emergence, resulting in yield losses exceeding 50%. Growers who adopt early planted cotton can minimize crop yield loss with no additional weed management expenses. 4b List other significant accomplishments, if any. Summer fallow tillage and solarization successfully abates yellow nutsedge. Yellow nutsedge is a troublesome weed and is particularly difficult to control in organic crop production. Trials in Tifton, GA have shown that shallow tillage combined with summer solarization using clear plastic mulch eliminated yellow nutsedge (initial densities of 43 plants/m2 reduced to 0 plants/m2) in future turnip green plantings, a crop which has no effective control options for yellow nutsedge. These benefits extended to the following growing season and were seen in future crop plantings. This system will be beneficial to organic crop producers or conventional producers of small-acreage crops of which there are few options to control perennial nutsedges. 4d Progress report. Significant progress has been made in development of weed management systems in organic peanut production. Weed densities in peanut seeded no- till into a mowed crimson clover cover crop were greatly reduced compared to peanut planted in a strip-tillage system. When this cultural control practice was combined with early-season propane flaming and one handweeding, weeds were successfully controlled in organic peanut production. Given the value of certified organic peanut, this system appears to be an effective and economically feasible system to manage weeds in organic production systems. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. This project (70%) addresses research priorities in ARS National Program 304 (Crop Protection and Quarantine). This focuses equally on Component X - Weed Management Systems and elements of Component VII - Weed Biology and Ecology. The remainder (30%) of the project addresses research priorities in ARS National Program 308 (Methyl Bromide Alternatives), Preplant Soil Fumigation Alternatives. Research trials have shown that a system of metham and halosulfuron effectively control perennial nutsedges in transplanted cucurbit crop production. Methyl bromide fumigation is the standard weed control practice in transplanted cucurbit crops, but methyl bromide will no longer be available after 2005. Application techniques for metham and halosulfuron have been developed, refined and validated in watermelon, cantaloupe, cucumber, and squash production systems and this alternative system is equally efficacious as methyl bromide fumigation and less costly. These results will allow growers to effectively manage perennial nutsedges in transplanted cucurbit crops in the absence of methyl bromide and potentially increase profits due to less costly weed control. Studies in cooperation with University of Georgia and North Carolina State University scientists demonstrate that tropical spiderwort is tolerant to glyphosate (Trade name: Roundup) and control of tropical spiderwort is improved with the addition of residual herbicides to glyphosate. Tropical spiderwort (Commelina benghalensis) occurred in only five Georgia counties in 1998 and spread to 52 counties in 2003, becoming the most troublesome weed of cotton in Georgia. The overwhelming majority (>89%) of the cotton acreage in the southeast U.S. is planted to glyphosate tolerant cultivars, and glyphosate is often the sole herbicide used on these acres. Our research results demonstrate that the wide- spread adoption of glyphosate tolerant cotton causes the rapid spread of this invasive weed in Georgia and modification of weed management practices with less dependence on glyphosate is necessary for successful management of the weed. Metham-sodium has been identified as a possible replacement for methyl bromide fumigation in vegetable crops, although questions persist regarding the optimum rate, timing, and need for polyethylene tarping for yellow nutsedge control. Field studies conducted in the ARS Crop Protection and Management Research Unit, Tifton, GA identified the application guidelines for controlling yellow nutsedge in transplanted cucurbit crops with metham-sodium. These trials showed that thin-film polyethylene mulch added consistency to metham-sodium efficacy and provided significant suppression of yellow nutsedge, even without a fumigant. These results suggest that the production practices for cantaloupe and other cucurbit crops can be easily altered to accommodate metham-sodium as a replacement for methyl bromide. The effectiveness of thin-film polyethylene mulches in suppressing nutsedge growth was evaluated in the wake of the impending elimination of methyl bromide. In greenhouse studies at the ARS Crop Protection and Management Research Unit, Tifton, GA, purple and yellow nutsedge growth was monitored in pots covered with black polyethylene mulch, clear polyethylene mulch, or not covered. Relative to the non-mulched treatments, mulches reduced yellow nutsedge tuber production 50% and shoot populations 96%, while there were no differences among the treatments for purple nutsedge. Polyethylene mulch can be an important component of a yellow nutsedge management system, while other factors will need to be explored for successful management of purple nutsedge. Costs of weed control in peanut are increasing, in spite of efforts to reduce production costs. The incumbents developed a system of cultural weed control tactics in Georgia that reduce herbicide use and improve net returns to peanut production. These modified cultural weed control practices include stale seedbed tillage to deplete numbers of viable weed seed in the plow-layer and seeding peanut in narrow-rows to shade weeds. These cultural weed control practices reduce herbicide use in peanut, increase yield, and improve production efficiency throughout the southeastern U.S. Methyl bromide is one of the key components in cucurbit crop production on polyethylene covered seedbeds, but methyl bromide is scheduled for cancellation in the future and remaining supplies are very costly. An implement was modified in Tifton, GA to apply metham-sodium, an alternative to methyl bromide. This implement was constructed from commonly available stock materials, without the need for out-sourcing to machine shops and correctly applies metham for yellow nutsedge control. The innovative design and simplicity of this implement gives cucurbit growers the opportunity to control yellow nutsedge at less cost than with methyl bromide, and can be readily adapted by growers throughout the region. Research was conducted to adapt and validate a computer-based weed management decision support system (HADSS) that utilizes weed biology, efficacy of weed control, and economics to make weed control recommendations in Georgia. The incumbent worked with the model developers at North Carolina State University, extension personnel at the University of Georgia, and county agents in Georgia to conduct field validation of the model. Significant alteration in the database has made HADSS a suitable tool for Georgia growers, closely approximating the recommendations of Georgia extension specialists. The validated HADSS model has been released for Georgia, assisting county extension agents, consultants, growers, and university scientists in making weed management recommendations, as well as serving as a training tool to instruct each of these groups concerning the complex interactions among weed biology, weed control, herbicide efficacy, and economics. Adoption of reduced tillage in peanut in the southeast coastal plain has increased over the last several years in an effort to reduce production costs and increase the timeliness of crop production operations. A multi- year study was initiated to evaluate changes in weed species composition and weed management costs in various reduced tillage systems that include peanut and cotton. In the fourth year of this study, the occurrence of perennial weeds in the reduced tillage systems has become apparent, causing significantly higher weed management costs. As reduced tillage and labor costs appeared to be a major advantage of reduced tillage systems, it is important that growers are aware that reduced tillage systems may affect the weed species composition, shifting from annual weeds to difficult to control perennial weeds that were previously held in check by tillage operations and that weed management costs may increase in these systems. The search for methyl bromide alternatives in vegetable crop systems has led to the exploration of alternative technologies, including solarization which has long been rumored to be an effective means of reducing weed populations. Studies were initiated to evaluate the combined effect of heat treatments and durations of exposure on the viability of tubers of purple nutsedge and yellow nutsedge, the primary means of reproduction for these weeds. Purple nutsedge tubers were shown to be more tolerant of elevated temperatures than were yellow nutsedge tubers; however, elimination of tubers viability was achieved. Using the available technology solarization cannot be relied upon as a means of reducing nutsedge tuber viability due to the inability to raise soil temperatures for critical durations of exposure. Texas panicum is among the most common and troublesome weeds of peanut in the southeastern coastal plain. Control is difficult and expensive, particularly in conservation tillage systems. Studies were initiated to determine the competitiveness of Texas panicum in peanut and develop an economic threshold. Texas panicum is among the most competitive weeds with peanut, reducing yields and greatly interfering in harvest efficiency. A Texas panicum density of 2 plants/m2 reduced peanut yields by 25% and causes peanut harvest losses of 870 kg/ha. The Texas panicum density at which control with herbicides is economically justified is 4 plants/m2. 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? Field day was conducted in Grady County, GA to share biology and management research for tropical spiderwort in multiple on-farm locations. Approximately 30 growers and industry representatives attended the field day on 24 August 2004 (this occurred late enough in the year that it was not included on last year's report). Demonstrated to the customers the benefit of planting cotton early in the growing season in fields infested with tropical spiderwort. This cultural practice can significantly minimize cotton yield loss attributed to tropical spiderwort competition. As tropical spiderwort control is difficult and costly, any cultural practice that will shift the competitive balance towards the crop, with minimal cost, is desirable. A presentation was made entitled: "Tropical spiderwort biology: managing to its weaknesses". This was in conjunction with the Tropical spiderwort Biology and Control Options Meeting in Grady County, GA. In attendance were approximately 60 growers, chemical industry representatives, and county extension agents, 10 March 2005. Shared research observations with the growers that tropical spiderwort emergence occurs later in the season than most other agronomic weeds. Tropical spiderwort requires high soil temperatures for germination. Late emergence in the season will have a significant impact in developing effective tropical spiderwort management systems. A presentation was made to vegetable growers at the 2005 Southeast Regional Fruit and Vegetable Growers Association entitled "Yellow Nutsedge Control with Metham-Sodium in Transplanted Cantaloupe". Metham- sodium is a cost-effective alternative to methyl bromide fumigation in transplanted cucurbit crops. This research showed the correct means to apply metham-sodium for effective yellow nutsedge control, with minimum cantaloupe phytotoxicity, and excellent yield. This conference is a regional meeting of commercial vegetable growers and approximately 1500 growers, many of whom need alternatives to methyl bromide fumigation, attend each year. 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). "Benghal dayflower [tropical spiderwort] invades the South" appeared in American Gardner, November/December 2004. This article described the rapid spread of this weed in Georgia. "Tropical spiderwort spreading fast: big trouble in the Southeast" by Sharon Durham appeared in Southeast Farm Press, 15 December 2004. This article describes the threat of this exotic invasive weed in the Southern US. Presented "The Perfect Storm: why an invasive weed (tropical spiderwort) threatens agriculture in the Southeast US" to scientists at the Ohio Agricultural Research and Development Center, Wooster, OH, 21 July 2005. A field demonstration and subsequent presentation was made to watermelon producers entitled: "Alternative mulching materials in strip-tillage watermelon production". This was part of a field day on organic watermelon production on a private farm near Owensboro, GA, 12 May 2005. Prostko, E. P., Culpepper, A. S., Webster, T. M., Flanders, J. T. 2004. Tropical spiderwort identification and control in Georgia field crops. Cooperative Extension Service/University of Georgia Research Report. Circular 884. 8 p. Available: http://pubs.caes.uga. edu/caespubs/pubs/PDF/C884.pdf. Davis, R. F., Webster, T. M. 2003. Weeds as hosts for the southern root-knot nematode. 2002 University of Georgia Cotton Research and Extension Report. p. 318-319.

Impacts
(N/A)

Publications

  • Martinez-Ochoa, N., Mullis, S. W., Csinos, A. S., Webster, T. M. 2004. First report of yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus) in Georgia naturally infected with impatiens necrotic spot virus. Plant Disease. 88(7):771.
  • Desaeger, J. A., Eger, Jr., J. E., Csinos,, A. S., Gilreath, J. P., Olson, S. M., Webster, T. M. 2004. Movement and biological activity of drip- applied 1,3-dichloropropene and chloropicrin in raised mulched beds in the southeastern USA. Pest Management Science. 60:1220-1230.
  • Culpepper, A. S., Webster, T. M., York, A. C., Barentine, R. M., Mullinix, Jr., B. G. 2004. Glyphosate/MSMA mixtures in glyphosate-resistant cotton (Gossypium hirsutum). Journal of Cotton Science. 8:124-129.
  • Webster, T.M., Culpepper, A.S. 2005. Halosulfuron has a variable effect on cucurbit growth and yield. HortScience. 40(3):707-710.
  • Webster, T. M., Hanna, W. W., Mullinix, Jr., B. 2004. Bermudagrass (Cynodon spp.) dose-response relationships with clethodim, glufosinate and glyphosate. Pest Management Science. 60:1237-1244.
  • Webster, T.M., Culpepper, A.S., Flanders, J.T., Grey, T.L. Planting date affects critical tropical spiderwort (Commelina benghalensis)-free interval in cotton [abstract]. In: Proceedings of the 2005 Beltwide Cotton Conferences, January 4-7, 2005, New Orleans, Louisiana, p. 2842- 2843.
  • Flanders, J.T., Culpepper, A.S., Webster, T.M., York, A.C. Controlling Tropical spiderwort with Roundup ready flex systems [abstract]. In: Proceedings of the 2005 Beltwide Cotton Conferences, January 4-7, 2005, New Orleans, Louisiana. p. 2873-2874.


Progress 10/01/03 to 09/30/04

Outputs
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? What does it matter? Cotton, peanut, and vegetable are important crops in the southeastern coastal plain. Sustainability of these systems is currently challenged by the increasing costs of crop production inputs while crop prices remain stagnant or decline. We are studying cost-effective systems of weed management with less dependence on herbicides. Integrated weed management systems are being developed and implemented using knowledge of weed control (e.g. modified cultural practices, alternative tillage methods, computer decision support systems) and weed biology (e.g. weed propagule ecology, weed seed germination patterns). Production costs for weed control are a major input for producers in the southeastern coastal plain. Acreages of cotton, peanut, and vegetable crops within this area have always fluctuated due to environmental conditions and economic constraints. However, these commodities consistently account for a significant proportion of the total agricultural value in the region. Weed management in peanut and vegetable crops is difficult and costly, with herbicides (including methyl bromide fumigation for vegetables) being the primary component of most weed management systems. Therefore, farmers are spending more for herbicides, while weeds are still causing major losses. Clearly, the state of weed management has not improved in recent years, despite new herbicide developments. Effective integration of cultural weed controls, alternative tillage systems, and current weed control practices will result in improved weed management and lower unit production costs in agronomic and vegetable crops in the southeastern coastal plain. This project directly addresses high research priorities in ARS National Programs 304 (Crop Protection and Quarantine) and 308 (Methyl Bromide Alternatives) in the pest management discipline: current integrated weed management technology is inadequate to assure effective, safe, and economical weed control, agroecosystem productivity, and environmental quality. 2. List the milestones (indicators of progress) from your Project Plan. Develop herbicide and fumigant application technology. Conduct herbicide and fumigant efficacy trials, particularly on perennial nutsedges. Conduct field and greenhouse trials on crop tolerance to new herbicide technologies. Conduct basic crop production research on modified cultural practices for weed control (modified row patterns, mulches, stale seedbed techniques). Validate results as part of long-term large-scale research trials on sustainable crop production and using on-farm demonstrations with the Cooperative Extension Service. Incorporate results into integrated crop management systems and transfer the information and feedback from stakeholders through programs held in conjunction with the Cooperative Extension Service. 3. Milestones: A. List the milestones (from the list in Question #2) that were scheduled to be addressed in FY 2004. How many milestones did you fully or substantially meet in FY 2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. 1) Develop herbicide and fumigant application technology. This milestone has been fully met during FY 2004. 2) Conduct herbicide and fumigant efficacy trials, particularly on perennial nutsedges. This milestone has been substantially met during FY 2004. Due to complexity of the ecology of perennial nutsedges and tropical spiderwort (a newly emerging noxious weed), this is a continual area of research. 3) Conduct field and greenhouse trials on crop tolerance to new herbicide technologies. This milestone has been substantially met during FY 2004. Due to the diversity in vegetable and agronomic crops served by this project, this is an area of continual research. 4) Conduct basic crop production research on modified cultural practices for weed control(modified row patterns, mulches, stale seedbed techniques) . This milestone has been substantially met during FY 2004. B. List the milestones (from the list in Question #2) that you expect to address over the next 3 years (FY 2005, 2006, & 2007). What do you expect to accomplish, year by year, over the next 3 years under each milestone? 1) Conduct herbicide and fumigant efficacy trials, particularly on perennial nutsedges. FY 2005. It is anticipated to continue research that refines perennial nutsedge management systems in an expanded array of vegetable crops. In addition, preliminary results on tropical spiderwort management systems in peanut and cotton will be available. FY 2006. Research that expands the data sets on tropical spiderwort management in peanut and cotton will continue. FY 2007. Herbicide efficacy studies on tropical spiderwort should be completed during FY 2007. Depending on the increasing distribution of tropical spiderwort, similar studies may be initiated in other crops, including turf and container ornamentals. 2) Conduct field and greenhouse trials on crop tolerance to new herbicide technologies. FY 2005. Research to address this milestone will be expanded during FY 2005 to include other vegetable crops and new herbicide technologies. New crops include crucifers, vegetable legumes, edible soybean, and Solanaceous vegetable crops. FY 2006. This area of research will continue in FY-2006, with expansion of the trials to include sensitivity of vegetable crop cultivars to the new herbicide technologies and methods of application. FY 2007. Herbicide tolerance studies should be completed during FY 2007. Depending on new herbicide developments and crop cultivar releases, similar studies may be initiated. 3) Conduct basic crop production research on modified cultural practices for weed control (modified row patterns, mulches, stale seedbed techniques). FY 2005. Research to address this milestone will be expanded during FY 2005 to include cover crop management (including living mulches), alternative mulching materials in transplanted vegetable crops, and different techniques to apply mulching materials for enhanced weed control. FY 2006. This area of research will continue in FY-2006, with expansion of the trials to include other vegetable crops and crops grown in rotation. FY 2007. Cover crop research in agronomic and vegetable crops should be completed during FY 2007. 4) Validate results as part of long-term large-scale research trials on sustainable crop production and using on-farm demonstrations with Extension Service. FY 2005. On-farm trials will conducted in FY 2005 to determine effective control measures and validate economic thresholds for tropical spiderwort. In addition, basic weed ecology studies will also be conducted on-farm. All of these trials will be in collaboration with Cooperative Extension Service personnel. FY 2006. These on-farm trials will be continued in FY 2006, with possible expansion into other on-farm sites with different cropping systems and soils, which greatly affect control of tropical spiderwort and losses due to the weed. FY 2007. These on-farm trials involving tropical spiderwort should be concluded at the end of FY 2007. Organic weed control systems developed by this research project will be demonstrated and validated beginning in FY 2007 on grower-owned certified organic farms. 5) Incorporate results into integrated crop management systems and transfer the information and feedback from stakeholders through programs held in conjunction with the Cooperative Extension Service. FY 2005. Research results will be shared with county agents at field and in-house training sessions. FY 2006. Research results will be presented to growers at regional trade shows, short courses, and field days throughout the region. Sponsors of specific events include the Southeast Fruit and Vegetable Growers Association, Georgia Organics Association, Georgia Peanut Commission, and Georgia Cotton Commission. FY 2007. Results from these research trials will be incorporated into weed management and general crop production recommendations developed by the Cooperative Extension Service. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2004 (one per Research (00D) Project): Research trials have shown that a system of metham and halosulfuron effectively control perennial nutsedges in transplanted cucurbit crop production. Methyl bromide fumigation is the standard weed control practice in transplanted cucurbit crops, but methyl bromide will no longer be available after 2005. Application techniques for metham and halosulfuron have been developed, refined and validated in watermelon, cantaloupe, cucumber, and squash production systems and this alternative system is equally efficacious as methyl bromide fumigation and less costly. These results will allow growers to effectively manage perennial nutsedges in transplanted cucurbit crops in the absence of methyl bromide and potentially increase profits due to less costly weed control. B. Other significant accomplishment(s), if any. Studies in cooperation with University of Georgia and North Carolina State University scientists demonstrate that tropical spiderwort is tolerant to glyphosate (Trade name: Roundup) and control of tropical spiderwort is improved with the addition of residual herbicides to glyphosate. Tropical spiderwort (Commelina benghalensis) occurred in only five Georgia counties in 1998 and spread to 52 counties in 2003, becoming the most troublesome weed of cotton in Georgia. The overwhelming majority (>89%) of the cotton acreage in the southeast U.S. is planted to glyphosate tolerant cultivars, and glyphosate is often the sole herbicide used on these acres. Our research results demonstrate that the wide- spread adoption of glyphosate tolerant cotton causes the rapid spread of this invasive weed in Georgia and modification of weed management practices with less dependence on glyphosate is necessary for successful management of the weed. C. Significant activities that support special target populations. None D. Progress Report--opportunity to submit additional programmatic information to your Area Office and NPS (optional for all in-house ("D") projects and the projects listed in Appendix A; mandatory for all other subordinate projects). Significant progress has been made in non-chemical weed management in the southeastern coastal plain. Preliminary research has shown that combinations of frequent shallow tillage and solarization during summer months greatly reduces the densities of yellow nutsedge and these benefits are extended into future crops. Since yellow nutsedge is a troublesome weed of regional significance, these results will be of significant benefit to organic crop producers in the region and home gardeners. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Metham-sodium has been identified as a possible replacement for methyl bromide fumigation in vegetable crops, although questions persist regarding the optimum rate, timing, and need for polyethylene tarping for yellow nutsedge control. Field studies conducted in the ARS Crop Protection and Management Research Unit, Tifton, GA identified the application guidelines for controlling yellow nutsedge in transplanted cucurbit crops with metham-sodium. These trials showed that thin-film polyethylene mulch added consistency to metham-sodium efficacy and provided significant suppression of yellow nutsedge, even without a fumigant. These results suggest that the production practices for cantaloupe and other cucurbit crops can be easily altered to accommodate metham-sodium as a replacement for methyl bromide. The effectiveness of thin-film polyethylene mulches in suppressing nutsedge growth was evaluated in the wake of the impending elimination of methyl bromide. In greenhouse studies at the ARS Crop Protection and Management Research Unit, Tifton, GA, purple and yellow nutsedge growth was monitored in pots covered with black polyethylene mulch, clear polyethylene mulch, or not covered. Relative to the non-mulched treatments, mulches reduced yellow nutsedge tuber production 50% and shoot populations 96%, while there were no differences among the treatments for purple nutsedge. Polyethylene mulch can be an important component of a yellow nutsedge management system, while other factors will need to be explored for successful management of purple nutsedge. Costs of weed control in peanut are increasing, in spite of efforts to reduce production costs. The incumbents developed a system of cultural weed control tactics in Georgia that reduce herbicide use and improve net returns to peanut production. These modified cultural weed control practices include stale seedbed tillage to deplete numbers of viable weed seed in the plow-layer and seeding peanut in narrow-rows to shade weeds. These cultural weed control practices reduce herbicide use in peanut and improve production efficiency throughout the southeastern U.S. Methyl bromide is one of the key components in cucurbit crop production on polyethylene covered seedbeds, but methyl bromide is scheduled for cancellation in the future and remaining supplies are very costly. An implement was modified in Tifton, GA to apply metham-sodium, an alternative to methyl bromide. This implement was constructed from commonly available stock materials, without the need for out-sourcing to machine shops and correctly applies metham for yellow nutsedge control. The innovative design and simplicity of this implement gives cucurbit growers the opportunity to control yellow nutsedge at less cost than with methyl bromide, and can be readily adapted by growers throughout the region. Research was conducted to adapt and validate a computer-based weed management decision support system (HADSS) that utilizes weed biology, efficacy of weed control, and economics to make weed control recommendations in Georgia. The incumbent worked with the model developers at North Carolina State University, extension personnel at the University of Georgia, and county agents in Georgia to conduct field validation of the model. Significant alteration in the database have made HADSS a suitable tool for Georgia growers, closely approximating the recommendations of Georgia extension specialists. The validated HADSS model has been released for Georgia, assisting county extension agents, consultants, growers, and university scientists in making weed management recommendations, as well as serving as a training tool to instruct each of these groups concerning the complex interactions among weed biology, weed control, herbicide efficacy, and economics. Adoption of reduced tillage in peanut in the southeast coastal plain has increased over the last several years in an effort to reduce production costs and increase the timeliness of crop production operations. A multi- year study was initiated to evaluate changes in weed species composition and weed management costs in various reduced tillage systems that include peanut and cotton. In the fourth year of this study, the occurrence of perennial weeds in the reduced tillage systems has become apparent, causing significantly higher weed management costs. As reduced tillage and labor costs appeared to be a major advantage of reduced tillage systems, it is important that growers are aware that reduced tillage systems may affect the weed species composition, shifting from annual weeds to difficult to control perennial weeds that were previously held in check by tillage operations and that weed management costs may increase in these systems. The search for methyl bromide alternatives in vegetable crop systems has led to the exploration of alternative technologies, including solarization which has long been rumored to be an effective means of reducing weed populations. Studies were initiated to evaluate the combined effect of heat treatments and durations of exposure on the viability of tubers of purple nutsedge and yellow nutsedge, the primary means of reproduction for these weeds. Purple nutsedge tubers were shown to be more tolerant of elevated temperatures than were yellow nutsedge tubers; however, elimination of tubers viability was achieved. Using the available technology solarization cannot be relied upon as a means of reducing nutsedge tuber viability due to the inability to raise soil temperatures for critical durations of exposure. 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? Provided information on tropical spiderwort (Commelina benghalensis) that was requested by scientists at Cotton Incorporated. This data was used in a presentation to the Cotton Incorporated Board of Directors to brief them on the status of this invasive exotic weed in the Southeast U.S., February 2004. Provided information on the effect of nutsedge density on bell pepper yield to University of Georgia scientists in preparation for the Georgia critical use exemption for methyl bromide. They were successful in extending the use of methyl bromide in several crops for another growing season. While methyl bromide use will soon be terminated, this will provide University extension and growers more time to adopt alternative controls for the wide-range of pests that were previously managed with methyl bromide. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. Information on tropical spiderwort (Commelina benghalensis), and exotic invasive weed on the list of Federal noxious weeds was presented to Agricultural Chemical Dealers, December 10, 2003. Provided information through an on-line seminar to North Carolina Department of Agriculture concerning the ecology and control of tropical spiderwort (Commelina benghalensis). They were considering an eradication program, which they have since implemented, December 16, 2003. Invited by the Weed Science Society of North Carolina to present "Tropical spiderwort (and you thought sicklepod was bad?)", March 11, 2004. Presented "Biology: growth habits of tropical spiderwort" at the Area Tropical Spiderwort Biology and Control Options Meeting in Grady County, GA. In attendance were approximately 60 growers, chemical industry representatives, and county extension agents, March 18, 2004. "Cotton weed shifts found in Georgia" by Paul Hollis appeared in Southeast Farm Press, March 17, 2004. This article detailed some of the cooperative research that is underway in Georgia and North Carolina on tropical spiderwort. Webster, T.M. 2001. Halosulfuron has a variable affect on squash growth and yield. 2001 University of Georgia Vegetable Research and Extension Report. p. 65-68. Webster, T.M. 2002. What soil temperatures will kill nutsedge tubers? 2002 University of Georgia Vegetable Research and Extension Report. p. 88- 97. Webster, T.M. 2002. A tale of two nutsedges: differential effects of polyethylene mulch on early season growth of purple nutsedge and yellow nutsedge. 2002 University of Georgia Vegetable Research and Extension Report. p. 98-102. Martinez, N., Csinos, A.S., Webster, T.M., Bertrand, P., Waldner, M.V., Whiddon, J., Duffie, W., Flanders, T., Cook, M.J. 2003. Preliminary results of survey of weeds as hosts of tomato spotted wilt virus and impatiens necrotic spot virus around tobacco fields in Georgia: 2002 growing season. 2002 University of Georgia Research and Extension Report. p. 318-319. Forcella, F., Webster, T.M., Cardina, J. 2003. Protocols for weed seedbank determination in agroecosystems. In: Labrada, R., editor. Addendum to Weed Management for Developing Countries. 120(Add.1). Rome, Italy: FAO. p. 3-18. Johnson, W.C., Brenneman, T.B., Baker, S.H., Johnson, A.W., Sumner, D.D., Mullinix, Jr., B.G. 2001. Southeastern coastal plain tillage and pest management in a peanut-cotton rotation. Available: http://www.cropdecisions.com/cca/ccaadv200107.pdf.

Impacts
(N/A)

Publications

  • Johnson, III, W.C. 2004. The non-chemical weed control research program in Georgia: The Good, The Bad, The Ugly [abstract]. Proceedings of the Southern Weed Science Society. 57:376.
  • Johnson, III, W.C. 2004. Weed control with organic production [abstract]. In: Proceedings of the Southeast Regional Fruit and Vegetable Conference, Georgia Fruit and Vegetable Growers Association, January 9-11, 2004, Savannah, Georgia. p. 13-14.
  • Johnson, III, W.C. 2004. Weed science research opportunities with USDA- ARS [abstract]. Proceedings of the Southern Weed Science Society. 57:381.
  • Burton, M.G., Webster, T.M., Prostko, E.P., Culpepper, A.S., York, A.C., Sermons, S. 2003. Rapid increase of Tropical spiderwort (Commelina benghalensis L.) in herbicide-resistant crops of southeastern USA agroecosystems [abstract]. Ecological Society Abstracts. 88:51-52.
  • Culpepper, A.S., Flanders, J.T., York, A.C., Webster, T.M. 2004. Tropical spiderwort (Commelina benghalensis L.) control in glyphosate- resistant cotton (Gossypium hirsutum L.). Weed Technology. 18(2):432-436.
  • Grey, T.L., Bridges, D.C., Prostko, E.P., Johnson, W.C., Eastin, E.F., Vencill, W.K., Brecke, B.J., MacDonald, G.E., Tredaway, J.A., Everest, J.W. 2003. Residual weed control with Imazapic, Diclosulam, and Flumioxazin in southeastern peanut. Peanut Science. 30:23-28.
  • Johnson, W.C., Culbreath, A.K. 2003. Preliminary results of non-chemical weed control research in peanut production using cultural controls and propane flaming [abstract]. American Peanut Research and Education Society Abstracts. 35:39.
  • Johnson, III, W.C., Mullinix, Jr., B.G. 2003. Yellow nutsedge (Cyperus esculentus) interference in peanut (Arachis hypogaea). Peanut Science. 30:15-19.
  • Martinez-Ochoa, N., Csinos, A.S., Webster, T.M., and Bertrand, P. 2003. Occurrence of mixed infections of tomato spotted wilt virus (TSWV) and impatiens necrotic spot virus (INSV) in weeds around tobacco fields in Georgia [abstract]. Phytopathology. 93:S58.
  • Webster, T.M. 2003. High temperatures and durations of exposure reduce nutsedge (Cyperus spp.) tuber viability. Weed Science. 51:1010-1015.
  • Webster, T.M. 2003. Polyethylene mulches suppress purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) growth [abstract]. Proceedings of the Ecological Society of America. 88:351.
  • Webster, T.M. 2002. Squash tolerance to halosulfuron and applying halosulfuron through drip tape [abstract]. In: Proceedings of the Southeast Regional Fruit and Vegetable Conference, Georgia Fruit and Vegetable Growers Association, January 11-12, 2002, Savannah, Georgia. p. 47.
  • Webster, T.M., Bednarz, C.W., Hanna, W.W. 2003. Sensitivity of triploid hybrid bermudagrass cultivars and common bermudagrass to postemergence herbicides. Weed Technology. 17:509-515.
  • Webster, T.M., Cardina, J. 2004. A review of the biology and ecology of Florida beggarweed (Desmodium tortuosum). Weed Science. 52:185-200.


Progress 10/01/02 to 09/30/03

Outputs
1. What major problem or issue is being resolved and how are you resolving it? Cotton, peanut, and vegetable are important crops in the southeastern coastal plain. Sustainability of these systems is currently challenged by the increasing costs of crop production inputs while crop prices remain stagnant or decline. We are studying cost-effective systems of weed management with less dependence on herbicides. Integrated weed management systems are being developed and implemented using knowledge of weed control (e.g. modified cultural practices, alternative tillage methods, computer decision support systems) and weed biology (e.g. weed propagule ecology, weed seed germination patterns). 2. How serious is the problem? Why does it matter? Production costs for weed control are a major input for producers in the southeastern coastal plain. Acreages of cotton, peanut, and vegetable crops within this area have always fluctuated due to environmental conditions and economic constraints. However, these commodities consistently account for a significant proportion of the total agricultural value in the region Weed management in peanut and vegetable crops is difficult and costly, with herbicides (including methyl bromide fumigation for vegetables) being the primary component of most weed management systems. Therefore, farmers are spending more for herbicides, while weeds are still causing major losses. Clearly, the state of weed management has not improved in recent years, despite new herbicide developments. Effective integration of cultural weed controls, alternative tillage systems, and current weed control practices will result in improved weed management and lower unit production costs in agronomic and vegetable crops in the southeastern coastal plain. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? This project directly addresses high research priorities in ARS National Programs 304 (Crop Protection and Quarantine) and 308 (Methyl Bromide Alternatives) in the pest management discipline: current integrated weed management technology is inadequate to assure effective, safe, and economical weed control, agroecosystem productivity, and environmental quality. Currently, the incumbents have the only active weed science research project on vegetable crops in Georgia, and only one of three in the southeastern coastal plain. The remainder of the incumbents= assignment is on weed science research on peanut, cotton, other agronomic crops, and turfgrass. The incumbents= project is the only one in the U.S. actively investigating alternatives to herbicides for weed control in peanut; specifically alternative cultural weed control systems and modified tillage practices. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishments during FY 2003: Metham-sodium has been identified as a possible replacement for methyl bromide fumigation in vegetable crops, although questions persist regarding the optimum rate, timing, and need for polyethylene tarping for yellow nutsedge control. Field studies conducted in the ARS Crop Protection and Management Research Unit, Tifton, GA identified the application guidelines for controlling yellow nutsedge in transplanted cucurbit crops with metham-sodium. These trials showed that thin-film polyethylene mulch added consistency to metham-sodium efficacy and provided significant suppression of yellow nutsedge, even without a fumigant. These results suggest that the production practices for cantaloupe and other cucurbit crops can be easily altered to accommodate metham-sodium as a replacement for methyl bromide. B. Other Significant Accomplishment(s), if any: The effectiveness of thin-film polyethylene mulches in suppressing nutsedge growth was evaluated in the wake of the impending elimination of methyl bromide. In greenhouse studies at the ARS Crop Protection and Management Research Unit, Tifton, GA, purple and yellow nutsedge growth was monitored in pots covered with black polyethylene mulch, clear polyethylene mulch, or not covered. Relative to the non-mulched treatments, mulches reduced yellow nutsedge tuber production 50% and shoot populations 96%, while there were no differences among the treatments for purple nutsedge. Polyethylene mulch can be an important component of a yellow nutsedge management system, while other factors will need to be explored for successful management of purple nutsedge. C. Significant Activities that Support Special Target Populations: None. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Costs of weed control in peanut are increasing, in spite of efforts to reduce production costs. The incumbents developed a system of cultural weed control tactics in Georgia that reduce herbicide use and improve net returns to peanut production. These modified cultural weed control practices include stale seedbed tillage to deplete numbers of viable weed seed in the plow-layer and seeding peanut in narrow-rows to shade weeds. These cultural weed control practices reduce herbicide use in peanut and improve production efficiency throughout the southeastern U. S. Methyl bromide is one of the key components in cucurbit crop production on polyethylene covered seedbeds, but methyl bromide is scheduled for cancellation in the future and remaining supplies are very costly. An implement was modified in Tifton, GA to apply metham-sodium, an alternative to methyl bromide. This implement was constructed from commonly available stock materials, without the need for out-sourcing to machine shops and correctly applies metham for yellow nutsedge control. The innovative design and simplicity of this implement gives cucurbit growers the opportunity to control yellow nutsedge at less cost than with methyl bromide, and can be readily adapted by growers throughout the region. Research was conducted to adapt and validate a computer-based weed management decision support system (HADSS) that utilizes weed biology, efficacy of weed control, and economics to make weed control recommendations in Georgia. The incumbent worked with the model developers at North Carolina State University, extension personnel at the University of Georgia, and county agents in Georgia to conduct field validation of the model. Significant alteration in the database have made HADSS a suitable tool for Georgia growers, closely approximating the recommendations of Georgia extension specialists. The validated HADSS model has been released for Georgia, assisting county extension agents, consultants, growers, and university scientists in making weed management recommendations, as well serving as a training tool to instruct each of these groups concerning the complex interactions among weed biology, weed control, herbicide efficacy, and economics. Adoption of reduced tillage in peanut in the southeast coastal plain has increased over the last several years in an effort to reduce production costs and increase the timeliness of crop production operations. A multi-year study was initiated to evaluate changes in weed species composition and weed management costs in various reduced tillage systems that include peanut and cotton. In the fourth year of this study, the occurrence of perennial weeds in the reduced tillage systems has become apparent, causing significantly higher weed management costs. As reduced tillage and labor costs appeared to be a major advantage of reduced tillage systems, it is important that growers are aware that reduced tillage systems may affect the weed species composition, shifting from annual weeds to difficult to control perennial weeds that were previously held in check by tillage operations and that weed management costs may increase in these systems. The search for methyl bromide alternatives in vegetable crop systems has led to the exploration of alternative technologies, including solarization which has long been rumored to be an effective means of reducing weed populations. Studies were initiated to evaluate the combined effect of heat treatments and durations of exposure on the viability of tubers of purple nutsedge and yellow nutsedge, the primary means of reproduction for these weeds. Purple nutsedge tubers were shown to be more tolerant of elevated temperatures than were yellow nutsedge tubers, however elimination of tubers viability was achieved. Using the available technology solarization cannot be relied upon as a means of reducing nutsedge tuber viability due to the inability to raise soil temperatures for critical durations of exposure. 6. What do you expect to accomplish, year by year, over the next 3 years? FY 2004: Expand the understanding of economic losses that Texas panicum causes peanut, which will be used to develop cost-effective management strategies and calculate an economic threshold for the weed in peanut. Information transferred on the effect of tillage systems, crop row spacing patterns, crop sowing densities, and post-harvest management strategies on weed-crop interactions to growers, county agents, and extension service specialists. FY 2005: Study the relationship between purple and yellow nutsedge growth in plastic mulch systems. Various mulches have been shown to affect the rate of nutsedge patch expansion, and inclusion of the appropriate mulch in the system may assist growers in suppressing nutsedge growth as a part of an integrated weed management system. FY 2006: Develop systems of non-chemical weed control in peanut and leguminous vegetable crops using an integration of cover crops, living mulches, stale seedbed tillage, row patterns, cultivation, and propane flaming. This non-chemical weed control system will be transferred to organic growers. 7. 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? Watermelon and cantaloupe growers were educated on integrated weed management strategies and related weed biology research at a vegetable production short-course in Eastman, GA, 20 February 2003. Representatives from the Agri-chemical Industry toured nutsedge- expansion plots as a part of the Georgia Methyl Bromide Alternatives Tour, 17 June 2003. Provided data throughout 2003 on perennial nutsedge ecology, biology, and integrated management to Dr. Stanley Culpepper (Asst. Professor, University of Georgia) for use in developing weed control recommendations, county-level meetings with vegetable crop growers, and training county extension agents. 8. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). Johnson, W.C.,III, Webster, T.M. Weed control in the life after methyl bromide. Southeast Farm Press. 2002. v. 29 p. 15 and 29 p. 10-14. (Article split between two issues). Johnson, W.C.,III, Webster, T.M. "Weed management in watermelon and cantaloupe transplanted on polyethylene covered seedbeds". 2001 Georgia Vegetable Extension and Research Report. 2002. p. 51-64. Webster, T.M. "Sandea has a variable effect on squash growth and yield". 2001 Georgia Vegetable Extension and Research Report. 2002. p. 65-68.

Impacts
(N/A)

Publications

  • Csinos, A.S., Webster, T.M., Sumner, D.R., Johnson, A.W., Dowler, C.C., Seebold, K.W. 2003. Application and crop safety paramenters for soil fumigants. Crop Protection. 21:973-982
  • Grey, T.L., Culpepper, A.S., Webster, T.M. 2003. Fall vegetables response to halosulfuron, metolachlor, and sulfentrazone spring applied under plastic [abstract]. Proceedings of Southern Weed Science Society. 56:116.
  • Johnson, W.C.,III. Yellow nutsedge control with metham-sodium in transplanted cantaloupe. Proceedings of the 2003 Southeastern Regional Vegetable Conference. 2003. p. 31-34.
  • Johnson, III, W.C. 2003. Yellow nutsedge control with metham-sodium in transplanted cantaloupe. Proceedings of Southern Weed Science Society. 56:109.
  • Johnson, W.C.,III, Mullinix, B.G.,Jr. Weed management in watermelon (Citrullus lanatus) and cantaloupe (Cucumis melo) transplanted on polyethylene covered seedbeds. Weed Technology. 2002. v. 16. p. 860-866.
  • Johnson, W.C., Prostko, E.P. 2003. Phytotoxicity of delayed applications of flumioxazin on peanut. Weed Science Society of America Abstracts. 43:80.
  • Johnson, W.C.,III, Prostko, E.P., Mullinix, B.G.,Jr. Texas panicum (Panicum texanum) control in strip-tillage peanut (Arachis hypogaea) production. Peanut Science. 2002. v. 29. p. 141-145.
  • McPherson, R.M., Johnson, W.C.,III, Mullinix, B.G.,Jr., Mills, W.A.,III, Peebles, F.S. Influence of herbicide tolerant soybean production systems on insect pest populations and pest-induce crop injury. Journal of Economic Entomology. 2003. v. 96. p. 690-698.
  • Webster, T.M. 2002. Halosulfuron: potential component of cucumber and squash systems [abstract]. Proceedings of the Southern Weed Science Society. 55:208.
  • Webster, T.M. 2003. Weed emergence patterns in the Coastal Plain [abstract]. Proceedings of the Southern Weed Science Society. 56:333.
  • Webster, T.M., Cardina, J., White, A.D. 2003. Weed seed rain, soil seedbanks, and seedling recruitment in no-tillage crop rotations. Weed Science. 51:569-575.
  • Webster, T.M. Culpepper, A.S., Johnson, W.C. 2003. Response of squash and cucumber cultivars to halosulfuron. Weed Technology. 17:173-176.
  • Webster, T.M., Culpepper A.S., Hardison, G.B., Wilson, Jr., S.G. 2002. Cotton HADDS: How we validated the Georgia database [abstract]. Proceedings of the Beltwide Cotton Research Conference, Cotton Weed Science Research Conference. Paper No. 1.


Progress 10/01/01 to 09/30/02

Outputs
1. What major problem or issue is being resolved and how are you resolving it? Cotton, peanut, and vegetable are important crops in the southeastern coastal plain. Sustainability of these systems is currently challenged by the increasing costs of crop production inputs while crop prices remain stagnant or decline. We are studying cost-effective systems of weed management with less dependence on herbicides. Integrated weed management systems are being developed and implemented using knowledge of weed control (e.g. modified cultural practices, alternative tillage methods, computer decision support systems) and weed biology (e.g. weed propagule ecology, weed seed germination patterns). 2. How serious is the problem? Why does it matter? Production costs for weed control are a major input for producers in the southeastern coastal plain. Acreages of cotton, peanut, and vegetable crops within this area have always fluctuated due to environmental conditions and economic constraints. However, these commodities consistently account for a significant proportion of the total agricultural value in the region. Weed management in peanut and vegetable crops is difficult and costly, with herbicides (including methyl bromide fumigation for vegetables) being the primary component of most weed management systems. Therefore, farmers are spending more for herbicides, while weeds are still causing major losses. Clearly, the state of weed management has not improved in recent years, despite new herbicide developments. Effective integration of cultural weed controls, alternative tillage systems, and current weed control practices will result in improved weed management and lower unit production costs in agronomic and vegetable crops in the southeastern coastal plain. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? The incumbents programs are dedicated to long-range, high-risk research on anticipated or emerging agricultural problems. This project directly addresses high research priorities in ARS National Programs 304 (Crop Protection and Quarantine) and 308 (Methyl Bromide Alternatives) in the pest management discipline: current integrated weed management technology is inadequate to assure effective, safe, and economical weed control, agroecosystem productivity, and environmental quality. Currently, the incumbents have the only active weed science research project on vegetable crops in Georgia, and only one of three in the southeastern coastal plain. The remainder of the incumbents assignment is on weed science research on peanut, cotton, other agronomic crops, and turfgrass. The incumbents project is the only one in the U.S. actively investigating alternatives to herbicides for weed control in peanut; specifically alternative cultural weed control systems and modified tillage practices. 4. What was your most significant accomplishment this past year? A. Single Most Significant Accomplishment during FY 2002: Adoption of reduced tillage in peanut in the southeast coastal plain has increased over the last several years in an effort to reduce production costs and increase the timeliness of crop production operations. A multi-year study was initiated to evaluate changes in weed species composition and weed management costs in various reduced tillage systems that include peanut and cotton. In the third year of this study, the occurrence of perennial weeds in the reduced tillage systems has become apparent, causing significantly higher weed management costs. As reduced tillage and labor costs appeared to be a major advantage of reduced tillage systems, it is important that growers are aware that reduced tillage systems may affect the weed species composition, shifting from annual weeds to difficult to control perennial weeds that were previously held in check by tillage operations and that weed management costs may increase in these systems. B. Other Significant Accomplishment(s), if any. The search for methyl bromide alternatives in vegetable crop systems has led to the exploration of alternative technologies, including solarization which has long been rumored to be an effective means of reducing weed populations. Studies were initiated to evaluate the combined effect of heat treatments and durations of exposure on the viability of tubers of purple nutsedge and yellow nutsedge, the primary means of reproduction for these weeds. Purple nutsedge tubers were shown to be more tolerant of elevated temperatures than were yellow nutsedge tubers, however elimination of tubers viability was achieved. Using the available technology solarization cannot be relied upon as a means of reducing nutsedge tuber viability due to the inability to raise soil temperatures for critical durations of exposure. C. Significant Accomplishments/Activities that Support Special Target Populations. None. 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? Costs of weed control in peanut are increasing, in spite of efforts to reduce production costs. The incumbents developed a system of cultural weed control tactics in Georgia that reduces herbicide use in peanut and improves net return to peanut production. These modified cultural weed control practices include stale seedbed tillage to deplete numbers of viable weed seed in the plow-layer and seeding peanut in narrow-rows to shade weeds. These cultural weed control practices reduce herbicide use in peanut and improve production efficiency throughout the southeastern U. S. Strip-tillage peanut production is being rapidly implemented as a labor and time-saving alternative to conventional tillage peanut production. Weed control in strip-tillage peanut production is difficult and expensive. The incumbent has developed weed control strategies in strip-tillage peanut production that effectively control the major troublesome weed species; Texas panicum, common bermudagrass, and yellow nutsedge. These systems will reduce losses due to weeds in strip-tillage peanut production. Methyl bromide is one of the key components in cucurbit crop production on plastic covered seedbeds, but methyl bromide is scheduled for cancellation in the future and remaining supplies are very costly. An implement was modified in Tifton, GA to apply metham, an alternative to methyl bromide. This implement was constructed from commonly available stock materials, without the need for out-sourcing to machine shops and correctly applies metham for yellow nutsedge control. The innovative design and simplicity of this implement gives cucurbit growers the opportunity to control yellow nutsedge at less cost than with methyl bromide, and can be readily adapted by growers throughout the region. Research was conducted to adapt and validate a computer-based weed management decision support system (HADSS) that utilizes weed biology, efficacy of weed control, and economics to make weed control recommendations in Georgia. The incumbent worked with the model developers at North Carolina State University, extension personnel at the University of Georgia, and county agents in Georgia to conduct field validation of the model. Significant alterations in the database have made HADSS a suitable tool for Georgia growers, closely approximating the recommendations of Georgia extension specialists. The validated HADSS model has been released for Georgia, assisting county extension agents, consultants, growers, and university scientists in making weed management recommendations, as well serving as a training tool to instruct each of these groups concerning the complex interactions among weed biology, weed control, herbicide efficacy, and economics. 6. What do you expect to accomplish, year by year, over the next 3 years? FY 2003: Transfer information to customers and stakeholders on weed phenology in relation to environmental cues. Present to cucurbit (i.e. watermelon, muskmelon, squash, and cucumber) growers an integrated system of weed control that will include alternatives to methyl bromide and innovative herbicide application technology. FY 2004: Expand the understanding of economic losses that Texas panicum causes peanut, which will be used to develop cost-effective management strategies and calculates an economic threshold for the weed in peanut. Transfer information on the effect of tillage systems, crop row spacing patterns, crop sowing densities, and post-harvest management strategies on weed-crop interactions. FY 2005: Study the relationship between purple and yellow nutsedge growth in plastic mulch systems. Various mulches have been shown to affect the rate of nutsedge patch expansion, and inclusion of the appropriate mulch in the system may assist growers in suppressing nutsedge growth as a part of an integrated weed management system. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What are the constraints, if known, to the adoption durability of the technology? Significant research effort has been devoted to developing a more cost-effective integrated weed management system in peanut, with less dependence on herbicides. These innovative approaches to weed management were transferred to peanut growers from the Georgia Young Farmers Association and those from Georgia, Florida, and Alabama attending the Southeastern Peanut Growers Conference. Cucurbit crop production in the southeastern U.S. is changing to a system using transplants on plastic covered beds. Integrated weed management techniques are largely unknown in this cropping system. The incumbents research program has successfully integrated alternatives to methyl bromide into this system, with better efficacy and less cost than the standard system. Furthermore, modifications in tillage and application technology radically improved weed control. The computer decision support system (HADSS) has been validated for Georgia and transferred to county agents and made available for growers, scientists, and educators to access and utilize through the internet (www.cropsci.ncsu.edu/webhadss/Georgia.asp). 8. List your most important publications and presentations, and articles written about your work (NOTE: this does not replace your review publications which are listed below) Johnson, W.C., III. "Weed control and cantaloupe tolerance to halosulfuron." Presentation, Sandea (halosulfuron) Symposium: a potential new herbicide for use in several cucurbit and fruiting vegetables at the Georgia Fruit and Vegetable Grower's Winter Conference, Savannah, GA, 12 January 2002. Johnson, W.C. III. "Weed control considerations in conservation tillage." Presentation, Effingham County Young Farmers Association, Springfield, GA, 9 April 2002. Johnson, W.C., III., Prostko, E.P., Grey, T.L. "Annoying trends in strip- tillage weed control in peanut." Presentation, 25th Annual Southern Conservation Tillage Conference for Sustainable Agriculture, Auburn University, AL, 25 June 2002. Webster, T.M. "Applications of halosulfuron through drip tape irrigation: differences among cucurbits." Presentation, Sandea (halosulfuron) Symposium: a potential new herbicide for use in several cucurbit and fruiting vegetables at the Georgia Fruit and Vegetable Grower's Winter Conference, Savannah, GA, 12 January 2002. Webster, T.M. "Nutsedge eradication? How do biology and ecology affect this goal?" Presentation, Southern Nursery Association, Gainesville, FL, 16 July 2002. Webster, T.M. "Annual weed survey of the Southern Weed Science Society: Broadleaf crops subsection." Proceedings of the Southern Weed Science Society. 2001. v.54.p. 274-282.

Impacts
(N/A)

Publications

  • Baughman, T.A., Dotray, P.A., Grichar, W.J., Johnson, W.C., III, Keeling, J.W., Lemon, R.G., Porter, B.L., Karnei, J.A., Besler, B.A., Brewer, K.D. Tolerance of peanut to glyphosate spot applications. American Peanut Research and Education Society. 2001. v.33:Abstract p.62.
  • Johnson, W.C., III. Texas panicum control in strip-tillage peanut production. Proceedings of the Southern Weed Science Society. 2001. v. 54:Abstract p.199.
  • Johnson, W.C., III, Prostko, E.P., Grey, T.L. Annoying trends in strip- tillage weed control in peanut - what are our options? Proc. 25th Annual Southern Conservation Tillage Conference for Sustainable Agriculture. 2002. v.25:Abstract p.165-170.
  • Johnson, W.C., III, Wauchope, R.D., Sumner, H.R. Pesticide runoff and washoff from simulated rainfall in conventional-tillage peanut production. American Peanut Research and Education Society. 2001. v.33:Abstract p.64.
  • Webster, T.M., MacDonald, G.E. A survey of weeds in various crops in Georgia. Weed Technology. 2001. v.15(4).p.771-790.
  • Webster, T.M., Hanna, W.W., Mullinix, B.G., Jr. Herbicide dose-response relationships among several bermudagrass cultivars. Proceedings of the American Society of Agronomy Meeting. 2001. Paper No.512.
  • Webster, T.M., Culpepper, A.S., Hardison, G.B., Bennett, A.C., Wilkerson, G.G. Validation of cotton HADSS in Georgia. Proceedings of the Southern Weed Science Society. 2001. v.54:Abstract p.184.
  • Webster, T.M., Culpepper, A.S. Cotton HADSS for Georgia. Available at www. cropsci.ncsu.edu/webhadss/georgia.asp.[2002]


Progress 10/01/00 to 09/30/01

Outputs
1. What major problem or issue is being resolved and how are you resolving it? Cotton, peanut, and vegetables are important crops in the southeastern coastal plain. Sustainability of these systems is currently challenged by the increasing costs of crop production inputs while crop prices remain stagnant or decline. We are studying cost-effective systems of weed management with less dependence on herbicides. Integrated weed management systems are being developed and implemented using knowledge of weed control (e.g. modified cultural practices, alternative tillage methods, computer decision support systems) and weed biology (e.g. weed propagule ecology, weed seed germination patterns). 2. How serious is the problem? Why does it matter? Production cost for weed control are a major input for producers in the southeastern coastal plain. Acreage of cotton, peanut, and vegetable crops within this area have always fluctuated due to environmental conditions and economic constraints. However, these commodities consistently account for a significant proportion of the total agricultural value in the region. Weed management in peanut and vegetable crops is difficult and costly, with herbicides (including methyl bromide for vegetables) being the primary component of most weed management systems. Therefore, farmers are spending more for herbicides, while weeds are still causing major losses. Clearly, the state of weed management has not improved in recent years, despite new herbicide developments. Similar problems exist with cotton production, in spite of the introduction of herbicide-tolerant cotton. Effective integration of cultural weed controls, alternative tillage systems, and current weed control practices will result in improved weed management and lower unit production costs in agronomic and vegetable crops in the southeastern coastal plain. 3. How does it relate to the National Program(s) and National Component(s)? The incumbents' program is dedicated to high-risk and long-range research on anticipated or emerging agricultural problems. This project directly addresses high research priorities in ARS National Programs 304 and 305 in the pest management discipline: current integrated weed management technology is inadequate to assure effective, safe, and economical weed control, agroecosystems productivity, and environmental quality. Currently, the incumbents have the only active weed science research projects on vegetable crops in Georgia, and only one of three in the southeastern coastal plain. The remainder of the incumbents' assignment involves weed science research in peanut, cotton, other agronomic crops, and turfgrass. The incumbents' project is the only one in the U.S. actively investigating alternatives to herbicides for weed control in peanut; specifically alternative cultural weed control systems and modified tillage practices. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY 2001: Methyl bromide is one of the key components in cucurbit crop production on plastic covered seedbeds, but methyl bromide availability is scheduled for cancellation in the future and remaining supplies are very costly. ARS scientists at the Crop Protection and Management Research Unit, Tifton, GA, have developed systems of integrated weed management in transplanted cucurbit crops that is a cost-effective alternative to conventional weed control systems. This system is an integration of several distinct weed control practices, proven on a commercial scale of production, and can be readily implemented by growers. The system includes alternatives to methyl bromide, improved application technology, and basic principles of weed biology that will benefit producers. B. Other Significant Accomplishment(s), if any. Methyl sodium is one of the potential replacements for methyl bromide in cucurbit crop production on plastic covered seedbeds, but previous yellow nutsedge control from this compound has been inconsistent. An implement was modified to apply metham, an alternative to methyl bromide. This implement was constructed from commonly available stock materials, without the need for out-sourcing to machine shops and correctly applies metham for yellow nutsedge control. The innovative design and simplicity of this implement gives cucurbit growers the opportunity to control yellow nutsedge at less cost than with methyl bromide, and can be readily adapted by growers throughout the region and will apply metham sodium in a manner that maximizes the potential for adequate yellow nutsedge control. C. Significant Accomplishments/Activities that Support Special Target Populations. Information presented at traditional research updates often fails to reach growers. The incumbents have actively sought opportunities to inform growers on research developments in peanut, cotton, and vegetable crop weed management. The incumbents presented seminars to growers on the principles of cost-effective weed control, with emphasis on integrated weed management and pesticide stewardship. This information will help growers effectively manage weeds and improve crop production efficiency. 5. Describe the major accomplishments over the life of the project including their predicted or actual impact. Costs of weed control in peanut are increasing, in spite of efforts to reduce production costs. The incumbents developed a system of cultural weed control tactics in the southeastern coastal plain that reduce herbicide use in peanut and improve net returns to peanut production. These modified cultural weed control practices include stale seedbed tillage to deplete numbers of viable weed seed in the plow-layer and seeding peanut in narrow-rows to shade weeds. These cultural weed control practices reduce herbicide use in peanut and improve production efficiency throughout the southeastern U.S. Strip-tillage peanut production is being rapidly implemented as a labor- and time-saving alternative to conventional tillage peanut production. Weed control in strip-tillage peanut production is difficult and expensive. The incumbent has developed weed control strategies in strip-tillage peanut production that effectively control the major troublesome weed species; Texas panicum, common bermudagrass, and yellow nutsedge. These systems will reduce losses due to weeds in strip-tillage peanut production. Methyl bromide is widely used as a broad-spectrum fumigant in vegetable crop production. The incumbent and co-workers found efficacious and cost-effective alternatives to methyl bromide in vegetable crop production. Metham applied effectively controls yellow nutsedge in cucurbit crops and is less costly than methyl bromide. By adapting the alternative fumigant system developed by this research team, growers in the southeastern U.S. will reduce fumigation costs by 43%, resulting in approximately $12,000,000 savings in the region. Furthermore, research has shown metham can be safely applied closer to transplanting than previously thought and possibly without the need for a plastic tarp. These discoveries will allow growers to use metham and achieve optimum control of yellow nutsedge, using a system with greater flexibility to growers. Research was conducted to adapt and validate a computer-based weed management decision support system that utilizes weed biology, efficacy of weed control, and economics to make recommendations concerning weed control in Georgia. As a part of 22-state effort to validate HADSS (Herbicide Application Decision Support System), I worked with the model developers at North Carolina State University (Drs. Gail Wilkerson and Harold Coble), extension personnel at University of Georgia (Dr. Stanley Culpepper), and county agents in Georgia to put out field tests and pose weed control validation scenarios to extension personnel with expertise in cotton weed management in Georgia. Significant alteration in the database of the model have made HADSS a more suitable tool for Georgia growers, however at least one more iteration of validation and one more season is required before making this model available for use by county extension agents. Ultimately this model could be used to assist county extension agents, consultants, growers, and university scientists in making weed management recommendations as well as a training tool to instruct each of these groups concerning the complex interactions among weed biology, weed control efficacy, and economics. Vegetable growers will soon be without methyl bromide and will require alternatives to manage weeds, nematodes, insects, and soil-borne plant pathogens. A multi-disciplinary team composed of a weed scientist, a nematologist, and two plant pathologists conducted field studies in Tifton, GA, that evaluated pest control in alternative systems. A combination of 1,3-dichloropropene + chloropicrin + metham as well as methyl iodide controlled nutsedges at a level consistent with methyl bromide, but nutsedges began to emerge by the middle of the year and differences among these alternatives and the nontreated control could not be detected by the conclusion of the season. We have made some progress in understanding the needs of a methyl bromide replacement; however, further efforts will need to be investigated to find a suitable nutsedge management system in vegetables. 6. What do you expect to accomplish, year by year, over the next 3 years? FY 2002: Present total package of alternative cultural weed control practices to peanut growers that will reduce costs of weed control and improve net returns and include conventional-tillage and strip-tillage peanut production. Release HADSS-Cotton, an interactive weed management decision support system, to county extension agents. Transfer information to customers and stakeholders on the affect various cultural practices have on weed propagule production. Transfer information to customers and stakeholders on the efficacy of common weed management practices on sterile hybrid bermudagrass, prior to the introduction of herbicide resistance. Transfer information to customers and stakeholders on the interactions of vegetable weed management and weed population dynamics. FY 2003: Transfer information to customers and stakeholders on weed phenology in relation to environmental cues. Present to cucurbit (watermelon, cantaloupe, squash, and cucumber) growers an integrated system of weed control that will include alternatives to methyl bromide, thresholds for weeds, and innovative herbicide application technology. FY 2004: Expand the understanding of economic losses that Texas panicum causes in peanut, which will be used to develop cost-effective management strategies and calculate an economic threshold for the weed in peanut. Transfer information on the effect of tillage systems, crop row spacing patterns, crop sowing densities, and post-harvest management strategies on weed-crop (peanut and cotton) interactions. 7. 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 & durability of the technology product? Significant research effort has been devoted to developing a more cost-effective integrated weed management system in peanut, with less dependence on herbicides. These innovative approaches to weed management were transferred to peanut growers from the Georgia Young Farmers Association and those from Georgia, Florida, and Alabama attending the Southeastern Peanut Growers Conference. Cucurbit crop production in the southeastern U.S. is changing to a system using transplants on plastic covered beds. Integrated weed management techniques are largely unknown in this cropping system. The incumbents' research programs have successfully integrated alternatives to methyl bromide into this system, with better efficacy and less cost than the standard system. Furthermore, modifications in tillage and application technology radically improved weed control. Management of weeds in cotton using economic thresholds has become available through the use of a computer decision aid, HADSS. This system has been validated in Georgia at a total of 12 locations over the last three growing seasons. County extension agents and growers have been shown (through presentations and field days) the potential benefits of using this program. This program is in limited release in 2001 (via CD ROM and http://www.cropsci.ncsu.edu/webhadss/) and will be available to all county extension agents in 2002. 8. List your most important publications in the popular press (no abstracts) and presentations to non-scientific organizations and articles written about your work (NOTE: this does not replace your peer-reviewed publications which are listed below) Sandusky, D. Skip the Package Approach. Georgia Farmer. 2000. No.3.p.12-13. Webster, T.M., Culpepper, A.S., Hardison, G.B. Validation of Cotton-HADSS (Herbicide Application Decision Support System): Year 2. Cotton Research and Extension Report. 2000. p.196-202. Culpepper, A.S., Webster, T.M. Managing Yellow and Purple Nutsedge Between Spring and Fall Vegetable Crops. Georgia Extension Vegetable News. 2001. v.1(5).p.1. Hollis, P.L. Weed Control Costly in Peanut Crop. Southeast Farm Press. 2001. v.28(15).p.1. Holman, S. Growers vs. Weeds: the Battle Rages On. The Peanut Grower. 2001. No.2.p.12-16. Johnson, W.C., III. Integrated Weed Management in Peanut. Presentation made to Peanut Growers at the Henry County, AL Peanut Production Meeting, Headland, AL, February 2001. Johnson, W.C., III. Tillage Considerations in Row Crops. Presentation made to the Worth County Young Farmers Association, Sylvester, GA, February 2001. Johnson, W.C., III. Texas Panicum Control in Strip-Tillage Peanut Production. Research poster presented at the Southeastern Peanut Growers Conference, Panama City, FL, July 2001. Webster, T.M., Hanna, W.W. Bermudagrass Sensitivity to Clethodim, Glufosinate, and Glyphosate. Presentation made at the 55th Annual Georgia Turfgrass Conference, Tifton, GA, May 2001. Webster, T.M. Nutsedge Biology: Implications for Management. Presentation made to Auburn University Southern Forest Nursery Management Cooperative, Savannah, GA, July 2001. Webster, T.M., Culpepper, A.S. A Demonstration of HADSS - Herbicide Application Decision Support System. Presentation made to Growers of Irwin County at the HADSS Field Day, Ocilla, GA, July 2001.

Impacts
(N/A)

Publications

  • Webster, T.M., Johnson, W.C., III, Dowler, C.C., Csinos, A.S., Johnson, A.W., Sumner, D.R. Vegetable weed management using alternatives to methyl bromide. Proceedings of the Southern Weed Science Society. 2001. v.53.p.61.
  • Culpepper, A.S., York, A.C., Webster, T.M. Glyphosate/MSMA mixtures in glyphosate-resistant cotton (Gossypium hirsutum). Weed Science Society of America. 2001. v.41:Abstract p.6.
  • Johnson, W.C., III, Brenneman, T.B., Baker, S.H., Johnson, A.W., Sumner, D. R., Mullinix, B.G., Jr. Tillage and pest management considerations in a peanut-cotton rotation in the southeastern coastal plain. Agronomy Journal. 2001. v.93.p.570-576.
  • Johnson, W.C., III, Webster, T.M. A modified power-tiller for metham application on cucurbit crops transplanted to polyethylene covered seedbeds. 2001. Weed Technology. v.15:p.387-395.
  • Johnson, W.C., III. Using narrow row patterns and premium herbicides for cost effective weed control in peanut. Weed Science Society of America. 2001. v.41:Abstract p.7.
  • Webster, T.M., Csinos, A.S., Johnson, A.W., Dowler, C.C., Sumner, D.R., Fery, R.L. Methyl bromide alternatives in a bell pepper-squash rotation. Journal of Crop Protection. 2001. v.20(7).p.605-614.
  • Webster, T.M. Cultural practices in cotton affect weed seed production. Weed Science Society of America. 2001. v.41:Abstract p.27.
  • Webster, T.M. Nutsedge (Cyperus spp.) management in cucurbits. Proceedings of the International Research Conference on Methyl Bromide Alternatives and Emissions Reductions. 2001. p.64.1-64.2.