2006 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? 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) 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. The difficulty and costs of weed management in peanut and vegetable crops are a major problem throughout the region, 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 by year the currently approved milestones (indicators of research progress) Objective 1. Develop weed management systems for conventional peanut, organic peanut, cotton, and cucurbit crops with emphasis on reducing (or eliminating) herbicide use, altering cultural practices to reduce weed losses, and minimizing weed propagation. Objective 2. Develop a greater understanding of the biology of tropical spiderwort and apply that knowledge to improve weed management efficiency and maximize crop growth and yield. Objective 3. Develop alternative methods of weed management in cucurbit and solanaceous vegetable crops without methyl bromide fumigation by evaluating herbicides, application technology, cover crops, living mulches, solarization, and fallow tillage for pre-plant weed control. The expected accomplishments during the life of this project include: FY 2006: 1. Elimination of waiting period following cucurbit crop transplant eliminates the competitive advantage of nutsedge species in methyl bromide systems. 2. Weed control in organic peanut production will be evaluated in altered row spacing patterns in combination with cultivation. 3. Organic peanut: use of smother crops, propane flaming, and OMRI herbicides. 4. Organic cucurbits: use of smother crops, propane flaming, and OMRI herbicides. 5. Yellow nutsedge dynamics in long-term strip tillage peanut. 6. Cotton-peanut rotation in three long-term tillage systems. 7. Cotton and peanut: tropical spiderwort critical period of weed control. 8. Seed packet burial of tropical spiderwort. 9. Zero-seed return study with tropical spiderwort. 10. Emergence patterns of tropical spiderwort monitored in different crops. 11. Crop type affects tropical spiderwort growth and fecundity. 12. Application of halosulfuron through drip-irrigation for perennial nutsedge control. 13. Cucumber tolerance to halosulfuron. 14. Nutsedge patch expansion with different mulches. 15. Summer solarization using clear mulch in summer fallow. 16. Biofumigation with Brassica green manure crops. 17. Living mulches and cereal cover crops in cucurbits. 18. Fumigant alternatives to methyl bromide with different mulch types. 19. Different application timings of methyl bromide alternative fumigants for nutsedge suppression. FY07: 1. Elimination of waiting period following cucurbit crop transplant eliminates the competitive advantage of nutsedge species in methyl bromide systems. 2. Weed control in organic peanut production will be evaluated in altered row spacing patterns in combination with cultivation. 3. Alternate row patterns will be explored in peanut for tropical spiderwort suppression. 4. Organic peanut: use of smother crops, propane flaming, and OMRI herbicides. 5. Organic cucurbits: use of smother crops, propane flaming, and OMRI herbicides. 6. Post-Harvest field management to interrupt the tropical spiderwort growing cycle. 7. Yellow nutsedge dynamics in long-term strip tillage peanut. 8. Cotton-peanut rotation in three long-term tillage systems. 9. Cotton and peanut: tropical spiderwort critical period of weed control. 10. Competitiveness of tropical spiderwort in cotton and peanut will be evaluated. 11. Seed packet burial of tropical spiderwort. 12. Zero-seed return study with tropical spiderwort. 13. Crop type affects tropical spiderwort growth and fecundity. 14. Application of halosulfuron through drip-irrigation for perennial nutsedge control. 15. Nutsedge patch expansion with different mulches. 16. Living mulches and cereal cover crops in cucurbits. 17. Fumigant alternatives to methyl bromide with different mulch types. 18. Different application timings of methyl bromide alternative fumigants for nutsedge suppression. FY08: 1. Weed control in organic peanut production will be evaluated in altered row spacing patterns in combination with cultivation. 2. Alternate row patterns will be explored in peanut for tropical spiderwort suppression. 3. Organic peanut: use of smother crops, propane flaming, and OMRI herbicides. 4. Organic cucurbits: use of smother crops, propane flaming, and OMRI herbicides. 5. Post-Harvest field management to interrupt the tropical spiderwort growing cycle. 6. Yellow nutsedge dynamics in long-term strip tillage peanut. 7. Cotton-peanut rotation in three long-term tillage systems. 8. Competitiveness of tropical spiderwort in cotton and peanut will be evaluated. 9. Seed packet burial of tropical spiderwort. 10. Zero-seed return study with tropical spiderwort. 11. Application of halosulfuron through drip-irrigation for perennial nutsedge control. 12. Nutsedge patch expansion with different mulches. 13. Living mulches and cereal cover crops in cucurbits. 14. Fumigant alternatives to methyl bromide with different mulch types. FY09: 1. Alternate row patterns will be explored in peanut for tropical spiderwort suppression. 2. Post-Harvest field management to interrupt the tropical spiderwort growing cycle. 3. Yellow nutsedge dynamics in long-term strip tillage peanut. 4. Cotton-peanut rotation in three long-term tillage systems. 5. Competitiveness of tropical spiderwort in cotton and peanut will be evaluated. 6. Seed packet burial of tropical spiderwort. 7. Zero-seed return study with tropical spiderwort. 8. Nutsedge patch expansion with different mulches. 9. Living mulches and cereal cover crops in cucurbits 10. Fumigant alternatives to methyl bromide with different mulch types. FY10: 1. Alternate row patterns will be explored in peanut for tropical spiderwort suppression. 2. Post-Harvest field management to interrupt the tropical spiderwort growing cycle. 3. Yellow nutsedge dynamics in long-term strip tillage peanut. 4. Cotton-peanut rotation in three long-term tillage systems. 5. Competitiveness of tropical spiderwort in cotton and peanut will be evaluated. 6. Seed packet burial of tropical spiderwort. 7. Zero-seed return study with tropical spiderwort. 8. Nutsedge patch expansion with different mulches. 9. Living mulches and cereal cover crops in cucurbits. 10. Fumigant alternatives to methyl bromide with different mulch types. 4a.List the single most significant research accomplishment during FY 2006. Tropical spiderwort can eliminate peanut yield. Tropical spiderwort, an exotic invasive weed that is also on the Federal Noxious Weed List, has quickly spread in the Southeast Coastal Plain and become the second most troublesome weed in peanut. Researchers from USDA-ARS in Tifton and Dawson cooperated with University of Georgia scientists to conduct field studies to determine the length of time that peanut fields needed to be kept free of tropical spiderwort in order to minimize yield losses. Research demonstrated that tropical spiderwort was capable of causing 100% peanut yield loss after just six weeks of competition. Peanut yield loss was less than 10% when plots were kept free of spiderwort for 3 to 6 weeks after peanut planting. This critical period of weed control coincided with peak spiderwort emergence. Growers will be able to use this information when devising a weed management strategy, targeting weed control that eliminates spiderwort competition during this interval. This research addresses Component X - Weed Management Systems and Component VII - Weed Biology and Ecology of ARS National Program 304 (Crop Protection and Quarantine). 4b.List other significant research accomplishment(s), if any. Glyphosate-resistant Palmer amaranth confirmed in Georgia. Glyphosate (trade name: Roundup) is the foundation for weed management in many crops across the U.S., including cotton, corn, and soybean. Even with glyphosate, Palmer amaranth is among the most-troublesome weeds to manage across the Southern U.S. Researchers from USDA-ARS and University of Georgia confirmed the existence of glyphosate-resistant Palmer amaranth in several central Georgia cotton fields. This is the first documented case in the world of glyphosate-resistance in a pigweed species. Palmer amaranth is a wind-pollinated plant that is capable of out-crossing with other pigweeds; pigweeds are significant weeds in all other regions of North America. This research addresses Component X - Weed Management Systems and Component VII - Weed Biology and Ecology of ARS National Program 304 (Crop Protection and Quarantine). 4c.List significant activities that support special target populations. Addressed organic growers at the Tillage School on methods of weed management in organic peanut production. Organic growers tend to be small acreage growers. 4d.Progress report. None 5.Describe the major accomplishments to date and their predicted or actual impact. 1. Methyl bromide alternative for nutsedge management in cucurbits. 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 is no longer available without Critical Use Exemption from the United Nations. Application techniques for metham and halosulfuron have been developed, refined, and validated in watermelon, cantaloupe, and cucumber production systems and this alternative is as equally efficacious as methyl bromide 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. This research addresses priorities in ARS National Program 308 (Methyl Bromide Alternatives). 2. Early planted cotton minimizes tropical spiderwort competition. Tropical spiderwort has become the most troublesome weed in cotton production in Georgia due to its tolerance of glyphosate and the widespread adoption of glyphosate-tolerant cotton cultivars (>90%). Management of tropical spiderwort in cotton is expensive (doubling the cost of weed control) and weather-dependent. On-farm studies were conducted to determine the competitive relationship between cotton and tropical spiderwort at two planting dates, early-May and mid-June. Results indicate that cotton has a significant advantage if it is planted early in the growing season because it establishes prior to the bulk of tropical spiderwort emergence in June and July. When cotton emerges with tropical spiderwort, cotton yield losses exceeded 50%. Growers who adopt early planted cotton can minimize crop yield loss with no additional pest management expenses. This research addresses Component X - Weed Management Systems and Component VII - Weed Biology and Ecology of ARS National Program 304 (Crop Protection and Quarantine). 3. Nutsedge growth affected by mulch type and nutsedge type. The effectiveness of thin-film polyethylene mulches in suppressing nutsedge growth was evaluated in preparation for 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. These results were validated in field trials and integrated into an alternative system of weed management in the absence of methyl bromide. This research addresses Component X - Weed Management Systems and Component VII - Weed Biology and Ecology of ARS National Program 304 (Crop Protection and Quarantine) and ARS National Program 308 (Methyl Bromide Alternatives). 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? Tropical Spiderwort Symposium, Tifton, GA: "The Ecology of Tropical Spiderwort in Agro-Ecosystems of the Southeast US". Information on tropical spiderwort biology and management was presented to growers and industry personnel in Grady County, GA. Approximately 50 growers were in attendance. American Peanut Research and Education Society: Tropical Spiderwort Symposium: A New Troublesome Exotic-Invasive Weed In Peanut. Data on novel application technology of halosulfuron and on nutsedge response to various mulch types was provided to scientist in preparation of the Critical Use Exemption for Methyl Bromide to United Nations' MBTOC (Methyl Bromide Technical Options Committee). 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). Coordinated the Tropical Spiderwort Symposium in Tifton, GA (http://www.cropsoil.uga.edu/weedsci/tsw2005/index.html). This meeting, attended by approximately 80 customers, stakeholders, and collaborators brought together people from eight states. Attendees included representatives from the State Departments of Agriculture of Alabama, Georgia, North Carolina, and South Carolina, federal regulators from USDA-APHIS, agrichemical industry, horticultural industry, Georgia Cotton Commission, Cotton Incorporated, the Smithsonian Institution, and five universities. An article explaining the cooperative study between our CRIS project and University of Georgia weed scientists on large-scale pollen flow was written for the Georgia Associated Press network and appeared in several newspapers in Georgia, including the Macon Telegraph and Tifton Gazette. Review Publications Webster, T.M., Burton, M.G., Culpepper, A.S., Flanders, J.T., Grey, T.L., York, A.C. 2006. Tropical spiderwort (Commelina benghalensis) control and emergence patterns in preemergence herbicide systems. Journal of Cotton Science. 10:68-75. Webster, T. M., Burton, M. G., Culpepper, A. S., York, A. C., Prostko, E. P. 2005. Invasive Weed Alert - Tropical spiderwort (Commelina benghalensis): A tropical invader threatens agroecosystems of the southern United States. Weed Technology. 19:501-508. Webster, T.M. 2005. Mulch type affects growth and tuber production of yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus). Weed Science. 53:834-838. Webster, T.M. 2005. Patch expansion of purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) with and without polyethylene mulch. Weed Science. 53:839-845. Webster, T., Culpepper, A. 2005. Eggplant tolerance to halosulfuron applied through drip irrigation. HortScience. 40(6):1796-1800. Singh, B.P., Granberry, D.M., Kelley, W.T., Boyhan, G., Sainju, U.M., Phatak, S.C., Sumner, P.E., Bader, M.J., Webster, T.M., Culpepper, A.S., Riley, D.G., Langston, D.B., Fonsah, G. 2005. Sustainable Vegetable Production. In: Dris, R. editor. Vegetables: Growing Environment and Mineral Nutrition. Helsinki, Finland: WFL Publisher. p. 1-38. Webster, T.M. 2006. The effect of plastic mulch on nutsedge growth. In: Proceedings of the 2006 Southeast Regional Vegetable Conference, January 5-8, 2006, Savannah, GA. p. 49-51. Webster, T.M., Grey, T.L., Burton, M.G., Flanders, J.T., Culpepper, A.S. 2006. Tropical spiderwort (Commelina benghalensis): The worst weed in cotton? In: Proceedings of the 2006 Beltwide Cotton Conference, January 3-6, 2006, San Antonio, Texas. p. 2181-2183. Burton, M.G., York, A.C., Webster, T.M., Prostko, E.P. 2006. Demography and distribution of troublesome dayflowers. In: Proceedings of the 2006 Beltwide Cotton Conferences, January 3-6, 2006, San Antonio, Texas. p. 2226-2227. Grey, T.L., Culpepper, A.S., Webster, T.M., Mantri, N. 2006. Dissipation of field applied herbicides from low density polyethylene mulch [abstract]. Weed Science Society of America Abstracts. 46:94. Culpepper, A.S., Kickler, J., York, A.C., Grey, T.L., Webster, T.M. 2006. Managing glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in Georgia cotton (Gossypium hirsutum)[abstract]. Weed Science Society of America Abstracts. 46:59-60. Prostko, E.P., Flanders, J.T., Culpepper, A.S., Webster, T.M., Grey, T.L., Vencill, W.K., Carter, J.R. 2006. Extension and research programs addressing the threat of Tropical spiderwort (Commelina benghalensis) in Georgia [abstract]. Weed Science Society of America Abstracts. 46:66. Vencill, W.K., Grey, T.L., Culpepper, A.S., Shilling, D., Webster, T.M. 2006. Physiology of glyphosate-resistant Palmer amaranth (Amaranthus palmeri). In: Proceedings of the 2006 Beltwide Cotton Conference, January 3-6, 2006, San Antonio, Texas. p. 2254-2258. Wauchope, R.D., Johnson, W.C., Sumner, H.R. 2004. Foliar and soil deposition of pesticide sprays in peanuts, and washoff/runoff under simulated worst-case rainfall conditions. Journal of Agricultural and Food Chemistry 52(23):7056-7063(2004). Johnson, III, W.C., Prostko, E.P., Mullinix, Jr., B.G. 2005. Improving the management of dicot weeds in peanut with narrow row spacings and residual herbicides. Agronomy Journal. 97:85-88. Johnson, III, W.C., Mullinix, Jr., B.G. 2005. Effect of herbicide application method on weed management and crop injury in transplanted cantaloupe production. Weed Technology. 19:108-112. Johnson,III, W.C., Prostko, E.P., Mullinix, Jr., B.G. 2006. Phytotoxicity of delayed applications of flumioxazin of peanut (Arachis hypogaea). Weed Technology. 20:157-163. Johnson, III, W.C. 2005. Yellow nutsedge control with metham-sodium in transplanted cantaloupe. In: Proceedings of the Southeast Regional Vegetable Conference, Georgia Fruit and Vegetable Growers Association Winter Conference, January 6-9, 2005, Savannah, Georgia. p. 104-108. Johnson, W. C. 2005. Starting from scratch: Growing peanut without herbicides [abstract]. Proceedings of the Weed Science Society. 58:92. Wauchope, R.D., Webster, T.M., Potter, T.L., Wade, L. 2005. Precision spray application for presistence and washoff studies of foliar pesticide residues: Method development. American Chemical Society Abstracts. 229:U86.