Brief Summary of Minutes of Annual Meeting

David Stoltenberg (WI, Local Host) and Christy Sprague (MI, Chair) welcomed us to Madison, WI and to the NC-202 summer annual meeting at 8:00 am on Tuesday morning. Randy Woodson commented on the fact that this next year was critical for the NC-202 group because of our project re-write. Jim Parochetti shared that the House budget was looking good and that formula $$ (Hatch, Smith-Lever) were available to continue support of agricultural research projects. The location and date for next years summer annual meeting were determined: Minneapolis-St. Paul, Minnesota on Tuesday and Wednesday, July 26-27, 2005. Local host will be the Minnesota group (Frank Forcella and Gregg Johnson). Gregg Johnson is Chair for 2005 and Adam Davis was elected Chair for 2006.

1. Objective 1: Understand the basis and relative importance of spatial, temporal, and biological variability in weed-crop competition.
   1. Standard Regional Protocol (years 1-3)
      1. Subobjective 1A: Determine the relative competitive indices of selected annual grass and broadleaf weed species in corn and soybean cropping systems.
      2. Subobjective 1B: Determine the effect of time of emergence (i.e., cohort) on the relative competitive ability of these species.
   2. Optional Expanded Protocol (years 1-3)
      1. Subobjective 1E: Determine the relative competitive indices of selected annual grass and broadleaf weed species based on corn and soybean yield loss.
      2. Subobjective 1F: Determine the effect of time of emergence (i.e., cohort) of these weed species on corn and soybean yield loss.
   3. Standard Regional Protocol (years 3-5)
      1. Subobjective 1C: Incorporate weed competitive indices and time of emergence (i.e., cohort) effects into a weed management DSS
      2. Subobjective 1D: Determine corn and soybean grain yield loss associated with four cohorts of a multi-species weed community to use as validation data sets for the weed management DSS

   Accomplishments: Field studies have been completed for Objective 1: subobjectives 1A,B and 1E, F during 2000 - 2003 at many locations across the North Central region. Data have been presented at North Central Weed Science Society annual meetings each year by individual state representatives, some presenting state-specific data, other presenting a regional summary of data. Manuscripts are currently being prepared to bring regional data and results together. Impacts: One major impact of this project has been the greater understanding of weed/crop interactions throughout the North Central Region. This is particularly important as current trends have dictated the use of glyphosate applications at various weed stages in Roundup Ready crops. This project has shown that the time of weed emergence as well as weed species type has a major impact on weed/crop interactions and is important when devising weed management strategies. One example how this data can impact weed management efforts is that information collected from this research has been incorporated into WeedSOFT, a computer-based decision support system. WeedSOFT is commercially available in the following states: Nebraska, Missouri, Kansas, Wisconsin, Illinois, Indiana, and Michigan.

2. Objective 2: Understand spatial, temporal and biological variability of weed seed in the soil seedbank and impact on weed-crop competition.
   1. Subobjective 2A: conduct a regional protocol to assess the fates (primarily predation) of weed seed in the soil seedbank.
   2. Subobjective 2B: conduct a regional protocol to assess weed seed decay due to depth, field site, and cropping system.
   3. Subobjective 2C: conduct a regional protocol assessing the predictability of seedling emergence from the weed seedbank.
   Accomplishments: This second objective has fostered close collaboration with other states and researchers regarding the three primary weed species of the north central states. Researchers have determined robust estimates of seed persistence for velvetleaf, common lambsquarters, and giant foxtail. When the seed persistence data are pooled over sites within burial periods, persistence rates for each burial period are the same across years for each of the species (ABUTH: Oct Mar, 75%, Mar-Oct, 59%; CHEAL: Oct-Mar, 70%, Mar-Oct, 67%; SETFA: Oct-Mar, 73%, Mar-Oct, 32%). This has led to considerably heightened understanding and insights into how these species survive in soil seedbanks. As a consequence, our ability to forecast the population dynamics of these species under differing soil management scenarios has increased significantly. Impacts: An impact of this project has been a greater understanding on the management of weed seed banks. Weed management strategies have typically focused on the seedling to mature stage of the plants life-cycle. One focus of this project has been to evaluate how management strategies influence weed seed bank degradation. Results have shown that seed depth and environmental factors such as moisture and temperature have a significant impact on weed seed dynamics. This is just the beginning of understanding what factors affect weed seed bank degradation. This information could potentially be important in constructing models to manage weed populations. Additionally, working groups have been constructed in Michigan to work with growers to discuss and implement different practices to help manage the weed seed bank.
3. Objective 3: Develop DSS modules to incorporate risk into weed management recommendations.
   1. Subobjective 3A: develop a DSS module based on stochastic weed-crop competition to incorporate yield loss risk into weed management recommendations.
   2. Subobjective 3B: develop a DSS module based on stochastic seedbank dynamics to incorporate time of emergence risk into weed management recommendations.
   Accomplishments: There is an overlap of participants in both the multi-state research project with the regional development of the decision support system, WeedSOFT. Knowledge generated from research projects is directly input into annual updates of WeedSOFT for each state. Members of NC202 have met with the WeedSOFT group on numerous occasions to discuss opportunities and plans for integrating information. Impacts: NC202 derived data is input into a widely available decision support tool across the North Central region. As of 2004, 620 new, updated, or complementary copies of WeedSOFT were in the hands of crop consultants, agronomists, county agents, and producers across 7 states in the Midwest. The success of NC202 could serve as a model for regional research efforts. The participating scientists developed research protocols that were conducted in multiple environments, leading to a database much more powerful than would have been possible working independently. The result is the generation of valuable biological and environmental data in a very efficient manner.

Andersen, S., S.A. Clay, L.J. Wrage, and D. Matthees. 2004. Soybean foliage residues of dicamba and 2,4-D and correlation to application rates and yield. Agron. J. 96:750-760. Banken, K. 2000. Influence of yellow foxtail on corn growth and western corn rootworm development. M.S. Thesis, Brookings, SD 128 p. Blinka, E.L. 2004. Growth analysis of shattercane (Sorghum bicolor), common sunflower (Helianthus annuus), Palmer amaranth (Amaranthus palmeri), and corn (Zea mays). MS Thesis, Kansas State University, Manhattan. Burton, M.G., D.A. Mortensen, and J.L. Lindquist. 2004. Effect of cultivation and soil heterogeneity on survival, growth and fecundity of Helianthus annuus in maize. Soil Tillage Research (in press). Burton, M.G., D.A. Mortensen, D.B. Marx, and J.L. Lindquist. 2004. Factors affecting the realized niche of common sunflower (Helianthus annuus L.) in ridge tillage corn. Weed Science 52:779-787. Chang, J., D.E. Clay, K. Dalsted, S.A. Clay, and M. ONeill. 2004. Corn (Zea mays L.) yield prediction using multispectral and multidate reflectance. Agronomy J. 95:1447-1453. Chang, J., S.A. Clay, D.E. Clay, and K. Dalsted. 2004. Detecting weed-free and weed-infested areas of a soybean (Glycine max) field using near-infrared spectral data. Weed Sci. 52:642-648. Clay, D.E., S.A. Clay, J. Jackson, K. Dalsted, C. Reese, Z. Liu, D.D. Malo, and C.G. Carlson. 2003. C13 discrimination can be used to evaluate soybean yield variability. Agron. J. 95:430-435. Clay, S., J. Kleinjan, D.E. Clay, F. Forcella, and W. Batchelor. 2005. Growth and fecundity of several weed species in corn and soybean. Agronomy Journal 97: in press (accepted 10 September 2004). Clay, S.A. 2000. Herbicide management to maintain environmental quality: Lessons to be learned from North American herbicide management practice. P. 167-176. In: Wilson, M.J. and B. Maliszewska-Kordybach. Soil Quality, Sustainable agriculture and environmental security in Central and Eastern Europe. Series 2. Environmental Security. Vol. 69. Klewer Academic Publishers. Boston, MA. Clay, S.A. and G. Johnson. 2002. Scouting for weeds. Crop Manage. Doi:10.1094/cm-2002-1206-01-MA Published Dec. 2002. Clay, S.A., J. Chang, D.E. Clay, C.L. Reese, and K. Dalsted. 2004. Using remote sensing to develop weed management zones in soybeans. Site Specific Management Guidelines. SSMG-42. April 2004. Online at www.ppi-far.org/ssmg. Conley, S. P., D. E. Stoltenberg, C. M. Boerboom, and L. K. Binning. 2003. Predicting soybean yield loss in giant foxtail (Setaria faberi) and common lambsquarters (Chenopodium album) communities. Weed Sci. 51:402-407. Conley, S. P., L. K. Binning, C. M. Boerboom, and D. E. Stoltenberg. 2003. Parameters for predicting giant foxtail cohort effect on soybean yield loss. Agron. J. 95:1226-1232. Conley, S. P., L. K. Binning, C. M. Boerboom, and D. E. Stoltenberg. 2002. Estimating giant foxtail cohort productivity and fecundity in soybean based on weed density, leaf area, or volume. Weed Sci. 50:72-78. Deines, S.R. 2002. Shattercane (Sorghum bicolor (L.) Moench) and common sunflower (Helianthus annuus L.) interference in corn (Zea mays L.) and light level influence on their relative competitiveness. MS Thesis, Kansas State University, Manhattan. Deines, S.R., J.A. Dille, E.L. Blinka, D.L. Regehr, and S.A. Staggenborg. 2005. Common sunflower (Helianthus annuus) and shattercane (Sorghum bicolor) interference in corn. Weed Science (accepted 7/14/04). Dekker J. and M. Hargrove. 2002. Weedy adaptation in Setaria spp.: V. Effects of gaseous environment on giant foxtail (Setaria faberii R. Hermm.) (Poaceae) seed germination. American Journal of Botany 89(3):410-416. Dekker, J, B. Atchison, and K. Jovaag. 2003. Setaria spp. seed pool formation and initial assembly in agro-communities. Aspects of Applied Biology 69:247-259. Dekker, J. 2000. Emergent weedy foxtail (Setaria spp.) seed germinability behavior. Pages 411-423 In: Seed Biology: Advances and Applications (M. Black, K.J. Bradford, and J. Vasquez-Ramos, Eds). CAB International, Wallingford, UK. Dekker, J. 2003. The foxtail (Setaria) species-group. Weed Science 51:641-646. Dekker, J. 2004a. The evolutionary biology of the foxtail (Setaria) species-group. Pages 65-113 In: Weed Biology and Management; Inderjit (Ed.). Kluwer Academic Publishers, The Netherlands. Dekker, J. 2004b. Invasive plant life history determinants of yield in disturbed agro-ecosystems. XIIth International Conference on Weed Biology, Dijon, France. Association Française pour la Protection des Plantes Annales: 5-14. Dekker, J., J. Lathrop, B. Atchison, and D. Todey. 2001. The weedy Setaria spp. phenotype: How environment and seeds interact from embryogenesis through germination. Proceedings of the Brighton Crop Protection Conference-Weeds 2001:65-74. Ekeleme, F., F. Forcella, D. W. Archer D, I. O. Akobundu, and D. Chikoye. 2005. Seedling emergence model for tropic ageratum (Ageratum conyzoides). Weed Science 52: (Accepted 31 August 2004). Ekeleme, F., F. Forcella, D. W. Archer, D. Chikoye, and I. O. Akobundu. 2004. Emergence model for cogongrass (Imperata cylindrica) in the humid tropics. Weed Science 51: (Accepted 6 July 2004). Ellsbury, M. M., Clay, S. A., Fleischer, S. J., Chandler, L. D., and Schneider, S. M. 2000. Use of GIS/GPS Systems in IPM: Progress and Reality. Pages 419-438 in: Emerging Technologies for Integrated Pest Management: Concepts, Research, and Implementation. G. C. Kennedy and T. B. Sutton, eds. American Phytopathological Society, St. Paul, MN. Ellsbury, M., S.A. Clay, K.H. Banken, and F. Forcella. 2004. Interactions among western corn rootworm (Coleoptera: Chrysomelidae), yellow foxtail, and corn. Environmental Entomology (in press). Ellsbury, M.M., S.A. Clay, and K. Banken. 2004. Interactions Among Western Corn Rootworm (Coleoptera: Chrysomelidae),Yellow Foxtail, and Corn. Econ. Entom. (accepted) Evans, S.P., S.Z. Knezevic, J.L. Lindquist, and C.A. Shapiro. 2003. Influence of nitrogen and duration of weed interference on corn growth and development. Weed Science 51:546-556. Evans, S.P., S.Z. Knezevic, J.L. Lindquist, C.A. Shapiro, and E.E. Blankenship. 2003. Nitrogen application influences the critical period for weed control in corn. Weed Science 51:408-417. Fischer, D.W., R.G. Harvey, T.T. Bauman, S. Phillips, S.E. Hart, G.A. Johnson, J.J. Kells, J.L. Lindquist, and P. Westra. 2004. Chenopodium album interference with Zea mays across the north central USA. Weed Science (in press). Forcella, F. and G.A. Amundson. 2004. Methods in weed ecology: Glue retains seeds in shatter-prone seedheads. Weed Technology 18: 183-185. Forcella, F., T. Webster, and J. Cardina. 2003. Protocols for weed seed bank determination in agro-ecosystems. In: Weed management for developing countries, Addendum I. R. Labrada (Ed.). FAO-Rome Plant Production and Protection Paper 120, pp. 3-18. Guza, C. J. and J. J. Kells. 2003. Weed growth and corn yield as affected by time of weed emergence. Proc. North Cent. Weed Sci. Soc. 58 Hock, S.M., S.Z. Knezevic, A.R. Martin, and J.L. Lindquist. 2005. Competitive indices of major weed species in soybean. Weed Science (in review). Hock, S.M., S.Z. Knezevic, A.R. Martin, and J.L. Lindquist. 2005. Influence of soybean row spacing and emergence time on velvetleaf (Abutilon theophrasti). Weed Science (in press). Kegode, G. O. and M. J. Christoffers. 2003. Intriguing World of Weeds: Biennial wormwood (Artemisia biennis Willd.). Weed Technology 17:646-649. Kegode, G. O., F. Forcella, and B. R. Durgan. 2003. Effect of common wheat management alternatives on weed seed production. Weed Technology. 17:764-769. Knezevic, S.Z., S.P. Evans, E. Blankenship, R. Van Acker, and J.L. Lindquist. 2002. Critical period of weed control: The concept and data analysis. Weed Science 50:773-786. Lindquist, J.L. 2001. Light-saturated CO2 assimilation rates of corn and velvetleaf in response to leaf nitrogen and development stage. Weed Science 49:706-710. Lindquist, J.L. 2001. Performance of INTERCOM for predicting Zea mays - Abutilon theophrasti interference across the north central USA. Weed Science 49:195-201. Liphadzi, K.B. 2004. Weed competitiveness and soil health response to weed management practices. PhD Dissertation, Kansas State University, Manhattan. Mahoney, K. J. and G. O. Kegode. 2004. Biennial wormwood (Artemisia biennis) biomass allocation and seed production. Weed Science 52:246-254. Mengistu, L. W., M. J. Christoffers, and G. O. Kegode. 2004. Genetic diversity of biennial wormwood. Weed Science 52:53-60. Moechnig, M.J., C.M. Boerboom, D.E. Stoltenberg, and L.K. Binning. 2003. Growth interactions in communities of common lambsquarters (Chenopodium album), giant foxtail (Setaria faberi), and corn. Weed Sci. 51:363-370. Moechnig, M.J., D.E. Stoltenberg, C.M. Boerboom, and L.K. Binning. 2003. Empirical corn-yield loss estimation from common lambsquarters (Chenopodium album) and giant foxtail (Setaria faberi) in mixed communities. Weed Sci. 51:386-393. Murphy, C. and J. L. Lindquist. 2002. Growth response of velvetleaf to three post emergence herbicides. Weed Science 50:364-369. Paz, J.O., W.D. Batchelor, D.E. Clay, S.A. Clay, and C. Reese. 2003. Characterization of Soybean Yield Variability Using Crop Growth Models and 13C Discrimination. Trans. ASAE. ASAE meeting presentation # 033044. Schirmacher, K. 2004. Interference of eight annual weeds in corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) in Kansas. MS Thesis, Kansas State University, Manhattan. Smeltekop, H., D.E. Clay, and S.A. Clay. 2002. The impact of sava snail medic cover crop on corn production, stable isotope discrimination, and soil quality. Agron Journal 94:917-924. Tranel, D. and J. Dekker. 2002. Differential seed germinability in triazine-resistant and -susceptible giant foxtail (Setaria faberii). Asian Journal of Plant Sciences 1(4):334-336. Traore, S., J.L. Lindquist, A.R. Martin, D.A. Mortensen, and S.C. Mason. 2002. Comparative ecophysiology of grain sorghum and Abutilon theophrasti in monoculture and in mixture. Weed Research 42:65-75. Waltz, A.L., A.R. Martin, F.W. Roeth, and J.L. Lindquist. 2004. Glyphosate efficacy varies with application time of day. Weed Technology (in press). Wolf, R., S.A. Clay, and L.J. Wrage. 2000. Herbicide strategies for managing kochia (Kochia scoparia) resistant to ALS-inhibiting herbicides in wheat (Triticum aestivum) and soybean (Glycine max). Weed Tech. 14:268-273.