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Kathleen Delate

Because cropping systems must fit into the environmental, social, cultural and economic reality of the farming community, it is essential that practitioners are included in designing experimental techniques and evaluating application for their farms. Iowa State Univ. conducted a series of Focus Groups with growers and agribusiness professionals to assist in the design of vegetable cropping systems research trials. Trials were established to investigate vegetable agroecosystem status and needs. An agroecosystem analysis seeks to identify indicators of sustainability in a system, including plant health, biological diversity, soil/water quality, and level of biological control of insects and diseases. From this work, a checklist of ecological parameters has been developed for use in cropping systems research. Examples from Iowa, California, and North Carolina will be presented as case studies, exploring multi-disciplinary approaches to cropping systems research.

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Joseph N. Aguyoh, John B. Masiunas and Catherine Eastman

Integrated weed management strategies maintain sub-threshold levels of weeds. The remaining weeds may impact the feeding and habitation patterns of both potato leafhoppers and bean leaf beetles in a snap bean agroecosystem. The objective of our study was to determine the effect of interference between snap beans (Phaseolus vulgaris L.) and either redroot pigweed (Amaranthus retroflexus L.) or large crabgrass (Digitaria sanguinalis L.) on populations of potato leafhopper [Empoasca fabae (Harris)] and bean leaf beetle [Cerotoma trifurcata (Forster)]. Plots were seeded with redroot pigweed or large crabgrass at either the same time as snap bean planting (early) or when snap bean had one trifoliate leaf open (late). The weed density averaged two plants per meter of row. Bean leaf beetle populations, snap bean pod damage, and leaf defoliation were lower in weed-free plots compared to those with either early emerging pigweed or crabgrass. Leafhopper nymphs and adults were 31% to 34% less in plots with crabgrass emerging with snap beans compared to those in weed-free snap bean plots. Thus, the effect of sub-threshold densities of pigweed and crabgrass on insect pests in snap bean varied depending on the species and should be considered when deciding to integrate weed management approaches.

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Jason Walker, John S. Caldwell and Robert H. Jones

To assess the value of uncultivated vegetation for control of cucumber beetles, populations of striped (Acalymma vittatum Fabr.), spotted (Diabrotica undecimpunctata howardi Barber), and western cucumber beetles (Acalymma trivittatum Mann.) (Coleoptera: Chrysomelidae) and natural enemy Diptera flies (as an indicator of Celatoria spp. parasitoids), Pennsylvania leatherwings (Chauliognathus pennsylvanicus DeGeer) (Coleoptera: Cantharidae), lady beetles (Coleoptera: Coccinellidae), Hymenoptera wasps, and spiders were monitored with sticky traps on 50-m transects running through a field of Cucumis sativa L. `Arkansas Littleleaf' into bordering uncultivated vegetation. Plant species composition was determined in square plots around each sticky trap by estimating total plant cover and height distribution of plants from 0 to 1.0 m. In both years, numbers of cucumber beetles increased and numbers of Diptera decreased towards the crop. These trends increased monthly to peaks in Aug. 1995 (0.3 to 6.0 striped cucumber beetles; 40.0 to 15.3 Diptera) and July in 1996 (0.1 to 7.1 striped cucumber beetles; 46.7 to 15.5 Diptera). Abundance of individual plant species contributed more to maximum R 2 regression of insect populations than did measures of plant diversity in sampling squares. Diptera were negatively correlated with sweet-vernal grass (r = –0.65 at 0 m) and wild rose (r = –0.62 at 0.5 m) in 1995, and goldenrod (r = –0.31, –0.59, and –0.53 at 0.5, 0.75, and 1.0 m, respectively) in 1996, but positively correlated with wild violets (Viola spp.) (r = +0.38 at 0 m) in 1996. Cucumber beetles were negatively correlated with wild violets (r = –0.30 at 0 m) and white clover (Trifolium repens) (r = –0.37 at 0 m) in 1996. These results suggest that increasing or decreasing specific plants in uncultivated vegetation might be useful for influencing pest and beneficial insect populations in cucurbit production.

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J.P. Mueller, M. E. Barbercheck, M. Bell, C. Brownie, N.G. Creamer, A. Hitt, S. Hu, L. King, H.M. Linker, F.J. Louws, S. Marlow, M. Marra, C.W. Raczkowski, D.J. Susko and M.G. Wagger

The Center for Environmental Farming Systems (CEFS) is dedicated to farming systems that are environmentally, economically, and socially sustainable. Established in 1994 at the North Carolina Department of Agriculture and Consumer Services (NCDACS) Cherry Farm near Goldsboro, N.C.; CEFS operations extend over a land area of about 800 ha (2000 acres) [400 ha (1000 acres) cleared]. This unique center is a partnership among North Carolina State University (NCSU), North Carolina Agriculture and Technical State University (NCATSU), NCDACS, nongovernmental organizations (NGOs), other state and federal agencies, farmers and citizens. Long-term approaches that integrate the broad range of factors involved in agricultural systems are the focus of the Farming Systems Research Unit. The goal is to provide the empirical framework to address landscape-scale issues that impact long-run sustainability of North Carolina's agriculture. To this end, data collection and analyses include soil parameters (biological, chemical, physical), pests and predators (weeds, insects and disease), crop factors (growth, yield, and quality), economic factors, and energy issues. Five systems are being compared: a successional ecosystem, a plantation forestry-woodlot, an integrated crop-animal production system, an organic production system, and a cash-grain [best management practice (BMP)] cropping system. An interdisciplinary team of scientistsfrom the College of Agriculture and Life Sciences at NCSU and NCATSU, along with individuals from the NCDACS, NGO representatives, and farmers are collaborating in this endeavor. Experimental design and protocol are discussed, in addition to challenges and opportunities in designing and implementing long-term farming systems trials.

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Nicholas D. Warren, Richard G. Smith and Rebecca G. Sideman

beneficial effects of the LM on other aspects of agroecosystem performance, including suppression of weeds ( Brainard and Bellinder, 2004 ; Chase and Mbuya, 2008 ; Infante and Morse, 1996 ) or insect pests ( Bhan et al., 2010 ; Costello, 1994 ; Hooks and

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Kevin R. Kosola and Beth Ann A. Workmaster

role in N nutrition in cultivated cranberries. Establishing the role of mycorrhizal utilization of organic N in cranberry N cycling is a reasonable goal in these agroecosystems. This work would be enhanced by characterization (e.g., Allen et al., 2003

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Neil S. Mattson and Marc W. van Iersel

, the traditional paradigm has been supplying nutrients to meet plant demands, perhaps this should be shifted to adjusting crops and agroecosystems to be tuned to nutrient supply. An in-depth understanding of mineralization of nutrients in cover crops

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Sam Marshall, David Orr, Lucy Bradley and Christopher Moorman

in agroecosystems Ecol. Appl. 6 276 284 Menalled, F. Marino, P. Gage, S. Landis, D. 1999 Does agricultural landscape structure affect parasitism and parasitoid diversity? Ecol. Appl. 9 634 641 Milesi, C. Running, S.W. Elvidge, C.D. Dietz, J.B. Tuttle

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Laurie E. Drinkwater

Systems approaches to research can be used to study characteristics of agricultural systems that cannot be addressed using conventional factorial experiments. The goal of a factorial experiment is to break down a complex system in order to isolate and study specific components and identify cause-effect relationships. In contrast, systems experiments aim to understand how a complex system functions as a whole and thus requires that intact systems be studied. Two approaches have been successfully applied to agricultural systems research: 1) field station experiments where simulated cropping systems are established in replicated plots and 2) studies of intact agroecosystems using commercial farms as study sites. These two approaches have complementary strengths and limitations and have made significant contributions to our understanding of ecological processes in agricultural systems. The development of sustainable agroecosystems will be best accomplished using an integrated research approach combining systems experiments with appropriately designed factorial experiments.

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William Reid

Pecans (Carya illinoinensis) are produced under a wide array of environmental conditions—from the warm humid southeastern states, to the continental climate of the central plains, to the arid climates of the American west. In addition, pecan cultural systems vary from the low-input management of native stands of seedling trees to the intensive management of single-cultivar pecan orchards. This wide diversity of pecan agroecosystems has fostered the development of innovative, site-specific approaches toward pecan pest management. Current pecan pest management programs require an intimate knowledge of orchard ecology. Growers use monitoring methods and prediction models to track pest populations. Biological control agents are conserved by habitat manipulation and/or augmented through inoculative releases. Selective pesticides are used to control target pests while conserving natural enemies. Four pecan cultural systems are described in detail to illustrate how ecological principles are applied to widely diverse pecan agroecosystems.