2007 Annual Report 1a.Objectives (from AD-416) Agricultural production in the New England Region has seriously declined in recent years. Within the past decade alone, farmland in New England has decreased by 393,000 acres. Sustainable cropping systems and management practices are needed to improve agricultural viability and rural economic vitality in this region. Research will be conducted to. 1)identify the constraints to cropping system sustainability,. 2)develop practices and management strategies to overcome or reduce those constraints, and. 3)transfer the technology gained to growers for improving cropping system sustainability. FY 06 Program Increase Objective: Develop effective control measures for potato late blight. Characterize the genetic diversity of P. infestans present in the Northeast. Evaluate the virulence and over-wintering potential of those genotypes identified. Develop chemical, biological and/or cultural methods for controlling new genotypes of P. infestans. 1b.Approach (from AD-416) Limitations to achieving sustainability will be identified through interdisciplinary evaluation of cropping systems designed and managed as a) Status Quo, b) Soil Conserving, c) Soil Improving, and d) Pest Suppressive Systems. Each system will be evaluated for its impacts on soil physical, chemical, and microbiological properties; plant diseases; weeds; profitability and risk; nutrient and water use efficiencies; and their interactions. Simultaneously, research will be conducted to overcome or reduce these limitations through new tillage practices, potentially profitable rotations, improved nutrient and water use efficiences, and biological/cultural control of plant diseases. Knowledge gained from these studies will be integrated into a decision support system and transferred to growers through multiple avenues, including distribution on compact disks, hands-on demonstration at grower meetings, and on-farm trials. The research and technology transfer endeavors proposed in this project are expected to improve agricultural viability and rural economic vitality in the Northeast. 3.Progress Report 1915-62660-001-02T – Trust Fund Agreement with the Maine Potato Board 1915-62660-001-03R – Reimbursable Cooperative Agreement with the University of Maine 1915-62660-001-04N – Outgoing Trust Fund Agreement with the Maine Potato Board All subordinate projects are making good progress toward meeting their research goals and objectives. Progress is monitored through frequent face-to-face meetings and email correspondence with stakeholders and collaborators. For a complete report on the progress of these subordinate projects, see the corresponding annual report. 4.Accomplishments Brassica Green Manure Crops Reduce Soilborne Potato Diseases Soilborne diseases are persistent, recurring problems in potato production and are difficult to control, resulting in reduced plant growth, tuber quality, and yield. Brassica rotation crops and green manures have the potential to control multiple soilborne diseases through biofumigation and changes in soil microbial communities. In on-farm field trials conducted over 2 years, mustard, canola, and rapeseed green manures reduced powdery scab by 15-40%, and canola and rapeseed reduced black scurf by 70-80%. A mustard green manure also reduced common scab by 25%. Overall, mustard was most effective in reducing powdery and common scab diseases, and rapeseed and canola were most effective in reducing Rhizoctonia diseases. This research provides growers with a viable tool for reducing soilborne disease levels without additional pesticides. This accomplishment contributes to the NP216 Action Plan, Component 2, Specialty Crop Production Systems, Problem Area 2A, Alternative Management Strategies, Objective 2A2, Develop ecological-based pest management strategies that enhance yields and market quality, while reducing the need for pesticides. Combining Biological Amendments and Cultural Practices Improves Disease Control and Productivity Potatoes frequently suffer from numerous soilborne diseases that reduce plant growth, tuber quality, and yield. Biological amendments, including biocontrol organisms, microbial inoculants, and compost teas, may be used to increase soil microbial diversity and antagonism towards soilborne pathogens. In multi-year field trials, combining conifer-based compost and biocontrol amendments resulted in significant reductions in Rhizoctonia disease (23-48%) and improved tuber yield (30-50%). Combining biological amendments with an effective crop rotation (barley underseeded with ryegrass) reduced stem canker, black scurf, and common scab by 18-33% and increased yield by 20-32%. This research indicates that combining biological and cultural practices can provide substantial benefits for reducing disease and increasing yield without additional pesticides. This accomplishment contributes to the NP216 Action Plan, Component 2, Specialty Crop Production Systems, Problem Area 2A, Alternative Management Strategies, Objective 2A2, Develop ecological-based pest management strategies that enhance yields and market quality, while reducing the need for pesticides. Reducing Sediment and Phosphorus Movement in Potato Systems The current potato production system is vulnerable to erosion and runoff, especially before potato emergence and after potato harvest. Greenhouse research was conducted using rainfall simulators to evaluate the effects of mulch and polyacrylamide PAM) application rate and cover crop seeding rate on sediment load and phosphorus (P) movement. Reducing sediment loss by 50% required mulch application rates of only 500-700 pounds per acre, with the positive effect lasting through four successive rainfall events. Higher application rates reduced sedimentation by up to 90%. The application of PAM also consistently reduced sediment loss, with 10-12 pounds of PAM per acre needed to reduce sediment loss by 50%, although this effect declined with successive rainfall events. Under field conditions, we demonstrated the fall-applied mulch significantly reduced sediment loss through the following spring, while PAM had only short-term effects on sediment loss. This research information helps to optimize conservation practices appropriate for the potato production system that will reduce soil loss and maintain or increase yields. This accomplishment contributes to the NP216 Action Plan, Component 1, Agronomic Crop Production Systems, Problem Area 1A, Strategies for Reducing Costs and Risks, Objective 1A2, Develop specific conservation management practices and document their benefits on natural resource quality for agronomic crop production systems. Production System Characteristics Affect Potato Yield Soil management, crop rotation, and irrigation can all constrain potato yield and quality. A long-term field experiment was established in 2004 to assess the individual and interactive effects of these factors on potatoes in Maine. Cropping systems include two status quo rotations (potato-potato and barley-potato), along with soil conserving, soil improving, and disease suppressive three-year rotations. Annual application of compost in the soil improving system since 2004 increased marketable potato yield by 31% in 2006 compared to the status quo continuous potato system. Soil carbon or organic matter was also increased by nearly 20% in the soil improving system, due to both the compost and a reduction in tillage intensity. This research helps to identify constraints to the sustainability of cropping systems in the Northeast. This accomplishment contributes to the NP216 Action Plan, Component 2, Specialty Crop Production Systems, Problem Area 2A, Alternative Management Strategies, Objective 2A1, Identify management practices to lower total production costs and maintain market quality. Altering Carbon and Nitrogen Retention in Potato Systems Maintaining soil organic carbon (C) in intensively tilled potato systems is difficult, and mineralized soil C is emitted to the atmosphere. Three of the production scenarios compared in a long-term field experiment in Presque Isle, ME, are directly related to soil C sequestration and greenhouse gas emission: a status quo system (barley-potato rotation); and two similar systems that seek to increase soil C concentration, either without amendment (no till barley-sod-potato) or with amendment (no till barley-sod-potato with annual compost application). To assess the impact on greenhouse gas emissions from different production systems, we monitored the release of carbon dioxide, methane, and nitrous oxide at approximately weekly intervals. Carbon dioxide emission was much higher during the potato phase of the rotation, which is attributed to intensive tillage during the potato phase. Application of nitrogen as both compost and fertilizer also affected nitrous oxide emission. This research expands our ability to assess the environmental impact of different potato production systems. This accomplishment contributes to the NP216 Action Plan, Component 2, Specialty Crop Production Systems, Problem Area 2A, Alternative Management Strategies, Objective 2A1, Identify management practices to lower total production costs and maintain market quality. It also contributes to the cross-location GRACEnet project within USDA-ARS. Potato Late Blight Infection from a Common Weed Potato Late Blight, caused by Phytophthora infestans, is a serious worldwide threat to the potato and tomato industries. We previously reported the first identification in Maine of P. infestans on a common weed, hairy nightshade. In 2007, we further evaluated the significance of hairy nightshade as an alternate host to potato Late Blight. We found that Late Blight severity varied with source of inoculum (9-37%), weed growth stage (6-21%), temperature (1-14%) and relative humidity (6-18%). This research shows potato growers that they can reduce their risk of potential Late Blight infection by controlling hairy nightshade weed populations. This accomplishment contributes to the NP216 Action Plan, Component 2, Specialty Crop Production Systems, Problem Area 2A, Alternative Management Strategies, Objective 2A2, Develop ecological-based pest management strategies that enhance yields and market quality, while reducing the need for pesticides. 5.Significant Activities that Support Special Target Populations Research accomplishments from this project will benefit small farms, because approximately 23,000 farms in the New England Region (94%) are classified as small farms (1997 Census of Agriculture). 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 26 Number of newspaper articles and other presentations for non-science audiences 6 Review Publications Larkin, R.P., Griffin, T.S. 2007. Control of soilborne potato diseases using brassica green manures. Crop Protection Journal. 26:1067-1077. Olanya, O.M., Larkin, R.P. 2006. Efficacy of Essential Oils and Biopesticides on Phytophthora Infestans Suppression in Laboratory and Growth Chamber Studies. Biocontrol Science and Technology; 16:901-917. Larkin, R.P. 2007. Relative Effects of Biological Amendments and Crop Rotations on Soil Microbial Communities and Soilborne Diseases of Potato. Soil Biology and Biochemistry. 10:1016. 40:1341-1351. Heckman, J.R., Jokela, W., Morris, T., Beegle, D.B., Sims, T., Coale, F.J., Herbert, S., Griffin, T.S., Hoskins, B., Jemison, J. 2006. Soil test calibration for predicting corn response to phosphorus in the northeast usa. Agronomy Journal. 98:280-288 Olanya, O.M., Starr, G.C., Honeycutt, C.W., Griffin, T.S., Lambert, D.H. 2007. Microclimate and potential for late blight development in irrigated potato. Crop Protection Journal. 26:1412-1421