2004 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? What does it matter? Conventional field cropping systems have been criticized as being unsustainable because they contribute to environmental degradation (on-farm and off-farm), and are often economically uncertain. Reducing production costs, through the use of conservation tillage and reducing inputs as a means of increasing environmental and economic sustainability of cropping systems are needed. There is a critical need to develop management technologies to improve soil quality with adaptation of suitable cover crops for off season soil management, reduced tillage and weed management. Integrated cropping systems for potatoes which optimize rotational crops in irrigated light texture soils are needed to maximize yield, crop quality and minimize potential adverse impacts on soil and water resources. Two long-term cropping systems experiments have been established to evaluate the sustainability of reduced-till, and conventional till cropping systems and the use of fall-planted cover crops in irrigated potato rotations. The project was designed with the aid of a group of farmers, extension agents, agribusiness professionals, and other agricultural researchers. The major focus of this research is to evaluate the sustainability of the irrigated potato production systems by measuring agronomic performance, soil quality, nutrient dynamics, soil biological activity and community structure, and weed density and species shifts in several cropping systems. Specific objectives of this project are to:. 1)determine the effects of reduced tillage and fall-planted cover crops in irrigated potato production systems on weed dynamics and develop weed management strategies that minimize the negative impacts of weeds. 2.) Understand the processes controlling soil biological activity and community structure of the: i. soil micro-flora, ii. plant pathogens, iii. nematodes, and iv. insects under reduced tillage and cover crops in irrigated potato production systems.. 3)Determine and understand the mechanisms controlling carbon and nitrogen cycling and trace gas (CO2, N2O, CH4) fluxes under reduced tillage in irrigated potato production systems.. 4)Evaluate potato crop performance, potato tuber quality, soil fertility and nitrate leaching below the root zone under variable rates of pre-plant and in-season N applications under conventional and reduced tillage.. 5)Evaluate the soil and plant growth parameters of a potato growth model, and validate the model for major potato cultivars and different management practices. This research will provide a greater understanding of the relative sustainability of conventional and alternative cropping systems, identify key challenges to increased sustainability, and develop a better understanding of mechanisms controlling ecological processes in these diverse cropping systems. Conventional, high input, high disturbance cropping systems have been criticized as being unsustainable because they contribute to environmental degradation (on-farm and off-farm), and are often economically uncertain. Potato production in the US is a $2.5 billion industry with production costs ranging from $480 to $1050 ha-1 across the country, more than for any other crop. Potatoes are grown commercially in every state in the U.S. However, over the past few years, ten states have consistently accounted for 88 percent of output. Since the 1950's, the bulk of U.S. potato production has gradually shifted to the Western states. The Pacific Northwest (PNW) accounted for 52% of U.S. potato acreage in 2000. Russet potatoes account for about two-thirds of the U.S. crop and are heavily concentrated in PNW. Currently, 70 million pounds of pesticides (not including sprout inhibitors used in storage) are used in potato production nationwide (NASS, 2001). Of that amount, the PNW accounts for 80% of all pesticides used. Potatoes are typically grown on soils low in organic matter content that are highly susceptible to agrichemical leaching under poor irrigation scheduling, and wind erosion after harvest. Increasing public concern about environmental quality and the sustainability of irrigated agro-ecosystems has emphasized the need to develop and implement management strategies that maintain and protect soil and water resources. Both of these issues are related to maintaining the quality of soil resources through improved soil management. Cover cropping systems and conservation tillage that reduce erosion, reclaim excess N, build organic matter, and suppress pests could improve soil and environmental quality. Conservation tillage has shown success in dry-land applications and its continued adoption is a means of improving environmental, biological and economic sustainability of diverse cropping systems. However, limited information about the applicability of conservation tillage under irrigated vegetable (potato) production is available to make similar assessments. There are many unanswered questions about the ecological interactions fundamental to the productivity and sustainability of potato cropping systems. Assessing sustainability and studying basic interactions among system components are multifaceted tasks that require long-term studies. Long-term studies are necessary to account for year-to-year variability in system performance and to account for ecological processes that change slowly and respond to episodic events. Long-term studies also provide a rich database that can enhance multidisciplinary research and support investigations by system modelers. This research will benefit the agricultural industry by improving the efficiency of production inputs that optimizes crop yield and quality, and protects soil and environmental quality. The general public benefits through reduced adverse impacts on soil, water, and air quality. Potato growers of irrigated annual crops, extension personnel, and crop consultants will use new information and recommendations that result from this research. This research will result in development of recommendations for integrating reduced tillage, cover crops, improved nutrient and irrigation management, and alternative weed and crop management practices in annual irrigated cropping systems to reduce pests, reduce herbicide and other pesticide inputs, and minimize negative impacts on the environment. Improved irrigation and nutrient management, weed control, and cover crop management prescriptions for potato and rotational crops will increase input use efficiencies, protect soil and groundwater quality, capture nutrients and reduce the severity of disease, insect pests, and weeds. 2.List the milestones (indicators of progress) from your Project Plan. Objective 1: Year 1 (2004) Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control (year 1 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 1 of 3). Determine weed density and biomass and crop (potato, sweet corn, and wheat) yield following four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 3 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 2 (2005) Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control (year 2 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 2 of 3). Determine weed density and biomass and crop yield (potato, sweet corn, and wheat) following four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 4 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 3 (2006) Establish tillage plots and herbicide treatments for volunteer potato control (year 3 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 3 of 3). Summarize the long term effects of fall planted cover crops on weed density and crop yield. Generate cover crop recommendations based on results obtained. Year 4 (2007) Summarize volunteer potato control data from 3 year tillage study. Establish volunteer potato management recommendations based on results. Publish results on weed management using fall planted cover crops in refereed scientific publications and present results at scientific and farm organization meetings and local field days. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of volunteer potato management in reduced and conventional tillage study in refereed scientific publications and trade journals. Present results at scientific and farm organization meetings and local field days. Objective 2: Year 1 (2004) Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 1 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 1 of 3). Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 3 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 2 (2005) Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 2 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 2 of 3). Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 4 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 3 (2006) Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 3 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 3 of 3). Summarize the long term effects of fall planted cover crops on soil microbial populations and diversity. Generate cover crop recommendations based on results obtained. Year 4 (2007) Summarize soil biological data from 3 year tillage study. Establish soil management recommendations based on results. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of reduced and conventional tillage effects on soil biological activity in refereed scientific publications. Present results at scientific and farm organization meetings and local field days. Objective 3: Year 1 (2004) Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 1 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 1 of 3). Year 2 (2005) Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 2 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 2 of 3). Year 3 (2006) Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 3 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 3 of 3). Year 4 (2007) Summarize soil C and N and trace gas flux data from 3 year tillage study. Establish soil management recommendations based on results. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of reduced and conventional tillage effects on soil carbon and N pools and trace gas fluxes in refereed scientific publications. Present results at scientific and farm organization meetings and local field days. Objective 4: Year 1 (2004) Field evaluation of pre-plant and in-season N management practices on tuber yield and quality of new potato cultivars (year 5 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 1 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 3 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Year 2 (2005) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 2 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 4 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 1 of 3). Year 3 (2006) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 3 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 5 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 2 of 3). Year 4 (2007) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 3 of 3). Potato tuber yield and quality response data analysis - effects of various pre-plant and in-season N management under conventional and reduced tillage. Year 5 (2008) Evaluation of N transformation, fate and transport under conventional and reduced tillage. Evaluation of set points for scheduling irrigation using capacitance probes. Develop N and irrigation BMPs for Ranger Russet in sandy soils to maximize N and water uptake efficiency, while minimizing leaching losses. Objective 5: Year 2 (2004) Update the crop coefficients in potato crop growth simulation model - SIMPOTATO. Integration of SIMPOTATO (VB version) into CROPSYST model. Year 2 (2005) Evaluation of SIMPOTATO - CROPSYST for simulation of plant growth, yield, and fate and transport of nitrogen in potato rotation systems. Year 3 (2006) Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model (year 1 of 2). Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. Year 4 (2007) Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model (year 2 of 2). Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. Year 5 (2008) Developing phenology model based decision support system for irrigated potato rotation system. 3.Milestones: Objective 1: Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control (year 1 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 1 of 3). Determine weed density and biomass and crop (potato, sweet corn, and wheat) yield following four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 3 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Objective 2: Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 1 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 1 of 3). Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 3 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Objective 3: Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 1 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 1 of 3) Objective 4: Field evaluation of pre-plant and in-season N management practices on tuber yield and quality of new potato cultivars (year 5 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 1 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 3 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Objective 5: Update the crop coefficients in potato crop growth simulation model - SIMPOTATO. Integration of SIMPOTATO (VB version) into CROPSYST model. All milestones were met. A long term reduced tillage study was initiated utilizing a three year crop rotation of sweet corn/sweet corn/potato. Main plots consisted of conventional tillage and a reduced tillage treatment. Split plots included two herbicide treatments to manage volunteer potatoes in sweet corn and an untreated control. Data was collected on volunteer potato tuber production and corn yield. A long term cover crop study was established and is in the third year of the crop rotation. Effects of soil fumigation and fall planted cover crops of mustard, oat/vetch/ winter wheat, or sorghum-sudangrass on crop yield, weed density and weed seed bank and weed seed viability is being measured each year. Publications and technology transfer milestones are listed under questions 6-9 below. B. Objective 1: Year 2 (2005) Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control (year 2 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 2 of 3). Determine weed density and biomass and crop yield (potato, sweet corn, and wheat) following four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 4 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 3 (2006) Establish tillage plots and herbicide treatments for volunteer potato control (year 3 of 3). Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage (year 3 of 3). Summarize the long term effects of fall planted cover crops on weed density and crop yield. Generate cover crop recommendations based on results obtained. Year 4 (2007) Summarize volunteer potato control data from 3 year tillage study. Establish volunteer potato management recommendations based on results. Publish results on weed management using fall planted cover crops in refereed scientific publications and present results at scientific and farm organization meetings and local field days. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of volunteer potato management in reduced and conventional tillage study in refereed scientific publications and trade journals. Present results at scientific and farm organization meetings and local field days. Objective 2: Year 2 (2005) Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 2 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 2 of 3). Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (year 4 of 4). (Continuation of the previous CRIS 5354-13610-002-00D) Year 3 (2006) Establish reduced and conventional tillage plots for determining processes that control soil biological activity (year 3 of 3). Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage (year 3 of 3). Summarize the long term effects of fall planted cover crops on soil microbial populations and diversity. Generate cover crop recommendations based on results obtained. Year 4 (2007) Summarize soil biological data from 3 year tillage study. Establish soil management recommendations based on results. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of reduced and conventional tillage effects on soil biological activity in refereed scientific publications. Present results at scientific and farm organization meetings and local field days. Objective 3: Year 2 (2005) Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 2 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 2 of 3). Year 3 (2006) Establish reduced and conventional tillage plots for determining processes that control soil carbon and nitrogen cycling under irrigation. (year 3 of 3). Measure soil C and N pools, residue decomposition rates, and trace gas (CO2, N2O, CH4) fluxes in conventional and reduced tillage irrigated potato production systems (year 3 of 3). Year 4 (2007) Summarize soil C and N and trace gas flux data from 3 year tillage study. Establish soil management recommendations based on results. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. Year 5 (2008) Publish results of reduced and conventional tillage effects on soil carbon and N pools and trace gas fluxes in refereed scientific publications. Present results at scientific and farm organization meetings and local field days. Objective 4: Year 2 (2005) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 2 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 4 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 1 of 3). Year 3 (2006) Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 3 of 3). Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling (year 5 of 5). (Continuation of the previous CRIS 5354-13610-002-00D) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 2 of 3). Year 4 (2007) Nitrogen mineralization from crop residues under conventional and reduced tillage (year 3 of 3). Potato tuber yield and quality response data analysis - effects of various pre-plant and in-season N management under conventional and reduced tillage. Year 5 (2008) Evaluation of N transformation, fate and transport under conventional and reduced tillage. Evaluation of set points for scheduling irrigation using capacitance probes. Develop N and irrigation BMPs for Ranger Russet in sandy soils to maximize N and water uptake efficiency, while minimizing leaching losses. Objective 5: Year 2 (2005) Evaluation of SIMPOTATO - CROPSYST for simulation of plant growth, yield, and fate and transport of nitrogen in potato rotation systems. Year 3 (2006) Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model (year 1 of 2). Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. Year 4 (2007) Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model (year 2 of 2). Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. Year 5 (2008) Developing phenology model based decision support system for irrigated potato rotation system. 4.What were the most significant accomplishments this past year? A. Field bindweed (Convolvulus arvensis) is an aggressive perennial weed that infests approximately 10% of irrigated acres in the Columbia Basin, is present throughout North America, and control with herbicides is usually incomplete. Rick Boydston, USDA-ARS agronomist, integrated mite (Aceria malherbae) feeding with sublethal doses of herbicide to control field bindweed. Growth of field bindweed was reduced more with a combination of mites and herbicides than with either alone with no apparent detrimental effect on mite populations. Integrating mites with herbicides allows growers to reduce potential crop injury from herbicides, maintain beneficial mite populations, and reduce herbicide rates while improving control of this troublesome weed. B. Pea growers have no method to determine if nightshade seedlings emerging during the growing season would require control to prevent the contamination of the harvested crop with nightshade berries that are difficult to separate from processing peas. Rick Boydston, agronomist with USDA-ARS, conducted field trials develop a model to predict growing degree days required for hairy nightshade to produce berries larger than 6 mm diameter, which are difficult to separate from peas. Hairy nightshade required approximately 1300 heat units (base 40) to produce berries 6 mm diameter. The model can be used as a decision tool by growers to determine whether to apply a postemergence herbicide for nightshade control and could save growers $25 per acre in herbicide cost by eliminating treatments on later emerging nightshade that are not able to produce berries large enough to contaminate peas. Systemic Acquired Resistance (SAR) is a process where a plant that successfully resists a pathogen becomes highly resistant to subsequent attacks of disease. Dr. Harold P. Collins, Soil Microbiologist, studied the effectiveness and role of several SAR plant activators (BTH, harpin and a beta-glucan) on below ground parts of potato and their effects on microbial populations in the rhizosphere. Bacterial populations increased in the rhizosphere as the season progressed. The SAR inducing compounds tested did not control Rhizoctonia root rot or root knot nematodes but did reduce the numbers of lesion nematodes. Powdery scab, caused by Spongospora subterranean, is a serious problem for potato production in the Pacific Northwest, and the pathogen cannot be cultured using microbiological methods, so early detection of the pathogen in soil and plant tissue has not been possible. George Vandemark, USDA-ARS Research Geneticist, developed a real-time PCR assay to detect and quantify Spongospora subterranean. The PCR assay was tested against several other potato pathogens to confirm the specificity of the assay towards S. subterranea, and used to detect and quantify the pathogen in soil and in the roots of infected potato and alternate weed hosts. The assay can be used to identify fields that are infested with the pathogen, information that will assist growers in choosing an appropriate resistant variety, and may also be useful for rapidly identifying potato seedlings with resistance to S. subterranea. C. None. D. Progress Report: Long term on-farm studies evaluating the effects of reduced tillage, cover crops, and fumigation on soil microbial populations, nitrogen transformation processes, soil organic matter, weed population dynamics, and soil pathogens is continuing near Paterson, WA. Cover crops or fumigation treatments are being tested in a four-year crop rotation of potato/wheat/sweet corn/sweet corn under center pivot irrigation. Cover crops include white mustard, sudangrass, winter wheat, and an oat/vetch mix. In addition, weed seed bank, weed density by species, and effects on buried weed seed will be determined through the crop rotation. Effects of the above cropping practices on the long-term changes in soil chemical properties and nutrient transformation are being evaluated. Fall fumigation reduced weed seed bank and weed density in the following season greater than four cover crops being evaluated. 5.Describe the major accomplishments over the life of the project, including their predicted or actual impact. Potato tubers left in the ground after harvest can survive mild winter soil temperatures and become a serious weed problem in the succeeding crop, reducing the yield of corn and providing a host for late blight, potato virus Y, and root knot nematodes. Field trials were conducted at Paterson, WA to evaluate herbicide treatments for volunteer potato control in field corn. A treatment of mesotrione at the 5 to 7 leaf stage of potato reduced the number of new potato tubers produced by 99 percent while maintaining corn yields equal to hand-weeded checks. Growers can save $100/acre by using this technology to eliminate or reduce hand weeding of volunteer potatoes in corn, while maintaining corn yields and greatly reducing infestations in the succeeding years rotation crop. Corky ringspot (CRS) is a serious disease of potato that infests 5% of the PNW potato acreage and soil fumigation is the only method available to growers for control of CRS. Researchers at the ARS Prosser, WA, Vegetable and Forage Crops Research Unit conducted greenhouse trials that demonstrated the disease can be eliminated from soil by growing weed-free alfalfa or Scotch spearmint. Over thirty weed species were tested as hosts of the virus or nematode vector and nightshade was a particularly suitable host of both tobacco rattle virus and the nematode vector. These findings allows growers to target specific weed hosts in the rotation crops, therefore controlling CRS with crop rotation, and eliminating the need for soil fumigation saving $250/acre. Soil fumigation with broad spectrum soil fumigants like metam-sodium have been assumed to have minor impacts on the general soil microbial community. Studies were conducted at the USDA-ARS Paterson field site as well as on four on-farm field trials to evaluate the effects of soil fumigation and mustard cover crops on soil microbial populations and their functions. Fumigation and mustard cover crops reduced soil fungi, soil pathogens and weeds but had only minor effects on general soil microbial populations and their functions. These studies indicate that potato growers incorporating mustard cover crops in rotation can reduce fumigation inputs with savings up to $150/acre. Within field spatial variability of yield and quality is common in potato production. Understanding this variability could lead to more efficient use of inputs and more consistent yield and quality. Using grid sampling of soil, causes of within-field spatial variability in potato yield and quality were determined on a commercial farm in southeastern Washington. The soil variable which had the highest r with yield differed among fields. Yield variation was highly correlated with either the sand content, silt, clay, or soil pH. Stepwise linear regression analyses also showed that the variation in tuber yield was highly dependent on soil textural class, pH, and OM. Transformation of organic nitrogen (N) from both soil organic matter and from crop residues into inorganic forms is an important process which determines the pool of available N for the subsequent crop. A study was conducted in the Pacific Northwest (PNW) on an irrigated Quincy fine sand where potato was grown in three or four year rotations with either corn or wheat. The decomposition of crop residue and the mineralization of nitrogen (N) provides a source of plant available N to the next crop. An in-situ column incubation technique was used to determine the N mineralized during January through September 2000 from corn, wheat, and potato crop residues. The soil was sieved to determine the amount of crop residues present in the soil which contributes to N mineralization. The dry weight of the crop residue in January soil samples, taken at the top 30 cm depth, ranged from 8.4 for potato to 26.5 Mg ha-1 for corn, but decreased to 4.6 for potato and 12.7 Mg ha-1 for corn in March. Total N content in the crop residue was used to estimate potentially mineralizable N (PMN) at the time of sampling. The PMN in the top 30 cm depth, on the basis of residues sampled in January, were 398, 378, and 121 kg ha-1 for the corn, wheat, and potato crop residues, respectively, but decreased to 189, 114, and 68 kg ha-1, respectively, in March samples. Cumulative N mineralized in the top 30 cm depth of soil during January through September was 172, 128, and 72 kg ha-1 for corn, wheat, and potato residues, respectively. Cumulative N mineralized during January through May accounted for 53 percent of the total N mineralized from January through September. Accumulation and partitioning of dry matter and nitrogen (N) during the growing period were evaluated in this four year study for two potato cultivars in high yielding production conditions in the Columbia Basin production region in Washington, under irrigated farming. Studies were conducted on a Quincy fine sand, which represented a typical potato production soil in this region. A full season indeterminate potato cultivar (Russet Burbank) and an early maturing determinate cultivar (Hilite Russet) were used in this study. Partitioning of assimilates into the tuber was similar for both cultivars. The tuber weight accounted for 76 to 87% of total plant weight, while that of stem and leaf weight accounted for 3 to 11, and 9 to 13%, respectively. Tuber weight increased rapidly during 60 to 100 days after planting. Nitrogen content in the tuber, in relation to the total N in the plant, accounted for 81 to 86, and 83 to 89%, for the Hilite Russet and Russet Burbank cultivars, respectively. Nitrogen in the leaves comprised 6 to 18%, and in the stem 3 to 5% of the total plant N. Prior to senescence of the vines, total N in the plants (excluding roots) accounted for up to 350 kg ha-1. At this growth stage, the N in tubers, leaves, and stems represented 68.6, 19.4, and 12.0%, respectively. The above information is useful for N management with the knowledge of soil residual N and availability of N from mineralization of crop residue during the crop growing season. Water stress at various stages of potato growth can adversely influence the production and quality of tubers. Optimal irrigation scheduling is important to support high production of good quality tubers and to minimize potential adverse impacts on water quality. Effects of two irrigation regimes and three tillage practices on production of two potato varieties were studied under four years rotation with either corn or wheat. In two out of three years, as compared to irrigation to replenish full evapotranspiration (ET), deficit irrigation (85% or ET) decreased total tuber yield by 8 to 11% and 10 to 17%, and U.S. No. 1 tuber yield by 5 to 17% and 16 to 25%, in Russet Burbank and Hilite Russet cultivars, respectively. Tillage treatments evaluated were (i) conventional including raised ridges with dammer-dike; (ii) optimal, i.e., lower depth of the tillage and shallow furrow; and (iii) reduced tillage, i.e., flat planting. During the first two years of the study, the effects of tillage treatments were non-significant on the total as well as U.S. No. 1 tuber yield in both cultivars. On the third year, the tuber yield was significantly lower in flat planting treatment as compared to that in the other tillage treatments. This study demonstrated that in coarse textured soils with adequate water infiltration, excessive tillage and/or dammer-diking may not benefit potato production. The soil and climate conditions prevalent in the Pacific Northwest region are favorable for production of high potato yields. Much of this production occurs on coarse, low organic matter, sandy soils which can be subject to wind and water erosion, and excessive leaching of water and soluble agrichemicals below the rootzone, particularly when irrigation is not managed adequately. Optimal irrigation scheduling is important to support high production of good quality tubers and to minimize potential adverse impacts on water quality. Effects of two irrigation regimes and three tillage practices on production of two potato varieties were studied under four years rotation with either corn (Zea mays L.) or wheat (Triticum aestivum L.). In two out of three years, as compared to irrigation to replenish full ET, deficit irrigation [85% of evapotranspiration (ET) decreased total tuber yield by 8 to 11 percent and 10 to 17 percent, and U.S. NO. 1 tuber yield by 5 to 17 percent and 16 to 25 percent, in Russet Burbank and Hilite Russet cultivars, respectively. Tillage treatments evaluated were: (i) conventional, including raised ridges with dammer-dike; (ii) optimal, i.e., lower depth of the tillage and shallow furrow; and, (iii) reduced tillage, i.e., flat planting. The effects of tillage treatments were non-significant on the total as well as U.S. No. 1 tuber yield in both cultivars. This study demonstrated that in coarse textured soils with adequate water infiltration, excessive tillage and/or dammer-diking may not benefit potato production. Contributed to the development of use patterns of rimsulfuron (Matrix) herbicide for weed control in potatoes and determined that methylated seed oil improved postemergence activity of rimsulfuron on common lambsquarters. Pacific Northwest potato growers are using this new herbicide to help control triazine resistant weeds in potatoes. Weed management in potatoes is accomplished primarily with a combination of herbicides and timely cultivations. Five weed management systems utilizing combinations of cover crops, herbicides, and cultivation were tested in potatoes. Using a combination of all-planted winter rye or rapeseed cover crop with herbicide banding resulted in reduction of early season weed density and final weed biomass and potato tuber yield equal to using a full rate of herbicide broadcast. This integrated system was an effective alternative weed management strategy, which controlled weeds, decreased PRE applied herbicide inputs 66%, and maintained tuber yield. Determined the effect of several environmental parameters on seed and seedling behavior of puncturevine and longspine sandbur, which are serious weed problems in many irrigated horticultural crops and for which effective control programs are lacking. Basic information gained from this research serves as basis for planning the length of weed control period required to prevent seed production and establishment of these two species, depth of herbicide placement required, and has led to improved control programs for these troublesome weeds. Developed new weed control methods for winter and summer annual weeds in spearmint and peppermint. Effective and economical weed control programs were developed that involved timing of tillage, tillage methods, and herbicides. The data from these studies were used to obtain section 18 emergency exemptions for the use of clopyralid (Stinger), sethoxydim (Poast), quizalofop (Assure II), pendimethalin (Prowl), and pyridate (Tough) in mint. Determined that Brassica green manure crops suppress weeds selectively in potatoes and that several isothiocyanates (decomposition products of Brassica tissues) inhibit seed germination and growth. Using different Brassica green manures, we developed weed management systems in potatoes and peas that can reduce herbicide inputs. Use of this technology allows producers to reduce pesticide inputs, decrease soil erosion, reclaim leachable nutrients, and increase wildlife habitat. Capacitance probes which work on the principle of dielectric constant of soil, air, and water provide a valuable tool for automated and continuous monitoring of soil moisture content as basis for best management of irrigation for minimizing water, nutrient, and agrichemical leaching below the crop rootzone, which could adversely impact groundwater quality. The capability to continually monitor the soil moisture content within and below the rooting depth provides required data to develop water mass balance which can be used to calculate the crop evapotranspiration (ET), as well as leaching losses below the target rooting depth. On sandy soils in the Pacific Northwest with low rainfall (less than 7 inches per year), irrigation is a critical factor to support intensive production systems. Deficit irrigation (85% of evapotranspiration, ET) decreased the total tuber yield (8 to 17%) and U.S. No. 1 tuber yield (5 to 25%) in Russet Burbank and Hilite Russet potato varieties as compared to that with irrigation to replenish full ET. Established map of weed seed bank on two commercial potato fields. Two commercial potato fields were grid sampled at one acre interval and weed seed bank and soil characteristics (pH, texture, percent organic matter, phosphorus, potassium, nitrogen) were determined. The spatial distribution of several weed species was quite varied. Weed seed bank relationships to soil physical and chemical properties will be determined. If relationships between weed seed bank and soil characteristics exist and can be defined, more cost effective methods of prescribing weed management inputs using soil characteristics could be developed. Identified new herbicides for nightshade control in potatoes. Nightshade species are difficult to control in potato and currently labeled herbicides and cultivation provide only partial control of nightshade species. Sulfentrazone and flumioxazin applied after final hilling provided greater than 98% control of hairy nightshade and black nightshade prior to potato row closure. Both herbicides did not cause visible injury to potatoes at lower rates that controlled nightshade. Both herbicides were safe on potatoes in combinations with several currently labeled herbicides. Efficacy and residue studies are in progress to obtain data required to label these herbicides on potatoes in the Pacific Northwest. 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? Improved management of volunteer potatoes in rotation crops through use of specific herbicides and cultivation. Presentations were made at the Potato Field Day, Paterson, WA July 16, 2003, Pacific NW Vegetable Association Conference, Pasco, WA on November 20, 2003, Idaho Potato School, Pocatello, ID on January 22, 2004, and at the Weed Science Society of America meetings, Kansas City, MO on February 10, 2004. Technology was transferred to growers, research faculty and scientists, crop consultants, and farm managers. Technology can be utilized by end user immediately. Improved management of corky ringsport disease by controlling specific weed hosts in the crop rotation. Presentations were made at the Potato Association of America meetings, Spokane, WA, on August 11, 2003 and the Washington State Potato Convention, Moses Lake, WA on February 4, 2004. Technology was transferred to growers, research faculty and scientists, potato processors, and crop consultants. 7.List your most important publications in the popular press and presentations to organizations and articles written about your work. A. Presentations: Boydston, R.A. Management of volunteer potato in crop rotations. Presented at the Idaho Potato School, Pocatello, ID, Jan. 22, 2004. Collins, H.P. Carbon sequestration: Emerging agricultural markets. Presented to the Columbia Basin Crop Consultants Association, Moses Lake, WA, Jan 16, 2003 Collins, H.P. Soil Biology: Organic Soil Activity. Presented to the Wilbur-Ellis, Organic Growers Meeting, Sunnyside WA, Feb 20, 2003. Collins, H.P. Integrated Potato Cropping Systems. Presented to the Washington State Society of Soil Scientists Annual Meeting, Prosser, WA. July 31, 2003. Alva, A.K. Pre-plant and in-season nitrogen management for Ranger Russet and Umatilla Russet in the Pacific Northwest. Washington Potato Information Exchange meeting. (i) Kennewick, WA, March 24, 2004; (ii) Moses Lake, WA, March 25, 2004. Vandemark, G.J. Un resumen sobre los patogenos que atacan la papa (A review of the pathogens that attack potato). Presented as part of the ¿Taller de Produccion de Papa en Espanol¿ conducted as part of the 2004 Washington State Potato Conference. Moses Lake, WA, February 3, 2004. Boydston, R. A. Volunteer potato control in corn, weed control in potato, and use of cover crops in potato rotations. Presented at the USDA-ARS Potato Field Day at Paterson, WA July 16, 2003. Boydston, R. A. Influence of nightshade species on corky ringspot persistence in crop rotations. Presented at the Potato Association of America meetings at Spokane, WA, August 11, 2003. Boydston, R. A. Ethofumesate and prometryn: New weed management tools in carrot production. Presented at the Pacific Northwest Vegetable Association Conference in Pasco, WA, Nov. 20, 2003. Boydston, R. A. Weed Control in Pacific Northwest Mint Production. Preseted at the Tri-State Mint Meetings in Boise, ID, Jan. 5, 2004. Boydston, R. A. Weed Control in PNW Mint Production. Presented at the Mint Industry Research Council meetings in Las Vegas, NV, Jan. 15, 2004. Boydston, R. A. Oxyfluorfen labeled for Weed Control in Carrots. Presented at the Washington State Vegetable Seed Growers Association meeting in Moses Lake, WA, Jan. 15, 2004. Boydston, R. A. Importance of weed hosts for management of Corky Ringspot Disease in Potato Rotations. Presented at Washington State Potato Convention in Moses Lake, WA, Feb. 4, 2004. Boydston, R. A. Effect of fall-planted cover crops on weed populations. Presented at the Organic Agriculture Principles Workshop in Wilsonville, OR, Feb. 24, 2004. Boydston, R. A. Weed Research in Peppermint and Spearmint. Presented at the Mint Growers Research Field Day in Prosser, WA, June 3, 2004. B. Popular Publications: Boydston, R. A. Take cover from the elements. Brassica cover crops can control weeds and reduce the use of crop protectants in vegetable rotations. American Vegetable Grower, March 2004, p. 18-19. (ARIS 163322) Boydston, R., M. Williams, G. Prest, and D. Spellman. Carrot Weed Control ¿ Research with Caparol and Nortron. Columbia Publishing, Yakima, WA. Carrot Country. 2004. v. 12 (1). p. 6-8. (ARIS 163326) Alva, A.K. Nitrogen management on Columbia Basin cultivars. Potato Country, Vol. 20(3):8-11. 2004. Alva, A.K. Nitrogen mineralization from potato crop residues. Potato Grower, April 2004. P. 40-42. Boydston, R., H. Collins, A. Alva, P. Hamm, and E. Riga. Fall Planted Cover Crop Trial in Four Year Crop Rotation. Ecological and Organic Farm Management Workshop Proceedings, Wilsonville, OR. Wash. St. Univ. Center for Sustaining Agric. and Nat. Resources. Feb. 2004. p.19. (ARIS 163327) Boydston, R. A., K. Al-Khatib, S. F. Vaughn, H. P. Collins, and A. K. Alva. Weed suppression using cover crops and seed meals. First International Symposium, Biofumigation: A Possible Alternative to Methyl Bromide. Research Institute for Industrial Crops (ISCI Bologna, Italy). 2004. Abstracts. p.16. (ARIS 164539) Collins, H.P., F. Pierce, R. Boydston, N. Grunwald and J. Munyaneza. 2003. Adopting conservation tillage in irrigated cropping systems. Proceedings 42nd Washington State Potato Conference. p. 81-92. (ARIS 148261) Review Publications BOYDSTON, R.A., WILLIAMS, M.M. EFFECT OF FUMIGATION ON VOLUNTEER POTATO (SOLANUM TUBERSOUM) TUBER VIABILITY. WEED TECHNOLOGY. 2003. 17:352:357. BOYDSTON, R.A. MANAGING VOLUNTEER POTATO (SOLANUM TUBEROSUM) IN FIELD CORN (ZEA MAYS) WITH CARFENTRAZONE-ETHYL AN DICAMBA. WEED TECHNOLOGY. 2004. VOL 18:83-87. BOYDSTON, R.A., WILLIAMS, M.M. COMBINED EFFECTS OF ACERIA MALHERBAE AND HERBICIDES ON FIELD BINDWEED GROWTH. WEED SCIENCE. 2004. 52:297-301. HE, Z.L., CALVERT, D.V., ALVA, A.K., LI, Y.C., STOFFELLA, P.J., BANKS, D.J. NITROGEN TRANSFORMATION AND AMMONIA VOLATILIZATION FROM BIOSOLIDS AND COMPOST APPLIED TO CALCAREOUS SOIL. COMPOST SCIENCE AND UTILIZATION, 11:81-88. 2003. ALVA, A.K., COLLINS, H.P., FRAISSE, C., BOYDSTON, R.A. EVALUATION OF ENVIROSCAN CAPACITANCE PROBES FOR MONITORING SOIL MOISTURE IN CENTER PIVOT IRRIGATED POTATOES. JOURNAL OF APPLIED IRRIGATION SCIENCE, 38:93-110. 2003. HUTCHINSON, P., BEUTLER, B.R., BOYDSTON, R.A., RANSOM, C.V., FLETCHER, F.E. DIMETHENAMID-P, SULFENTRAZONE, AND FLUMIOXAZIN: THREE NEW PREEMERGENCE HERBICIDES FOR WEED CONTROL IN POTATO. POTATO ASSOCIATION OF AMERICA PROCEEDINGS. 2003. G55, p. 48. BOYDSTON, R.A., MOJTAHEDI, H., CROSSLIN, J., THOMAS, P.E., RIGA, E., ANDERSON, T.L. INFLUENCE OF NIGHTSHADE SPECIES ON CORKY RINGSPOT PERSISTENCE IN CROP ROTATIONS. POTATO ASSOCIATION OF AMERICA PROCEEDINGS. 2003. P31, p. 75. COLLINS, H.P., GRUNWALD, N.J., NAVARRE, D.A., PIERCE, F.J. EFFECT OF PLANT ACTIVATORS ON SOIL-RHIZOSPHERE MICROBIAL COMMUNITIES. AMERICAN SOCIETY OF AGRONOMY ABSTRACTS - CD, SO3-Collins 760503. 2003. COCHRAN, R.L., COLLINS, H.P., GRUNWALD, N.J., KENNEDY, A.C. SOIL MICROBIAL RESPONSES TO CONVERSION OF NATIVE SHRUB-STEPPE ECOSYSTEM TO IRRIGATED AGROECOSYSTEM. AMERICAN SOCIETY OF AGRONOMY ABSTRACTS - CD-SO3, Cochran 697377. 2003. RIGA, E., MOJTAHEDI, H., COLLINS, H.P., WILSON, J. EDAPHIC AND BIOLOGICAL FACTORS IMPACTING METHAM SODIUM EFFICACY TO CONTROL ROOT-KNOT NEMATODES IN THE PACIFIC NORTHWEST. POTATO ASSOCIATION OF AMERICA PROCEEDINGS. 2003. G17, p. 35. RIGA, E.H., COLLINS, H.P. THE EFFECT OF COMBINING SYNTHETIC NEMATICIDES AND ORGANIC NEMATICIDES ON PLANT PARASITIC NEMATODES OF POTATOES. POTATO ASSOCIATION OF AMERICA PROCEEDINGS. 2003. G18, p.35. ALVA, A.K., SAJWAN, K.S., PARAMASIVAM, S. COPPER ADSORPTION AND DESORPTION IN DIFFERENT PH SOILS. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America Annual Meeting Abstract(On CD) 2003. DELISE, J., SIVAPATHAM, P., SAJWAN, K.S., YOUNG, C.L., ALVA, A.K., FARES, A. PHOSPHORUS LEACHING FROM SEWAGE SLUDGE AMENDED SOILS OF FLORIDA AND GEORGIA. AGRONOMY ABSTRACTS. ON CD. 2003. ALVA, A.K., COLLINS, H.P., BOYDSTON, R.A. NITROGEN MINERALIZATION IN A POTATO CROPPING SYSTEM. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America Annual Meeting Abstracts(on CD) 2003. MARCOS, J., FRAISSE, C., TIMLIN, D.J., ALVA, A.K. COMPARISON OF POTATO SIMULATION MODELS UNDER EASTERN WASHINGTON CONDITIONS. AGRONOMY ABSTRACTS. ON CD. 2003. WILLIAMS, M., BOYDSTON, R.A. ACERIA MALHERBAE FEEDING IMPROVES SUPPRESSION OF FIELD BINDWEED WITH HERBICIDES. WEED SCIENCE SOCIETY OF AMERICA ABSTRACTS. 2004. Vol. 44:28 #102. BOYDSTON, R.A., WILLIAMS, M. MANAGING VOLUNTEER POTATO IN FIELD CORN WITH MESOTRIONE AND COLORADO POTATO BEETLE. 2004 WEED SCIENCE SOCIETY OF AMERICA ABSTRACTS. 2004. Vol. 44:58-59 #204. Paul, E.A., Collins, H.P., Paustian, K., Elliott, E.T., Frey, S., Cole, C.V., Juma, N., Janzen, H., Campbell, C.A. 2004. The effect of management on the dynamics and storage capacity of soil organic matter in the canadian prairies. Canadian Journal of Soil Science. 84:49-61. Paramasivam, S., Sajwan, K.S., Alva, A.K., Adriano, D.C., Punshon, T., Vanclief, D., Hostler, K.H. 2003. Elemental transport and distribution in soils amended with incinerated sewage sludge. Journal of Environmental Science and Health. A38:807-821. SAJWAN, K.S., ALVA, A.K., KEEFER, R.F. CHEMISTRY OF TRACE ELEMENTS IN FLY ASH. KLUWER ACADEMIC/PLENUM PUBLISHERS, NEW YORK, NY. 2003. P. 346.