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? 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. This project is assigned to National Program 207. 2.List by year the currently approved milestones (indicators of research progress) FY 2004 (Year 1) 1. Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control, processes that control soil biological activity and carbon and nitrogen cycling under irrigation.. 2. Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage. 3. Determine weed density, biomass and crop (potato, sweet corn, and wheat) yield following four fall-planted cover crop treatments and fallow or fallow-fumigated treatments. (Continuation of the previous CRIS 5354-13610-002-00D). 4. Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage. 5. Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (Continuation of the previous CRIS 5354-13610-002-00D) 6. 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). 7. 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) 8. Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage. 9. 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). 10. Update the crop coefficients in potato crop growth simulation model – SIMPOTATO. Integrate SIMPOTATO (VB version) into CROPSYST model. FY 2005 (Year 2) 1. Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control, processes that control soil biological activity and carbon and nitrogen cycling under irrigation. 2. Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage. 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) 4. Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage. 5. Determine soil microbial biomass, indices of microbial diversity (FAME) in four fall-planted cover crop treatments and fallow or fallow-fumigated treatments (Continuation of the previous CRIS 5354-13610-002-00D). 6. 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. 7. Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage (year 2 of 3). 8. 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) 9. Nitrogen mineralization from crop residues under conventional and reduced tillage. 10. Evaluation of SIMPOTATO - CROPSYST for simulation of plant growth, yield, and fate and transport of nitrogen in potato rotation systems. FY 2006 (Year 3) 1. Establish reduced and conventional tillage plots and herbicide treatments for volunteer potato control, processes that control soil biological activity and carbon and nitrogen cycling under irrigation. 2. Measure volunteer potato density, tuber number, and tuber weight in sweet corn after treating with herbicides in conventional and reduced tillage. 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. 4. Measure microbial populations, plant pathogens, nematodes and insects in conventional and reduced tillage. 5. Summarize the long term effects of fall planted cover crops on soil microbial populations and diversity. Generate cover crop recommendations based on results obtained. 6. 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. 7. Evaluation of pre-plant and in-season N management under conventional vs. reduced tillage. 8. Evaluation of capacitance probes for real time monitoring of soil moisture as basis to improve potato irrigation scheduling. (Continuation of the previous CRIS 5354-13610-002-00D) 9. Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model. 10. Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. FY 2007 (Year 4) 1. Summarize volunteer potato control data from 3 year tillage study. Establish volunteer potato management recommendations based on results. 2. 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. 3. Initiate and plan new cover crop/fumigation research that might develop based on results and new information gained in previous 4 year study. 4. Sinapis alba (mustard) seed meal will be tested at three rates for weed control in potato as a surface applied band on the hill with cultivation between hills. 5. A field trial will be initiated evaluationg weed free alfalfa as a strategy to eliminate corky ringspot disease of potato. Alfalfa and wheat (control treatment) will be seeded into corky ringspot infested field. 6. Summarize soil biological data from 3 year tillage study. Establish soil management recommendations based on results. 7. Summarize soil C and N and trace gas flux data from 3 year tillage study. Establish soil management recommendations based on results. 8. Expand trace gas research to determine influence of biofuel oilseed cropping systems on greenhouse gas emissions. 9. Nitrogen mineralization from crop residues under conventional and reduced tillage. 10. Potato tuber yield and quality response data analysis - effects of various pre-plant and in-season N management under conventional and reduced tillage. 11. Irrigation x nitrogen interaction field experiment for plant growth, biomass accumulation / partitioning, and tuber yield / grade data collection to refine the SIMPOTATO model. 12. Update the SIMPOTATO (VB) - CROPSYST model for wide range of major potato cultivars. FY 2008 (Year 5) 1. 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. 2. Sinapis alba (mustard) seed meal will be tested for weed control in potato (2nd year) as a surface applied band on the hill with cultivation between hills. 3. Alfalfa and wheat will be maintained a second year evaluating weed free alfalfa as a strategy to eliminated corky ringspot disease of potato. Wheat will be reseeded. 4. A second field trial will be initiated evaluating weed free alfalfa as a strategy to eliminated corky ringspot disease in potato. Alfalfa and wheat (control treatment) will be seeded into corky ringspot infested field. 5. 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. 6. 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. 7. Continue trace gas studies initiated in 2007 on biofuel cropping systems to include greenhouse gas emissions in switchgrass production and C and N sequestration potentials. 8. Evaluation of N transformation, fate and transport under conventional and reduced tillage. 9. 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. 10. Develop phenology model based decision support system for irrigated potato rotation system. 4a.List the single most significant research accomplishment during FY 2006. National Program #207 Component III. Examples of Integrated Agricultural Systems in ARS f. The Management Improvement Program Volunteer potato control in carrots: Volunteer potato is the most troublesome weed in carrot production is currently controlled with hand weeding, repeated cultivation, and soil fumigation. Washington ranks second nationally in carrots grown for processing and are commonly rotated with potato. ARS scientists at Prosser, WA, quantified the influence of volunteer potato competition on carrot yield and developed new control methods using ethofumesate and prometryn. Use of prometryn and ethofumesate in carrot production could reduce or eliminate the need for hand weeding and soil fumigation in carrot production saving growers $150 or more per acre. 4b.List other significant research accomplishment(s), if any. NP 207 Component III. Examples of Integrated Agricultural Systems in ARS f. The Management Improvement Program. Hairy nightshade control in potato: Hairy nightshade, a close relative of potato, is the most frequently found weed and most difficult to control weed in potato production in the Western U.S. Weed control and potato varietal tolerance to flumioxazin, dimethenamid-P, and sulfentrazone were determined in field trials in Idaho, Oregon, and Washington by scientists with the USDA-ARS at Prosser, University of Idaho at Aberdeen, ID, and Oregon State University at Ontario, OR. Research trials identified proper application timing and rates of these herbicides for nightshade control while minimizing potato injury. Improved nightshade control utilizing this technology will improve potato yield and decrease potato disease, nematode, and insect problems worsened by hairy nightshade. NP 207 Component III, Integrated Nutrient and Water Management. N available to potatoes from cover crops: Farmers in the Pacific Northwest are using cover crops in rotation with potatoes because they reduce wind erosion and serve as a bio-control method for a number of plant pathogens. Cover crops can also be used in rotation to sequester excess N and supply N to high value vegetable crops such as potatoes. Cooperative research conducted by USDA-ARS Prosser, WA and USDA-ARS Fort Collins, CO scientists quantified the ability of mustard cover crops to supply N to potatoes. The use of mustard cover crops preceding potato was found to provide 27 to 36 lbs N ac-1 towards the N requirement of potato and could save growers $20 or more per acre in fertilizer costs. NP 207 Component III, Sustainable and Organic Farming Sustainable production of bio-fuel crops: As oil prices continue to rise and public support for alternative fuels broaden, bioenergy crops have attracted ever-increasing attention in the political, environmental, and commercial arenas across the country. In a cooperative study, USDA-ARS and Washington State University scientists at Prosser, WA evaluated the production aspects of a variety of oilseed crops (safflower, soybeans, mustard, canola) as feedstocks for biodiesel production and wheat straw, corn stover, and switchgrass feedstocks for ethanol production. Canola, rapeseed and safflower were determined to be the best selections for biodiesel production because of their high oil content (45%) and ability to fit into both dryland and irrigated crop rotations. For ethanol production, 30-60,000 acres of switchgrass, wheat straw, or corn stover would be necessary to support a 20 million gallon ethanol facility. These findings are essential in estimating economic viability of feedstock resources for development of a sustainable biofuels industry in the PNW. 4c.List significant activities that support special target populations. None. 4d.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, trace gas fluxes, weed population dynamics, and soil pathogens are continuing near Paterson, WA. Fluroxypyr controlled volunteer potato greater in conventionally tilled sweet corn than in reduced till sweet corn whereas mesotrione controlled volunteer potato well regardless of tillage level. A four year study evaluating cover crops and fumigation treatments in a four-year crop rotation of potato/wheat/sweet corn/sweet corn under center pivot irrigation was completed. Cover crops tested included white mustard, sudangrass, winter wheat, and an oat/vetch mix. Impacts of cover crop treatments on weed seed bank, weed density by species, and effects on buried weed seed are summarized and in a publication is being prepared. 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 to date and their predicted or actual impact. Corky ringspot disease (CRS) is a serious disease of potato, caused by Tobacco Rattle Virus (TRV) transmitted by stubby root nematode, that infests approximately 5,000 acres in the Pacific Northwest potato producing region and is currently controlled by soil fumigation at considerable cost to the grower. We have demonstrated the disease can be cleansed from nematode vector by growing weed-free alfalfa or Scotch spearmint. However, several weed species including hairy nightshade, prickly lettuce, henbit, and green foxtail were found to be suitable hosts of the stubby root nematode. The presence of these weeds in alfalfa and Scotch spearmint often nullified the cleansing effect of these crops on CRS disease. Targeted control of these weeds in alfalfa or Scotch spearmint will allow growers to use crop rotation as a means of eliminating CRS from problem fields and eliminated the need to fumigate. NP 304, Component X, Integrated Weed Management in Cropland. Conventional field cropping systems have been criticized as being unsustainable because they contribute to environmental degradations (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. We have evaluated the processes controlling soil biological activity and community structure of the soil micro-flora, and understand the mechanisms controlling carbon and nitrogen cycling and trace gas (CO2, N2O. CH4) fluxes under reduced tillage in irrigated potato production systems. We have found that significant amount of N is lost (10-12%) as N2O within 12 hours of fertigation under laboratory conditions. Currently additional analyses are being conducted to determine the timing and the mechanisms of loss. Sandy soils have generally not been thought to have substantial denitrification. This finding may account for as much as 50% of N lst or unaccounted for from agricultural systems. NP 304, Component X, Integrated Weed Management in Cropland. Few studies have examined the combined effect of herbicide-induced stress and arthropod herbivory to suppress weeds. Herbicide dose response bioassays on volunteer potato were conducted in the presence and absence of Colorado potato beetle feeding. Sixty-five to over 85% less herbicide was needed to reduce volunteer potato tuber production in the presence of beetle feeding compared to herbiced needed to reduce tuber production an equivalent amount in the absence of beetles. An experimental approach is described that optimizes the combined effects of arthropod feeding and reduced herbicide doses. NP 304, Component X, Integrated Weed Management in Cropland. Sustainability is a requirement for all new biobased technologies. Sustainability is dependent upon; acceptable environmental impact of products; economic viability for all participants; and a positive social impact of the product and its production. We have initiated a series of trials evaluating a number of oilseed crops grown to maturity for an emerging biodiesel market and to determine how they will fit into current high value irrigated vegetable cropping systems. We are evaluating five oil seed crops that can be grown in the PNW, as well as, nationally. These include: spring and winter rapeseed, mustard, sunflower, safflower, and soybean. Our data indicates that to support a 5 million gallon biodiesel facility the land area required ranges from 50-180,000 acres depending on the oilseed crop grown. NP 207 Component III, Sustainable and Organic Farming Research. 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 are continuing near Patterson, WA. Cover crops of fumigation treatments are being tested in a four-year crop rotation of potato/wheat/sweet corn/sweetcorn 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 are being 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 band and weed density in the following season greater than four cover crops being evaluated. Fluroxypyr controlled volunteer potato greater in conventionally tilled sweet corn than in reduced till sweet corn where as mesotrione controlled volunteer potato well regardless of tillage level. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 207 Component III, Sustainable and Organic Farming Research. 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. NP 207 Component III, Sustainable and Organic Farming Research. 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. NP 207 Component III, Integrated Nutrient and Water Management. 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. NP 207 Component III, Integrated Nutrient and Water Management. 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. NP 207 Component III, Integrated Nutrient and Water Management. 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. NP 207 Component III, Integrated Nutrient and Water Management. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 207 Component III, Integrated Nutrient and Water Management to protect groundwater quality. 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. NP 207 Component III, Integrated Nutrient and Water Management to protect groundwater quality. 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. NP 304, Component X, Integrated Weed Management in Cropland. 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. NP 304, Component X, Integrated Weed Management in Cropland. Field bindweed (Convolvulus arvensis) is an aggressive perennial weed that infests approximately 10% of irrigated acres in the Columbia Basin and is present throughout North America. Control of field bindweed with herbicides is usually incomplete resulting in crop losses and perpetuating the problem in ensuing years. A population of gall forming mites, Aceria malherbae was established in Washington State that was originally native to the Mediterranean region. Integrating mite feeding and with herbicides reduced growth of field bindweed more than mites or herbicides alone with no apparent detrimental effect on mite populations. Combinations of the mite with sublethal herbicide doses suppressed field bindweed while reducing potential herbicide injury to crops and maintaining mite populations. Establishment of the mite and integrating mites with herbicides should allow growers to reduce herbicide rates while improving control of this troublesome weed. NP 304, Component X, Integrated Weed Management in Cropland. Nightshade berries present during pea harvest are similar in size, color, and density to peas and difficult to separate from processing peas. Previously, growers had no method to determine if nightshade emerging at various periods during the growing season would require control methods to prevent contamination of berries in the harvest pea crop. Field trials in 2002 and 2003 were conducted to develop a model to predict growing degree days required for hairy nightshade to produce 6 mm diameter or larger berries, which are difficult to separate from peas. Hairy nightshade required approximately 1300 heat units (base 40) to produce 6 mm diameter berries. The model can be used as a decision tool by growers to determine whether to apply a postemergence herbicide for nightshade control using early season scouting and temperature data. The model recommends no herbicide application for later emerging hairy nightshade based on predicted berry sizes and lack of pea yield response. NP 304, Component X, Integrated Weed Management in Cropland. 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 reduced tillage corn: Presentations were made at the Potato Field Day, Paterson, WA July 15, 2005; at the Columbia Basin Crop Consultants Association in Moses Lake, WA January 19, 2006; and at the Western Society of Weed Science meeting in Reno, NV March 13, 2006. Technology was transferred to growers, research faculty and scientists, crop consultants, and farm managers. Technology can be utilized by end users immediately. Improved management of weeds in potato, mint, and irrigated vegetable crops: Presentations were made at the Mint Growers Research Field Day in Prosser, WA on June 2, 2005, at the USDA Potato field Day in Paterson, WA on July 15, 2005; at the Pacific Northwest Vegetable Association meeting in Pasco, WA on November 17, 2005; at the Washington State Mint Growers Winter meeting in Pasco, WA on December 6, 2005; at the Sustainable Ag Workshop (Yakima Indian Nation) in Toppenish, WA on January 12, 2006; at the Mint Industry Research Council Meetings in Las Vegas, NV on January 28, 2006; and at the Weed Science Society of America meetings in New York, NY on February 15, 2006. Technology was transferred to growers, researchers and scientists, crop consultants, farm managers, and processors and oil buyers. Technology can be utilized by end users immediately. Identified nematode and disease problems in potato worsened by hairy nightshade presence and improved management of nightshade in potato and snap beans: Presentations were made at Potato Field Day, Paterson, WA July 15, 2005; Potato Association of America, Calgary, Canada, July 19, 2005; Hermiston Farm and Trade Show, Hermiston, OR November 30, 2005; Washington State Potato Convention, Moses Lake, WA on February 8, 2006; and Weed Science Society of America, New York, NY, February 15, 2006. Technology was transferred to potato and rotational crop growers, processors, crop consultants, farm managers, extension and research faculty/scientists. Technology can be used by end users immediately. Improved management of reduced tillage in potato production: Presentations were made at Potato Field Day, July 15, 2005, , Paterson, WA; Agricultural Systems Design Class November 17, 2005 Washington State University, Pullman WA; Hermiston Farm Fair and Trade Show, November 30, 2005, Hermiston, OR. Technology was transferred to growers, research faculty, crop consultants, and farm managers. Technology can be utilized by end user immediately. Management of alternative bioenergy crops: Presentations were made at Potato Field Day, Paterson, WA July 15, 2005; to the Mid-Columbia Hay Growers Annual Meeting. December 15, 2005, Moses Lake, WA; Congressional Expert Panels; Pasco, WA August 3, 2005; Walla Walla, WA, August 4, 2005; Richland, WA, November 16, 2005; Harvesting Clean Energy Conference, Spokane, WA, February 27-28, 2006; Biocycle Conference, Portland, OR, March 20-22, 2006;USDA-ARS Palouse Field Day, Pullman, WA, June 22, 2006, Technology was transferred to the public, growers, research faculty, crop consultants, and farm managers. Technology can be utilized by end user immediately. 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). Popular Press and presentations: Boydston, R. 2005. Timing of dormant herbicide applications. Washington Mint Drops. Washington Mint Growers Association. Pg. 4, Spring. 185611. Boydston, R. 2005. Emerging weed problems in mint. Washington Mint Drops. Washington Mint Growers Association. Pg. 1-2, Fall. 189644. Boydston, R. 2006. Volunteer Potato Management and Outlook for 2006. Potato Progress 6 (1):3-6. Boydston, R. 2006. Potato disease, nematode, and insect problems worsened by hairy nightshade. Proceedings 45th Washington State Potato Conference. Boydston, R., Baker, R. 2006. Weed Research in Mint Industry Research Council 2005 Research Reports, Las Vegas, NV. 23 pp. Boydston, R., Baker, R. 2005. Weed Research in Mint. Proceedings of the Washington Mint Growers Winter Conference. December. pp. 14-37. Boydston, R. A., Parker, R. 2006. Crop response to carfentrazone applied preemergence. Western Society of Weed Science Research Progress Report. Pp. 41-42. Boydston, R. A.,Williams, M. M. II. 2005. Integrated weed management in vegetable crops. Proceedings Pacific Northwest Vegetable Association Meetings, Pasco, WA, Nov. 17, pp 1-4, http://www.pnva.org. Collins, H.P., R. Boydston, A. Alva, F. Pierce and P. Hamm. 2005. Reduced Tillage in a Three Year Potato Rotation. pp. 33-48. Cropping Systems Research Progress Report http://www.ars.usda.gov/pwa/prosser. Stockle, C.O., A.R., Kamanian, D.R. Huggins and H.P. Collins. 2005. Modeling carbon and nitrogen cycling and greenhouse gas emissions from agricultural systems. USDA Symposium on Greenhouse Gases & Carbon Sequestration in Agriculture and Forestry. Weeds in Integrated Pest Management for Potatoes in the Western United States, 2nd Edition, ed. L. Strand. 2005. Western Regional Extension Publication 011. (Technical coordinator for Weeds Chapter) 189572. Williams, M. M. II., Boydston, R. A. 2005. Crop hybrid selection of a tool to manage annual grasses in sweet corn. Illinois Fruit and Vegetable Research Report. 182498. Articles Written About Research: Boydston, R. A., A. McGuire, and E. Riga. 2006. Mustard: more than just a condiment. Top Crop Manager. February. Pp. 8-10. Boydston, R. 2006. Growers warned on the importance of controlling hairy nightshade. Potato Country. Pp. 4-5. March. Boydston, R. 2006. Volunteer potato management for 2006. Potato Country. Pp.10-11. May-June. Collins, H.P., A. Alva, R. Boydston, F.J. Pierce. Researchers look at reduced tillage for potato production. May/June2006. Potato Country. Pp. 20-22. Newspapers Capitol Press. July 2006. Bioenergy refrain accompanies field tours. Vol 79 No. 27, pp1/8. USDA-ARS Magazine. May 2006. Healthy potatoes, healthy people, healthy profit: Improving conservation in the potato field. Pp. 10-12. Review Publications BOYDSTON, R.A., AL-KHATIB, K. UTILIZING BRASSICA COVER CROPS FOR WEED SUPPRESSION IN ANNUAL CROPPING SYSTEMS. CHAPTER IN HANDBOOK OF SUSTAINABLE WEED MANAGEMENT, ED. H.P. SINGH, D.R. BATISH, AND R.K. KOHLI. HAWORTH PRESS, BINGHAMTON, NY. (PLANNED EARLY 2004) 2004. Boydston, R.A., Hutchinson, P.J. 2005. Herbicides-weeds: a practical approach to resistance management in potato cropping systems. Pesticide Resistance Management for Potato Growers Publication Series: National Potato Council, Washington, DC, p. 2. Boydston, R.A., Mojtahedi, H., Brown, C.R., Anderson, T.L. 2005. Hairy nightshade presence affects the durability of nematode resistance in potato. Western Society of Weed Science Meeting Proceedings. 58:11. Hutchinson, P.J., Boydston, R.A., Ransom, C.V., Tonks, D.J., Beutler, B.R. 2005. Potato (solanum tuberosum) variety tolerance to flumioxamin and sulfentrazone in the pacific northwest. Weed Technology. 19:683-696. Hutchinson, P., Ransom, C., Boydston, R.A., Beutler, B. 2005. Dimethenamid-p: efficacy and potato (solanum tuberosum) variety tolerance. Weed Technology. 19:966-971. Parker, R., Boydston, R.A. 2005. Weed management and herbicide performance during drought conditions. Washington State University Website Extension Bulletin. 2 pp. Steiner, C.M., Newberry, G., Boydston, R.A., Yenish, J., Thornton, R. 2005. Volunteer potato management in the Pacific Northwest rotation crops. Washington State Extension Publications, EB1993, p 12. Williams, M., Boydston, R.A. 2005. Alternative to handweeding volunteer potato (Solanum tuberosum)in carrot (Daucus carota). Weed Technology. 19(4):1050-1055. Williams, M., Boydston, R.A. 2006. Volunteer potato(Solanum tuberosum l.) interference in carrot. Weed Science. 54(1):94-99. Boydston, R.A. 2006. Evaluation of halosulfuron applied postemergence alone and in combination with rimsulfuron for weed control in potato. Weed Science Society of America Meeting Abstracts. 46:63. Collins, H.P., Navarre, D.A., Riga, E., Pierce, F.J. 2006. Effect of foliar applied plant elicitors on microbial and nematode populations in the root zone of potato. Communications in Soil Science and Plant Analysis. 37:1747-1759. Alva, A.K. 2006. Set points for scheduling potato irrigation using capacitance probes. World Congress of Soil Science. On CD. Alva, A.K., Paramasivam, S., Sajwan, K.S. 2006. Nitrogen transformation from three organic amendments in a sandy soil. Archives of Agronomy and Soil Science. 52: 1-11, 2006. Alva, A.K., Sajwan, K., Paramasivam, S. 2005. Can potatoes withstand disposal rates of soil amendments?. ASA-CSSA-SSSA Annual Meeting Abstracts. On CD. 2005 Alva, A.K., Paramasivam, S., Obreza, T.A., Schumann, A.W. 2005. Nitrogen best management practice for citrus trees: i. fruit yield, quality, and leaf nutritional status. Scientia Horticultureae. 107:233-244. Alva, A.K., Paramasivam, S., Fares, A., Obreza, T.A., Schumann, A.W. 2006. Nitrogen best managment practice for citrus trees: ii. nitrogen fate, transport, and components of n budget. Scientia Horticultureae. 109:223-233. Alva, A.K., Paramasivam, S., Fares, A., Delgado, J.A., Mattos, Jr, D., Sajwan, K. 2004. Nitrogen and irrigation management practices to improve nitrogen uptake efficiency and minimize leaching losses in soils under citrus. Journal of Crop Improvement. 15:421-470. Collins, H.P., Riga, E., Pierce, F. 2005. Spatial and seasonal patterns of c and n mineralization in an irrigated potato rotation. Agronomy Abstracts. On CD. Delgado, J.A., Alva, A.K., Fares, A., Paramasivam, S., Mattos, Jr, D., Sajwan, K. 2004. Numerical modeling to study the fate of nitrogen in cropping systems and best management case studies. Journal of Crop Improvement. 15:369-420. Liu, G., Li, Y., Alva, A.K. 2005. Effects of moisture, nitrogen source and temperature on ammonia emission from florida and washington soils-grown potatoes. American Society of Agronomy Meetings. On CD. Marcos, J., Stockle, C., Alva, A.K., Timlin, D.J., Reddy, V. 2005. Calibration of a potato growth model for prediction of nitrogen dynamics in potato systems in the pacific northwest. ASA-CSSA-SSSA Annual Meeting Abstracts. On CD. Paramasivam, S., Sajwan, K.S., Alva, A.K. 2005. Organic amendments to improve soil productivity and nutrient cycling. 15th International Plant Nutrition Colloquium Proceedings, Beijing, China, Sept 14-19, 2005, p. 1090-1091. (And on CD). Paramasivam, S., Richards, K., Cooper, A., Sajwan, K., Alva, A.K. 2005. Leaching losses of trace elements from soils amended with poultry litter and fly ash. American Society of Agronomy Meetings. On CD. Sajwan, K.S., Paramasivam, S., Alva, A.K., Richardson, J.P., Ghuman, G.S. 2005. Plant uptake and leaching potential of selected macronutrients from soils amended with poultry litter. Plant Nutrition Colloquium Proceedings. Beijing, China. On CD. Sajwan, K., Richards, A., Butterbaugh, T., Potts, M., Paramasivam, S., Alva, A.K. 2005. Release pattern of selected nutrient elements in soils amended with poultry litter and fly ash. American Society of Agronomy Meetings. On CD.