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Our goals are to support the growth of the organic certified seed potato industry in the Midwest region of the United States, to support organic potato growers in raising healthy and profitable potato crops, and to increase availability of heirloom and specialty potato varieties suited to organic production. <P>Our objectives are: <OL> <LI>Characterize heirloom and specialty potato varieties expected to perform well in organic production, and increase availability of these varieties; <LI>Develop organic methods for production of seed potatoes that meet certification standards; <LI>Conduct an economic analysis of organic certified seed potato production, using a whole-farm planning approach. </OL> Objective 1: We will collaborate with Seed Savers Exchange to treat their collection of tissue culture plants of heirloom varieties to eliminate pathogens. Depending on pathogen incidence in the collection, 20-70 heirloom varieties will be made available as pathogen-free tissue culture clones. On-farm trials of at least 12 heirloom and specialty varieties will generate detailed information on agronomic, disease resistance, tuber sensory and nutritional characteristics. <P>Objective 2: We will test methods of tuber multiplication from tissue culture plants and greenhouse-produced minitubers that limit virus spread and maximize seedpiece production, comparing row covers and mineral oil sprays. In on-farm trials of field-scale certified seed potato production, we will test strategies to limit spread of aphid-borne potato viruses, including borders around seed potato plots, live mulch or straw mulch between potato rows, mineral oil sprays, and green-sprouting. We will determine the value of strategies to manage Potato Virus Y (PVY) spread, and formulate recommendations combining a set of best management practices based on new knowledge about the relationship between aphid alightment patterns and PVY incidence. We will determine the practicality of our "best management" recommendations on a small field scale. <P>Objective 3: We will use data from field trials, together with wholesale and retail price data, to develop an econometric model to forecast organic potato prices. We will evaluate the management strategies in Objective 2 from an economic perspective by conducting a whole farm budgeting analysis of each strategy. Since the demand for organic seed potatoes is derived from the demand for organic potatoes for human consumption, both market segments will be modeled. The end result will be a publication and worksheet that displays typical costs for producing organic seed potatoes, the costs of different management strategies and a blank worksheet for users to calculate their costs. We will inform growers about characteristics and seed sources for specialty and heirloom potatoes, seed potato certification resources and pathogen testing procedures, and assist organic growers with integrating use of these resources into their management decisions. We will develop extension materials and distribute them at organic farming and sustainable agriculture meetings, training courses, field days, online, and through industry publications.
Non-Technical Summary: Use of certified seed potatoes has proven benefits for potato production. Use of disease-free planting stock limits tuber-borne diseases in potato crops, improving yield and quality. The current situation, with limited organic production of certified seed potatoes in the Midwest, forces organic growers to import at least some of their planting stock from other regions, and increases the risk of accidental introduction and spread of potato diseases. This project will support organic production of certified seed potatoes in the Midwest through field-based and economic research. Organic potato growers are also in need of access to a greater diversity of varieties, and to varieties adapted to organic production system. Heirloom varieties are likely to perform well in low-input organic conditions, and there is increasing consumer interest in the flavor and nutritional qualities of specialty potatoes. Our research will provide growers with detailed agronomic, sensory and nutritional data on heirloom and specialty potato varieties. Heirloom potato varieties will be grown in on-farm trials and characterized for yield, quality, disease resistance, taste and nutritional quality. Heirloom potato varieties are difficult to obtain as seed potatoes. Our collaboration with Seed Savers Exchange to eliminate pathogens from their heirloom potato collection is crucial to increase the availability of these varieties. We will conduct on-farm trials to define best management practices for organic production of seed potatoes, testing strategies for control of aphid-transmitted viruses which are a major seed potato production problem. A microeconomic analysis will be conducted based on the results of on-farm trials, and will be complemented by a macroeconomic analysis of organic markets. A grower-oriented publication focusing on the feasibility of growing organic seed potatoes will include worksheets useful to growers as operating guidelines and as financial documents for loan applications. Extension materials on heirloom and specialty varieties, best management practices for seed potato production, and the economics of organic seed potato production will be provided to growers and extension professionals through industry meetings and publications, field days, and online. Increased regional access to high quality seed potatoes for varieties that perform well in organic production will benefit organic growers in the Midwest by reducing seed potato costs (including shipping costs), reducing crop loss due to disease, increasing profitability by use of varieties suited to organic production, and increasing growers' ability to serve high value specialty potato markets. Economic risk to growers entering the seed potato industry will be reduced by providing them with analyses of the economic feasibility of organic seed potato production and markets for organic seed and tablestock potatoes. Increased economic stability of organic growers will benefit rural communities by providing employment opportunities and a demand for services in rural areas. Improved disease management of potato crops by cultural methods will reduce pesticide use, improving ecosystem health. <P> Approach: Objective 1. Tissue culture plants for 100 heirloom varieties from the Seed Savers Exchange (SSE) collection will be tested for potato spindle tuber viroid, Potato Virus A, M, S, X, Y and Potato Leafroll Virus, and Clavibacter michiganensis subsp. sepodonicus (Cms). Infected plants will be treated with antivirals, antibiotics and/or thermotherapy as needed. On-farm variety trials will evaluate performance of ten to twelve heirloom and specialty potato cultivars. Yield variables and defects due to common scab, silver scurf, soft rot, and black scurf will be recorded for harvested tubers. Varieties will be assessed for PVY, late blight and common scab resistance. The effects of variety, production site and year on yield and disease variables will be analyzed by ANOVA. Tubers from the on-farm variety trials will be used in taste panels and assessed for antioxidant and amylose assays. The effects of variety, production site, year, and storage time on flavor, antioxidant activity and amylose will be analyzed by ANOVA. Objective 2. We will test small- and field-scale methods of organic seed potato production. PVY-control tactics evaluated will include row covers, borders, live or straw mulch, mineral oil sprays, and green-sprouting. Aphid populations will be monitored using pan traps and visual inspection. To determine the spatial distribution of aphid alightment relative to the field border, and the contribution of aphid alightment to PVY incidence, we will collect alightment and PVY data along four transects into the field; alightment patterns will be analyzed by a permutation procedure. The effect of management tactics on aphid alightment and colonization will be analyzed by ANOVA. Weight, number, size distribution and quality of harvested tubers will be recorded. Harvested tubers will be tested for Cms and PVY. ANOVA will be used to detect significant differences in yield variables and disease incidence related to management tactics. Objective 3. The first phase of the economic analysis will consist of a deterministic model in which the values of key variables, such as yield, are assumed or taken as averages, providing profitability estimates under typical conditions. The second phase will build a stochastic model that includes risk and incorporates ranges and probabilities of yields, quality and prices, using data from the field trials as well as wholesale and retail prices. This will enable us to estimate best management strategies in the real world of production and price risks. The end result will be a publication and worksheet that displays costs for producing organic seed potatoes and a blank worksheet for users to calculate their costs. Our outreach plan will inform growers about characteristics and seed sources for specialty and heirloom potato varieties, seed potato certification resources and pathogen testing procedures, and assist organic growers with integrating appropriate use of these resources into their management decisions. Data from field trials and economic analysis will be used to develop extension materials that will be distributed at industry meetings, training courses, field days, in industry publications and online.