Building Resilience and Flexibility into Midwest Organic Potato Production: Participatory Breeding and Seed Potato Production

Project Overview

Project Type: Research and Education
Funds awarded in 2014: $199,106.00
Projected End Date: 11/30/2018
Grant Recipient: University of Wisconsin-Madison
Region: North Central
State: Wisconsin
Project Coordinator:
Dr. Rue Genger
University of Wisconsin-Madison

Annual Reports


  • Agronomic: potatoes


  • Education and Training: demonstration, farmer to farmer, on-farm/ranch research, participatory research, workshop
  • Farm Business Management: budgets/cost and returns, feasibility study
  • Pest Management: cultural control, economic threshold, genetic resistance, mulching - plastic, mulching - vegetative
  • Production Systems: organic agriculture
  • Sustainable Communities: local and regional food systems, new business opportunities

    Proposal abstract:

    Organic farmers in the North Central Region face a shortage of organically produced seed potatoes, limited availability of desired specialty varieties, and limited information on variety performance under organic management. Very little potato breeding and selection focuses on the needs of organic farmers. A decentralized system of seed potato production and breeding by a network of organic farmers would meet regional seed potato demands, enable farmers to evaluate and select outstanding lines from crosses between existing varieties, and promote interaction and learning among farmer peers. We propose a collaboration between researchers and farmers to develop goals for breeding and seed production, to trial seed potato production and breeding on organic farms, and to assess economic impacts of on-farm seed potato production.Many pathogens that may infect potato plants can be carried in the daughter tubers and will impact the productivity of the next crop. Minitubers, small tubers produced from pathogen-free tissue culture plantlets, will be planted for three popular varieties in field and hoophouse beds on organic farms. Different planting dates and spacings will be trialed for the effect on yield. In subsequent years, harvested tubers will be compared to purchased organic seed potatoes for crop health and yield. The effect on farm income of on-farm seed potato production versus purchase will be determined using partial budgets. Farmers will be provided with true potato seed from crosses between varieties that performed well on organic farms in our previous trials, and trained to make their own crosses as desired. We will collaboratively generate selection guidelines for on-farm breeding line trials to address breeding goals. Tubers from selected breeding lines will be saved and replanted for comparison with standard varieties. Promising lines will be introduced into tissue culture for long term maintenance and production. Participating farmers will gain knowledge, awareness, and skills in potato breeding and seed production, and will be able to share these skills with their peers. On-farm seed potato production, if economically viable (as our previous research suggests), will increase variety choice and protect farmers from risks of pathogen introduction with seed potatoes. Farmer-selected varieties are likely to be better suited to organic production and thus are anticipated to increase farm profits. In the long term, development of a network of farmer-breeders and seed potato producers will have benefits for sustainability of potato production in the Midwest and preservation of potato genetic diversity.

    Project objectives from proposal:

    Objective 1: Evaluate the practical and economic feasibility of on-farm production of high quality seed potatoes
    from minitubers.

    Minitubers are the initial seedpiece in seed potato production – small tubers produced from pathogen-free tissue culture plantlets in protected greenhouse conditions. Since many yield-limiting diseases can be carried in seed potato tubers, the ability to maintain potato varieties in pathogen-free culture is one of the major factors in production of healthy seed potatoes. Tissue culture plantlets will be maintained, and minitubers will be produced, by the Wisconsin Seed Potato Certification Program (WSPCP).

    We will test seed potato production for three varieties at each of five farms. Two of these varieties will be in common between all farms, and will be varieties that we have previously found to perform well under organic management. Two likely choices are Dark Red Norland, a popular and dependable red variety, and German Butterball, an heirloom yellow variety known for excellent flavor. Each farm will choose their third variety from a list of available standard, specialty and heirloom varieties. Trials will be run at six organic farms in each year, and on organic-certified land at WMARS.

    In previous research station and on-farm trials, we have compared plastic mulch and straw mulch, trialed different plant spacings, and used mineral oil sprays to reduce the spread of Potato Virus Y (PVY). While general principles emerged from these studies, indicating how the production system can be manipulated to produce the desired results, overall productivity is site-dependent and variety-dependent. The “best” method is also dependent on grower preferences – for example, a preference for producing small seed tubers that do not need to be cut versus producing the maximum possible yield. Trials at WMARS will include the following factors: mulch (plastic or straw), mineral oil (spray or no spray), and spacing (8” or 12” in row); in a replicated block design. Individual trial plots will consist of 20 minitubers. We will discuss with participating farmers the production methods best suited to their farm system, and help with the design of replicated trials for those farmers wishing to trial more than one production method. Four farms (Redozo Farm, Whitewater Gardens, LCO Ojibwe Community College Farm, and Stoney Acres Farm) will trial hoophouse production (in addition to field) to explore season extension potential. Farmers will collect information about characteristics of their site including planting and harvest dates; plot distance from other potatoes and solanaceous crops; symptoms of virus infection in other potato plots; neighboring crops; field history; management practices including fertility, irrigation, and weed and pest control; and soil type. These characteristics will be included as control variables in analyses of seed potato yield and quality, as they may have predictive value for success in future sites. Total and marketable/usuable
    yield will be recorded, and a sample of 10% of the usable tubers will be tested for PVY infection. “Field year 1” (FY1) tubers with PVY incidence below 5% (the allowable limit for certified seed potatoes) will be saved for replanting. Seed production from minitubers will be trialed in each year. In years 2 and 3, FY1 tubers (and FY2 tubers in year 3) will be replanted at the originating farm or at WMARS. Saved tubers and purchased organic certified seed potatoes for the same varieties will be planted in replicated plots (2 rows by 20 feet). Plants will be assessed for emergence, vigor, and disease symptoms mid-season, and total and marketable/usable yield will be recorded. Data will be analyzed using a mixed model approach, and subjected to principal component analysis to look for potentially meaningful correlations among farms, management practices, and varieties.

    Partial budgeting will be used to analyze the net effect on farm income of growing seed potatoes on-farm versus purchasing seed potatoes. Partial budgets are a simple decision tool to compare the net financial effect of incremental changes in farm activities, and are ideally suited to analyzing the change in costs and income from raising seed potatoes versus buying them (15). We will work through partial budgets with each farmer, incorporating input costs and income from sales of potatoes produced from replanted and purchased seed potatoes, to determine the net economic effect.
    Production and economic data from these on-farm studies will be analyzed to assess the practical and economic feasibility of on-farm seed potato production. Thus analysis, combined with the hands-on experience of participating farmers, will allow them to make informed decisions about the best source of their seed potatoes. A peer reviewed paper and extension bulletin will be produced to extend the knowledge gained to a wider audience. These outputs will provide dependable guides to organic farmers interested in seed potato production, and are expected to play a role in increasing organic seed potato production in the North Central Region.

    Objective 2: Provide training, coordination and resources for a farmer-participatory potato breeding network.

    Our previous potato variety trials on organic farms identified commercial and heirloom varieties that yielded reliably across most organic environments, and that showed field resistance to pests and diseases including potato leafhopper, early blight, and Potato Virus Y (Table 1, attached). Such varieties are ideal parents for a breeding program focused on organic production. We initiated crossing studies and now have a good understanding of varietal fertility and compatibility. Since not all potato varieties are fertile or compatible, this information will assist participating farmers in avoiding potential early pitfalls.

    In year 1, participating farmers who wish to make their own crosses will choose among the varieties listed in Table 1 (attached), and will be provided with 10-20 seed potatoes for chosen varieties, to plant in greenhouses/hoophouses (preferred for ease of crossing), or in the field. To ensure that different varieties overlap in time of flowering, seed potatoes will be planted at staggered intervals. Farmers will also be provided with “breeding kits” containing equipment including electric toothbrushes (for pollen collection), tweezers and scalpels (for anther removal), colored tags (to identify crossed flowers), mesh bags (for bagging developing fruit), finemeshed tea strainers (for extracting seed) and seed envelopes. We will provide farmers with training on crossing and saving true potato seeds (TPS) through in-person training sessions on campus and during farm visits, and via online instructions incorporating pictures and video.

    Participating farmers will also be provided with TPS from crosses between the varieties listed in Table 1 (attached), previously made by researchers. Potato seedlings will be raised from TPS by participating farmers, who all have facilities for raising their own seedlings. The number of seedlings raised by participating farmers will depend on their facilities, but we anticipate that all will be able to raise at least 100 seedlings for each of 5 crosses. We will provide guidance on raising transplants from TPS, and will also raise potato seedlings for at least 20 crosses, with 100 seedlings each. Potato seedlings will be transplanted into the field after the danger of frost has passed. In partnership with researchers, farmers will evaluate seedlings to identify the most promising breeding lines. (Note: a “breeding line” is derived from a single progeny plant, and once selected can be maintained clonally through tubers.) Lines will be evaluated twice during the growing season, for emergence, vigor, pest damage and disease damage. At harvest, lines will be evaluated for yield, external tuber defects and diseases, and visual appeal. Promising lines will be further evaluated for tuber characteristics including size, shape, skin and flesh color. The procedures described above will be repeated in years 2 and 3 with TPS produced by on-farm crosses or researcher-made crosses. In years 2 and 3, promising lines from years 1 and 2 will be replanted on-farm for a second year of evaluation alongside standard check varieties. For each line, 10-20 tubers will be planted. It is unlikely that sufficient tubers will be available for replication of breeding line plots, but check plots will be replicated in an augmented design, allowing analysis of line performance relative to standard check varieties. Lines will be evaluated for emergence, vigor, pest and disease damage during the growing season, and for yield, external tuber defects and diseases, and visual appeal. Lines that perform better than check varieties in years 2 and 3, or that have other appealing characteristics, will be saved for future evaluation at multiple sites. Up to ten of the best lines will be introduced into tissue culture for genotype maintenance and future minituber production. In all three years, similar potato breeding line evaluations will occur at West Madison Agricultural Research Station (WMARS) on certified organic land. We will conduct evaluations similar to on-farm evaluations, supplemented with ratings for damage caused by specific pests and diseases (Colorado potato beetles, potato leafhopper, mosaic virus, Verticillium wilt, early blight, common scab, silver scurf, black scurf) and for maturity. We will not screen for late blight resistance in the field since this endangers nearby potato crops.

    All participating farmers have previously collaborated with us to conduct on-farm potato variety evaluation. Additional variety evaluation training will be available via written and pictorial instruction sheets, YouTube videos, and phone conversations. Growers will be interviewed to collect information on farm environment and management practices, and these data will be used as control variables in analysis of variety evaluation data, to extract environmental and management factors important in the performance of specific cultivars or cultivar groups.

    We anticipate that this project will lead to a network of potato breeders in the North Central Region. Participating farmers and workshop participants will gain an understanding of crossing and seed saving, and the enormous diversity of tuber types that can be generated. We will provide online instruction guides that will make these skills highly accessible, and we will promote networking among interested farmers at outreach events.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.