Tomatoes are a key crop for organic and diversified fresh market vegetable growers in the North Central Region (NCR). Growers face challenges with field tomato production, due to short seasons, increasingly erratic weather producing larger rainfall events, and high disease pressure. Many growers have begun using high tunnels as a partial solution to these problems, because this too offers some protection from high rainfall events and foliar disease while extending the growing season. However, high tunnels come with challenges of their own, particularly stationary high tunnels that reduce growers’ rotational options. Mobile high tunnels allow for rotation and soil building practices, but are more expensive than high tunnels. Caterpillar tunnels may provide some of the same benefits as mobile high tunnels with a much lower cost but this has not been tested in the NCR.
In addition, tomato varieties developed specifically for field and the high tunnel production would benefit growers in the NCR. This includes varieties bred for organic field environments, with better combinations of flavor, disease resistance, durability and resistance to cracking than current options, and varieties developed specifically for high tunnel production, with more concentrated fruit set and shorter production seasons, to allow for rotation to a cover or winter crop without sacrificing flavor, quality or overall yield. This project has three objectives designed to address the challenge of producing high quality tomatoes organically for local markets in the NCR: 1) comparing production, disease mitigation and cost in high tunnels, caterpillar tunnels and field production, so growers can base management decisions on reliable information about the benefits and drawbacks of each system, 2) selecting early tomato varieties for high tunnels, with improved flavor and more concentrated fruit set to give growers more rotational options, and 3) selecting tomato varieties that are more robust for the field, with improved disease resistance and flavor. These build on our current work and respond to grower needs.
In our current work and for this project, we rely on participatory research with growers, including on-farm trials managed by growers and on-station trials advised by growers. This project involves farmers in both the management trials and in variety selection. Outcomes from this research will include information on the relative costs and benefits of different management systems, advanced tomato breeding populations developed for organic field and high tunnel production, and a stronger network of participatory research and farmer-focused cultivar development in the NCR.
This project will develop new breeding populations of tomatoes with excellent quality and adaptation to organic diversified vegetable farming in the upper Midwest. We will provide recommendations on the use of lower-cost mobile alternatives to high tunnels. We will develop better variety options for high tunnel production and for field production, with traits specific to those systems. We will strengthen our current on-farm trial network to continue to support peer-to-peer information sharing among growers. This will help farmers meet market demand for high quality local produce.
Tomatoes are one of the most profitable crops for organic and direct market growers in the North-Central Region (NCR). An increasing number of diversified vegetable growers are using high tunnels to improve tomato production in the short growing season of the upper Midwest. High tunnel conditions extend the season and reduce disease pressure, which is particularly important as direct market growers often prioritize varieties with good quality over disease resistance if they must make a choice. Field-grown tomatoes, while still profitable, are more at risk for disease and splitting, and many growers report a much higher rate of loss from field grown than hoop house tomatoes (Healy et al., 2016). Many farmers are struggling to find sustainable rotations for high tunnel structures, because the value of tomatoes makes it difficult to take a hoop house out of tomato production for a season.
The goals of this project are to improve options for sustainable and profitable direct-market tomato production in the Upper Midwest. We will evaluate strategies that will give growers economical options for improving production, including: 1) evaluating lower-cost alternatives to high tunnel production such as caterpillar tunnels, 2) selecting varieties for shorter-season production in high tunnels, giving growers more rotational options before or after tomatoes, and 3) lowering the risk of field grown tomatoes through selecting disease resistant and dual purpose varieties, with both excellent fresh and processing characteristics. We will conduct both on-farm participatory trials and certified organic trials on two research stations to ensure that results provide immediately relevant results to farmers.
High Tunnels are a common management strategy, and provide many benefits, but also present both management and financial difficulties to growers.
NCR organic farmers increasingly rely on high tunnels to extend the season and protect crops from foliar disease pressure. The Environmental Quality Incentives Program (EQIP) Seasonal High Tunnel Initiative, a project of the Natural Resources Conservation Service (NRCS), reports assisting farmers in constructing over 12,000 high tunnels in the United States between 2010 and 2014 (NSAC, 2015). High tunnels can increase the length of the season for cold climates, reduce disease pressure by permitting greater control of water, and increase yields. High tunnels may also play a role in mitigating high rainfall events experienced in the upper Midwest in recent years. At the same time, high tunnels increase the risk of loss due to storms or extreme weather events that may destroy high tunnel plastic and frames. Lower cost structures would present possibly less protection, but also much lower levels of financial risk if a structure or crop growing in the structure are destroyed.
Our SARE-funded research (LNC14-357) compared 20 varieties in high tunnel and field management and found an increase in yield of 20% in 2014 (a low disease year for the field), 45% in 2015, and 200% in 2016 (a very high disease pressure yield for the field) in the high tunnel compared to field trials over the same set of cultivars (see Figure 1). The increased yields were primarily due to reduced disease pressure in the high tunnel. Our main foliar diseases are early blight and septoria. Because of the reduction in spore deposition of these pathogens in the high tunnel and the reduction of rain splashing and continued moisture that allows pathogens to spread, high tunnel plants remain healthy during most of the growing season, while neighboring field production may collapse due to high foliar disease pressure. However, after multiple years of cultivating tomatoes in the same location in a stationary high tunnel, many growers report a buildup of other diseases, such as grey mold and various types of mildew (Miller, 2015). Soil quality may also suffer from a lack of adequate rotation, as high tunnel tomatoes require considerable amounts of nutrients each year, and as they are full season crops, there is little time to put in a cover crop after tomato plants are removed in late October or November. Growers frequently rely on external nutrient sources (composts and other organic fertilizers) to supply fertility. This, combined with the lack of rainfall, may lead to nutrient imbalances, and salt buildup as well as general depletion of soil organic matter.
Mobile high tunnels present a possible solution to the linked problems of inadequate rotation, disease buildup and declining soil fertility. The objective of a mobile tunnel is to allow growers to move the tunnel in the rotation with the high value crop that is grown in it, so that they are not always using the same spot for high tunnel production. With a mobile tunnel, growers can use rotations, cover cropping and other standard techniques for preventing pest, pathogen and soil problems without giving up a season of high tunnel production for their tomatoes. Moving the high tunnel also allows rainfall to flush salts back down into the soil profile. Mobile high tunnels however, have significantly greater costs than stationary tunnels, often up to twice the cost for materials. This is mostly because the frame must be built more solidly to withstand winds and other severe weather, as a mobile tunnel frame cannot transfer this force to the ground as a stationary tunnel does. Mobile tunnels on tracks also restrict equipment access to parts of the field and need to be maintained.
For these reasons, many growers are looking at caterpillar tunnels as a potentially lower cost structure to achieve the goals of mobile high tunnels with less capital cost up front and lower costs of yearly maintenance (see Figure 2). However, there has not been much research done comparing the relative cost/benefit of these structure types in terms of tomato season extension, productivity, or disease mitigation. Caterpillar tunnels are certainly more affordable and provide a great degree of flexibility, but may provide fewer benefits. While several SARE projects have looked at high tunnel or caterpillar tunnel production, none have compared tomato production in the field, caterpillar tunnels and high tunnels for a representative set of varieties. A SARE graduate student project (GNC10-146) compared cucumber and tomato production in caterpillar tunnels to field production, with caterpillar tunnels only being left on for the beginning of the season, which provided benefits for earliness but not disease protection. SARE has funded multiple on/farm partnership high tunnel projects. Recent ones include ONE13-191 compared 12 varieties and ONE05-046 had two trials one for slicers and one for heirlooms, comparing 4 varieties each. The projects found differences between varieties but did not have comparisons to field or low tunnel conditions. Another grant (ONE04-028), compared determinate and indeterminate tomatoes in high tunnels and found greater yields, fruit weight and fruit numbers for indeterminate tomatoes in a hoop house environment. Growers in the upper Midwest are experimenting with caterpillar tunnels and high tunnels on their own, but would like to see reliable numbers on expected production and labor for caterpillar tunnels compared to high tunnels so that they can weigh the costs and benefits when making decisions about where to invest on their farms.
In addition to providing information comparing management options, we need to develop cultivars specifically for high tunnel and field management to give growers the best options for each system.
Tomatoes have been repeatedly identified as a top priority for breeding work focused on organic systems (Lyon, 2015; Dawson, 2016 focus groups). While a wide variety of tomato cultivars are available to organic direct-market growers, few have been bred or trialed for adaptation to organic systems, and even fewer have been developed with a focus on the upper Midwest and a commitment to farmer participation.
The Tomato Organic Management and Improvement (TOMI) project funded by USDA OREI and led by Lori Hoagland at Purdue focuses on developing organic disease management strategies, including breeding for resistance in organic systems. Dawson is a co-PI on this grant and co-leads the breeding component. The objective is to combine good flavor and disease resistance in slicer tomatoes, but we still see significant field losses of project lines. The proposed project would build on the work done in the TOMI project to create more robust populations for field production through crossing to tomatoes with higher solids content for dual-purpose use.
Despite the growth in high tunnel usage, cultivar development focused on organic high tunnel systems remains rare. There are selection programs for greenhouse tomatoes, but the constraints of a greenhouse system are considerably different than those of a high tunnel, as high tunnels are used for main-season tomato production, in the existing soil, with different disease pressures and nutrient regimes than greenhouses. This project will use results from our current SARE-funded project to develop breeding populations specifically for high tunnels. For both high tunnel and field conditions, we have identified new varieties with good field performance that also have very high acceptance with our group of participating chefs (see Table 1).
The lack of tomato cultivars specifically adapted to regional organic production systems reflects a global trend in cultivar availability for organic farms; an estimated 95% of organic production worldwide is dependent on crops that were bred for the conventional sector, rather than organic or low-input systems (Lammerts van Bueren, et al, 2011). Farmers in the NCR will benefit significantly from access to tomato varieties bred specifically for northern organic farm systems, with quality traits attractive to direct market customers and production characteristics suited to farmers’ management systems. Organic farmers’ ability to adapt to new weather patterns and market needs, will in part depend on how well adapted their crops are to regional climate trends and shifting priorities in organic management. This need for responsiveness creates an opportunity to build breeding programs committed to farmer participation, on-farm trialing and selection, and continued education about how farmers can build a seed system attuned to their needs.
Decentralized, participatory research designs have been shown to be an effective tool for yielding rigorous and immediately applicable research results, while developing stakeholder knowledge and increasing the effectiveness of extension and outreach education (Dawson et al., 2011; Soleri et al., 2002). Over 60 organic or low-input farmers in our region have already invested in participatory research by conducting on-farm variety trials as part of our Seed to Kitchen Collaborative https://dawson.horticulture.wisc.edu/chef-farmer-plant-breeder-collaboration/. These farmers continue to participate in trials because they are interested in seeing the next step: cultivar development and release. The proposed project will initiate the cultivar development phase for tomatoes, a high value crop for sustainable and organic farmers in the region, with a focus on adaptation to both organic field and hoop house production. This project serves not only the immediate need for productive, flavorful tomato cultivars adapted to organic production and season extension in the NCR, it also serves the broader need for more regional and participatory plant breeding and for more organic plant breeding students primed for careers in the public sector.
Dawson, Julie C., et al. “Collaborative plant breeding for organic agricultural systems in developed countries.” Sustainability 3.8 (2011): 1206-1223.
Lammerts van Bueren, E.T., S.S. Jones, L. Tamm, K.M. Murphy, J.R. Myers, C. Leifert, and M.M. Messmer. 2011. The need to breed crop varieties suitable for organic farming, using wheat, tomato and broccoli as examples: A review. NJAS-Wageningen Journal of Life Sciences 58: 193-205.
Lyon, Alexandra, Erin Silva, Jared Zystro & Michael Bell. 2015. Seed and Plant Breeding for Wisconsin’s Organic Vegetable Sector: Understanding Farmers’ Needs. Agroecology and Sustainable Food Systems. DOI: 10.1080/21683565.2015.1017786.
Miller, S. 2015. Managing diseases of organic tomatoes in greenhouses and high tunnels. Ohio State University Extension. 6 October 2016 < http://articles.extension.org/pages/18337/managing-diseases-of-organic-tomatoes-in-greenhouses-and-high-tunnels>
National Oceanic and Atmospheric Association. 2017. National Overview, 2017. accessed: March 25, 2017. https://www.ncdc.noaa.gov/sotc/national/201702#MRCC
National Sustainable Agriculture Coalition. 2015. High tunnels continue to serve new farmers. accessed: March 25, 2017. http://sustainableagriculture.net/blog/2014-high-tunnel-update/.
Soleri, D., D.A. Cleveland, S.E., Smith, S. Ceccarelli, S. Grando, R.B. Rana, D. Rijal, and H. R. Labrada, 2002. Understanding farmers’ knowledge as the basis for collaboration with plant breeders: methodological development and examples from ongoing research in Mexico, Syria, Cuba and Nepal. Farmers, scientists and plant breeding: integrating knowledge and practice. Cleveland and Daniela Soleri. CAB International: 19-60.
We will compare caterpillar tunnels with high tunnels and field production for yield, disease mitigation, earliness, and quality (flavor and percent fruit that are marketable). We hypothesize that caterpillar tunnels will provide similar benefits to high tunnels (increased yield, decreased disease pressure, increased earliness and increased quality. We will quantify the benefit to determine if caterpillar tunnels are significantly different than field or high tunnel production for organic tomatoes. We will verify our research station results with on-farm trials comparing the three systems.
We hypothesize that by making crosses and conducting selection in either organic high tunnels or organic field conditions, we can improve tomato populations for those management systems by addressing key issues in each system. We will test breeding lines in organic high tunnel and field production under organic conditions and will work with farmers to do on-farm selection of the promising populations.
We will address the challenges farmers face in producing high quality organic tomatoes through a combination of breeding and management options. Our approach has three interrelated strategies to provide growers with improved options for high quality tomato production in the Upper Midwest. These are: 1) compare production, disease mitigation and cost in high tunnels, caterpillar tunnels and field production, so growers can base management decisions on reliable information about the benefits and drawbacks of each system, 2) select early tomato varieties for high tunnel production, with improved flavor and more concentrated fruit set to give growers more rotational options, and 3) select dual-purpose tomato varieties that are more robust for the field, with improved disease resistance and flavor. These three strategies build on our current work and respond to grower needs identified through our current SARE funded project.
We regularly involve farmers in research priority discussions and have farmers already interested in participating in these trials (see letters of support). This group of growers has been instrumental in defining these research objectives, will serve as an advisory group on this project, and will participate in both the research and outreach components. Participatory research and outreach is critical, particularly for organic growers, who have developed strong peer networks and often conduct on-farm experimentation themselves. Combining the level of detail possible in research-station based trials with flexible on-farm, participatory trials creates information that is reliable, relevant and trusted. It also forms a platform for outreach led by farmers, having done trials on their farms and having been involved in the planning and implementation of the research project.
Detailed methods for each of the three components of this project follow:
- Comparing high tunnel, caterpillar tunnel and field production
We will compare caterpillar tunnels with high tunnels and field production for yield, disease mitigation, earliness, and quality (flavor and percent fruit that are marketable). We have certified organic high tunnels at two agricultural research stations with adjoining organic land for field and mobile caterpillar tunnel trials. We will conduct a replicated trial at the West Madison Agricultural Research Station and the Arlington Agricultural Research Station with six varieties. All six varieties are either check varieties in our current trials or have been selected as parents in the field or high tunnel breeding projects because they have had good performance in our field trials.
- Big Beef (large slicer, F1 hybrid, check),
- Defiant (small slicer, F1 hybrid, field and HT parent variety)
- Damsel (large slicer, F1 hybrid, excellent flavor in both field and HT, farmer choice)
- Pruden’s Purple (Brandywine-type purple heirloom, open pollinated, check)
- Japanese Black Trifele (medium sized purple heirloom, open pollinated, field and HT parent variety)
- Paul Robeson (medium sized purple heirloom, open pollinated, farmer choice)
Varieties will be planted in a randomized complete block design in a high tunnel, in a caterpillar tunnel, and in the field at each location on certified organic land (see Figure 3). Data collected will include the date of first harvest, date of last harvest, foliar disease ratings and marketable and unmarketable yield weekly. Flavor evaluations will be conducted at each location when all plots are producing fruit. Flavor evaluation will follow the same methods used in our current SARE project, with field crew members receiving basic training in sensory evaluation at the beginning of the season, and rating varieties for overall flavor intensity, sweetness, acidity, umami (savory), texture and appearance on a scale from 1-5. Data will be analyzed using standard ANOVA methods similar to those used in Healy et al. (2016) to compare varieties, management, location and year effects on earliness, marketable yield, percent unmarketable, the area under the disease progress curve, and flavor ratings Labor hours for management and harvest will be collected so that we can compare the relative production of each system to the labor costs of managing that system.
Six farmers with both caterpillar tunnels and high tunnels will receive three of the six varieties and all material for the trial. Three farms each will receive the slicer set (Big Beef, OSA404 and Defiant) and the Heirloom-type set (Pruden’s Purple, Perfect Flame, 45L23). They will plant two replicates of the three varieties in each management system. Data collection will be simplified compared to the research station trials. Farmers will record the date of first harvest for each variety in each system, and then give an overall evaluation of the disease incidence, productivity and quality in each system, following a modification of the qualitative data sheet we use for variety trials which as been very successful. This will provide other farmers with realistic assessments of the performance of each of the three management systems while remaining reasonable in terms of the time commitment for participating farmers.
- Selecting varieties for high tunnel or caterpillar production with excellent flavor and a sustained high fruit set early in the season.
Our current SARE-funded high tunnel trials have identified several indeterminate varieties with early fruit set and excellent flavor. From our current data, we see significant differences in earliness in the high tunnel as well as differences in the concentration of yield over time. Current extra early tomatoes with more concentrated fruit set are typically determinate, have lower overall yields and poorer flavor than their main season counterparts. We will combine earlier fruit set and more concentrated yields with good flavor, and then select for higher yielding plants, with mid-sized fruit.
We have several outstanding early tomatoes from independent and university breeders. Particular standouts are the lines SGLL4 and 45L23 from independent farmer/breeder Keith Mueller of Kansas City and breeding lines in the P322 family from Jim Myers of Oregon State University. We are collaborating with them to expand the selection of these lines for high tunnels in more northern climates (see letter of support). These lines have early production and above average yields, but their production is spread across the entire high tunnel season (July – October). We will cross these lines to higher yielding, early varieties with more resistance to cracking, such as Perfect Flame from Ball Seeds (a heirloom by heirloom cross) and to some lines that have more concentrated yields, including some of the determinate early tomatoes. Selection methodology will follow the protocols outlined at the end of this section, with selection being conducted in an organic high tunnel environment at the West Madison Agricultural Research Station and on participating farms with high tunnel tomato production. The primary traits to be evaluated will be earliness, fruit size (to avoid only selecting smaller fruit), flavor, productivity per week and shorter duration of harvest.
- Selecting tomatoes with disease resistance, flavor and dual purpose use under field conditions.
Growers often choose to use hybrids or paste tomatoes in the open field because of their durability, however these often do not have the flavor characteristics that command good prices in local markets. High quality dual-purpose (for fresh eating and processing) tomatoes would increase returns from field production. We have conducted three years of trials under field conditions and have identified varieties with above average yield and disease tolerance and good flavor.
We had two seasons (2015 and 2016) with high disease pressure, including bacterial speck, early blight and septoria. While the top yielding varieties are predominantly hybrids, we have identified open pollinated varieties that have better than average yields with very good flavor and good resistance to cracking. We plan to use these lines as our starting parents, as well as two hybrid varieties with good flavor and yields (crossing to an F1 hybrid is called a top-cross, and produces a population that is 25% each of the parents of the hybrid and 50% the second parent). These varieties include two entries from the TOMI project OSA404 and OSA405, heirloom varieties Crimson Sprinter and Japanese Black Trifele, and hybrids Garden Gem from the University of Florida and Defiant, from Johnny’s Selected Seeds. We also have identified paste tomatoes Quadro and Iraqi Heart, with good fresh flavor, and the higher solids content of paste tomatoes usually makes them more resistant to cracking and more robust in the field. These varieties are primarily from Adaptive Seeds in Oregon, which has specialized in finding and selecting open pollinated oxheart and dual purpose paste tomatoes for the Pacific Northwest. These varieties are not optimally adapted to the climate of the upper Midwest, but have good quality, and so we will cross them to some of the best performing lines in our trials and select for high yield, good flavor, high solids content and good disease tolerance.
Field trials and selection
For objectives 2 and 3, we will carry out crosses in the 2017 field season, and increase the F1 hybrid seed in the greenhouse over the winter before this project starts. This initial crossing is a relatively low-cost activity and this will advance the lines so that we can start our project the first year with second-generation (F2) progeny to test in the field. See Figure 4 for more details on the timeline. In year one, we will plant the F2 progeny from each cross under organic conditions at the West Madison Agricultural Research Station and will select based on family mean performance for the traits described above. We will primarily select families, rather than individual plants, as in the F2 generation individual plants will not breed true to type. We will grow and self-pollinate selected families in the greenhouse over the winter, advancing to the fourth (F4) generation for the following year. In season two, we will start selection on individual plants within each F4 family, and also continue family selection. Participating Madison-area chefs will evaluate selected lines in comparison to parental varieties, using the same methodology we are successfully employing in our current SARE-funded project. Chefs rate varieties for intensity, and whether they would purchase that variety for their restaurant, followed by descriptors of the variety flavor and general preference. They also use a similarity-based method called projective mapping to group and compare varieties to each other to obtain quantitative information on the degree of similarity and difference among the tomato samples for all flavor attributes at once. We will again advance selected lines in the greenhouse over the winter and will plant the F6 generation in the field in 2020. We will conduct selection again in the 2020 season, including chef evaluation of flavor. This selection will include feedback gained from farmers in the 2019 field season (see below). We will select individuals within high performing families and multiply this in the greenhouse in the last winter of the project.
In year two, six participating farms will receive their choice of F4 seed from three families selected in year one, three from field selections and three from high tunnel selections. They will plant 12-20 plants of each family and score families for overall performance, flavor, and disease resistance. They may also select individuals within each family and save seed from individual plants. The research team will work with farmers who would like to save seed to ensure that the workload is reasonable and that farmers have training in tomato seed saving if requested (some of the farmers we are working with have many years of experience saving seed and some have not done this before but would like to learn). In year three, farmers will plant seed that they have saved and we will distribute seed selected in on-station trials. We will follow standard protocols for hot water treatment of seed if there is any risk of seedborne disease from bacterial speck. Farmers will follow the same protocol for the second season of selection.
We will move our final selections to larger field trials and release finished varieties in the years immediately following the project completion. Variety release will use mechanisms to ensure that varieties are available for continued breeding and that farmers are allowed to save seed, with proper credit given to all breeders and farmers involved in the creation of those varieties.
The results from this project will include recommendations for growers on high tunnel and caterpillar tunnel costs and benefits, and advanced breeding populations selected for field and high tunnel production.
- Breeding populations for field production
- Breeding population with high quality for dual-purpose use, with good yields and disease tolerance under field production.
- At least one improved open pollinated population for continued on-farm selection by growers and potentially released as a variety after more extensive field testing by growers
- Advanced populations selected by participating growers for their own use.
- Breeding populations for high tunnel production
- Breeding population with excellent flavor, early production, good yields and more concentrated fruit set for high tunnel production
- At least one improved open pollinated population for continued on-farm selection by growers and potentially released as a variety after more extensive field testing by growers
- Advanced populations selected by participating farmers for their own use
- Educational resources for growers and extension educators
- An extension bulletin and accompanying scientific publication with a detailed comparison of high tunnel, caterpillar tunnel and field production including cost of production, yield, disease mitigation, earliness, and quality.
- Informational resources describing on-farm selection techniques, seed saving and basic breeding strategies for farmers interested in continuing to develop populations on their farms.
We trialed three heirloom and three modern varieties in organic field, caterpillar tunnel and high tunnel production systems in Madison, WI and Spooner, WI, two very different growing environments. Data collected included the date of first harvest, date of last harvest, foliar disease ratings and marketable and unmarketable yield weekly. Flavor evaluations were conducted at each location for all three systems when all plots were producing fruit. Three farmers conducted side by side trials of either the heirloom or the modern varieties in high tunnel, caterpillar tunnel and field systems with two replications.
We grew out F1 and F2 populations of crosses for the high tunnel and for the field in Madison WI. We have made selections on family performance for productivity, disease resistance and flavor, and are advancing selected families in the greenhouse this winter.
We continued trialing of three heirloom and three modern varieties in organic field, caterpillar tunnel and high tunnel production systems in Madison, WI and Spooner, WI, two very different growing environments. Data collected included the date of first harvest, date of last harvest, foliar disease ratings and marketable and unmarketable yield weekly. We collected weather data and temperature in each system throughout the season. Flavor evaluations were conducted at each location for all three systems when all plots were producing fruit. Three farmers conducted side by side trials of either the heirloom or the modern varieties in high tunnel, caterpillar tunnel and field systems with two replications.
We grew out F3 and F4 populations of crosses for the high tunnel and for the field in Madison WI. We have made selections on family performance for productivity, disease resistance and flavor, and advanced selected families in the greenhouse this winter. Four farmers were sent segregating populations of families that met their criteria for shape, color, size of fruit and which showed good performance in Madison in the F2 generation. These four farmers conducted selection on farm and sent observations and seed back to Madison for advancement in the greenhouse over the winter. The same farmers were sent seed for the 2020 growing season of F3 seed that they had selected and F4 selections from Madison. Selections have been planted in Madison for the 2020 growing season.
We completed trialing of three heirloom and three modern varieties in organic field, caterpillar tunnel and high tunnel production systems in Madison, WI and Spooner, WI, two very different growing environments. Data collected included the date of first harvest, date of last harvest, foliar disease ratings and marketable and unmarketable yield weekly. We collected weather data and temperature in each system throughout the season. Flavor evaluations were conducted for all three systems when all plots were producing fruit. Three farmers conducted side by side trials of either the heirloom or the modern varieties in high tunnel, caterpillar tunnel and field systems with two replications. On-farm trials for both the management trials and selection experiment were complicated this year due to COVID related restrictions on travel which made it impossible for the research team to do farm visits.
We grew out F5 and F6 populations of crosses for the high tunnel and for the field in Madison WI. Performance of field selections was disappointing in terms of disease resistance, and we do not expect to release varieties from this particular set of crosses, but we are using the populations created to study field disease resistance as part of two successful grant applications which were funded. It is likely that with the severe septoria and early blight pressure in the midwest, we will need to incorporate stronger qualitative resistance alleles in addition to the quantitative resistance we were hoping to select for. We are continuing this work as part of an OREI-funded project led by Purdue University and a Wisconsin Organic Initiative grant that will fund a PhD student.
In the high tunnel results are much more promising. We have made selections on family performance for productivity, disease resistance and flavor, and are advancing selected families in the greenhouse this winter. Four farmers were sent segregating populations of families that met their criteria for shape, color, size of fruit and which showed good performance in Madison and in on-farm trials last year. These four farmers conducted selection on farm and sent observations back to Madison for advancement in the greenhouse over the winter. The best lines are nearly stable and will be tested for on-farm performance as part of our Wisconsin Organic Initiative grant and a different OREI-funded project led by Oregon State University. In addition, we will be working with independent plant breeders in the Upper Midwest to build on this work as part of a third OREI-funded project that we are leading in collaboration with SeedLinked and Organic Seed Alliance.
Management trial results
We are in the process of submitting the results of the management trials for publication in a scientific journal, and are also preparing an extension bulletin for farmers with the results. A summary is provided here. Complete results are available in the Horticulture Masters thesis of Juan Astroza, available from the University of Wisconsin Library System or by request.
In both WMARS and Spooner, caterpillar tunnels and high tunnels had higher daily maximum temperatures compared with the open field, at times reaching a difference of 15 ˚C or more. Minimum daily temperatures were very similar for all systems and in both locations. High tunnels and caterpillar tunnels accumulated growing degree days (GDD) more quickly that the field and continued to accumulate GDD later in the season, maintaining optimal conditions for tomato growth for a longer period of time than the field. There was very little difference in GDD accumulation between the high tunnel and caterpillar tunnel systems.
For tomato production the high tunnel and caterpillar tunnel both had significantly higher marketable yields than the field production system in both locations. The caterpillar tunnel outperformed the high tunnel in Spooner largely due to exceptional performance in 2018. The high tunnel and caterpillar tunnel systems were not significantly different than each other in Madison. The field was the lowest yielding system in both locations.
There was consistent performance of the different genotypes between management and location. There were no significant changes in ranking of varieties across the three systems within a location, and there was only one significant change in rank across locations, with Defiant as having the highest marketable yield in Madison and Big Beef having the highest marketable yield in Spooner.
All varieties had higher performance in the tunnels and variety recommendations can be made for each location without having to make recommendations specific to management systems. However, as there were system-specific differences in the prevalence of certain causes of unmarketability, such as blossom end rot, choosing varieties that are less susceptible to these particular problems for specific systems may be beneficial to growers. Between management systems, the open field had much higher levels of unmarketable yield compared to both tunnels.
Disease incidence and severity:
The open field had significantly higher total area under the disease progress curve (all diseases combined) followed by the high tunnel, then the caterpillar tunnel. The high tunnel may have had higher levels of humidity than the caterpillar tunnels, leading to higher levels of leaf mold in the high tunnel. Field disease pressure was primarily septoria leaf spot and early blight, and in the two tunnels disease pressure was primarily early blight and leaf mold. The reduction in septoria leaf spot in the two tunnel systems was particularly striking.
Both tunnel systems had higher ˚Brix levels compared to open field but there were no significant differences between tunnels. This may be explained by the higher temperatures and lower soil moisture levels in both tunnels compared to the open field. The healthier foliage in the tunnels may also have been able to produce more sugars as fruit ripened due to higher sustained levels of photosynthesis. Citric acid levels were higher in the open field compared to both tunnels.
Significant differences between varieties were seen, supporting the strong effect on genotype on sugar accumulation. Damsel had the highest sugar accumulation across management systems, which may be due to the fact that this variety was bred specifically for flavor. Damsel also had generally higher levels of CA compared to other varieties, which may also be due to selection specifically for flavor. The results with Damsel were borne out in taste evaluations and farmer preferences for the variety.
The tastings confirm what was found in the ˚Brix and CA, with higher perceived sweetness in the tunnels compared to the open field, and higher acidity in the open field compared to both tunnels, with no significant difference between tunnels. The high tunnel and caterpillar tunnel both showed a significantly higher overall flavor rating compared to the open field. Damsel had the highest mean value for overall flavor although it was not significantly different than most other varieties in each system. Most varieties showed improved flavor in both tunnels compared to the open field, however, there was some variation in whether varieties had better overall flavor in the high tunnel or in the caterpillar tunnel.
The qualitative results from on-farm trials align with our on-station trials, with the open field generally performing worse than both tunnels. Also, for some variety/location/year combinations the caterpillar tunnel does better and in some the high tunnel does better. For the slicer market class, Damsel seemed to be the preferred variety due to its good performance and excellent flavor. The best variety in the open field was Paul Robeson for the heirlooms and Damsel for the slicers. For the tunnels, the best slicer was again Damsel but Japanese Black Trifele was the preferred heirloom.
Educational & Outreach Activities
Our outreach program consists of two to three annual field days, three winter workshops, presentations at 4 to 6 regional conferences and one extension bulletin presenting trial results. Our largest field day will be held annually at the West Madison Agricultural Research Station, the primary site of our trialing and breeding work. Farmers will be invited to walk the fields with local chefs, seed company representatives, and project personnel, learning about how potential varieties perform in hoop house, field and low-cost mobile season extension systems. These field days will involve presentations from project personnel and hoop house/ caterpillar tunnel experts, tasting breeding lines and trial varieties, and well is time for participants to network and share experiences with each other. Additional field days will be held on participating farms in Northern, WI and Milwaukee (at a different farm each year). Though the public will be welcome to attend these field days, the target audience will be local direct-market farmers and programming will be tailored accordingly.
In each year of the project we will host a winter workshop in Madison, WI. We already host annual winter meetings as part of the Seed to Kitchen Collaborative, and would expand these meetings into educational events allowing farmers to reflect on trials collaboratively, learn about the previous season’s trial results, and participate in shaping plans for the future.
In addition to hosting field days and winter workshops, we will publish an extension bulletin in the final year of the project, summarizing trial results and translating findings into useable information for direct-market tomato growers. Final results will also be presented at fresh market and organic vegetable grower conferences in the North Central Region after the third growing season