[Editor’s Note: To see the report with tables properly formatted open the PDF version.]
My wife, Julianna and I have owned and operated Two Onion Farm in Lafayette Co., southwestern Wisconsin since 2003. Our farm occupies 12 acres, of which we use five to raise produce. Currently we raise over twenty-five vegetables and fruits in the field and in plastic covered hoophouses. Some of our most important crops are lettuce, tomatoes, onions, broccoli, winter squash, and carrots. All of our produce is certified organic.
Our primary market is a 400 member community-supported agriculture (CSA) program. Members in Madison and Platteville, WI; Dubuque, IA; and Galena IL receive vegetables from us for a 24 week delivery season. In addition to our CSA, we sell produce to a local grocery store, a restaurant, and to wholesale distributors.
Our farm has been certified organic since 2009. We rely on compost, cover crops, rock minerals, and other organic inputs to maintain soil structure and fertility. In 2009 and 2010, in cooperation with our local NRCS office, we installed a grassed waterway and drainage ditches to reduce soil erosion on our gently sloping fields. Since 2007, we have employed numerous workers from the area. We strive to pay a fair wage, provide a safe and respectful workplace, and train our workers in sustainable vegetable production.
(1) Collect data on expenses (including labor) and yields to evaluate the profitability of organically-grown maypops in hoophouses (a.k.a. high tunnels). Maypops are a heat-loving crop, benefit from a long growing season, and are likely well suited to hoophouse cultivation.
(2) Compare winter survival of maypops in a hoophouse when they are covered and uncovered by fabric cover and compare yields and profitability in the first and second year after planting. The maypop can be grown as an annual because it will flower and fruit prolifically in its first year, and as an annual it would fit best into crop rotations on many vegetable farms. However, it may be more profitable as a perennial if yields are higher in the second year or if the expense of establishing new plants is high. If the maypop is best grown as a perennial it is important to know whether covers are needed for overwintering within a hoophouse in our region.
(3) Compare yields of hand-pollinated and non-hand-pollinated maypops to determine if lack of insect pollination limits yield in hoophouse maypops. If so, future research could evaluate managed bumblebees or other introduced pollinators.
(4) Compare yields and growth of maypop plants from several seed dealers and nurseries. There are no named maypop varieties, but clones from some sources may be better suited to our region.
(5) Assess consumer and chef acceptance of maypops. Provide free maypop fruits to a local grocery store and restaurant and also to a sample of our CSA members and solicit feedback.
Plant and seed sources. I purchased approximately 100 maypop seeds from each of five commercial sources: West Seed Farm (abbreviated WSF hereafter), SmartSeeds (SS), Where The Wild Things Grow (WTWTG), Turtlegaby’s Tropical Oasis (GABY), and Onalee’s Home Grown Seeds (ONA). All five are eBay vendors. I obtained 13 live plants from each of five other sources: Shooting Star Nursery (www.shootingstarnursery.com, abbreviated hereafter SSN), Niche Gardens (www.nichegardens.com, NG), Brushwood Nursery (www.gardenvines.com, BN), Lazy S’S Farm Nursery (www.lazyssfarm.com, LSS), and Companion Plants (www.companionplants.com, CP). I selected the ten seed and plant sources on the basis of price, availability, and vendor reputation (as judged primarily from reviews on eBay and the Dave’s Garden website).
Plant and seedling care until transplanting. Live plants were received between 3/27/2012 and 5/9/2012. The plants were small potted plants apparently grown from root or stem cuttings. We held the plants in a heated greenhouse and watered as needed but did not fertilize or provide other care until transplanting on 5/18/2012.
We raised seedlings similarly to the way in which we raise vegetable seedlings on our farm. On 4/6/2012, we planted seeds on 2 inch soil blocks made from Johnny’s Selected Seeds 512 soil mix. We covered seeds with a thin layer of vermiculite, inserted the trays of soil blocks into plastic bags to maintain humidity, and placed them in a dark, heated germination chamber at 85 degrees for 7 days. After 7 days, a few seedlings had sprouted and emerged and were very etiolated. We moved the trays to a heated greenhouse. Seedlings continued to emerge gradually over several weeks and eventually about 40-50% of seedlings emerged for most varieties. On 4/25/2012 we selected the 12 most vigorous seedlings of each variety and potted them on into 4 inch soil blocks and grew them in those blocks until transplanting on 5/18/2012.
Transplanting. On 5/18/2012 we transplanted all plants into a 16 foot x 132 foot unheated hoophouse. I chose to raise the plants in a hoophouse because they are heat loving plants which require a long growing season to ripen a full crop of fruit. I also wanted to determine if maypops would overwinter inside a hoophouse since they are generally not winter hardy in our region. We planted in three rows 4 feet apart, plants were spaced 3 feet apart within the row. Plants were arranged in a semi-random pattern: the hoophouse was divided into 4 equal sized sections so that one-quarter of each row lay within each section. Sections 1 and 3 were designated for hand-pollination (see below), and section 2 and 4 were not hand-pollinated. Each of the ten plant sources had one plant in each row within each section. Sections 1 and 2 were designated to be covered overwinter with crop cover (see below).
Soil tests indicated that the soil there was high in nutrients and organic matter and we rototilled but applied no fertility prior to planting. We placed the plants in the ground, covered with field soil, watered each planting with 6 oz of Drammatic K fish fertilizer diluted at a ratio of 4 cups Drammatic K: 7 quarts of water and then immediately ran drip irrigation.
Irrigation. We drip irrigated thereafter once per 4-7 days depending on temperature and plant size. We used a low flow drip tape (.34 GPM per 100 feet) and watered 10-12 hours per session.
Trellising and Training. Maypops are vigorous tendrilled vines. We provided support to keep the plants off the ground, improve airflow, and ease work. We ran 9 gauge galvanized brace wire above each plant row. The wire was suspended approximately 6 feet above the ground on extension hangers dangling from the purlins of the hoophouse frame. We suspended Hortonova trellis mesh from each wire by wrapping rope around the wire and trellis mesh for the entire length of the wire according to instructions from the Hortonova supplier (Johhny’s Selected Seeds). During the season, we periodically tucked stray shoots from the maypops into the mesh to keep the aisles clear.
Weeding. Landscape fabric was applied to the ground between rows for weed control. We also weeded the hoophouse as needed to eliminate all weeds.
Hand pollination. Several studies have shown that maypops are self-incompatible (maypop plants cannot pollinate themselves). The most effective pollinating insects are large bees, especially carpenter bees. Small bees such as honeybees visit the flowers to collect pollen and nectar, but the flowers are so large and the parts of the flower so far apart that small bees rarely touch the female parts of the flower and deposit pollen there. Some cultivated maypop plantings receive few visits from large bees and the vines flower profusely but set few fruits, suggesting that poor insect pollination may limit fruitset. Insect pollinators are often scarce in hoophouses, and so poor pollination is particularly a concern in hoophouse-grown maypops. To test whether inadequate insect pollination limited yield, we hand pollinated all flowers on half of our maypop vines and compared yield between hand pollinated (HP) and non-hand pollinated (NHP) plants. Maypop flowers open around noon. We performed pollinations between 1:00 and 5:00 PM daily. We collected pollen from flowers and used forceps or paintbrushes to smear the pollen on stigmas of flowers from other plants. We pollinated daily between 6/28 and 8/17. Few flowers were open before 6/28, and after 8/17 very few flowers were open and these flowers were unlikely to have sufficient time to mature fruit before frost.
Harvest. Maypop fruits fall from plants when ripe. Ripe fruits do not spoil quickly. We collected and counted maypop fruits approximately once per week in late summer and fall. Yield data was collected separately for each plant.
Overwintering. In December, plants in sections 1 and 2 were covered overwinter by lifting the trellis from the ground and covering the ground with Dupont 5131 crop cover (1.25 oz/sq yard).
Taste. Family members and I sampled numerous fruits from each variety. As yield increased later in the harvest season, we planned to supply a local restaurant, a retail store, and some of our CSA members with fruit. However, several members of our family experienced severe stomach cramping repeatedly after eating the fruit. We subsequently decided not to distribute the fruit to our customers out of concern for their safety and our farm’s reputation.
Cessation of research Our original grant proposal included plans to evaluate winter hardiness of maypops in our hoophouse and to collect another year’s worth of data on growth and yield. However, we discontinued the study as of January 1, 2013 because we felt it was a poor use of SARE program funding and our time given the stomach upset we experienced after eating the fruit.
Kiera Mulvey, Executive Director and Dennis Fiser, Grower Program Manager, Fairshare CSA Coalition, Madison WI. Kiera and Dennis advised us on the design of the study and offered to help disseminate our results in 2014 through a field day sponsored by Fairshare. After consultation, we cancelled the planned field day because of the disappointing results of the first year’s research.
Jesse Strassburg, Program Director, Farmer Training Initiative, CRAFT, Rockton, IL. Jesse also offered to co-sponsor the planned field day through the CRAFT program.
Ryan Boughton, Chef, One Eleven Main restaurant, Galena IL. Offered to trial maypop fruit in a commercial restaurant kitchen. After consultation, we cancelled the trial.
Robin Timm, Produce department manager, Driftless Market, Platteville WI. Offered to trial maypop fruit as a retail item in a grocery store. After consultation, we cancelled the trial.
Effects of hand pollination. We harvested 262 fruits from hand-pollinated plants and 142 fruits from non-hand pollinated plants. The NHP section which was at the end of the hoophouse (Section 4) produced 120 fruits, but the NHP section towards the center of the house (Section 2) produced only 22 fruits. No comparable difference was observed between the two HP sections (sections 1 and 3), suggesting that pollinating insects which enter the house may tend to stay near the end.
We observed some bumblebees loaded with pollen in the hoophouse (in an hour in the hoophouse during the afternoon, it was common to see 2-3 bumblebees), and very rarely we saw a honeybee. Many flies visited flowers for nectar and may have provided occasional pollination. We observed small beetles eating the pollen voraciously and this may have reduced fruitset.
Future maypop growers may want to experiment with introducing managed bumblebee hives into hoophouses to increase fruitset.
Yield. Total yield was 404 fruits. Fruits typically weigh 20-40 grams. About 25-50 fruit are required to produce a cup of juice, because most of the fruit weight is in the inedible rind and seeds. Yield peaked in early September. Plants varied enormously in yield, producing 0 to 31 fruits. Plant size and yield were greatest in the middle row within the house (171 fruits), less in the southmost row (138 fruits), and least in the northmost row (95 fruits). We expect that cool spring temperatures limited the plants in both the north and south rows. (The north and south sidewalls of the hoophouse were often rolled up for ventilation in the spring.) Shading from the vigorous middle row may have further limited growth and yield in the north row.
The plants are extremely vigorous, branch profusely and send up many suckers. We observed repeatedly that flowering is most prolific where shading is least. Plants at the edges of rows produced the most flowers and fruit. Most areas of the hoophouse were in dense shade by late July because of the vigorous maypop growth. Wider spacing or taller trellising may be appropriate.
Differences between plant sources. Plants raised from seed from the same source showed some commonalities but were variable. Purchased plants from a single source were generally quite uniform and may have been vegetatively propagated clones.
Variety, Total fruit yield, Comments
WSF, 17, Large plants with very high vegetative vigor.
GABY, 30, Some plants produced fruit with pleasant, sweet, fruity flavor. Some plants also produced high yields of large fruit.
ONA, 42, Some plants produced fruit with pleasant, sweet, fruity flavor. Some plants also produced high yields of large fruit.
SSN, 14, Fruit with pleasant, sweet, fruity flavor.
NG, 36, Large fruit with copious juice and indifferent flavor.
BN, 148, Flowered and fruited early and prolifically. Small fruits with very sour and badly flavored juice.
LSS, 47, Bland fruit with unpleasant aftertaste
CP, 41, 31 of the fruits came from a single non-hand pollinated plant at the end of the middle row
Costs of Production. After tracking time and expenses growing maypops, we prepared the following budget. It excludes time and expenses (such as recording detailed harvest data for each plant or writing this report) which were specifically research and outreach related. In addition, we excluded time for hand pollinations because these would presumably not be performed in most commercial plantings.
Item, Cost, Description
Labor, $561.80, See separate table below
Drip irrigation line, $7.29, 360 feet of 508-08-340 T-Tape
Hortonova trellis netting, $132.25, 2 rolls 79 inch x 250 foot hortonova mesh
Galvanized brace wire, $39.60, 3 rolls 9 ga brace wire for trellis
Rope, $34.75 1/4 inch x 350 foot polyester rope for attaching Hortonova mesh to brace wire
Extension hangers, $90.32, S-hooks 12 inch, 18 inch, and 24 inch for hanging trellis
Wire staples, $35.50, Wire staples to anchor bottom of trellis netting to ground
Drammatic K fish fertilizer, $5.50, Used at transplanting
Soil mix, $64.85, 3.5 60 qt bags of Johnny’s 512 OG soil mix used for raising seedlings
Landscape fabric, $339.50, 4 foot x 250 foot 5 mil DeWitt brand
Crop cover, $78.70, 15×100 foot 1.25 oz/sq yd for winter cover
Sowing seeds 2.5
Potting on 2.5
Watering plants in greenhouse 3
Erecting trellis and training plants 22
At our farm’s average labor cost of $10.60 per hour, the cost of this labor is $561.80. No marketing time is included because we did not market the maypops.
• We will not continue growing maypops on our farm because of their adverse gastrointestinal effects. We encourage other interested growers to proceed cautiously because of this issue.
• Wide spacing and/or pruning is needed to accommodate these vigorous plants and reduce self-shading. From our experience we would recommend only 2 rows in a 16 foot wide hoophouse such as ours.
• Juice yield from our planting was low and a much higher yield would appear needed to justify the high costs of hoophouse construction, trellising, and growing the plants.
• We did observe definite differences between plant sources in flavor, yield, and growth pattern, suggesting that breeding and selection might develop improved varieties.
• Inadequate insect pollination appeared to limit fruitset and growers might wish to consider introducing bumblebee hives to increase pollination.
We have published a full report of our research online at http://www.twoonionfarm.com/Maypop.pdf
Future plans for disseminating the results are:
• Publishing report of research in Pomona, the journal of the North American Fruit Explorers
• Present results from my study at the research poster session of the annual Organic Farming Conference held in La Crosse, WI in 2014
Photographs submitted separately.
Problem/solution: One problem is that the market for local produce is crowded and that many produce growers in our region seek new and alternative crops to distinguish their farms in the local marketplace and to diversify their sources of income. A second problem is that there are few cultivated fruits suitable for our climate: growers seeking to produce fruit for local markets have limited options. (This is also a problem for stores and consumers who would like to purchase locally grown fruit but have few choices).
I propose to evaluate the maypop as a potential new fruit crop in our region to address both of these problems. The maypop is an excellent candidate for a new fruit crop: (1) it is closely related and very similar in appearance and taste to the widely-grown tropical passionfruit, (2) it has a long history of being eaten as a wild fruit where it is native in the southeastern United States, (3) it is similar in growth habit and cultural requirements to the cucumber and tomato, crops which many growers in our area already have experience with, and (4) it is unrelated to most crops grown in the region and would thus diversify crop rotations.
From a farmer’s standpoint, a major barrier to raising a new crop such as the maypop is the lack of information: growers do not know basic information about the cultural requirements of the maypop and the potential profitability of raising it. I propose to collect and disseminate this information.
The specific goals of my project are: (1) Collect data on expenses (including labor) and yields to evaluate the profitability of organically-grown maypops in hoophouses (a.k.a. high tunnels). Maypops are a heat-loving crop, benefit from a long growing season, and are likely well suited to hoophouse cultivation. (2) Compare winter survival of maypops in a hoophouse when they are covered and uncovered by fabric cover and compare yields and profitability in the first and second year after planting. The maypop can be grown as an annual because it will flower and fruit prolifically in its first year, and as an annual it would fit best into crop rotations on many vegetable farms. However, it may be more profitable as a perennial if yields are higher in the second year or if the expense of establishing new plants is high. If the maypop is best grown as a perennial it is important to know whether covers are needed for overwintering within a hoophouse in our region. (3) Compare yields of hand-pollinated and non-hand-pollinated maypops to determine if lack of insect pollination limits yield in hoophouse maypops. If so, future research could evaluate managed bumblebees or other introduced pollinators. (4) Compare yields and growth of maypop plants from several seed dealers and nurseries. There are no named maypop varieties, but clones from some sources may be better suited to our region. (5) Assess consumer and chef acceptance of maypops. I will provide free maypop fruits to a local grocery store and restaurant and also to a sample of our CSA members and solicit feedback.
Specifically, I will source maypop seeds and root cuttings from ten commercial sources and raise young plants in pots in heated greenhouses. I will transplant 120 plants (12 from each source) to a 16’ x 132’ hoophouse after danger of frost in the hoophouse has passed. Plants will be raised on trellises in rows four feet apart, plants spaced three feet apart within the rows. I will randomly divide plants from each source among four experimental treatments: covered/ hand-pollinated, uncovered/hand-pollinated, covered/unpollinated, and uncovered/unpollinated. Plants in the covered treatments will have their roots covered by heavy fabric row covers after the tops have died from frost (the natural growth habit of the maypop is that the aboveground parts die each winter but the roots survive and grow new shoots in the spring). Plants in the hand-pollinated treatments will have all of their flowers hand-pollinated during the growing season.
Research: I have read extensively about maypops in scientific journals and in fruit growers periodicals and I have corresponded and spoke with several maypop growers. My proposal builds on and expands previous work:
1. Growers in New York State, Kansas, and Tennessee have grown trial plantings of maypop fruit, but no one has rigorously measured and reported expenses in a commercial planting and there is only one report of fruit yields in a cultivated planting. Our research will be the first to report both expenses and yields. This information is very important for evaluating the maypop as a potential crop.
2. When maypops have been cultivated outdoors in central New York State and in Kansas, yields are limited by the short growing season – frost kills the vines before many fruits are mature. Trials have also shown that maypop plants typically do not overwinter in Wisconsin or central New York State. This research will be the first to evaluate maypops grown in a hoophouse environment to both extend the growing season and moderate winter temperatures.
3. Several studies have shown that maypops are self-incompatible (maypop plants cannot pollinate themselves). The most effective pollinating insects are large bees, especially carpenter bees. Small bees such as honeybees visit the flowers to collect pollen and nectar, but the flowers are so large and the parts of the flower so far apart that small bees rarely touch the female parts of the flower and deposit pollen there. Some cultivated maypop plantings receive few visits from large bees and the vines flower profusely but set few fruits, suggesting that poor insect pollination may limit fruitset. Insect pollinators are often scarce in hoophouses, and so poor pollination is particularly a concern in hoophouse-grown maypops. I will test whether pollinators limit fruit yield in my study by comparing yield from hand-pollinated and non-hand-pollinated plants.
Outreach: In 2013 I will hold a field day on our farm in late summer to display the maypop planting to other farmers and to discuss research results. I plan to have fruits available for tasting. Two area non-profit organizations which are heavily involved in farmer training have agreed to co-sponsor the field day: CRAFT (Collaborative Regional Alliance for Farmer Training, based in Caledonia, IL), and MACSAC (Madison Area Community Supported Agriculture Coalition, based in Madison, WI). The field day will be promoted through the MACSAC and CRAFT mailing lists and events calendars, and I will also publicize the day through other regional events calendars and email discussion groups.
I hope to present results from my study at the research poster session of the annual Organic Farming Conference held in La Crosse, WI. This conference attracts 3000+ attendees. Permission to present at the forum is awarded on a competitive basis; I have contacted the conference organizers and they said that my research would be well suited for presentation there.
I will submit the results of my research for publication in Pomona, the publication of the North American Fruit Explorers, which is read by fruit growers interested in new and unusual fruits.
I will publish data and pictures from my study on our farm website, www.twoonionfarm.com, in a portion of the site which I will establish specifically for this study.
Evaluation: To assess profitability of maypop growing, compare plants from different plant sources, measure overwinter survival with and without cover, and test for pollinator limitation of fruitset: I will track expenses, including seeds, plants, and materials. I and employees who assist in raising the maypops will use data forms to record the date, hours worked, and tasks performed on each day that we work in the maypop plantings. I will record dates of planting, transplanting, trellising and other important cultural operations, as well as the dates that plants begin flowering and die from frost. I will record yields (number and weight of fruits) and harvest dates. In the second year of growth I will also record data on winter survival and the dates that plants emerge in spring. All data on plant growth and fruit yield will be recorded separately for plants from each source and for plants from each experimental treatment. I will enter data into a computer database and summarize the results for different plant sources and experimental treatments. I will take pictures of the plants at different stages of growth, of harvested fruits, and of insect pollinators and pests.
To assess consumer acceptance: I will provide a survey to the chef, grocery store produce manager, and CSA members to whom I provide sample maypop fruits. These surveys will ask questions about flavor, ease of preparation, and appearance. I will also keep a log of comments I receive from consumers outside of formal surveys.
To assess my outreach activities: I will record attendance at the on-farm field day. I will collect contact information from field day attendees and send them a survey afterwards to ask whether they will consider raising maypops on their farm, what they learned at the event, and what barriers they see for raising maypops commercially. I will track data on website hits for my research results web page. I will also keep a log of comments I receive from correspondents, field day attendees, and others outside of formal surveys.