Evaluation of hardy fig varieties in a northern New England high tunnel

Evaluation of hardy fig varieties in a northern New England high tunnel

Summary

This research is exploring the potential for organic fig (Ficus carica) fruit production in a northern New England high tunnel (Zone 5b). Building on the success of fig producers who have utilized high tunnels in the mid-atlantic states and on variety trials of fig enthusiasts in New England, this project is the first to quantify the survivability, productivity, and economics of four hardy fig cultivars grown in a high tunnel in coastal Maine. The study was conducted over the course of two growing seasons (2014-2015) and included on-farm and off-site outreach in 2015.

In 2014, Bill Errickson (owner) and Mark Fulford (technical advisor) amended the soil in the high tunnel and planted eight figs each of the four varieties (Gino’s Black, Marsailles Black VS, Ronde de Bordeaux, and Sal’s GS) for a total of 32 plants. Wood chip mulch and landscape fabric were applied after planting and water was supplied throughout the season using drip irrigation.   After leaf drop, four trees of each cultivar were wrapped with fabric row cover to evaluate the necessity of additional winter protection. The row covers were removed in the spring of 2015, at which time winter dieback was measured. During the 2014 and 2015 growing seasons, data was also collected to measure the following parameters: flowering dates, harvest dates, total yield of fruits, yield of marketable fruits, yield of unripe fruits, fruit size (average weight per fruit), plant height, Brix levels, taste, and economics.

Objectives/Performance Targets

The objective of this research is to identify one or more varieties of fig tree that can be successfully grown to produce marketable fruit in USDA Zone 5b with the protection of a high tunnel. In addition to showing varietal differences, the results suggest how variation in winter protection practices influences fruit production and survivability.

In the spring of 2014, four varieties of the hardiest available fig trees (Gino’s Black, Marsailles Black VS (MBVS), Ronde de Bordeaux (RDB), and Sal’s GS) were planted in a 26×48 foot high tunnel in mid-coast Maine, Zone 5b. Eight trees of each variety (a total of 32 trees) were planted on five foot centers into soil that had been amended for optimum fig tree nutrition with a mineral and worm castings blend, which included granite meal, colloidal phosphate, bone char, and kelp meal, based on a soil test taken prior to planting. All trees were mulched with wood chips and landscape fabric and were watered with drip irrigation at regular intervals throughout the growing season. In the fall of 2014, four trees (half the total number) of each variety were wrapped with fabric row cover for the winter to assess whether there is a benefit to providing extra protection from freezing temperatures.

In 2014 and 2015, data was collected for the following parameters: flowering dates, harvest dates, total yield of fruits, yield of marketable fruits, yield of unripe fruits, fruit size (average weight per fruit), peak plant height, Brix levels, taste, and economics. Winter survival data was collected in the spring of 2015 by measuring the percentage of winter injury/die back on each tree. The effects of wrapping trees in the winter are quantified by comparing wrapped vs. un-wrapped trees on the basis of the above parameters.

Accomplishments/Milestones

The winter of 2014-2015 saw temperatures of -15 degrees F, and resulted in all the fig trees dying back to the ground, regardless of whether they were wrapped for additional winter protection or not. In the spring, all tress began growing again from the base, with the single exception of the uncovered GB trees, which experienced winter mortality in two out of four plants.

Figs produce an inflorescence, called a syconium, which contains numerous unisexual flowers that are not outwardly visible; thus, flowering dates were recorded as the first observance of syconium formation. In 2015, the first syconiums were observed on SGS on June 19th, followed by MBVS on June 26th, and RDB and GB on July 3rd.

Vegetative growth was calculated for each variety by measuring stem length for covered and uncovered trees (Figure 1). Vegetative growth was greater in covered varieties of GB, MBVS, and RDB, while winter protection did not result in greater vegetative growth for SGS. RDB displayed the greatest amount of vegetative growth of the four varieties. Fruit set for each variety is displayed in Figure 2, with covered GB and MBVS trees showing greater fruit set when compared to uncovered trees. Fruit set in RDB and SGS does not appear to have increased with winter protection with row cover. Uncovered RDB set the most fruit per plant, closely followed by covered MBVS.

For covered trees, each variety did successfully produce ripe fruits, which were weighed, and evaluated for Brix levels. From the covered GB trees, 3 fruits were harvested, with an average weight of 0.33 oz, and an average Brix of 16. Covered MBVS trees yielded 17 fruits, with an average weight of 0.57, and an average Brix of 19. Covered RDB trees produced 12 fruits, with an average weight of 0.56 oz, and an average Brix of 16.5. Covered SGS trees were the first to bear, and produced 23 fruits, with an average weight of 0.52 oz, and an average Brix of 17.7. RDB was the only variety to ripen fruit on trees that were not covered through the winter, yielding 2 fruits, with an average weight of 0.55oz and an average Brix of 16.

Independent blind taste tests were also conducted for each variety in 2015. Taste test participants were given one variety at a time, with a scorecard to rank the qualities of each variety ranging from one to five for texture, sweetness, floral/aromatic, and overall flavor. An open ended “comments” section was also included on the cards for additional feedback. Participants were unaware of which variety they were sampling during each phase of the taste test.

• 2015 Graphs

Impacts and Contributions/Outcomes

In 2015, Singing Nettle Farm hosted an on-farm field day in which 20 participants visited the farm to observe the figs growing in the high tunnel and to learn about the research underway. Each participant received a handout summarizing the variety trials. Attendees were able to tour the high tunnel, ask questions, and even sample ripe figs on this day.

The outreach component of this study also extended to the MOFGA Common Ground Fair, where Errickson delivered a presentation to 75 participants. Attendees received handouts summarizing the study, while viewing a slideshow summarizing the research. A question and answer session followed the presentation, and participants were invited to continue the conversation at the Singing Nettle Farm booth in the Farmers Market.

Collaborators: