Extending the Market Season with High Tunnel Technology for Organic Fruit Production

2015 Annual Report for LS12-250

Project Type: Research and Education
Funds awarded in 2012: $214,948.00
Projected End Date: 12/31/2015
Region: Southern
State: Arkansas
Principal Investigator:
Dr. Curt Rom
University of Arkansas

Extending the Market Season with High Tunnel Technology for Organic Fruit Production


The goal of this project was to develop a high-tunnel production system for blackberries and raspberries that may compliment a field system by extending the harvest season, expanding cropping, improving fruit quality, and be especially adaptable to sustainable and organic production systems.  A series of two primary studies using high tunnel technologies and modifications to tunnels were conducted to determine how the technologies may fit into sustainable and organic fruit production systems in the south. The two studies were using high tunnels (HT) for 1) advancing summer ripening blackberries, and 2) extending the harvest season of autumn ripening blackberries and raspberries. Preliminary studies have indicated the potential for both. Tunnels were modified to include A) low-tunnels within tunnels (tunnel-in-tunnel: TnT) around the fruiting plants, B) and total screening of the tunnels to exclude insect pests, and C) an overhead micro-fogger system to reduce summer temperatures. Additonal studies on the use of shade to delay flowering and fruiting in primocane fruit blackberries were conducted with assistance of the SARE Young Scholar Enhancement (YSE) subgrants.  Organic insect pest management practices and grower decision support tools including interactive enterprise budgets and a grower sustainability self-assessment, and outreach were key components of this project.

Activities of 2015 focused largely on finalizing field experiments, finalizing interactive economic budgets, finalizing “Sustainable Blackberries and Raspberries: A Self-Assessment Workbook for Growers” and several outreach activities to extend project results and outputs. In additional to open field, high tunnel (HT) and tunnel in tunnel (TNT) production comparisons, an observational study of bumble bee pollinator activity was conducted in high tunnel and tunnel in tunnels. A high tunnel fogger/mist system was also constructed to determine the potential for reducing extreme summer temperatures in the high tunnel.  Interactive economic budgets for blackberries, raspberries and blueberries were validated and finalized.  Project information on organic HT production considerations, insect pest management, economic potential and farm sustainability was extended to current and potential growers, students, and extension educators `through several presentations at regional winter conferences, a workshop on high tunnel fruit production and field tours.

Objectives/Performance Targets

The purpose of this project was to extend the sustainable production of summer berries using HT technology to achieve earlier spring harvest of blueberries and blackberries, and to allow for an extended autumn production of new primocane blackberries and raspberries. The goal of the project was to develop an environmentally and economically sustainable organic fruit production systems combining HT production with traditional FD production and providing for further expansion of organic crop production in the southern region. The specific project objectives were:

  1. To develop High Tunnel (HT) production systems for season extension of organic high value fruit crops for the southern region.
  2. To develop and test pest management strategies for organic HT crop production systems adapted to the southern region.
  3. To estimate economic models and to create decision support tools that help producers to manage production systems for profitability considerations
  4. To extend the knowledge acquired through the production, pest management, and economic analyses into a multi-dimensional educational, outreach, and extension program.



Objective 1. To develop High Tunnel (HT) production systems for season extension of organic high value fruit crops for the southern region.

Study 1. Advance cropping of summer floricane ‘Natchez’ blackberry with High Tunnels (HT) and Tunnel-in-Tunnel (TNT) compared to field (FD) production.


  • TNT had the earliest first bloom (4/6) with HT shortly after (4/8)
  • First harvest was on 5/22 for both TNT and HT; FD was first harvested on 6/8
  • Peak harvest for TNT was on 6/8 at 1241.5 grams/plot; peak harvest for HT was on 6/15 with 8631.0 grams/plot and peak harvest for FD was on 6/15 with 7520.7 grams/plot
  • Last harvest for all treatments was on 7/9
  • HT resulted in significantly greater total yield than Field or TNT. HT yield was almost 2x Field yield. The TNT resulted in lower yield than Field, due to pollination issues inside the TNT structure resulting in poor fruit formation and development.
  • The marketable yield of the HT was significantly greater than the Field and TNT, with marketable yields of Field and TNT being similar. Marketable yield from the HT was nearly 3x the marketable yield of Field and TNT blackberries.
  • The percent marketable yield for HT and TNT were similar at 74% to 68%, with the percent of marketable berries from the FD being significantly lower at 33% due to rain and other environmental damage.
  • HT resulted in significantly larger berries than FD or TNT. The size of FD and TNT berries were comparable at a means of 8.87 and 8.97 grams respectively compared to a mean of 10.01 grams for HT berries.
  • Fruit brix was not significantly different between the treatments, with % soluble solids ranging from 8 to 10.

Study 1b. Advancing blueberry harvest with HT and TNT, compared to Field.

Organic blueberry establishment was difficult with attempts made in both 2013 and 2014 to establish plants, with limited success. Plants in open field plots experiences 100% death in both years. In 2015, there was the opportunity to place a movable HT on an established, 6-year-old, organic blueberries variety trial to test the potential for early cropping and identify potential yield advantages.  Two replications of high tunnel, TNT and open field treatments were placed over six blueberry cultivars: Aurora, Blue Crop, Chandler, Draper, Liberty, Ozark Blue. 

  • HT or TNT advanced first harvest date from 0 (Bluecrop) to 11 days (Chandler)
  • Berries in HT numerically out-yielded field plots, 4800 vs 3310 grams/plot average (45% increase), respectively, however yields were not significantly different due to limited replication
  • Berries in TNT plots yielded significantly lower than other treatments, likely due to limited access of the bumblebees to the blueberry flowers.
  • Some cultivars performed better in HT and other performed as well or better in open field conditions, indicating the need for variety trials for HT systems.
  • Liberty showed significant response to HT treatment, yielding 1.4 x greater in the HT compared to the FD

Study 2. Extend the harvest season of autumn primocane blackberries with HT, TNT, and shade treatments compared to the FD.

2015 Fall Blackberry Study (Prime-Ark 45, Prime-Ark Traveler, APF 205)

  • HT increased yield 2-3x and increased marketable yield across all cultivars
  • Marketable yield and berry brix were impacted by cultivar and HT treatment
  • Prime-Ark Traveler in the HT had the highest marketable yield with a mean of 85.4% compared to all other cultivars and treatments
  • A killing frost on 16-November; HT extended harvest for an additional week; TNT extended harvest for an additional 5 weeks into mid-December.

Prime-Ark Traveler

  • Prime-Ark Traveler grown in HT had greater marketable yield with a mean of 85.4% compared to 72.5% from the field

APF 205

  • HT led to greater berry size for APF 205 compared to FD, with a mean of 7.26g compared to 5.05g
  • HT led to higher total yields for APF 205 compared to the field, with average total yield 2.5x higher in HT compared to FD
  • Marketable yield was greater in the HT, at 2.7x the marketable yield for field
  • Soluble solids measured by Brix was higher for FD berries compared to HT berries, at a mean of 12.5 in the field and 11.2 in the high tunnel

Prime-Ark 45

  • Prime-Ark was the only cv to also have TNT.
  • Total yield was not statistically different for TNT, HT, and Field, however TNT and HT resulted in greater total yield mean values compared to the Field. There was significant aphid and broad mite damage to PA45 blackberries in the HT and TNT, which likely caused a reduction in yield and increased plot variability.
  • There was significant aphid and broad mite damage in the HT and TNT, which likely caused a reduction in yield and increased plot variability.
  • Brix was higher for berries in the FD and TNT compared to the HT, at 12.5, 11.9 and 10.9% soluble solids respectively

Due to raspberry crop failure and disease in 2014, the raspberry crop study was discontinued in January 2015;  there was no experimental results in 2015.

Bee study: Although TNT advanced bloom, plants did not crop much earlier and often had lower yields that HT or FD treatments.  It was  an hypothesis that the TNT created an unfavorable environment for bumble bees flight and activity, and prevented adequate pollination.  Bee activity studied by recording activity and flight five minute increments at four plots per treatment, HT, TNT, FD. Activity was recorded at three times throughout the day: 10:40 am, 1:00 pm and 4:00 pm.  Bee activity was similar in HT and TNT at 10:40 and 1:00 time frames, however during the 4:00 time, activity was significantly lower in TNT, 2 visits vs 9 visits, respectively.  Continued research is needed to isolate the reason for a reduction in pollination.  Although TNT are promising to protect blossoms in hard freezes, possibly advancing flowering and fruiting, additional research on TNT management is needed.

Mist study: Two years of studying misting systems as a means of tunnel cooling were conducted.  The micro-mister system that was installed along the ceiling center purlin in 2014 was modified for a finer mist or fog and tested again in 2015 to reduce high summer temperatures in a screened HT. This addition was managed by the SARE Young Scholar Enhancement apprentice and intern. The cooling system effectively reduced temperatures to ambient external temperatures after running just 1 hour. Although this system needs additional modifications, it shows potential for reducing high summer temperatures in a screened HT.


Objective 2. To develop and test pest management strategies for organic HT crop production systems adapted to the southern region.

There were several significant insect pest that affected high tunnel and/or open field production of blackberries and raspberries.   Over the past 3 years spotted winged drosophila and broad mites have emerged as key pest that threaten sustainable bramble production. Broad mites are a new pest and it is believed that Arkansas is ground zero for this pest.  The broad mite causes terminal leaf bronzing and cupping on primocanes and can kill terminals and new lateral shoots and flower buds reducing fruit yield on primocane production in late summer/fall.  Mesh screening has been used on high tunnels to protect from SWD however, because of the microscopic size of broad mites, it offers no protection against this pest.  Approaches we used to control key pests are highlighted below.

  • Emerging primocanes in the primocane fruiting HT were infested with aphids and flea beetles causing shot holes in new leaves. AzaDirect was applied to emerging blackberry primocanes which provided reduction in subsequent shot hole damage by flea beetles but had no effect on the aphids.
  • Colonies of odorous house ants developed under the landscape cloth covering compost and mulch in HT and were tending aphids on the blackberry terminals and protecting them from natural enemy predation
  • The combination of Safer Soap and release of Coleomegilla maculate in cooperation with Eric Riddick, USDA-ARS, (multiple releases throughout the season) may have contributed to a reduction in aphid density.
  • JMS stylet oil and M-Pede was used to reduce broad mite and two spotted spider mite populations. Spider mites were much worse on raspberry than on blackberry.  The mite populations increased rapidly in the HD and caused significant bronzing and tissue dieback of raspberries. 
  • Screens were used on HT to exclude SWD. Entrust was rotated with Pyganic on field plots to reduce SWD infestation
  • Several biological control releases were made including Coleomegilla maculate provided by Eric Riddick, USDA-ARS Stoneville, MS); predatory mites, californicus and N. cucumeris and aphid parasitoid, Aphidius colemani (Rincon-Vitova, Ventura, CA); Scymnus creperus larvae (Scott Creary, IPM Labs, Inc., Locke, NY)
  • Organic pesticides used to control pests include M-Pede, Pyganic, Javelin, Entrust, JMS Stylet oil, Azera, Botanigard, Ecotrol, and AzaDirect
  • an increase in numbers of predatory beetles, syrphids larvae and parasitized aphids was observed


Objective 3. To estimate economic models and to create decision support tools that help producers to manage production systems for profitability considerations

User-friendly interactive decision support tools were developed in Microsoft Excel using VBA programming interfaces to simulate blackberry, raspberry and blueberry production in Arkansas and across the south. These interactive tools are designed to represent a real berry production using information gathered at the University of Arkansas Experiment and Extension Stations across Arkansas and information gathered from producers in the region as default values.  The horticulture team and fruit growers have validated the production practices, quantities and demos used in the blackberry and raspberry budgets. Three different types of economic analyses can be performed using this tool. The results are presented in terms of net present values. The user can perform breakeven, sensitivity and risk analyses. These tools are available for free on the Center for Agricultural and Rural Sustainability website, http://cars.uark.edu/ourwork/Specialty-Crop-Production-and-Marketing/fruit_budget.aspx

Objective 4. To extend the knowledge acquired through the production, pest management, and economic analyses into a multi-dimensional educational, outreach, and extension program.

Project co-PIs and staff gave presentations and presented posters at multiple winter conference and workshops to extend project information.  At the Missouri Organic Association annual conference (2015), PIs led a half-day session on organic high tunnel fruit production. Rom presented on high tunnel berry production; Johnson gave two talks on organic pest management in high tunnels and spotted winged drosophila in blackberries; and Popp presented on economic budget tools to assess high tunnel returns.  Additional talks were given based on project results on modifications to high tunnels and overall caneberry production. Approximately 40-50 people attended each of these talks.

Co-PIs presented at the 2015 AR-OK Horticulture Industry Show in the high tunnel fruit session, extending information on performance of berries in high tunnels and field, high tunnel pest management and organic spotted winged drosophila management, economic budget tools and the project workbook, Sustainable Blackberries and Raspberries: A Self-Assessment Workbook for Growers. Approximately 20-30 people attended each of these talks.

A high tunnel fruit production workshop was held in Fayetteville in May 2015 with 50 participants in attendance.  Presentations were given on high tunnel fruit production, modifications and additions to high tunnels for improved performance, insect pest management in high tunnels, interactive budgets, the sustainability self-assessment and field tours of high tunnel blueberries, blackberries, raspberries, grapes and strawberries.

At the North America Raspberry and Blackberry Association conference in February, 2015 in Fayetteville AR, two project posters were on display to 250 conference goers.  One posters provide information on the overall project and the second, created by SARE Young Scholar Enhancement participant Olivia Caillouet, was on her experience and research within the project. Olivia also travelled to the National ASHS meeting to present her project results, and won third prize in the undergraduate poster competition.

Presentations, budget tools and the sustainability workbook can be found on the Center for Agricultural and Rural Sustainability (CARS) website, http://cars.uark.edu/ourwork/Specialty-Crop-Production-and-Marketing/hightunnelorganic_fi.aspx .

Four videos are being finalized for release by the end of the summer. The videos provide information on blackberry pruning, biological control, bumble bees as HT pollinators and pesticide safety.


Impacts and Contributions/Outcomes


  • Growers have increased knowledge of sustainable and organic high tunnel production of blackberries and raspberries, pest management of key pests including SWD,
  • There is increased interest in production of blackberries and primocane fruiting raspberries and blackberries in the region.
  • There is an increased interest in using high tunnels for fruit production
  • The Sustainable Production and Assessment Workbook is providing production guidance to growers for beginning/novice and intermediate producers.
  • Greater number of growers have the knowledge and ability to use the sustainability self-assessment to track and improve their farm sustainability.
  • Practices have been identified to cool HT summer environment, especially those with screening material, with mist system
  • Demonstrated use of screening material for organic control of SWD; co-PI Johnson is working on two national grants on SWD
  • Greater number of growers have the knowledge and ability to use the interactive enterprise budgets to make informed fruit management decisions



Donn Johnson

Professor, Entomology
University of Arkansas
AGRI 311
Fayetteville, AR 72701
Office Phone: 4795752501
Website: http://comp.uark.edu/~dtjohnso/
Jennie Popp

Professor, Ag Business and Economics
University of Arkansas
AGRI 217
Fayetteville, AR 72701
Office Phone: 4795752279
Elena Garcia

Professor Extension Specialist
University of Arkansas Cooperative Extension
316 PTSC
Fayetteville, AR 72701
Office Phone: 4795752790