Project Overview
Commodities
- Fruits: berries (strawberries)
Practices
- Crop Production: greenhouses, high tunnels or hoop houses, Biocontrol
- Pest Management: biological control, chemical control
Summary:
TCBC has created and implemented a methodology for affordable, climate-resilient, and high density strawberry production within modified caterpillar tunnel structures we call 'Fruit Factories' (FF) [Photos 1-3]. These techniques are geared specifically towards new and emerging farmers with limited access to land and/or startup capital. We have found FF production to provide:
- higher yields
- superior quality fruit
- lower total labor requirements compared to open field strawberry production, using a fraction of the physical space. Summary statistics of our 2023 field season, including yield and labor metrics can be found here.
For open-field strawberry pests looking to make their way into the tunnels (such as lygus and spotted wing drosophila), our previous SARE research has found netting to be even more effective than traditional spray regimens at controlling populations. However, volunteer pests(namely 2-spotted spider mite and thrips) often 'piggyback' their way into tunnels during planting. The hot and dry tunnel conditions are an ideal environment for unchecked infestation of these pests. The traditional control method for these pests are sprays such as Grandevo or Venerate. However, this practice is antithetical to the goal of many farmers (and of insect netting particularly) to eliminate the use of sprays on their farms. Our solution was to deploy beneficial insect Amblysius swirskii in several, distinct densities within separate production tunnels, compared to a traditional spray control. By doing this, we could determine which biocontrol density (if any) would be able able to match the efficacy of organic sprays for the control of several common pests. After the data collection, we could then run an economic analysis to determine the cost of matching spray control with biocontrol.
After 2 years of thorough data collection, we found that placing sachets of Amblysius swirskii on every plant within a tunnel provided spray-free control of spider mites and aphids inside tunnel environments at a similar (and sometimes superior) efficacy to traditional spray regimens. It cost $302.13 more per tunnel to achieve comparable suppression of spider mites and aphids using biocontrol techniques versus a traditional spray regimen. This extra cost should be considered when pricing the goods for sale.
Amblysius swirskii can be purchased in individual paper sachets, or in a shaker bottle, where they can be deposited loosely. Economically, we recommend the shaker option, making sure to cover each plant, as this method will reduce total application and cleanup time for the grower.
Project objectives:
We compared the use of modern biocontrol techniques against sprays to investigate the potential of a true spray-free production environment.
OBJECTIVE 1- Compare the efficacy of utilizing beneficial insects vs traditional spray regimen for the control of 2-spotted spider mite and thrips inside tunnels for high-density strawberry production.
OBJECTIVE 2- Compare the economic impact of utilizing beneficial insects vs traditional spray regimen for the control of 2-spotted spider mite and thrips inside tunnels for high-density strawberry production.
EXPERIMENTAL DESIGN
The investigation took place within four caterpillar tunnels modified for high-density strawberry production, also known as 'Fruit Factories' [Photos 1-3]. Each tunnel is 1600 sq feet (16' x 100') and will function as separate experimental units for the project. Within each unit, we randomly assigned one of four treatments:
- Control: traditional spray regimen using Grandevo and Venerate sprays according to technical cooperator recommendations, BFG Supply Company
- Biocontrol (Bioline Starskii 500 CRS, utilizing benefical insect Amblyseius swirsk) with control sachets placed in every strawberry container
- Biocontrol (Bioline Starskii 500 CRS, utilizing benefical insect Amblyseius swirsk) with control sachets placed in every two strawberry containers
- Biocontrol (Bioline Starskii 500 CRS, utilizing benefical insect Amblyseius swirsk) with control sachets placed in every three strawberry containers
Photos of biocontrol sachets are shown in Photos 5 and 6, with visual outline of experimental design presented in Figure 1. Bioline sachet treatment densities were based on BFG recommendation. Biocontrol within high-density strawberry tunnels have not has been formally tested by BFG, but our BFG technical cooperator (Daniel Graham-Boire) recommended a sachet every other container as a 'baseline'. Therefore, we assigned a stepwise incrementation in either direction of that baseline (every container and every 3 containers, respectively) to create our 3 experimental treatments. Spray frequency inside the control treatment are also determined in consultation with the BFG technical cooperator: Grandevo at 1oz/gallon, functioning as a 'maintenance' spray every 2 weeks with the option of Venerate spray for 'knockdown' events, if thrip numbers cause bronzing of fruit or spider mite densities create visual 'webs' on the strawberry leaf tissue [Photos 7 and 8].
TIMELINE
The project took place over 2 growing seasons, 2024 and 2025. Strawberry planting concluded within each tunnel by the first week of May. Placing biocontrol sachets and insect sticky traps began immediately after planting within each experimental treatment. Grandevo spray events began in the control treatment on May 15 of each growing season, with Venerate spray events ocurring as needed. Analysis of sticky trap and observational data took place in the 2024/2025 and 2025/2026 off-seasons. Data analysis coincided with MDA Specialty Crop Block project B0423F91268X which also measures yield and labor metrics within each tunnel. Visualization of timeline is outlined in Figure 2.