Utilizing Beneficial Insects to Eliminate Sprays in Affordable Controlled Environment Systems

Commodities

Practices

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. Unfortunately, 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. 

We will compare 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 investgation will be taking 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 will
randomly assign 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. Additionally, each
unit/tunnel will receive 6 insect sticky traps for monitoring as
recommended by our technical cooperator at the University of
Minnesota, Dr. Mary Rogers.
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 will take place over 2 growing seasons, 2024 and
2025. We expect strawberry planting to conclude within each
tunnel by the first week of May. Placing biocontrol sachets and
insect sticky traps will begin immediately after planting within
each experimental treatment. Grandevo spray events will begin 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 will take place in the 2024/2025 and
2025/2026 off-seasons. Data analysis will coincide 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.