UV-C Light Application Technology for Field-Grown Strawberries to Control Fungal Diseases and Arthropod Pests

Final report for LNE20-411R

Project Type: Research Only
Funds awarded in 2020: $187,733.00
Projected End Date: 09/30/2023
Grant Recipients: Appalachian Fruit Research Station, US Department of Agriculture, Agricultural Research Service; TRIC Robotics
Region: Northeast
State: West Virginia
Project Leader:
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Project Information

Summary:

Problem Addressed and Solution Pursued: Strawberry farmers in the Northeast use synthetic pesticides to manage persistent diseases and arthropod pests (e.g. Botrytis fruit rot, powdery mildew, anthracnose, whitefly, and two-spotted spider mite).  This can be costly due to expenses of the treatment.  With the threat of pesticide resistance and increasing annual costs for growers (currently ~$500/acre in the Northeast), alternative strategies are needed for managing diseases and pests.  A novel non-chemical strategy we have developed for this purpose is called PhylloLux technology.  This innovative method uses a relatively low UV-C light dose combined with a prescribed dark period and application of beneficial microbes (antagonists) to control fungal pathogens (e.g. Botrytis cinerea, Colletotrichum acutatum and C. gloeosporioides and Podosphaera aphanis).  Night-time UV-C light applications are a strategy that maximizes killing power on microorganisms at levels that are not damaging to strawberry plants.  UV-C applications also decrease populations of whitefly (Trialeurodes vaporariorum) and two-spotted spider mite (Tetranychus urticae) populations.   Our overall goal is to incorporate PhylloLux technology into an autonomous robot platform to develop an affordable,  non-chemical alternative to pesticides for management of strawberry diseases and pests.  USDA will collaborate with TRIC Robotics to develop an autonomous vehicle for the delivery of UV-C technology to field-grown strawberry plants at night to reduce impacts on day-active pollinators and effective for managing persistent diseases and pests.  

Research Objective and Implementation:  In 2020, strawberry plots with 'Albion' were planted in the spring. Plots were randomized to receive ± UV-C applications alone or in combination with routine fungicide and/or insecticide applications (8 treatments total).  Following planting, the experimental autonomous UV-C platform was delivered onsite.  Beginning in mid-July, the robotic platform was trialed troubleshoot operational issues including the GPS and computer components, and overheating of mechanical components.  From mid-August to mid-October, the autonomous platform was able to deliver UV-C applications to the strawberry field with 24 successful runs.  A late-season freeze led to very little strawberry fruit being available for evaluation.   In 2021, the robot was delivered by mid-April with troubleshooting into early May.  Twice-weekly nighttime runs on strawberry plots began in mid-May and continued until Mid-June.  Some runs required manual operation due to issues with autonomous operation. Nine harvests were conducted between mid-May to mid-June.   In late 2021-present, TRIC began trials in CA strawberry plantings, and ARS personnel began laboratory research on UV-C impacts against the invasive spotted wing drosophila and exploration of the genetic underpinnings of differential gene expression in plants treated with UV-C. 

Research Findings and Conclusions: In 2020, the autonomous UV-C delivery platform reached the point of successful operation in an experimental strawberry plot with 24 successful runs completed by the end of the season.  In 2021, the UV-C platform delivered twice weekly applications to strawberry plots from early May until Mid-June.  Some applications had to be performed manually due to programming issues.  Harvest data revealed no major differences in pest or disease incidence on fruit treated with UV-C compared with those treated with standard pesticides.  When UV-C and standard pesticides were combined, injury was nearly 20-40% lower compared with UV-C or pesticide treatments alone. 

Outreach Efforts: Due to Covid-19 pandemic restrictions, on-site meetings were not scheduled.  All Extension educators were made aware of the progress that the research project had made at the June NE berry educators telephone conference and presentations made at the 2020 NASGA and NARBA conferences.  Also, articles prepared for grower magazines were distributed to keep advisory board members updated.  Updates from this project also have been reported annually to a Stakeholder Focus group at the Appalachian Fruit Research Station through virtual meetings in 2021-2023.  This group includes diversified growers from the mid-Atlantic and industry representatives associated with temperate fruit production.  

Project Objective:

The objective is to improve control of persistent disease and arthropod pests of strawberry while decreasing pesticide use by deploying an autonomous vehicle that applies UV-C light to strawberry fields and is affordable for small-scale growers.  We will compare disease and pest control achieved with synthetic pesticides, UV-C and the combination on two strawberry varieties.  We will work specifically with TRIC Robotics technologies to make this system affordable and commercially feasible. 

Introduction:

Strawberry farmers in the Northeast use repeated pesticide applications to manage persistent disease and arthropod pests.  With the threat of pesticide resistance and increasing costs for growers (currently $500/acre season-long), alternatives are needed.  A novel non-chemical strategy has been developed for this purpose by USDA scientists.  This innovative method uses a relatively low UV-C light dose combined with a prescribed dark period to control fungal diseases.  Nighttime UV-C application also decreases white fly and two-spotted spider mite populations.  There was a need to develop an autonomous vehicle for the delivery of UV-C technology to field-grown strawberries that is affordable and effective for managing persistent diseases and pests.  In 2020, a planting of 'Albion' strawberry was established in plasticulture system.  A robot was designed and manufactured by our cooperator TRIC Robotics with UV-C light array mounted on its frame.  A program was developed to enable the robot to apply UV-C treatment at night on specified plots within a 12 row x 4 plots per row field planting.  Night-time UV-C applications were made at least twice per week from early August to early November in 2020 and from mid-May to Mid-June in 2021.  Our UV-C technology application on field-grown plants twice a week had no deleterious effects on strawberry plants.  In 2020, few fruit were available for evaluation in WV plot, but .  studies in DE clearly showed a reduction of two-spotted spider mite population in UV-C treated plots.  In 2021, trials in WV revealed no deleterious effects on plants, and an increase in yield in UV-C treated plots compared with controls. 

Cooperators

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  • Dr. Adam Stager (Researcher)
  • Dr. Fumiomi Takeda (Researcher)
  • Wojciech Janisiewicz (Researcher)

Research

Hypothesis:

A robotic system for application of UV-C Phyllolux technology to field-grown strawberries can be developed to increase production sustainability at a cost affordable to small-scale strawberry farmers in the Northeast. 

Materials and methods:

Hypothesis:  Automation makes UV-C treatments at night feasible.  A robotic system for field-grown strawberries can be developed at a cost that is affordable to small-scale strawberry berry farmers in the Northeast.  PhylloLux technology can be developed as a non-chemical alternative to pesticides for control of strawberry diseases and pests.  

Materials and methods:  A new field plot at the Appalachian Fruit Research Station was established in early June 2020 with raised beds covered with black plastic mulch.  Bare-root plants of 'Albion' were inserted through slits in the plastic and into moistened soil.  Transplants were drip irrigated daily until transplants were well rooted.  Thereafter, the plots were irrigated and fertilized as needed.  UV-C irradiation treatments were initiated in mid August following troubleshooting period.  The robot travel control system was modified as needed to fine tune the travel down the row and make the turns at the ends of the row to go more smoothly.  Other electronic components of the CPU controlling the robot was modified to improve GPS signal reception.  Each plot was treated with one of the following 8 treatments: ± UV-C applications alone or in combination with routine fungicide and/or insecticide applications.   The designated plots were irradiated between 10pm-1am two nights each week until mid-October 2020. A late-season freeze reduced overall availability of fruit for scouting for diseases and pests.   Similar trials were conducted with a grower cooperator in DE. 

In 2021, the autonomous UV-C platform was delivered in mid-April.  Troubleshooting continued until early May.  Again, each plot was treated with one of the following 8 treatments: ± UV-C applications alone or in combination with routine fungicide and/or insecticide applications.  Twice weekly nighttime applications continued from mid-May to Mid-June. Nine harvests were conducted between mid-May and mid-June with fruit assessed for fungal and arthropod damage. 

Research results and discussion:

Our research refined the engineering aspects of the robot technology and optimized the UV-C system to make the UV-C technology economically competitive with conventional chemical control approaches.  Further field-based validation confirmed the efficacy of the system as noted by reduction in two spotted spider mite counts in DE.  In the WV plots in 2021, the UV-C platform delivered twice weekly applications from early May until Mid-June.  Some applications had to be performed manually due to programming issues.  Harvest data revealed no major differences in pest or disease incidence on fruit treated with UV-C compared with those treated with standard pesticides.  When UV-C and standard pesticides were combined, injury was nearly 20-40% lower compared with UV-C or pesticide treatments alone. The prototype autonomous mobile UV-C irradiation unit traveled over multiple strawberry rows under field conditions and was able to make smooth turns at the end of the rows to treat other specialty crops. 

The positive results obtained from night-time application and relatively low doses of UV-C irradiation for controlling fungal pathogens and arthropod pests to date indicate the potential of UV-C treatments to reduce disease incidence and alter insect behavior impacting their herbivory and egg laying.  We will continue to explore the efficacy of the UV-C irradiation system for management of pestiferous mites and insects on other specialty crop plants.   USDA has continued to ollaborate with TRIC Robotics (https://www.tricrobotics.com) which has highly skilled robot engineers, manufacturing capacity, and provides on-the-go solutions for autonomous UV-C application in soil-grown specialty crops.  Our next target will be thrips. 

Research conclusions:

These studies demonstrated that UV-C treatments can be delivered to field-grown strawberries using an autonomous delivery platform. Harvest data revealed no major differences in pest or disease incidence on fruit treated with UV-C compared with those treated with standard pesticides.  When UV-C and standard pesticides were combined, injury was nearly 20-40% lower compared with UV-C or pesticide treatments alone. UV-C is an effective replacement for pesticides aimed at controlling fungal pathogens, and insect and mite pests of strawberry.  TRIC robotics has already commercialized this technology through additional support from the USDA SBIR program and this platform is being used to manage 95 acres of strawberries in CA.  This work has spurred additional innovations in terms of the use of far UV, and new target crops (cherry) and pests (thrips) for its usage.  

Participation Summary

Education & Outreach Activities and Participation Summary

Educational activities:

5 Consultations
4 Published press articles, newsletters
3 Webinars / talks / presentations

Participation Summary:

200 Farmers participated
50 Number of agricultural educator or service providers reached through education and outreach activities
Outreach description:

Outreach activities include presentations on UV-C technology at the 2020 North American Strawberry Growers Association annual meeting (200 people in the audience) and a 90-minute workshop on UV-C technology with ~30 strawberry growers from 10 U.S. states and Canada.  A short presentation was given (virtual) on UV-C technology for disease and pest management at the 2020 N. American Raspberry and Blackberry Association annual conference (20 berry farmers).  Dr. Takeda was the invited speaker for the June 2020 Northeast Berry Educators conference call hosted by Cornell University where he made a presentation on UV-C technology (~30 extension educators from the Northeast on the call).  From 2021-2023, stakeholders comprising the Appalachian Fruit Research Station Focus Group were provided updates on this project through presentations during virtual meetings.  

Learning Outcomes

20 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
10 Service providers reported changes in knowledge, attitudes, skills and/or awareness as a result of project outreach
10 Educators or agricultural service providers reported changes in knowledge, skills, and/or attitudes as a result of their project outreach
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:
While there were some difficulties in providing updates through the COVID-19 pandemic, we were able to work with farmers through virtual meeting opportunities including NARBA, NASGA and the Appalachian Fruit Research Station Focus Group.  During these meetings, farmers were provided with updates on the efficacy of UV-C against fungal pathogens and insect and mite pests, and innovations aimed at autonomous delivery.   Farmers were enthusiastic about the technology, but also raised some important questions.  One in particular was related to the plant microbiome (beneficial microbes) and beneficial insects and if UV-C could have negative impacts on them.  This discussion point will likely lead to future research endeavors. 

Project Outcomes

4 Grants applied for that built upon this project
2 Grants received that built upon this project
$978,000.00 Dollar amount of grants received that built upon this project
2 New working collaborations
Success stories:

UV-C technology is considered a major success story by USDA-ARS.  This accomplishment was highlighted as one of the 50 agency-wide accomplishments included in the President's budget request to congress.  And Drs. Fumi Takeda and Wojciech Janisiewicz  (both retired) were highlighted in USDA-ARS Outreach pieces on UV-C technology including the following: https://tellus.ars.usda.gov/stories/articles/mold-free-strawberries-yes-please; https://tellus.ars.usda.gov/stories/articles/researchers-harness-the-sun-s-rays-to-fight-strawberry-disease/; and https://www.youtube.com/watch?v=Dm9yLvnENd0. TRIC robotics won the FIRA USA 2023  (annual premiere agriculture robotics trade event) startup pitch for their autonomous UVC platform for use in field-planted strawberries.  

The baseline work conducted by the USDA-ARS team and TRIC robotics has led to a rapidly growing industry of automated robotic delivery of this technology to small fruit as well as other crops.  Examples of trade magazine articles covering this project, and related projects are provided.  

Assessment of Project Approach and Areas of Further Study:

Overall, our project has been successful at confirming the utility of UV-C applications for management of arthropod pests and plant diseases and collaborating with a commercial partner to deliver this novel technology to end-user-stakeholders. UV-C technology has been successfully incorporated into an autonomous robotic unit.  This technology was developed in collaboration with TRIC robotics.  TRIC has conducted most of their demonstration trials with their autonomous unit in strawberry plantings in CA.  TRIC now has paying customers in CA with over 100 acres managed with UVC treatments.  Their new platform can cover 50-100 acres on its own and has an incorporated bug vacuum feature. See link to view this version: https://youtu.be/jqC_SJyoyg4

While these are strong outcomes, we acknowledge were hampered by the COVID-19 pandemic and issues with hiring, meetings, limitations in personnel onsite, and working with collaborators.  As we had federally mandated restrictions locally, TRIC was able to forge ahead in  2022 with the technology in CA and gain traction as an industry leader. 

Additionally, with changes in personnel due to retirements, our team has begun to explore the genetic underpinnings of differential gene expression in plants treated with UV-C. Preliminary results have identified a number of differentially expressed genes in strawberry plants treated with UV-C vs. untreated plants which we hope to use to identify induced resistance pathways in plants following UV-C treatment.  Additionally, we are working with a national team (including commercial partner TRIC) to obtain funding for management of thrips species in small fruit.  This pest complex includes longstanding pest species such as western flower thrips and newer, invasive species, chilli thrips.  Finally, the success of these projects has just led to a newly funded proposal from the Washington Tree Fruit Research Commission to study UV-C technology for management of cherry fungal pathogens and spotted wing drosophila. 

This project was and is successful because of the strong multidisciplinary nature of the project which incorporated horticulture, plant pathology and entomology expertise.  Additionally, the ability to work with a strong commercial collaborator capable of taking the technology to the field was also key.  Ultimately, these factors enabled this project to move from a laboratory and greenhouse project to field application very quickly.  

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.