Evaluation of Soil Solarization as a Sustainable Management Method for Pests, Pathogens, and Weeds in Southeastern High Tunnels

Project Overview

Project Type: Research and Education
Funds awarded in 2023: $383,000.00
Projected End Date: 03/31/2026
Grant Recipients: University of Kentucky; University of Tennesee
Region: Southern
State: Kentucky
Principal Investigator:
Dr. Rachel Rudolph
University of Kentucky
Dr. Nicole Gauthier
University of Kentucky
Dr. Erin Haramoto
University of Kentucky
Jonathan Larson
University of Kentucky
Dr. Margarita Velandia
Dept. of Agric. & Resource Economics, University of Tennessee
Dr. Annette Wszelaki
Dept. of Plant Sciences, University of Tennessee


Not commodity specific


  • Crop Production: high tunnels or hoop houses
  • Pest Management: soil solarization

    Proposal abstract:

    High tunnels (HTs) are used by small farms in Kentucky and Tennessee to help increase their resiliency and give many the ability to extend their growing season for year-round production of high-value specialty crops. HTs are economical, semi-permanent, passively heated and cooled covered structures. Growers are often able to collect a premium price because the fruit quality is often better and the product is available before or after crops grown in the open field. While HTs are semi-permanent structures, many are never moved due to land constraints, the time and labor required to move them, and because corner posts are often cemented into the ground to secure the structure from weather events. Continuously growing crops in non-rotated soil can intensify pathogen, pest, and weed population densities. Soil solarization is a management technique that uses passive solar heating of irrigated soil under transparent plastic tarping to achieve temperatures detrimental to soilborne pests, pathogens, and weeds. This technique has been shown to be effective in warmer climates. As temperatures in HTs are much warmer compared to outside temperatures, solarization may be effective in HTs in more moderate transitional zone climates like in Kentucky and Tennessee. However, the optimal timing and approach for solarization in HTs in our region are unknown. While it is more likely that sealing an entire tunnel during solarization will improve pest management due to hotter temperatures, growers would not be able to produce any crops during this period. Importantly, our project will compare the efficacy of solarizing sealed tunnels and individual beds within open tunnels. This individual bed solarization, if effective, could be more appealing to growers than the opportunity costs of sealing and solarizing an entire tunnel. We will investigate solarization during different seasons (spring, summer, and fall) as well as different durations (two and four weeks) to effectively manage various pathogens, pests, and weeds. Soil temperatures at three depths (2, 4, and 6 inches) will also be monitored, as different pests and pathogens are impacted by different temperatures. This project will help us determine if solarization is effective against our most problematic pathogens, pests, and weed seeds, sustainable to implement, and adoptable at the farm level. We also will evaluate the economic feasibility of solarization. We will work collaboratively with grower cooperators to determine optimal timing and duration for solarization based on their HT crops and production schedules. Extension and outreach materials will include traditional publications and online videos about solarization implementation, pros and cons, and things to keep in mind as well as solarization factsheets tailored with the specific results from our trials. We will also present the results alongside our grower collaborators at grower conferences, including the Kentucky Fruit and Vegetable Conference and the Pick TN Conference, and field days (UT Steak and Potatoes Field Day and UK Horticulture Research Farm Field Day).

    Project objectives from proposal:

    Objective 1: Determine the soil temperatures that can be reached at different depths (2, 4, and 6 inches) during soil solarization for two and four weeks at different time points of the year (April, July, and September) in open and closed high tunnels in our region.

    Objective 2: Evaluate effects of solarization during three different times of year and at three different soil depths on soilborne fungal and oomycete pathogens.  The goal is to evaluate effects of solarization during three different times of year and at three different soil depths. Five soilborne pathogens will be subjected to solarization and analyzed for survival under each variable (time and depth) and correlated to soil temperature.

    Objective 3: Evaluate how soil solarization for two or four weeks during different seasons affects weeds. Specifically, this objective will assess weed mortality during and recolonization after solarization events.

    Objective 4: Evaluate effects of soil solarization for two and four weeks on high tunnel colonization by aphids and other common high tunnel arthropod pests. 

    Objective 5: Evaluate the effects soil solarization for two and four weeks will have on lettuce growth and yield when planted soon after a solarization event in April, July, and September.

    Objective 6: Implement the most promising soil solarization treatments on commercial farms with known issues, such as root-knot nematode (Meloidogyne spp.), Fusarium, Sclerotinia, Pythium, insect and arthropod pests, and/or weeds.

    Objective 7: Evaluate the effects of soil solarization on the economics of high tunnel vegetable production, including yield and quality.

    Objective 8: Provide grower trainings and create recommendations for growers regarding timing and logistics of implementing solarization on their farm, including what kinds of issues can or cannot be managed with solarization based on the results of our trials in Objective 1 through 5 and the economics of  solarization at the farm level.

    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.