News » 07.07.2026 - "We couldn't maintain the humidity in the greenhouse, causing the plants stress"
The Controlled Environment Agriculture Research Center (CEARC) at The Ohio State University has published environmental data from a 21-month study on dry fog humidification in strawberry production. The dataset covers conditions before and after the installation of the AKIMist®E system in September 2024. Results show a 10 to 30 percentage point increase in relative humidity and a 50% reduction in low-humidity stress events following the installation.
The Dry Fog system was installed by the CEARC team themselves and integrated into the greenhouse control system using Priva environmental controls.
Technical specifications of dry fog technology
JD Tierney, Humidification Account Executive at Ikeuchi USA, was responsible for the installation of the AKIMist® system. He explains that dry fog consists of water droplets measuring 10 microns or less. "These droplets are non-wetting because they are small enough to bounce back from surfaces without bursting." The technology utilizes an atomizing nozzle that combines water and compressed air. Two streams collide to create an ultra-fine dry fog with droplets generally 10 microns or smaller, allowing rapid evaporation without wetting surfaces. This technology, which has been implemented in the automotive and semiconductor sectors, is designed to offer control over humidity levels in production facilities.
Humidity stabilization and stress reduction
Environmental data collected at the CEARC between August 2023 and May 2025 indicates that the installation of the dry fog system resulted in a 10 to 30 percentage point increase in relative humidity. Before the implementation, the greenhouse experienced fluctuations with humidity levels occasionally falling between 20% and 30%. Following the installation in September 2024, the data showed a more consistent humidity band, generally maintained between 60% and 75%. Low-humidity stress events, periods where humidity dropped below 50%, decreased by more than 50%, while drops below 40% were nearly eliminated.
The 7-day rolling average of relative humidity (RH) indicates long-term seasonal stability in the greenhouse environment. Data from the second year of the study shows a smoother trend line that remained elevated even during drier periods, compared to the volatility observed in the first year. A "difference ribbon" analysis, which calculates the margin between Year 2 and Year 1 RH percentages, shows a net increase throughout the monitoring period. During most periods, humidity levels in Year 2 were 10 to 30 percentage points higher than those recorded in Year 1. This consistency eliminated frequent low-humidity intervals and reduced the severity of occasional dips.
Inside the facility's strawberry greenhouse, Professor Dr. Chieri Kubota (left), Director of CEARC, and research specialist Mark Kroggel (right) are leading work focused on improving yield and fruit quality in controlled environments.
Prior to the dry fog installation, Year 1 data recorded unstable humidity characterized by rapid swings and drops below the 40% to 50% RH threshold. These extended low-humidity events, with levels occasionally reaching the 20% to 30% range, are conditions that increase plant stress and limit transpiration while complicating vapor pressure deficit (VPD) control. In Year 2, environmental conditions became stable, with RH measurements remaining within a tighter band between 60% and 75%. Low-humidity dips below 50% RH were rare, resulting in predictable parameters for crop development.
Managing disease risk in strawberry canopies
Chieri Kubota, Professor at Ohio State University's CEARC, stated that the system produces droplets that evaporate before wetting plant surfaces. Relevant, as canopy wetness is a key factor in plant health. "When water accumulates in the canopy, humidity inside the foliage can become much higher than the surrounding air." These conditions are associated with foliar diseases such as botrytis.
Dry fog humidification avoids this effect by increasing ambient humidity without introducing leaf surface wetting, a limitation often seen with other humidification methods. "This characteristic addresses the conflict between increasing humidity and managing foliar disease," she said. "Dry fog humidification enables humidity management to support plant productivity without increasing foliar disease risk."
Operational observations and worker environment
Mark Kroggel, Professor at Ohio State University's CEARC, observed that the system produces finer droplets than standard misting or fogging, allowing the humidity to cover more surface area per volume. "Because the droplets evaporate almost instantly, the environment is also more comfortable for workers", he adds. Regarding the financial aspects for growers, Mark indicated that being able to control humidity while minimizing disease risk makes systems like Dry Fog a worthwhile investment, particularly when the service life of the hardware is included. "For growers of soft fruits like strawberries, the ability to maintain humidity levels while minimizing disease risk is a factor in investment considerations."
The research center reported that the system required no maintenance during the study period. The researchers stated that if they were constructing the facility again, they would include the system in the initial design and are currently looking to implement dry fog in other chambers used for high-wire crops.
Source: www.floraldaily.com
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