Greenhouse Irrigation Water Disinfection: Root Rot and Biofilm Control with Ozone Technology
Introduction
In greenhouse farming, irrigation water is one of the fundamental inputs of productivity. But when mismanaged, that same water can become the fastest route through which plant pathogens spread. In a greenhouse irrigated by a drip system, a single pathogenic fungus or bacterium entering the water line can reach the roots of every plant within a single day.
Ozone technology eliminates this risk at the source — delivering a disinfection solution that leaves no chemical residue and is fully compatible with plant production. This post explains why irrigation water disinfection is critical in greenhouses, and how ozone works in this context.
Waterborne Diseases in Greenhouses
The vast majority of the most common pathogens in greenhouse production spread through water. Pythium and Phytophthora water moulds cause root rot and can result in substantial crop losses in a very short time. Fusarium species are carried through both substrate and irrigation water in soilless growing systems (hydroponics, coco peat). Bacterial diseases (Ralstonia solanacearum, Erwinia spp.) can travel significant distances directly via water.
The risk is even higher in closed irrigation systems where drainage water is recovered and reused: a single infected plant can affect the entire crop through the drainage water it releases back into the system.
Limitations of Conventional Disinfection Methods
Chlorine-based disinfectants are widely used in irrigation water applications; however, their efficacy drops in the presence of organic matter, they are pH-dependent, and they generate chemical residues over time. There is also a risk of phytotoxicity from chlorinated compounds reaching the plant.
UV disinfection is advantageous in that it leaves no residue, but it performs poorly against biofilm and biofilm formation in drip lines often remains an invisible ongoing risk. Hydrogen peroxide applications, meanwhile, can damage plant roots at high concentrations.
How Does Ozone Work in Irrigation Water?
Ozone is injected into irrigation water at low doses, providing continuous, lasting disinfection throughout the water line. It shows high efficacy against pathogenic microorganisms (bacteria, fungi, viruses) and breaks down biofilm — biofilm in drip systems is a chronic problem that blocks irrigation lines and shelters pathogens.
The critical advantage: ozone reverts to oxygen within minutes of application, leaving absolutely no chemical residue in the irrigation water. This is a decisive advantage for operations requiring organic farming certification and for crops with high sensitivity to chemical residues.
Application Dosage and Safe Limits
Ozone application in irrigation water requires correct dosing with plant physiology in mind. A residual ozone concentration of 0.1-0.5 mg/L — sufficient for disinfection — is below the limits considered safe for plant roots. This range is widely used in hydroponic systems, drainage water recycling, and open irrigation lines.
The system can be integrated with an ORP (Oxidation-Reduction Potential) sensor to automatically adjust the ozone dose, delivering consistent, continuous disinfection performance.
Which Greenhouse Systems Is It Used In?
Ozone irrigation water disinfection is successfully applied in conventional drip-irrigated greenhouse systems, hydroponic and NFT (nutrient film technique) systems, drainage water recovery lines, and subsurface irrigation systems. It is used across a wide range of crops including tomato, pepper, cucumber, strawberry, and leafy vegetables.
For operations that recycle drainage water, ozone simultaneously minimises disease risk while contributing to reduced water and fertiliser costs — a doubly beneficial approach from a sustainable agriculture perspective.
The OCS Ozone Approach
At OCS Ozone, we offer greenhouse operators ORP-controlled, integrated ozone disinfection systems sized according to their irrigation capacity, system type (drip, hydroponic, recirculation), and crop variety. For every project, we carry out on-site measurement, pilot testing, and water analysis to determine the correct dose and system configuration together.
If you would like information about ozone water disinfection for your greenhouse, get in touch.