UV-C is effective against Fusarium oxysporum f. sp. cubense (TR4), the fungus responsible for Panama disease in bananas. The mechanism is based on DNA damage from UV-C radiation, causing spores such as chlamydospores to lose their ability to germinate and cause infections.

Laboratory and field tests show that TR4 is relatively UV-resistant compared to bacteria, requiring higher UV doses. However, with correct system sizing, complete inactivation in irrigation water can be achieved, effectively interrupting spread via water flows.

Yes. Ralstonia solanacearum is a bacterial pathogen that is considerably more sensitive to UV-C than fungal spores. This allows strong reduction with relatively lower doses.

In well-designed irrigation systems, UV-C can reduce bacterial load to below detection levels, greatly reducing the risk of spread via irrigation water.

T10 (UVT) stands for the UV transmittance of water over 10 mm at 254 nm. It indicates what percentage of UV light passes through the water.

A high T10 means clear water with little absorption, while a low T10 indicates a lot of organic matter, suspended particles or dyes that block UV light.

T10 is crucial because it directly determines how much effective UV dose remains available in the water.

Filtration is not always legally required, but is often technically necessary in practice. Especially with surface water or recirculation, pre-filtration is essential to ensure sufficient UV transmittance.

Without filtration, UV-C effectiveness drops sharply due to shadowing and absorption by suspended particles.

UV-C systems have relatively low maintenance requirements. The main maintenance consists of cleaning quartz glass tubes, checking lamp output and periodic replacement of UV lamps.

Frequency depends strongly on water quality: with heavy fouling or low T10, more cleaning is needed. In well pre-treated systems, maintenance is limited and predictable.

At low T10, UV effectiveness drops sharply because less light penetrates the water. This can be addressed by:

• lower flow (more contact time)
• higher UV intensity
• better pre-filtration
• or a combination of these

In extreme cases (<50–60% UVT), pre-treatment is often essential to ensure reliable disinfection.

UV-C treats water before distribution. In closed or long irrigation lines, biofilm formation can still occur, especially with nutrient-rich water.

Therefore UV-C is often seen as a primary barrier, but not always as the only measure. Periodic line cleaning or additional strategies may still be needed, depending on system design.

Costs per m³ depend on flow, UVT and required dose. In general, costs per m³ drop sharply at higher flow rates.

UV-C becomes economically competitive in many irrigation systems when water is reused, because loss of water and fertilisers is reduced and chemicals are largely avoided.

Chlorine works through chemical oxidation, while UV-C is a physical process that damages DNA/RNA without leaving residues.

Chlorine can be effective, but is more sensitive to water quality, can form by-products and can cause phytotoxicity at higher concentrations.

UV-C is direct, reproducible and leaves no chemical residues, but requires good water transmittance and hydraulic design to be effective.