Articles
A REVIEW OF POSSIBILITIES FOR DISINFECTION OF RECIRCULATION WATER FROM SOILLESS CULTURES
Most root-infecting pathogens also occur in these new cultivation systems.
Some pathogens such as Pythium, Phytophthora, cucumber green mottle mosaic virus and tomato mosaic virus are easily transmitted in recirculation water as is Olpidium, the vector of several viruses.
To exclude any risk of dispersal of plant pathogens the water has to be disinfected before re-use.
Rainwater collected from the glasshouse roof and surface water can also be contaminated with pathogens and should be disinfected first when used as irrigation water.
Disinfection methods investigated in the Netherlands are heat treatment, ozonisation, ultra-violet(UV) radiation, membrane filtration, slow sand filtration, iodination and application of activated hydrogen peroxide.
Currently water disinfection by heat treatment, ozonisation or UV-radiation is applied on more than 500 nurseries.
These methods are effective against fungi, bacteria and viruses.
Membrane filtration is not used due to clogging of the pores and unreliability.
Selective disinfection against Phytophthora spp.. can be accomplished with slow sand filtration.
Iodination is not effective against viruses at concentrations below 15 ppm, but is very effective against fungi at a concentration of 0.7 ppm.
Application of activated hydrogen peroxide is still under investigation.