Chemical effects of disinfestation

In the greenhouse industry disinfestation is performed with soil as well with soilless cultures by various methods. The aim of this is the control of plant pathogens surviving in the root zone between successive crops. In soilless cultures it is carried out also with drainage water when it is reused in the growing system. The methods applied can be distinguished in chemical and physical methods and the choice which method will be applied depends on the pathogen and on the growing conditions. Chemical methods like fumigation with methyl bromide, the chemical method most recently applied on big scale is forbidden in most countries. However, when it legally can be used, it is not recommendable, because of the acute toxicity to people, the risk of environmental pollution and the Br residue in soil and substrate, which can be absorbed by plants to unacceptable levels. In this manner steam sterilisation survives as the method to sterilise soils and substrates.