Water vapor annihilates plant pests such as weeds, fungus, bacteria and viruses merely through its physical thermal energy by degenerating cell structures.
Thereby water vapor is highly effective due to the following two reasons:
On the one hand the majority of organic pathogens are heat-sensitive and die when overheated.
On the other hand due to its high energy content but low temperature of merely 100°C water vapor is able to emit the required heat to the surroundings during condensation in order to kill substances and organisms harmful to plants without burning and deteriorating the soil.
From a biological point of view steaming with hot water vapor is nevertheless considered a partial disinfection. Important heat resistant spore forming bacteria revive soil after cooling down. Hence nutrients are unblocked which counteracts soil fatigue.
Thereby steaming leads to a better starting position and faster plant growth as well as a better resistance against diseases and pests.
Many practitioners and scientists consider the application of hot steam the best and most effective method to sanitize sick soils, out substrate and compost.