Their effects on competing micro-organisms in the NFT solutions have not been described. Never the less they are fairly widely used but often regular treatment is needed to prevent resurgence of the disease. The above is a review of the literature and must not be taken as recommendations for the use of the chemicals mentioned. The use of these chemicals is governed by various regulations and rules which must be observed for the safety of the user and consumer. Other control methods.
Frequent chlorination is known to interfere with iron nutrition through breakdown of iron chelates.
UV light treatment was also shown to provide only partial kills of spores and viruses, and in addition also interferes with iron chelates. The best possibilities for solution treatment at present remain ultra-filtration and heat pasteurisation. Runia has suggested a practical heat pasteurisation scheme for nutrient solutions with heating to 95 for 10 seconds and suggests that such treatment does not interfere with iron or some fungicides in the solutions. Biological control is still in the early research stage. In New Zealand Trichoderma is available as Trichopel granules which have been used fairly widely and in some liquid preparations which not been used widely by our clients.