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Cleaning water pipes can be done safely with stabilised hydrogen peroxide
In irrigation systems, the presence of nutrients and temperature creates a layer of biofilm on the inside of pipes. This layer is formed by bacteria and fungi and can cause blockages in the system and the spread of diseases. Many growers use cleaning agents such as stabilised hydrogen peroxide or chlorine dioxide to remove this biofilm from the pipes or to prevent its formation.
Growers of phalaenopsis saw that the crop started growing better again after stopping the dosage of silver-stabilised hydrogen peroxide. This effect was investigated in a practical pilot by the Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research in collaboration with Glastuinbouw Nederland and a commercial company. Researcher Jim van Ruijven: “It is very surprising: growers saw an effect, but that effect was not found during this pilot.”
Hydrogen peroxide (H2O2) is a reactive molecule. To ensure that the active ingredient also reaches the end of the pipes, stabilisers are added. The effectiveness is therefore still present when the nutrient solution comes out of the dripper or sprayer, and can thus come into contact with the plant. Various types of stabilised hydrogen peroxide are used in horticultural irrigation systems: stabilisation with organic acids or with silver. The first variant can ensure that bacteria start growing faster again after hydrogen peroxide has stopped reacting. The second adds silver to the system and it is not yet clear where this ends up in the cultivation system, but phalaenopsis growers found a negative effect in cultivation.
In a pilot study at a commercial farm, two treatments were compared: a test section with a dosage of 30 mg/L silver-stabilised hydrogen peroxide and a test section without. After 14 weeks of cultivation (out of 46 weeks in total), there was no visible difference in the quality of the plants and this did not change when further monitoring the crop. Measurements showed small differences: a larger leaf surface, a thinner wax layer on the leaf and a slightly smaller number of root tips with the dosage of hydrogen peroxide. There was no difference in the presence of diseases and only minor differences were observed in the microbiome on leaves and roots between treatments. It therefore appears that the product can be safely applied to the crop. However, when dosing these types of agents there is always a risk of resistance developing, so caution is required in their application.
The research into stabilised hydrogen peroxide in Phalaenopsis is a sub-project of the Greenhouse as an Ecosystem project, with funding from Kennis in je Kas (KijK) and the Ministry of Agriculture, Nature and Food Quality in the context of the Crop Protection Implementation Program 2030.