A range of chemicals are used to keep greenhouse pipework clean. They include bleach, hydrogen peroxide, chlorine dioxide and ECA water.

Growers are concerned that the use of these substances could have side-effects. With the regulations on discharging becoming ever tighter, residues could accumulate in concentrations that could be harmful to the plant, and they may even have side-effects on pathogens. This issue was investigated last year as part of the “Prevention and Control of Leaching from Greenhouses“ PPP. It started with a survey conducted among a number of gerbera growers, followed by laboratory trials in which various concentrations of products were applied to a live fungus on a Petri dish. Then two products were used in a gerbera trial to investigate whether accumulation occurred. The initial results are encouraging: for the first time, we are gaining an understanding of the behaviour of these products in comparable conditions.
In 2018 we will be seeking additional funding from grower cooperatives and product suppliers so that we can test more products. More knowledge on this subject is urgently needed, not just for gerbera but also for other greenhouse crops.