Tholen – It has been common practice in the sector for years to disinfect the outside of harvest carts. This reduces the chance that the harvest cart will spread disease through the greenhouse. This disinfection usually takes place with chemicals but can also be done with the application of UV.
Growers have been doing this for years, also abroad. However, it is noticeable that more and more tomato growers have recently been investing in even heavier UV disinfection tunnels as a result of the Tomato Brown Rugose Fruit Virus (ToBRFV), says Arne Aiking of CleanLight. “We only applaud that because it ensures an even higher level of disinfection.”
In both the application of chemicals and UV, the following applies: follow the instructions and do not save on the most efficient operation. Only then will optimal results be achieved, and the risk of virus spreading by harvest carts in the greenhouse is reduced. In practice, however, this is not always the case.
Practical application
Arne says that some entrepreneurs are concerned about the use of disinfectants. Not because of the disinfectants, for which the temporary authorization of Virkon S against ToBRFV was recently extended in the Netherlands, do not work, but because the application in practice is not always optimal.
“Working times are stated on the label with disinfectants. However, we do not come across any growers where those relatively long times can be made available for treatment. Furthermore, in practice, chemicals are usually sprayed onto the cart sparingly. So there are places on the outside that are not touched. All in all, it is therefore likely that the disinfectants give less good results than we all wish for.”
Newer tunnels
That is why several growers switched to UV disinfection years ago, sees CleanLight. Account manager Arjo van der Sluis of the company that sells UV disinfection techniques: “A few UV tunnels have been running in practice since 2011. We have gained good experience with them. In terms of safety and terms of results.”
Arne agrees. He does point to a recent development, namely that growers have started asking for heavier decontamination tunnels. “In the past, at the request of growers, we sometimes had to make concessions when using our UV tunnels at growers. This involved fewer UV lamps and therefore a lower UV dose in the tunnel, or smaller tunnels due to a lack of space.”
Very high dose in a short time
The tunnels that CleanLight now supplies to growers on request are heavier, more robust, and better secured. “The newer tunnels produce a very high dose within 1 minute. A dose of UV light that is higher than what is prescribed in the Dutch drinking water supply. For this purpose, these professional, heavier tunnels are equipped with a vestibule, a treatment portal, and an after-treatment portal. As a result, the entire outside of the harvest carts is measurably free from germs by applying UV within a treatment time of 1 minute. It is more in line with the grower’s practice.”
High dose UV
Damian van Dijk, a colleague of Arjo and Arne, adds: “The output of UV lamps depends on the temperature of those lamps. If the lamps are too warm or too cool, you will see nice blue light, but our measurements confirm that they produce little UV at that time. One of the reasons for our great results is that we cool the lamps to their optimum temperature. This allows us to administer a very high dose within the short time available in practice.”
Recently, CleanLight has been supplying more and more of this type of heavy professional tunnels to growers in North America, among others, and the latest UV disinfection tunnels have already been delivered to growers in the Netherlands. According to Arne, this is the result of a business decision for growers who want to limit contamination risks as much as possible. “Growers know what chemical disinfection costs and does in practice and what UV can and does cost. As a result, on some projects, we are now able to set up a ready-to-use system within four weeks after the entrepreneur has given us the green light.”
This article is a translation of a Dutch article published on Groentennieuws.nl.