The mosaic virus hasn’t really been a big problem this year, states Rino Kaljouw. "But like many other growers we do have to deal with it, especially in the final stretch of cultivation. And once you have it, you won’t get rid of it. If it occurs at the end of the season, it may not be that bad. But it spreads rapidly. We want to avoid having to deal with it next season, but it’ll be tricky." Therefore, crop rotation is particularly thorough this year.
In addition to all the usual precautions, Kaljouw has Toon Hopmans of Hopmans Verhuur disinfect concrete paths, barn and yard with boiling water. Although the seemingly simple technique caused initial skepticism, more and more growers are now reverting to the chemical-free procedure. The treatment involves hosing down the place with steaming hot water.
"The boiling water makes treating the concrete paths with chemicals almost superfluous," he says. "The bacteria and fungi don’t survive the boiling water. So you’re sure to start with a clean slate." Because no chemicals are used, the treatment could even be done during cultivation.
The machine used to treat the greenhouse was designed by Hopmans himself, and is simply hooked on to the water supply in the greenhouse. The device is equipped with three high-pressure connections which are adjustable from 50 to 150 bar. Two of them lead to a floor cleaner. The third is connected to a hand-held high-pressure cleaner. With the aid of just one employee, Hopmans needs only two days to clean the average greenhouse.