Combined use of agents against mildew

In a lit winter tomato crop, the risk of mildew is always lurking. The rapid expansion of their company overtook Noud and Roy Steegh a bit. But through a sophisticated combination of agents, with an eye on the MRLs, they managed to ward off the problem.

Nursery de Grenspaal in Wellerlooi was the first company that used outside air for dehumidification, making father and son Steegh pioneers of the New Cultivation. For years, their conditioned environment was remarkably little affected by fungi.

Last year, they installed assimilation lighting in half the greenhouse. That changed everything: the way of cultivation, but also dealing with disease pressure. "We were warned to be vigilant for mildew. When we started planting on October 20, even before the lighting, we found the fungus already there. When the lights went on, we needed more venting than we were accustomed to, because of the heat. Which only worsened the problem," Noud Steegh recollects.

Noud Steegh and Roy Verlinden (right)

Fungaflor
On the advice of Roy Verlinden of Royal Brinkman (pictured right) he deployed Fungaflor as a curative agent. "I normally recommend a less aggressive agent, because we know that the crop is very sensitive during this stage, but the situation called for something else," he says. “Luckily, the crop responded to the spraying."

“Growth stopped for a few days, and there was some edge damage on the leafs," says the grower. Looking back, they pieced together the cause: the crops had to deal with too many stress factors at once. "We had just deployed the pepino virus, there was a lot of sunlight and too many lamps,” says Steegh.

The growers were somewhat hesitant to use the same agent for a second time, despite the fact that Roy Verlinden never saw any problems at other growers. "Then we chose Rocket, then Luna and a week later we sprayed Rocket again." The problem is now well under control. The approach makes it possible to do little sulphuring, causing the Macrolophus population to be very sturdy.

Maximum Residue Limits
Both Fungaflor and Rocket have the advantage that the waiting time is only one day. After that day, the residue is already below the MRL. An additional advantage of Fungaflor is that the agent also inhibits Botrytis.

The combination of the agents is also well suited for the unlit cultivation. Steegh is confident now: "The crop looks very robust under the lights. I do not expect any more mildew until the end of August. We have sure learned a lot..."

Source: Certis Glashelder
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