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Gerbera is a vulnerable crop and fungi such as Verticillium and Fusarium are to be avoided at all costs. Good hygiene helps growers to keep these fungi at bay. The crop rotation is the perfect moment to kill fungal spores. Quite a challenge, since there is often still crop in the greenhouse and the pipes are still being used. Gerbera grower Johan Reijm shares his experience.

"Every year we change a third of our greenhouse area. The old gerbera crop is removed and two weeks later the new crop starts. The most important reason for proper cleaning and disinfection at our nursery is to prevent Verticillium infestation. A gerbera crop lasts three to four years and it depends on the species, but we often see the first Verticillium appear in the second year of cultivation. We are very close to that, because the whole plant dies after an attack." Johan Reijm points out that it is very important that the fungal spores present from the old crop do not survive the crop rotation, so that they cannot immediately establish themselves in the new young gerbera crop. That's why at gerbera grower Reijm Nieuwerkerk in Nieuwerkerk aan den IJssel they apply a strict hygiene protocol during the crop rotation.

An important part is the cleaning and disinfection of only a part of the greenhouse, one of the bottlenecks in gerbera. First of all, the grower clears out the 1.5 hectares and ensures proper cleaning. "We spray everything with clean water at a pressure of 50 bar. This rough cleaning is a tough job, but very important in order to get rid of all loose plant residues." Johan Reijm then opts for disinfection with Menno Florades, a disinfectant based on benzoic acid with a horticultural permit. As a crop protection agent, this disinfectant has a proven effect against plant pathogenic bacteria, fungi, viruses and viroids. In addition to its powerful effect, it is gentle on materials and therefore does not affect the cultivation system.

For the application of Menno Florades, Johan Reijm opts for foam. "We start changing crops in early June, which means that the temperature in the greenhouse rises quickly and liquids evaporate quickly. You can choose to apply Menno Florades as a liquid for disinfection, but we choose foam. We do not disinfect in sunny conditions anyway, because disinfectants evaporate too quickly at high temperatures. By using foam, the penetration time is longer and you make the treatment more visible. A fast and effective effect is the result." Johan Reijm indicates that working with Menno Florades is not unpleasant for the user, it is not aggressive. However, the prescribed protective clothing must be used. Also gutters and cultivation materials are not damaged by the treatment.

Dirk Timmers, HortiHygienz product specialist at Royal Brinkman, advises a special foam lance for use during crop rotation. This lance has a venturi that sucks in air. In combination with the wetting agent contained in the product, this gives a good foam result. You can also spray with an ordinary spray gun, but then the agent does not foam.

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