Dirk Röse

Substrate solution to problem of sciarid infestation

Marked improvements for organic herbs and in the propagation of vegetable crops

In an EU research project, Klasmann-Deilmann and the University of Osnabrück investigated the causes of sciarid infestation, especially that which affects organic growers. A new substrate solution was developed that reduces development of sciarids by up to 80%. This is especially promising for growers that use organic herb substrates with low to moderate basic dressing, combining them with liquid fertiliser regimes during cultivation. Other potential uses are as propagation substrates for sensitive vegetable crops such as cucumbers and lamb’s lettuce.

The EU research project team found that the specific composition of organic substrates encourages sciarid infestation. In addition to raw peat materials, a high proportion of alternative substrate constituents is used in this segment, such as compost, coco pith and wood fibre. This blend provides sciarid larvae with good living conditions; organic fertilisers in particular are used as a food source.

Under this project, the selection of substrate constituents was changed such that the larvae were deprived of their natural food source. What is crucial here is the use of a fully rotted, stable green compost produced by Klasmann-Deilmann in compliance with RHP guidelines. A method of application and a novel fertiliser formulation were also developed that no longer provide an ideal life-sustaining medium for sciarid larvae. With their specially tailored blend of ingredients, these fertilisers achieve remarkably good outcomes not only in the suppression of sciarids but also in terms of plant growth. They are highly efficient in their nutrient potency and also rich in amino acids that strengthen plants.