More and more frequently, customers are buying organic vegetables, because these products are not treated with pesticides or laden with chemicals. However, if these plants are attacked by pests, farmers have few options to protect them. For instance, organically-grown cabbages are often plagued by the cabbage root fly, the common enemy of such plants, causing great damage to crop yield.
However, farmers will soon be able to repel these flies reliably – and will therefore be able to proceed with their organic farming practices. The Fraunhofer IGB together with colleagues from the University of West Hungary and the Research Institute Nor-tek in Oslo – on behalf of various organic agriculture associations – have produced pellets with combined fertilizer-repellent properties for the organic farming of cabbage (grant agreement no 218467-2). The pellets consisted of dried digested manure with 0.1 percent dried cyanobacteria. If the pellets are applied to freshly planted vegetables, then the cyanobacteria are degraded by the soil flora and release a scent that repels cabbage root flies. The nutrient-rich digestate additionally fertilizes the plants. The pellets are easy to apply, and the nutrients are directly available to the plants.
The fertilizing and repelling effect of this product was confirmed in open field trials in Hungary and Spain. Our project partners in both countries achieved highly satisfying results: white cabbage plants that were fertilized with the combined pellets grew significantly better than non-fertilized plants. None of the plants fertilized with the combined pellets in the field trials were infested with the cabbage root fly.