Losses in wheat production due to pathogen infection represent a major threat to modern agriculture. Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici (syn. Septoria tritici, is considered the most devastating foliar disease of wheat in Denmark and the EU. Fungicides are currently the primary control method of STB, as all commercially available wheat cultivars are susceptible to some extent. The increasing resistance to common fungicides therefore necessitates the development of innovative and sustainable strategies for effective disease control.Endophytes are microorganisms, mainly bacteria and fungi, which inhabit inner parts of the plant without causing apparent symptoms on their host. Some endophytes have even been shown to have beneficial effects in different pathosystems, including conferring abiotic stress tolerance, stimulation of growth and decreasing disease incidence and severity. Due to these beneficial effects there is an increasing economic interest in developing endophyte asbiocontrol agents. The aim of the project is to identify endophytes that efficiently control STB in a reliable manner and that are adapted to the local environmental conditions. In a screening approach, endophytes isolated from wheat are tested for control of Z. triticiin vitro and in planta, under both controlled and natural climatic conditions.