Endophytic microorganisms live inside the plant tissues symptomless. These microorganisma may present antagonistic activity against phytopathogens or produce metabolites with antifungal activity. We aimed to evaluate in vitro antagonism and competitive interactions between endophytic fungi of Diaporthe species and Sclerotinia sclerotiorum. We also carried out in vitro screening of antifungal activity of metabolic extracts of the two endophytes against the pathogen. The antagonism was performed by the paired-culture and two promising antagonists strains were selected for metabolic extraction from the fermented culture. Metabolic extracts were obtainment using two different organic solvents (Ethyl Acetate and Hexane) and their antifungal activity was carried out using the agar diffusion test. The in vitro antagonistic index ranged from 22.1 to 59.5%, with Diaporthe sp. PL03 (59.1%), D. schini PL40 (59.5%), D. infecunda PL63 (41.8%), D. anacardii PL64 (56.8%), with inhibition by mycelial contact. The endophytes PL01 (28.6%) and PL43 (28.5%), both D. anacardii, stood out blocking mycelial growth from a distance. In the antifungal assay, D. anacardii PL01 (31.7%) and D. schini PL40 (18.2%) acetate metabolite stood out. In summary, our results indicate a few Diaporthe endophytes able to antagonize a S. sclerotiorum pathogen under in vitro conditions
