ABSTRACTA disjunctor is a spindle- or needle-like crystalline organelle unique to the majority ofMoniliniaspp. It develops through the pores of septal lamellae of adjacent maturing conidia. At each end of a disjunctor one or two telomeric knobs are observed. The disjunctors are variable in size (3–10×0.25-2.5μm) and ornamentation, depending upon the species. In many taxa ornamentation consists of more or less concentric ridges which represent coalesced individual warts, some of which remain attached to the corresponding discrete warts on the septal lamellae. The development of the disjunctor inMonilinia vaccinii-corymbosi, a pathogen of blueberries, is described in detail and compared with that of several otherMoniliniaspp. A list of the species with or without disjunctors is provided.