A severe disease on sycamore (Platanus occidentalis L., P. orientalis L. y P. acerifolia [Ait.] Willd.) is described in the Center-South region of Chile, that causes death of buds, shoots, branches, inflorescences and leaves.
On the basis of disease symptons of plants in the field, the morfological and biometrical characteristics of the reproductive structure formed in naturally infected tree organs and the observation of in vitro cultures, the causal agent of the disease was identified as Gloeosporium platani Oud., which teleomorph is Gnomonia platani Kleb. Finally the most important factors that favors the disease and the host susceptibility are briefly discussed.