Older and more recent observations on esca: a critical overview.

The main research findings of studies in esca carried out over the last few years in a number of laboratories are discussed. The topics include: the disease model; the relationship between black dead arm and esca; the role of toxins and xylem cavitation in the development of leaf symptoms; the artificial reproduction of leaf symptoms and wood rot; the inoculum sources of the fungi Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Fomitiporia mediterranea, and the influence of climate on the incidence of esca. The purpose was to sum up the current state of esca research and where possible to present new suggestions and sometimes alternatives to the suggestions of other researchers. The ultimate aim was to draw attention to those questions in esca research that are open to differing and even opposing explanations because the hard data are still lacking.