PREFACEThis book is a collection of papers presented at a NATO Advanced Research Workshop held at Cape Sounion, Greece, in May of 1988. The primary objectives of the workshop were to bring together researchers who are involved in studies of vascular diseases of plants caused by bacterial and fungal pathogens, and whose primary involvement and approaches range from the ecological to the organismal, cellular and molecular. It was anticipated that the kind of interaction that would occur in an intimate meeting of several days duration, such as a NATO Workshop offers, would produce a broader appreciation and understanding of various aspects of wilt diseases, new levels of collaboration and, in the longer term, a more sound and broad base of measures for practical disease control.In all, eighteen lectures and twenty-seven research papers were presented. The first day was devoted to the life cycles of the pathogens, their colonization of root surfaces, entry into roots, and colonization of the vascular systems of plants. The second day was devoted to recognition phenomena, structural changes and physiological and biochemical interactions by which the plant defends itself and those by which the pathogen counters these processes and causes disease. On day three, these studies were carried to the genetic and molecular levels of understanding, principally for bacteria, but with exciting progress and prospects with fungi as well. Day four began the process of integrating these understandings with physical and biological components of the environment in ecological terms. Finally, day five was devoted to discussing comprehensive systems of control in light of the understandings gained during the week.The workshop was successful in its intended purpose of enhan-VI cing confluent thought at the ecological, organismal and molecular levels and, indeed, several collaborative ventures that cross these disciplinary lines were agreed upon or are being explored. For example, the use of immunohistochemistry has allowed far more precise studies of the colonization of epidermal and cortical tissues by species of Fusarium and Verticillium. The question arises, can these techniques not also be used to examine the colonization of roots by competing organisms found in suppressive soils with or without chemical additives, including fertilizers, that may enhance or reduce apparent suppressiveness? Again, colonization of epidermal and cortical tissues of roots by these species is commonplace and general along certain portions of roots, yet successful vascular colonization leading to apparent disease is a relatively rare event in comparison. Either suitable vascular infection courts or the conditions suitable for vascular infection must be of rare occurence. Can immunohistochemical procedures be used to help identify those places and conditions under which infection can take place, and if so, can we take steps to further reduce the frequency of successful vascular infection and colonization by pathogenic forms? Can genetic factors within the hos...