ABSTRACT
Dutch elm disease is the most widely known plant disease in the western world. It also is the most intensively studied tree disease and a prime example of a disease for which virtually every approach for control has been pursued. The story of Dutch elm disease thus represents a model for vascular diseases, as the life cycle of the pathogen is known in ever increasing detail, and transmittance of the disease is by vectors or root contact. Also, artificial infection of the host is simple, and trees having various degrees of resistance are known. Each one aims at a seemingly vulnerable spot in the complex relationship existing between the fungus, the beetles, and the susceptible elm species. Quarantines can theoretically exclude Dutch elm disease from an area, provided that there are elm-free natural barriers. In the experiments on biological control with Trichoderma, which is not known to produce any antibiotics, protective effects were observed after preventive treatments.
