In 1984, a new research working party on mechanismsofwoody plant resistance against insects and pathogens(lUFROS2. 05-06) was formed in the International Union ofForestryResearchOrganizations. Thepurposeofthisworkingparty istostimulate and facilitate research progress in this areathroughenhancedcommunication among themany researchscientistsscatteredamongthevariouscountriesoftheworld. This volume istheresultofthe first internationalsymposiumofthisworkingparty, which took place in Orleans. France on August 26-29, 1986. Thanks are due to Institute Nationalde laRechercheAgronomique,...