Araucaria angustifolia or Brazil Pine is a typicaltree of the endangered Atlantic Forest biome, and formany decades it was the source of Brazilian wood.This species is also very important in providing foodand feed, as well as raw material for joinery,cellulose pulp and varnish. Due to the economic andenvironmental importance of A. angustifolia, researchprojects involving the preservation and management ofthis species are becoming more urgent and necessary.Actinobacteria with antagonic effects against theplant pathogens Fusarium sp. and Armillaria sp. andplant growth promotion activity were isolated. Inthis book we describe several microbial isolationtechnics and greenhouse experiments that can be usedto screen for growth promoting characaters and arethe base for new biotechnological products. Ourresults constitute a solid fundament to lead to thedevelopment of plant growth promoting bacterialinoculants and innovating technologies and managementtechniques with regard to the control ofplant diseases, especially for coniferous tree species.