Many tree seedlings for reforestation are now being produced in small discreet containers. On these seedlings, losses and stunting from root pathogens occur widely and unpredictably. Some myxobacteria of the groupCytophagawhich produce powerful extracellular proteolytic and chitinolytic enzymes were introduced into fumigated or non-fumigated peat before or after sowing seeds of four species of conifer. They actively colonized the rhizosphere of the developing seedlings without affecting seedling development. In subsequent inoculation tests with pathogenic fungi, there was significantly less mortality, chlorosis, and stunting, than in checks without myxobacteria.