An evaluation of the efficacy of steam treatment on reducing levels of Fusarium, Cylindrocarpon, and Trichoderma within styroblock containers was conducted at the Plum Creek Nursery in Pablo, Montana. Although levels, of both Fusarium and Cylindrocarpon were significantly reduced by cleaning, relatively high populations of both these fungi persisted after cleaning. Fusarium propagules were mostly concentrated at the bottom of styroblock cells as were those of Cylindrocarpon. Levels of Cylindrocarpon were much higher than either Fusarium or Trichoderma. Trichoderma levels were not significantly affected by the cleaning treatment. Seedling height was not correlated with extent of styroblock cell colonization by either Fusarium or Cylindrocarpon. Abundance of pathogenic strains of Fusarium or Cylindrocarpon within the styroblock containers is unknown.