Fusarium culmorum development was studied in rhizosphere and on root surface of barley that was cultivated in soil added with cellulose (1 %), glucose (0.2 %) and in soil without organic amendments. F. culmorum in rhizosphere and on roots was identified with indirect immunofluorescence method. It was established that cellulose added in soil leads to increase of F. culmorum mycelia, macroconidia and chlamydospores amount in barley rhizosphere. However, F. culmorum amount on roots was significantly lower in soil with cellulose than those in soil without amendments. Intensity of barley root rot was significantly lower in soil with cellulose than those in soil without amendments. Biocontrol effect of cellulose is caused by opportunity of saprotrophic growth of F. culmorum under additional nutrient and weakening of competition for it.