Echinochloa spp. are the most important weeds in rice fields. In this research Fusarium equiseti and Colletotrichum graminicola were isolated from these weeds and then their pathogenicity effects were compared on these weeds and five rice cultivars in a completely random design with three replications in greenhouse conditions. Fungi were inoculated on weeds and rice cultivars using a spore suspension consisting of 10⁶ spore·ml^-1 of distilled water. Results indicated significant effect of F. equiseti and C. graminicola on Echinochloa oryzicola and E. crus-galli. Also, these rice cultivars showed significant reaction to F. equiseti and C. graminicola. The results showed that in comparison between effect of F. equiseti and C. graminicola on Echinochloa spp., disease rating caused by F. equiseti on E. oryzicola and E. crus-galli was more than disease rating caused by C. graminicola and these species of weeds were more susceptible to F. equiseti, but C. graminicola created less damage on rice cultivars and these rice cultivars were more tolerant to this fungus.

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