Any process that stops, prevents, or reduces the frequency, rate or extent of conidium formation, a process of producing non-motile spores, called conidia, via mitotic asexual reproduction in higher fungi. Conidia are haploid cells genetically identical to their haploid parent. They are produced by conversion of hyphal elements, or are borne on sporogenous cells on or within specialized structures termed conidiophores, and participate in dispersal of the fungus.
negative regulation of conidium formation