Thirty seven of Allium species and onion varieties were screened against Sclerotium cepivorum Berk, under controlled greenhouse conditions. Three laboratory trials were carried out under controlled conditions to study : (1) The effect of culture filtrate of cepivorum on germination of some Allium species and onion varieties seeds, (2) The effect of fungal toxin (oxalic acid) on germination of some Allium species and onion varieties seeds and (3) The effect of chemical synthetic oxalic acid on germination of some Allium species and onion varieties. There was a close agreement between varietal susceptibility using greenhouse technique and that using the effect of fungal toxin and that of oxalic acid on seed germination under laboratory conditions. Thus screening Allium species and onion varieties using oxalic acid method instead of the greenhouse and field experiments methods is practically useful in assessing the susceptibility of onion varieties especially between the highly susceptible and susceptible varieties.