In 1983, seed dressing of peas with fosetyl-Al (Aliette) compared favourably with all other treatments on a field heavily contaminated with foot and root rot pathogens. Experiments carried out in 1983 and 1984 could not establish the reason for this phenomenon. Artificial inoculation with the most frequently isolated pathogens (Fusarium oxysporum, Phoma medicaginis var.pinodella, Pythium ultimum andFusarium solani f.sp.pisi) of sterilized soil before planting treated seeds did not reproduce the field observations, but glasshouse experiments using soil from the experimental field did. Glasshouse experiments in 1989, afterAphanomyces euteiches had been identified as a frequently occurring pea pathogen in the Netherlands, confirmed the favourable effect of fosetyl-Al as a seed treatment whenA. euteiches was in the pathogen flora.