The microbial control ofAlliumwhite rot (Sclerotium cepivorum) has shown promise experimentally but has yet to be used in commerce.Alliumcrops are grown from dry or fluiddrilled seed at a range of seed rates, from bare root and module‐grown transplants and from sets and cloves. The period of susceptibility to infection may be prolonged or short in cool and hot climates, respectively. Primary infection of theAlliumhost results from the growth of hyphae from germinating sclerotia to the roots; secondary infection results from hyphal growth between plants. Sclerotial populations in the soil are often low, hence sclerotia are widely dispersed and therefore inaccessible to microbial control. New sclerotia form on host stem tissue, rarely on roots, rendering them accessible to microbial control. Hyphal parasites may therefore be effective at reducing primary and secondary infection and the formation of new sclerotia. Parasites of sclerotia may restrict the survival of new sclerotia and hence reduce primary infection in future, but not the current season's crops. The opportunities and problems that the variety of growing techniques and conditions ofAlliumcrops present for microbial control of white rot will be reviewe