Biofumigation refers to the suppression of soil-bome pests and pathogens by biocidal compounds (principally isothiocyanates) released in soil when glucosinolates in Cruciferous crop residues are hydrolysed. Interest in the use of Crucifers for biofumigation has increased recently due to the prohibition of several synthetic soil fumigants. The wide range in glucosinolate profiles, and the differential toxicity of the isothiocyanates evolved to different pests of plants provides scope to select or breed brassicas with enhanced biofumigation potential for particular target organisms. We consider factors which influence GSL production of Crucifers and present a framework for assessing their biofumigation potential. Crucifers with high biofumigation potential are being tested in Australia against pests of cereals, potatoes and other crops and preliminary results are presented.