The effect of previous crop species (oilseed, legum e and cereal) on the incidence and severity of crow n rot ( Fusarium pseudograminearum , Fp ) and yield of wheat was investigated in two field studies in northern NSW. The experiments were designed to compare the effectiveness of the brassica break crops canola (Brassica napus L.) and mustard ( B. juncea L.) with chickpea ( Cicer arietinum L.) on reduction of Fp in subsequent wheat crops. Canola and mustard were shown to provide an effective break crop for crown rot in northern NSW with the brassicas generally being more effective than chickpea in reducing the severity of crown rot but not whitehead formation. There was li ttle evidence that the lower disease and higher yie ld following brassicas compared with chickpea was related to Fp inoculum suppression by biofumigation. More plausible explanations are that residual cereal res idues decomposed more rapidly under dense brassica canopies reducing Fp inoculum and/or that brassicas resulted in soil/re sidue biology which was less conducive to the survival of Fp . Evidence for the latter was provided by consisten tly higher levels of Trichoderma spp. isolated from wheat following brassicas compa red to chickpea or cereals. Increased breakdown of standing cereal residue was also shown in a separate experiment to be facilitated by the amendment of stubble with a liquid solution contain ing both 5% carbon and 5% nitrogen.