Crop sequence as a tool for managing populations of Fusarium pseudograminearum and F. culmorum in south-eastern Australia

Crown rot caused by Fusarium pseudograminearum and/or F. culmorum affects all winter-grown cereals in south-eastern Australia. Control of crown rot relies heavily on a break from cereals to decrease inoculum borne on plant residues in the soil. This study used quantitative real-time polymerase chain reaction to measure the DNA of the crown rot pathogens in soil before and after cereal and non-cereal treatments in six field trials (four in Victoria, two in South Australia). Levels of F. pseudograminearum and F. culmorum DNA were highest after cereals (particularly durum and barley) and lowest after non-cereals (particularly field pea and fallow). F. pseudograminearum and F. culmorum generally responded to treatments in a similar manner. Some sites were more responsive to treatment than others, although the relative effects of the treatments were consistent at all sites. This study demonstrates that it is possible to decrease crown rot inoculum (and so decrease the risk of yield loss from this disease) by use of non-cereals in crop sequences. The potential for predicting the effect of a treatment on levels of Fusarium spp. DNA in soil is discussed.