Continuous cropping and minimum tillage have changed the agricultural landscape in WA, and it is important to monitor the system to determine if our farming system is under threat. In the context of disease; the implication is that the threat of diseases in cereal crops will increase over time. For example, if the soil-borne disease Crown Rot increases from one year to the next over successive years, then the farming system will become increasingly risky, as cereal crops will be less resistant to terminal drought. In seasons that are marginally profitable, such an increase in crown rot could turn a moderately profitable season into a loss making season.
For this reason, it is prudent to monitor the disease status of fields across the wheat belt, and determine whether the dominant diseases of Crown Rot and Rhizoctonia are increasing, decreasing, or remaining constant. Each disease has two measurable components; the level of inoculum (measured in this survey using the SARDI predictaB service, and an estimate of disease incidence (made in this instance by a DAFWA plant pathologist). The infection and expression of the disease is a consequence of both the level of inoculum and the conduciveness of the season, therefore it is important to monitor the pathogen and the disease to determine whether the farming system may be vulnerable to soil-borne diseases. Furthermore, trends may appear at a regional level and if an increase in a particular disease is detected, it is important to determine whether such an increase has occurred on specific paddocks, or occurs randomly throughout the wheatbelt. Of considerable concern is whether break crops are performing their expected function and reducing the expression of disease in both the break crop and in subsequent cereal crops.
Here, we explore the regional trends in the two major diseases of wheat Crown Rot and Rhizoctonia from 2010 to 2013. We then consider whether the problem sustains itself in an individual field, or whether management actions can successfully reduce the disease in the following season. Finally we explore the break crops and pastures and test whether the break crops are indeed reducing the disease levels
