Minimum disease resistance standards
Rust can be effectively managed by growing resistant varieties. The level of resistance varies between regions depending on weather and seasonal conditions. If a variety does not meet the minimum resistance level, then additional rust control will be needed.
As part of its role, the ACRCP CC revised the Minimum Disease Resistance Standards in March 2011 taking into account regional differences relating to rust threat. The following table indicates the suggested minimum levels of resistance required for wheat.
|Northern (Qld and northern NSW)||MR-MS||MR-MS||MS|
|Southern (southern NSW, Vic and SA)|
|Conventional spring wheats||MS||MR-MS||MS|
|Long season and early sown (before mid-April) wheats||MR-MS||MR-MS||MS|
Rating abbreviations: R = Resistant, MR = Moderately Resistant, MS = Moderately Susceptible, S = Susceptible, VS = Very Susceptible.
While rust can be controlled in susceptible and very susceptible varieties through the careful use of fungicides, growing these varieties jeopardises current and future disease resistance.
A poorly managed crop, combined with untreated volunteers following harvest could contribute significantly to building high inoculum levels within and between seasons.
If there are high levels of rust disease in a region then you, your neighbour and your industry are at risk. High levels of rust inoculum increases the risk of rust disease mutation, putting existing rust-resistance genes at risk.
Because rust is an airborne disease, the spores can spread quickly between regions.
By selecting varieties with appropriate levels of resistance it is possible to:
- Reduce the build-up of rust populations that cause regional epidemics.
- Decrease pressure from existing rust strains.
- Lower the risk of mutations in the current strains into more virulent forms.
- Reduce production costs associated with chemical use.
- Decrease the risk of rust fungi developing resistance to available chemical fungicides.