Key messages

• Geospatial maps of fungicide resistance detection in cereal pathogens are now accessible online (https://prim.ccdm.com.au/).

• The website provides direct links to expert information on fungicide resistance management.

Aims

• The development of an online platform to provide local-scale and nation-wide distribution mapping of fungicide resistances in foliar fungal pathogens of grain crops with links to expert advice on resistance management.

Background

Fungicides are important tools in the management of crop diseases. And like any tool, when placed under sufficient stress, they break. Unlike a busted ring-spanner left on the shed floor, a disease-causing fungus with a broken fungicide target-gene doesn’t stay put, it will spread throughout the entire grower community!

So, what should we do? We can bear the expense to implement resistance management strategies that reduce the likelihood to develop resistance in the first place, though, this will not stop resistance from developing elsewhere in the community. Applying resistance management approaches will slow the spread of resistance into our paddocks from neighbouring properties, however, management alone cannot stop the incursion of resistance from occurring. The efficacy by which fungicides control crop disease aligns with a tragedy of the commons, and in this regard, the development of resistance is inevitable.

Then how do we fix outbreaks of resistance? Globally, no solutions exist! Outbreaks of invasive pests provide us with similar context, yet, where early detection and rapid quarantine response have been shown to minimise the expense of pest eradication programs; there is a time-lag between the evolution of fungicide resistance and the development of detection capabilities for effective monitoring. This time-lag allows the escape and spread of resistance far beyond the centre of origin – so the genie escapes the bottle, every time. What of a future techno-fix? Highly unlikely, fungicide resistance is fundamentally a population genetics problem, making it intractable to standard broadacre treatment approaches.

Is there hope? Historically, tragedy of the commons scenarios are solved through community-led involvement and community-shared investment. We will only fix fungicide resistance by growers coming together as grower-groups, committed towards testing broadscale novel solutions. Australian growers are tight-knit communities that are world renowned for their ingenuity and innovation in the face of adversity – we have the right ingredients, so if anywhere in the world can solve fungicide resistance, it is here, but it will require your involvement.

Where do we start? Prior to developing and testing solutions to fix fungicide resistance, we need to know the target and have capacity to monitor for change. To enable community-level engagement between growers, we need to identify the extent of spatial distribution and the gene flow parameters of different pathosystems and resistances; this information needs to be made readily available and comprehensible, be locally focussed and regularly updated. The logical platform to provide such information is an open-access online mapping resource to provide visualisation of resistance extent, movement-over-time and population structural density, that is updated regularly with the latest results. The Analytics for the Australian Grains Industry (AAGI) program, The Centre for Crop and Disease Management (CCDM) and NGIS collaborated in the development of the Pesticide Resistance Integrated Mapping (PRIM) platform to provide growers and the community alike with resistance information at the click of a button (https://prim.ccdm.com.au/). While initially focussed on fungicide resistance, over time this tool will grow to include other forms of pesticides. Now, armed with an effective monitoring tool, we can bring the grower-community together and begin the work needed.

Development

Map design –The mapping platform displays sensitive-data for public release through masking of geospatial locations yet retains sufficient local-scale resolution for contextual benefit to growers. We use a grid-pattern overlay of a geographic map of Australia with minimum polygon-grid diameter of 25km. Polygon-grids that span non-agrarian landforms, (i.e. coast, lake, city) and contain less than 75% of area, are subsumed into adjacent polygon-grids. Two scales of grid-pattern are projected, offering users national- and landscape-scale visualisation options. Fungicide resistance data are categorised and then projected as colour coding onto polygon-grids.

Scope of pathosystems – Currently, four pathosystems of cereals with fungicide insensitivity are mapped; spot form net blotch and net form net blotch of barley andseptoria tritici blotch and powdery mildew of wheat. Resistance data among pathosystems span three fungicide groups; sterol demethylase inhibitors (Group 3), succinate dehydrogenase inhibitors (Group 7), and quinone outside inhibitors (Group 11).

Development of data –Data was taken from ten years of detection testing by the CCDM fungicide resistance group. Resistance data were produced across several assay platforms and required transformation prior to categorising polygon-grids into respective phenotypic-response to the fungicide group, as either; resistant, reduced sensitivity or sensitive.

Platform features –Several features were included for interrogation of mapped data; (i) a pop-up bubble to display the polygon-unit data-set, (ii) a timeline that re-generates maps of resistance by the selected year of detection, (iii) a resistance-over-time feature that graphs the temporal frequency of resistant populations of any location selected.