Airborne sampling and optical sensing methods for macro scale mapping

Jon S West1, Gail GM Canning1, Steph Heard1, Bart A Fraaije1, Peter Bonants2, Marga van Gent-Pelzer2, Mogens Nicolaisen3, Annemarie Fejer Justesen3 and Stuart G Wili4 

1 Rothamsted Research, West Common, AL5 2JQ Harpenden, United Kingdom

2 Plant Research International, Wageningen, The Netherlands

3 Aarhus University, Slagelse, Denmark

4 Burkard Manufacturing Co. Ltd, Rickmansworth, United Kingdom

Emerging technologies evaluated in the PURE project can provide practical solutions to improve disease control in response to temporal and spatial differences in epidemics of fungal plant diseases. Evaluation of optical sensing methods to map disease foci for spatially selective treatment, found that remote sensing using satellite images has limited potential for disease control, except for mapping relatively static patches of some soil-borne diseases. Currently available data has relatively poor resolution (usually >1m2 pixel size) and there are problems of revisit time and cloud cover. Secondly, because most fungicides are protectants rather than eradicants, established disease foci, which harbour a zone of incubating symptomless disease around them, are not controlled so for widely-dispersed polycyclic pathogens such as powdery mildews and rusts, by the time a few foci have been detected in a field, it is necessary to spray the entire field. More sophisticated proximal imaging techniques have greater ability to detect earlier, even pre-visible symptom stages of disease development for targeted control. For diseases that develop from airborne inoculum, timing of disease control methods can now be improved using automated air sampling devices, integrated with appropriate diagnostic methods. A system developed under the ‘SYield’ project using an air sampler developed partly in the PURE project, has produced promising results for automatic detection of spores of Sclerotinia sclerotiorum in recent testing in Canada. Further development is ongoing to integrate the same MVI air sampler with novel isothermal DNA-based diagnostics. We can expect a new approach to precision agriculture to emerge from this technology – farm-based devices that give precision on when to apply fungicides and when to omit applications that may have previously been advised purely on weather-based infection risk, but which growers will know can be omitted if inoculum is not present. The technology will reduce costs and the environmental impact of farming. Air sampling integrated with DNA analysis can also be used to monitor species composition and genetic changes within a species, such as fungicide resistance. Burkard seven-day spore traps were operated at rooftop level at Rothamsted Research (UK), Wageningen (NL) and at Slagelse (DK) for periods in the autumn and spring during 2011–2013. DNA extracted from daily samples was analysed using 454 amplicon sequencing. Numerous genera of fungal plant pathogens were detected.

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/ 2007-2013) under the grant agreement n°265865- PURE