ARE drones the ultimate rapid scouting method to detect aphid-induced stress in wheat crops?
Researchers from The University of Western Australia (UWA), including associate professor Ken Flower, associate professor Nik Callow and master's student Caroline Chua, as well as Department of Primary Industries and Regional Development (DPIRD) researchers Dustin Severtson and Amber Balfour-Cunningham, are investigating that very question.
Dr Severtson said the current methods to scout grain crops for pests and diseases were time-consuming and often inaccurate.
"Random sampling hopes to find pest hotspots in parts of paddocks, but often miss them," Dr Severtson said.
"This means growers are either losing money on unnecessary pesticide application or yield loss in parts of crops which are missed."
Spatial data, such as remote sensing using near-infrared and infrared spectra, can detect and map regions of crops that are experiencing biotic or abiotic stress.
Prior research has shown the potential for using reflectance indices to identify stressed areas of canola crops affected by biotic (eg aphid) and abiotic (eg potassium deficiency) factors.
Dr Flower said the specific objective of the project was to determine which reflected wavelengths were changed after infesting wheat plants with aphids and if these could be detected using drone-based multispectral sensors.
A field trial was seeded at DPIRD in Northam and plots were infested with different levels of aphid.
A multispectral drone was used to image the plots along with ground-based aphid counts and leaf chlorophyll (SPAD) measurements.
Unfortunately, heavy rains in the main growing season prevented large numbers of aphids accumulating in the plots and the early data sets were yet to be assessed for any aphid-induced crop differences.
As a result, a separate pot experiment was established at the UWA Plant Growth Facility, where wheat plants were grown and then infested with different levels of aphid.
The pots were kept in a 'bug-dorm' to prevent the aphids spreading within the glasshouse.
The control and infested plants/leaves were imaged on several occasions with a multispectral camera and spectroradiometer to assess reflectance data under more controlled conditions.
The project is expected to be completed early this year.
