Eye in the sky looks for crop stress

Three men with a remote controlled drone

(From left) Researchers John Moore, from DAFWA, and Nik Callow and Christian Nansen, from the University of Western Australia, testing out a new six-channel, multi-spectral camera for insect, nutrient deficiency and frost damage detection in plot trials in Perth.

PHOTO: Melissa Williams

There is a buzz in the air at the University of Western Australia’s (UWA) Shenton Park Field Station this year.

UWA’s entomology and geography scientists and their students are using an unmanned aerial vehicle (UAV) that can fly at fast speeds and hover to detect and assess crop plants that are under stress.

This GRDC-funded project aims to fast-track identification of specific crop stressors, such as insects, nutrient deficiencies or frost.

In time, using UAVs and the latest camera technologies could be a cost-efficient way for growers to:

  • detect patches of insects and pests in broadacre paddocks for strategic and targeted insecticide and pesticide applications;
  • find nutrient-deficient areas of paddocks for specific testing and treatment; and
  • quickly identify frosted areas to make marketing decisions.

UWA associate professor in applied entomology Christian Nansen is leading the GRDC-UWA UAV insect research in 2014 as part of his efforts to develop more strategic integrated pest management (IPM) practices for WA growers.

He says this includes better assessments of damage on emerging plants to encourage more effective and sustainable insecticide use.

Associate Professor Nansen and his team are testing a six-channel, multi-spectral camera attached to an UAV.

This system provides spectral images – similar to a normalised difference vegetation index (NDVI) image – for six different wavelengths.

The researchers are measuring changes in plant light-reflectance response to see if any of the wavelengths can be associated with a specific stressor.

Associate Professor Nansen says he can simulate a wide range of insect densities on several crop varieties in small plot trials to assess the likely success of detecting damage using the UAV – before trialling this new technology at a paddock scale.

PhD student Dusty Severtson is focusing on using the UAV technology for cabbage aphids in canola, which are often hard to detect in broadacre crops.

His initial laboratory trials have shown there are differences in plant light reflectance between canola plants damaged by cabbage aphids and undamaged plants.

This year, Mr Severtson is using the UAV to further assess plant stress levels under a range of aphid densities.

In conjunction with the Department of Agriculture and Food, WA (DAFWA), the UWA entomology team is undertaking sub-paddock-scale trials with the UAV to detect crop nutrient deficiencies – particularly potassium.

“We are interested in nutrients as a contributor to a plant’s stress mechanisms and susceptibility to insect damage,” Associate Professor Nansen says.

“Correct nutrient application, where needed, is a good preventative approach to maintain crop health and can save money on both fertilisers and insecticides.”

John Moore, a DAFWA senior weeds researcher at Albany, is using UAV technology to help with weed detection. UWA honours student and grower Scott Thompson is concentrating on UAV images for early frost detection and attractiveness of frosted wheat plants to insects – particularly cereal aphids.

UAV

The unmanned aerial vehicle:

  • creates a reflectance profile for stressed and healthy plants;
  • can fly to about 120 metres;
  • provides six-channel multi-spectral imagery covering one to 1.5 hectares per image;
  • can cover up to 5ha per flight by combining multiple images together in a mosaic map; and
  • is highly valuable for stable imagery.

“An exciting part of this project is that it is bringing together people with quite different backgrounds, such as entomologists, geographers, electrical engineers, plant physiologists and others, so that we can develop technology and solutions for growers,” Associate Professor Nansen says.

“It is really the first step towards insect-seeking technology that could have similar on-farm benefits to weed detection of all crop pests – including insects, diseases and weeds.

“This pilot work will tell UAV consultants – and growers with UAVs – what kinds of data to collect to inform their decision-making.”

Associate Professor Nansen says finding and targeting areas of insects and other pests in paddocks with robust insecticide and pesticide rates is becoming increasingly important as levels of resistance increase.

“There is also a lot of money wasted driving across paddocks to check for insects that this UAV technology might be able to replace,” he says.

“This is a good first step towards an IPM goal of more efficient and effective paddock sampling to find out where, when and how many insects are affecting crops and then using ‘patch’ treatments.”

More information:

Associate Professor Christian Nansen
08 6488 8672
christian.nansen@uwa.edu.au

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The science of soil biology rolled out on tour

GRDC Project Code UWA00165, UWA00144, UWA00158

Region West, North, South