Australian researchers develop eco-friendly nanotechnology pesticide spray

Australian researchers say they have developed a sustainable way to protect crops from pests and diseases, by spraying them with a special clay.

The discovery could also help the rural sector in the fight against pesticide resistance in certain crops.

The spray is known as 'BioClay' and was developed by the Queensland Alliance for Agriculture and Food Innovation (QAAFI) and the Australian Institute for Bioengineering and Nanotechnology (AIBN).

"It will produce huge benefits for agriculture in the next several decades, and the applications will expand into a much wider field of primary agricultural production," Professor Xu from AIBN said.

Agricultural biotechnologist and research leader, Neena Mitter, said the clay spray contained molecules that helped protect crops from invading pathogens.

"It is a [pest] control measure, which is environmentally sustainable, ecologically safe, stable, and easy to be adopted by farmers to protect their crop from diseases."

In the trials the researchers were able to protect a crop of tobacco from invading diseases for up to 20 days using the BioClay spray.

The team also trialled the spray on cowpeas and capsicums, and think it could also work for cotton and a range of other crops.

Chemical companies and researchers around the world, including Monsanto, are in a race to develop and commercialise similar technology.

However, the QAAFI and AIBN team is the first to produce long-lasting results, and to have the findings published.

Professor Mitter said she hoped to have a commercial product on the shelves in three to five years.

"There is a lot of work going on in using gene silencing in a spray, but I think we are fairly progressed in our own BioClay product," she said.

How it works

The clay contains molecules of double-stranded ribonucleic acid (RNA), a sibling of DNA, which can switch off gene expression and prevent plants from being susceptible to a virus.

The clay helps the molecules stick to the plant, and then peels off over time.

This means once a virus comes into contact with the RNA on the plant, the plant will kill the pathogen.

Using RNA as a defence against disease is not a new concept, and researchers have applied it to crops before.

However, the new aspect is Professor Mitter's invention of the spray on clay to help bind the RNA molecules to the plant.

RNA is traditionally used to silence genes in the genetic modification process.

However, Professor Mitter said her BioClay process did not genetically modify plants, because the process involved collecting RNA from a virus and turning it against itself, rather than changing the genome of a plant.

"We are using that RNA to silence a gene in the pathogen and that RNA has nothing to do with the plant, and has no similarity to the crop," she said.

"We are not modifying the genome of the plant, we are not doing genetic modification; we are just spraying it with RNA."

The researchers hope BioClay can be used as an alternative to traditional chemicals, to prevent crops from building up pesticide resistance.

"If you use a chemical, pathogens are clever and can adapt, but with BioClay we use RNA from the pathogen to kill the pathogen itself." Professor Mitter said.

"So we are strongly placed in terms of addressing the issue of pesticide resistance."

Can farmers afford it?

Finding a cost-effective way of applying RNA pesticides to plants has been difficult until now.

A criticism of using RNA to protect crops in the past has been that the technology was too expensive, but Professor Mitter said it was becoming cheaper and farmers would be able to afford it.

"The aim is to make it affordable because the clay part is cheap to manufacture," she said.

"The production of RNA could be expensive but companies around the globe are working on mass producing RNA at a very cheap scale.

"I'm hoping this product will be commercially viable."

"BioClay is a beautiful combination of biology and nanotechnology," she said.

"Once it is applied, the plant thinks it is being attacked by a disease or pest insect and responds by protecting itself from the targeted pest or disease.