Biology is beginning to replace chemistry in the crop protection toolbox
Every so often a piece of research appears that does more than add another brick to the wall of agricultural science, it quietly shifts how we think about what is possible. The recent work from the University of Queensland on RNA-based biopesticides looks set to be one of those moments, not because it promises an instant commercial product but because it changes our understanding of how biological crop protection could realistically function in the field.
For years researchers have known that double-stranded RNA can silence essential genes in pests and pathogens through RNA interference, effectively switching off the biological processes those organisms rely on to survive. The promise has always been clear. If the right RNA sequence reaches the right target control can be extremely precise, potentially affecting only the pest while leaving the crop and beneficial species untouched. What has been less certain is whether sprayed RNA could reliably move through plants to reach the places where many of the most damaging threats actually operate.
The University of Queensland team, led by Dr Chris Brosnan has now provided strong evidence that it can. Their research shows that when dsRNA is sprayed onto leaves it does not simply remain on the surface or degrade quickly. Instead it can move through the plant’s transport system, travelling long distances to new growth, flowers and crucially the root system. As Dr Brosnan explained, “we have shown in multiple species that when it’s sprayed on a plant’s leaf, the dsRNA is mobile, travelling between cells and throughout the plant including to the roots.”
That systemic movement matters because it addresses one of the long-standing challenges in biological crop protection. Many pests and pathogens do their damage out of sight, operating in roots or vascular tissues where traditional sprays struggle to reach. Soil treatments exist but often bring environmental trade-offs, inconsistent performance or high cost. The idea that a targeted molecule applied above ground could move through the plant and encounter pathogens wherever they are active opens up an entirely different delivery pathway.
The research also clarifies how that movement occurs, overturning assumptions that the RNA must enter plant cells directly to be effective. Instead the molecule travels largely through the plant’s external transport spaces and vascular system, remaining intact as it moves. That detail may sound academic, but in practice it means sprayed RNA can persist long enough to be transported and to remain biologically active once it reaches its destination.
For growers, the significance lies in what happens next. Once the dsRNA encounters a susceptible pest or pathogen, that organism’s own biological machinery processes the molecule and triggers gene silencing. In effect the pest’s genetics become the control mechanism. Essential genes are switched off and the organism can no longer function normally. The plant itself is unaffected, and non-target species remain untouched because the RNA sequence is designed to be highly specific.
Dr Donald Gardiner described the implications plainly, noting that “it’s a challenge to get anything protective into plant roots, so if we can spray RNA on a leaf and get it to move through the plant’s tissues as an intact molecule to its roots, that’s a significant opportunity to target hard-to-reach pests and pathogens.”
That opportunity is not theoretical. The team is already investigating organisms such as nematodes which quietly reduce yields across grains, cotton and horticulture yet remain difficult to control effectively with existing tools.
This matters because agriculture is entering a period where the pressure to reduce chemical inputs is growing steadily while the need for reliable crop protection remains unchanged. Regulatory scrutiny, environmental expectations and market demands are all pushing growers towards more selective solutions. Technologies that promise precision rather than blanket suppression inevitably draw attention in that context.
RNA-based approaches sit squarely in that emerging space. They offer the possibility of tailoring control measures at a genetic level, targeting only the organisms that need to be managed while leaving the surrounding ecosystem largely undisturbed. That does not mean they will replace conventional chemistry overnight. Crop protection rarely changes that quickly. But they do represent a direction of travel, one that aligns with both scientific capability and societal expectations.
The research also highlights how much of agricultural progress now occurs at the intersection of biology and engineering rather than within either discipline alone. The challenge ahead will not simply be proving that RNA sprays work, it will be developing formulations that are stable, affordable and compatible with real farming systems. RNA molecules degrade naturally in the environment, which is part of their environmental appeal but also part of the technical hurdle. Ensuring they persist long enough to be effective without lingering unnecessarily will be central to commercial success.
Even so, the broader importance of this work lies in the shift in understanding it represents. As Dr Gardiner observed, “this work changes the dogma around the stability, uptake and movement of dsRNA which is vital as we develop the technology.” In science, changing the underlying assumptions often matters more than any single result, because it opens pathways that previously seemed closed.
For the agricultural sector, that shift suggests crop protection is gradually moving into a new phase. The future toolkit will likely combine traditional chemistry, improved genetics, biological controls and increasingly precise molecular technologies. None of these approaches will stand alone. Instead they will form part of a layered strategy designed to manage risk while maintaining productivity.
Farmers and contractors tend to judge innovations not by how clever they sound but by whether they make practical sense. Any RNA-based product will ultimately have to prove its worth in the paddock, demonstrating reliability, value and compatibility with existing machinery and workflows. That process will take time, but the underlying science now appears far more robust than it did only a few years ago.
The University of Queensland findings do not represent the end of that journey, but they mark a clear step forward. They show that sprayed RNA can travel through plants, remain active and potentially influence pathogens far from the original application point. In doing so, they strengthen the case that biological precision may soon sit alongside chemistry as a mainstream crop protection tool.
If that happens, the impact will not be measured only in yield gains or reduced inputs. It will be measured in a gradual reshaping of how agriculture manages risk, moving from broad intervention towards targeted biological control.