Prevention, mitigation and adaptation

Recent technological developments

In the following paragraphs, one promising advance in technology – the use of nanotechnology – is highlighted as an example of how new technologies can be harnessed to protect plant health. Nanotechnology provides tools for innovative and improved crop-protection products to address increasing pest risk, including that due to climate change. It is still under development and not yet widely applied in practice. It may also not be easily available in low-income countries, at least not immediately, for economic reasons. But it illustrates what is potentially possible. Improving such tools is very important and will be crucial in the future.

Nanofertilizers and pesticides

Over the past two decades, advances in nanoscale science have driven new interest and research into the applications and implications of nanotechnology for sustainable agriculture (Scott, Chen and Cui, 2018). In addition to the foundational use of nanofertilizers for precision agriculture (Raliya et al., 2018), it has been suggested that nanotechnology may potentially improve the efficacy and safety of pesticides. The nanotechnology-produced pesticides would have a large surface area and be capable of precision delivery in response to environmental triggers such as temperature, pH, humidity, enzymes and light (Bingna et al., 2018), as well as being soluble in water, thereby minimizing environmental residues (Zhao et al., 2018). Early experiments with solid nanoparticles consisting of metal oxides, sulphur and silica proved successful in controlling a range of pests (Goswami et al., 2010).

More recently, nanotechnology applications in the agricultural domain typically consist of the encapsulation of known herbicides, fungicides or insecticides into synthetic nanocarriers composed of clays, silica, lignin or natural polymers, including alginate, chitosan and ethyl cellulose (Diyanat et al., 2019). Polycaprolactone has been used as a nanocarrier for the herbicide pretilachlor (Diyanat et al., 2019), the triazine herbicides atrazine, ametryn and simazine (Grillo et al., 2012), and the pesticide avermectin (Su et al., 2020). Polycaprolactone has become popular because it naturally degrades in the environment, is inexpensive to produce and is not reliant upon petroleum plastic production (Sabry and Ragaei, 2018).

Nanopesticides have been very successfully tested for control of pine wilt nematode, with nanoencapsulated avermectin shown to have superior toxicity to the nematode’s gastrointestinal system, greater sustained-release performance and improved photolytic stability in comparison to a traditional delivery of avermectin (Su et al., 2020). Nanoencapsulating atrazine has also been found to reduce the harmful environmental effects of this herbicide, without negatively affecting the mortality rate of Bidens pilosa seedlings (Preisler et al., 2020). Nanoencapsulated atrazine in the latter study had inhibitory effects at 200 g/ha that were equivalent to those of nonencapsulated herbicide at 2 000 g/ha, representing a ten-fold reduction in the herbicide concentration. Also, in the case of mustard plants, polycaprolactone-encapsulated atrazine at a ten-fold dilution has been found to be as effective as non-diluted, nonencapsulated atrazine (Oliveira et al., 2015).

Enhanced breeding for resistance

Another opportunity for the use of nanotechnology in agriculture is as a delivery method for DNA transfer in plants to promote resistance to pests (Rai and Ingle, 2012; Sabry and Ragaei, 2018), thereby reducing the use of potentially environmentally harmful chemical pesticides. It has been proposed that nanoparticles could be used to passively deliver nuclease-based genome editing payloads as a method of plant genetic engineering. This method would overcome challenges to current gene transfer methods (such as gene-gun and ultrasound) caused by the physical barrier of a multi-layered and rigid plant cell wall that has caused progress in plant genetic engineering to lag behind that in animal systems (Cunningham et al., 2018). Some techniques for delivering DNA into animal cells can be adapted to plants under controlled conditions (Chang et al., 2013; Torney et al., 2007).

Information sharing framework

To complement the development of advanced technologies such as those described above, there are also initiatives to promote the sharing of data and information. The MyPestGuide initiative in Australia, for example, incorporates weed reporting, field guides for pest identification, and decision management tools in a shared platform (Wright et al., 2018). A global framework for data sharing could help efforts to tackle fast-spreading and potentially high-impact pests (Carvajal-Yepes et al., 2019).