Plant health is important for the survival of our planet and all its living creatures. Now, imagine an instrument that contains a DNA chip from virtually every known plant pathogen, where one can simply snip off a piece of the infected plant material, slip it into the ‘plant disease tricorder’, and within seconds you have not only a diagnosis of the disease, but all the information about its control too.

According to Prof Wijnand Swart, Professor of Plant Pathology in the Department of Plant Sciences at the University of the Free State (UFS) and President of the Southern African Society for Plant Pathology (SASPP), this concept might be a bit far-fetched, but is a distinct possibility for the not-too-distant future. “Without a doubt …,” he believes.

He was recently a guest on a series of radio talks on plant health in South Africa, hosted by the National Science and Technology Forum (NSTF) in partnership with Plaas/Farm TV (YouTube broadcaster). His talk on the topic, Whither (or wither) Plant Pathology in the next 50 years, was specifically focused on understanding the latest research and dynamics of the discipline in a South African context.

In terms of this futuristic perspective, he says collaboration between plant pathologists and biomedical and aeronautical engineers, nanotechnologists, and computer scientists will aid the development of micro-sensory technologies for the detection of new plant diseases that are relevant to biosecurity, plant disease diagnostics, and epidemiological modelling.

In his discussion, Prof Swart referred to the work of Prof John Lucas, former Head of Plant Pathology and Microbiology at the Rothamsted Research Station in the United Kingdom, who believes that there are three key issues facing plant pathologists in the 21^st century. These are the strengthening of food security while simultaneously safeguarding the health of associated ecosystems and reducing the dependency on natural resources; the creation of pest and disease control systems that are sustainable and not compromised by the evolution of pest and pathogen strains; and the development of suitable crop protection technologies.

Future technologies

Based on the work of Prof Lucas, Prof Swart states that future technologies in plant health will develop in five areas. In the first area, he says DNA-based technologies will greatly increase the speed, sensitivity, and accuracy of pest and pathogen detection and diagnosis.

Also key here, is the integration of nanomaterials into disease management strategies and diagnostics. He says in the past decade, the use of nanotechnology in phytopathology has grown exponentially. According to him, nanotechnology can increase productivity using nano-pesticides and nano-fertilisers, improve soil quality by means of nano-zeolites and hydrogels, stimulate plant growth using nanomaterials, and provide smart monitoring via nano-sensors and wireless communication devices.

Prof Swart says according to Prof Lucas, the second area in which plant health technologies will grow is plant defence and immunity. When induced, plant resistance primes plants to deal with a diversity of biotic and abiotic stresses. Prospects of inducing chemically modulated plant resistance via biological agents (such as engineered microbes), might result in low-cost seed treatments, thereby removing the need for expensive chemical spray regimes.

Technology development in plant health will also become more evident in genetic diversification. Prof Swart believes sequencing the genomes of major crop species and their wild relatives will expand the known gene pool and diversify genetic resources available to plant breeders.

According to him, a new era is beckoning, where the prospect of crop pharmacology based on signal molecules and their receptors will become a reality. It will be based on the development of novel chemistries designed to manipulate specific molecular targets, by either regulating host resistance or disabling the disease-causing processes of pathogens.

The fifth area in which plant health technologies will develop, is ecological approaches to disease control. He says by understanding the ecology of pathogens, our ability to exploit their natural enemies will improve. Ecological approaches to plant disease control will have a significant impact on the introduction of invasive pathogen species, while the effect of climate change will influence the emergence of new plant diseases and epidemics. He strongly believes that it is important to take a holistic approach to understanding how and why plant pathogenesis occurs if we are to manage diseases effectively.

Future challenges

The development of these new technologies is very important, as there are several challenges that plant pathology will face in the future. These include the increasing demand for food to support the growing global population; the decreasing production potential of agriculture due to competition for fertile land; the increased risk of plant disease epidemics resulting from agricultural intensification; the depletion of natural resources; and the influence of climate change on interactions between plants and their pests or pathogens.

Prof Swart believes a ‘systems level understanding’ of phytobiomes (consisting of plants, their environment, and all their associated organisms) will enable us to produce sufficient crops to meet global demands while minimising negative impacts on our environment.

He concludes, saying that plant pathology will evolve as an interdisciplinary science. He adds that future research will focus on new problems that are traditionally seen as outside the core discipline of plant pathology. Furthermore, food security will be a dominant and important driver of plant pathology research, while the impact of climate change on plant diseases will be very significant. Finally, that the adaptive potential of plant and pathogen populations will be one of the most important predictors of the magnitude of climate change effects.

LISTEN: radio interview