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Prof Botma Visser takes on rust diseases threatening South Africa’s wheat

09 September 2025 | Story Martinette Brits | Photo Stephen Collett

Safeguarding one of the world’s most vital staple foods was at the heart of the inaugural lecture delivered by Prof Botma Visser, Professor in the Department of Plant Sciences at the University of the Free State (UFS), on Wednesday 3 September 2025. Prof Visser shared insights from nearly two decades of research into wheat rust – a devastating crop disease that threatens both South Africa’s harvests and global food security.

“Wheat production in South Africa is threatened by three fungal pathogens that cause rust disease on the crop. Understanding the factors that contribute to virulence on locally grown cultivars is crucial to ensure continued wheat production,” said Prof Visser.

The fight against evolving wheat rusts

For the past 17 years, Prof Visser’s research has focused on the genetic structure of rust populations and the risks they pose to food security. His work has shown that these populations are dynamic and constantly changing due to genetic mutations within existing races, as well as the introduction of new races into South Africa.

“Computer modelling showed that rust can spread over vast distances by prevailing winds. During the 20th Century, at least four Southern African stem rust races managed to move across the Indian Ocean from Southern Africa to Australia. South Africa, in turn, received multiple new races from mid-Africa across Zambia and Zimbabwe, without any means of stopping these introductions,” he explained.

To respond to this challenge, his team recently implemented MARPLE (Mobile And Real-time Plant disEase) diagnostics using fourth-generation nanopore sequencing technology. This approach allows the rapid characterisation of fungal isolates, specifically targeting genes linked to fungicide resistance and virulence.

“This work,” Prof Visser noted, “is part of an effort to safeguard global wheat production.”

His research is a collaborative effort with Prof Willem Boshoff (Department of Plant Sciences, UFS) and Dr Tarekegn Terefe (Agricultural Research Council – Small Grain, Bethlehem). Together, their work has positioned the UFS as an internationally recognised centre of excellence in wheat rust research.

About Prof Botma Visser

Prof Botma Visser obtained his BSc in Botany and Microbiology (1988), BSc Honours in Microbiology (1989), and MSc in Botany (1993) at the University of the Free State, where he also completed his PhD in Botany in 2004.

His career spans more than 18 years of research into wheat rust pathogens, combining annual surveys, race pathotyping, molecular genetics, and cutting-edge sequencing technologies. His expertise has not only advanced understanding of rust population dynamics in South Africa but also contributed to global collaborative studies on crop disease.

News Archive

Death may come in adorable little packages

2015-03-23

The main host of the Lassa virus is the Natal Mulimammate mouse.

Photo: Supplied

Postdoctoral researcher, Abdon Atangana, of the Institute for Groundwater Studies at the university recently published an article online about the Lassa Haemorrhagic fever in the Natural Computing Applications Forum. In addition to the terminal transmissible sickness recognised as Ebola haemorrhagic fever, there is another strain called Lassa haemorrhagic fever.

The disease is classified under the arenaviridae virus family. The first outbreaks of the disease were observed in Nigeria, Liberia, Sierra Leone, and the Central African Republic. However, it was first described in 1969 in the town of Lassa, in Borno State, Nigeria.

The main host of the Lassa virus is the Natal Mulimammate mouse, an animal indigenous to most of Sub-Saharan Africa. The contamination in humans characteristically takes place through exposure to animal excrement through the respiratory or gastrointestinal tracts.

Mouthfuls of air containing tiny particle of infective material are understood to be the most noteworthy way of exposure. It is also possible to acquire the infection through broken skin or mucous membranes that are directly exposed to the infective material.

“The aim of my research was to propose a novel mathematical equation used to describe the spread of the illness amongst pregnant women in West Africa. To achieve this, I used my newly-proposed derivative with fractional order called beta-derivative. Since none of the commonly used integral transform could be used to derive the solution of the proposed model, I proposed a new integral transform called Atangana-Transform, and used it, together with some iterative technique, to derive the solution of the model.

“My numerical simulations show that the disease is as deadly amongst pregnant women as Ebola,” Abdon said.

Abdon’s research was submitted to one of Springer’s top-tier journals with an impact factor 1.78. The paper was accepted and published February 2015.