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09 September 2025 | Story Martinette Brits | Photo Stephen Collett
Prof Botma Visser
Prof Botma Visser delivered his inaugural lecture at the University of the Free State, highlighting nearly two decades of research on wheat rust and global food security.

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

Plant-strengthening agent enhances natural ability of plants to survive
2015-07-27

Drought, diseases, and fungi. These are factors that farmers have no control over, and they often have to watch despondently as their crops are damaged. In addition, the practice of breeding plants in special and strictly-controlled conditions, has resulted in crops losing the chemical ability to protect themselves in nature.

Researchers in the Department of Soil, Crop, and Climate Sciences at the University of the Free State (UFS) have developed an organic agent that restores this chemical imbalance in plants. It enables the plant to build its own resistance against mild stress factors, and thus ensures increased growth and yield by the plant.

ComCat®, a plant-strengthening agent, is the result of extensive research by the German company, Agraforum AG, together with the UFS. Commercialisation was initially limited to Europe, while research was done at the UFS.

“Plants have become weak because they were grown specially and in isolation. They can’t protect themselves any longer,” says Dr Elmarie van der Watt from the department.

Dr Van der Watt says that, in nature, plants communicate by means of natural chemicals as part of their resistance mechanisms towards various stress conditions. These chemicals enable them to protect themselves against stress conditions, such as diseases and fungi (biotic conditions) or wind and droughts (abiotic conditions).

Most wild plant varieties are usually well-adapted to resist these stress factors. However, monoculture crops have lost this ability to a large extent.

The European researchers extracted these self-protection chemicals from wild plants, and made them available to the UFS for research and development.

“This important survival mechanism became dormant in monoculture crops. ComCat® wakes the plant up and says ‘Hey, you should start protecting yourself’.”

Research over the last few years has shown that the agent, applied mostly as a foliar spray, subsequently leads to better seedlings, as well as to growth, and yields enhancement of various crops. This is good news for the agricultural sector as it does not induce unwanted early vegetative growth that could jeopardise the final yield ? as happened in the past for nitrogen application at an early growth stage.

“The use of synthetic agents, such as fungicides which contain copper, are now banned. Nowadays, options for natural and organic agriculture is being investigated. This product is already widely used in Europe, but because farmers are often swamped by quacks, the South African market is still somewhat sceptical.”

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