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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

Research into veld fires in grassland can now help with scientifically-grounded evidence
2015-04-10

While cattle and game farmers are rejoicing in the recent rains which large areas of the country received in the past growing season, an expert from the University of the Free State’s Department of Animal, Wildlife, and Grassland Sciences, says that much of the highly inflammable material now available could lead to large-scale veld fires this coming winter.

Prof Hennie Snyman, professor and  researcher in the Department of Animal, Wildlife, and Grassland Sciences, warns that cattle and game farmers should be aware, in good time, of this problem which is about to rear its head. He proposes that farmers must burn firebreaks as a precaution.

At present, Prof Snyman focuses his research on the impact of fire and burning on the functioning of the grassland ecosystem, especially in the drier grassland regions.

He says the impact of fire on the functioning of ecosystems in the ‘sour’ grassland areas of Southern Africa (which includes Kwazulu-Natal, Limpopo, Mpumalanga, the Eastern Cape, and the Harrismith environs) is already well established, but less information  is available for ‘sweet’ semi-arid grassland areas. According to Prof Snyman, there is no reason to burn grassland in this semi-arid area. Grazing by animals can be effectively used because of the high quality material without having to burn it off. In the sourer pasturage, fire may well form part of the functioning of the grassland ecosystem in view of the fact that a quality problem might develop after which the grass must rejuvenate by letting it burn.

Prof Snyman, who has already been busy with the research for ten years, says quantified data on the impact of fire on the soil and plants were not available previously for the semi-arid grassland areas. Fires start frequently because of lightning, carelessness, freak accidents, or damaged power lines, and farmers must be recompensed for this damage.

The shortage of proper research on the impact of fires on soil and plants has led to burnt areas not being withdrawn from grazing for long enough. The lack of information has also led to farmers, who have lost grazing to fires, not being compensated fairly or even being over-compensated.

“When above-and below-ground plant production, together with efficient water usage, is taken into account, burnt grassland requires at least two full growing seasons to recover completely.”       

Prof Snyman says farmers frequently make the mistake of allowing animals to graze on burnt grassland as soon as it begins to sprout, causing considerable damage to the plants.

“Plant roots are more sensitive to fire than the above-ground plant material. This is the reason why seasonal above-ground production losses from fire in the first growing season after the fire can amount to half of the unburnt veld. The ecosystem must first recover completely in order to be productive and sustainable again for the long term. The faster burnt veld is grazed again, the longer the ecosystem takes to recover completely, lengthening the problem with fodder shortages further.  

Prof Snyman feels that fire as a management tool in semi-arid grassland is questionable if there is no specific purpose for it, as it can increase ecological and financial risk management in the short term.

Prof Snyman says more research is needed to quantify the impact of runaway fires on both grassland plant productivity and soil properties in terms of different seasonal climatic variations.

“The current information may already serve as valuable guidelines regarding claims arising from unforeseen fires, which often amount to thousands of rand, and are sometimes based on unscientific evidence.”

Prof Snyman’s research findings have been used successfully as guidelines for compensation aspects in several court cases.

 

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