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Rust diseases remain a serious threat to food crops in South Africa

07 August 2025 | Story Martinette Brits | Photo Stephen Collett

Prof Willem Boshoff shares insights from decades of rust disease research during his inaugural lecture at the University of the Free State.

Rust diseases of food crops remain one of agriculture’s most enduring and evolving challenges. In his inaugural lecture on 23 July 2025 at the University of the Free State (UFS), Prof Willem Boshoff shared how these complex pathogens continue to pose a significant threat to South Africa’s staple crops – and why continued research is more critical than ever.

Titled Battling rust diseases of food crops in South Africa, the lecture reflected on decades of rust research and recent developments in pathogen virulence. Prof Boshoff, from the Department of Plant Sciences, emphasised that the threat posed by rust fungi today stems from their “mechanisms of variability, their ease of long-distance spore dispersal, and subsequent foreign race incursions”.

A shifting disease landscape

Rust fungi are biotrophic organisms that cannot be cultured on artificial growth media. This makes rust research a technically demanding field that requires living pathogen collections, seed sources, skilled researchers, and specialised infrastructure. Prof Boshoff noted that for more than 35 years, the UFS has been at the forefront of this work, monitoring rust pathogens on wheat, barley, oats, maize, and sunflower.

While wheat remains the most extensively studied type, recent rust outbreaks across a range of crops point to a worrying trend. A localised outbreak of stem rust on spring wheat in the Western Cape has been linked to race BFGSF, which carries a previously unknown combination of virulence genes affecting both wheat and triticale. In 2021, leaf rust race CNPSK was detected, showing virulence to the highly effective Lr9 resistance gene.

More recently, stripe rust race 142E30A+ – first reported in Zimbabwe – was found in wheat cultivars from the Free State and northern irrigation areas. “Results revealed increased susceptibility of especially spring irrigation wheat cultivars,” Prof Boshoff explained, particularly due to its virulence to the Yr9 and Yr27 resistance genes.

Rust pathogens affecting other crops are also evolving. In maize, only a few lines with mostly stacked resistance gene combinations were effective against all tested isolates. In sunflower, just four of 30 Agricultural Research Council national trial hybrids showed resistance to local rust races.

Building better resistance

A key strategy in rust control lies in identifying and understanding resistance in host plants. This, Prof Boshoff stressed, requires optimised phenotyping systems for both greenhouse and field conditions, along with a solid understanding of available resistance sources. At the UFS, several recent studies have contributed valuable data to both local and international plant breeding programmes.

“Continued local and regional rust research is critical,” he said. “It supports early detection of new races, alerts to producers through updated cultivar responses, and enables efficient breeding strategies and other sustainable methods of rust management.”

The rust programme at the UFS has not only supported varietal release and on-farm risk management, but also strengthened collaboration between plant scientists, industry partners, and international researchers. With South Africa’s strategic location and history of rust surveillance, the programme continues to play a pivotal role in continental and global food security efforts.

About Prof Willem Boshoff

Prof Willem Boshoff is a plant pathologist with a strong background in wheat breeding and rust disease control. He holds four degrees from the University of the Free State, all awarded cum laude: a BScAgric (1994), BScAgric Honours (1995), MScAgric (1997), and PhDAgric (2001). His doctoral research focused on the control of foliar rusts in wheat.

Between 2001 and 2016, he worked as a wheat breeder and contributed to the release of several commercial cultivars. He joined the UFS Department of Plant Sciences in 2017 and has since been actively involved in national and international research projects, capacity development, and advancing disease resistance in food crops.

News Archive

UFS keeps the power on

2015-06-24

At a recent Emergency Power Indaba held on the Bloemfontein Campus, support structures at the university met to discuss the Business Continuity Intervention Plan to manage load shedding on the three campuses of the UFS.

Currently, 35 generators serving 55 of the buildings have already been installed as a back-up power supply on the three campuses of the university. According to Anton Calitz, Electrical Engineer at the UFS, the running cost to produce a kWh of electricity with a diesel generator amounts to approximately three times the cost at which the UFS buys electricity from Centlec.

Planned additional generators will attract in excess of R4 million in operating costs per year. For 2015, the UFS senior leadership approved R11 million, spread over the three campuses. Remaining requirements will be spread out over the next three years. University Estates is also looking at renewable energy sources.

On the Bloemfontein Campus, 26 generators serving forty-one buildings are in operation. On South Campus, two generators were installed at the new Education Building and at the ICT Server Room. Lecture halls, the Arena, the Administration Building, and the library will be added later in 2015. Eight generators serving 12 buildings are in operation on the Qwaqwa Campus. In 2015, the Humanities Building, Lecture Halls and the heat pump room will also be equipped with generators.

Most buildings will be supplied only with partial emergency power. In rare cases, entire buildings will be supplied because the cost of connecting is lower than re-wiring for partial demand. According to Nico Janse van Rensburg, Senior Director at University Estates, emergency power will be limited to lighting and power points only. No allowances will be made for air-conditioning.

“Most area lighting will also be connected to emergency power,” he said.

Where spare capacity is available on existing emergency power generators, requests received for additional connections will be added, where possible, within the guidelines. The following spaces will receive preference:
- Lecture halls with the lights, data projectors, and computers running
- Laboratories for practical academic work and sensitive research projects
- Academic research equipment that is sensitive to interruptions
- Buildings hosting regular events

According to Janse van Rensburg, all further needs will be investigated. Staff can forward all emergency power supply needs to Anton Calitz at calitzja@ufs.ac.za

Staff and students can also manage load shedding in the following ways:

1. Carry a small torch with you at all times, in case you are on a stairwell or other dark area when the lights go out. You can also use the flashlight app on your phone. Download it before any load shedding occurs. This can come in handy if the lights go out suddenly, and you cannot find a flashlight. Load-shedding after dark imposes even more pressure on our Campus Security staff. We can assist them with our vigilance and preparedness by carrying portable lights with us at all times and by assisting colleagues.
2. Candles pose a serious safety risk. Rather use battery- or solar-powered lights during load shedding.
3. Ensure that your vehicle always has fuel in the tank, because petrol stations cannot pump fuel during power outages.
4. Ensure that you have enough cash, because ATMs cannot operate without electricity.
5. The UFS Sasol Library has study venues available which students can use during load shedding.
6. When arranging events which are highly dependent on power supply, especially at night, organisers should consult the load-shedding schedule before determining dates and preferably also make back-up arrangements. If generators are a necessity, the financial impact should be taken into consideration.

The senior leadership also approved a list of buildings to be equipped with emergency power supplies.

More about load shedding at the UFS:
Getting out of the dark
More information, guidelines and contact information

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