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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

Multi-disciplinary research approach at UFS

2005-10-25

UFS follows multi-disciplinary research approach with opening of new centre

“A new way of doing business in necessary in the research and teaching of agriculture and natural sciences in South Africa. We must move away from departmentalised research infrastructures and a multi-disciplinary approach to research involving several disciplines must be adapted,” said Prof Herman van Schalkwyk, Dean: Faculty of Natural and Agricultural Sciences at the University of the Free State (UFS).

Prof van Schalkwyk delivered the keynote address during the launch of the Centre for Plant Health Management (CePHMa) at the Main Campus in Bloemfontein today (21 October 2005). CePHMa is an initiative of the UFS Department of Plant Sciences.

According to Prof van Schalkwyk a tertiary institution must practice multi-disciplinary research to be a world-class research institution. “It is difficult for researchers to admit that they do not know a lot about each other’s area of speciality. It is therefore necessary for researchers to make a paradigm shift and to focus on inter-disciplinary co-operation. To do this, we must encourage them to work together and to find a common language to communicate ideas en establish symbiotic relationships,” said Prof Van Schalkwyk.

“We tend to think that research is better and faster if it is specialised. This is not true. The new generation of scientists are young and they are trained to form a concept of the total system and not to focus on a specific area of speciality. At the UFS we encourage this approach to research. This was one of the main reasons for the establishment of CePHMa,” said Prof Van Schalkwyk.
CePHMa is the only centre of its kind in Africa and is established to extend the expertise in plant health management in South Africa and in Africa, to train experts in plant health and to conduct multi-disciplinary research about the health of agricultural crops.

“CePHMa is a virtual centre comprising of ten disciplines applicable to crop production and crop protection,” said Prof Wijnand Swart, Chairperson of CePHMa during the opening ceremony.

“The UFS is the leading institution in Africa in terms of news crop development and manages three research programmes that concentrate on new crops, i.e. the New Crop Pathology Programme, the New Crop Development Programme and the Insects on New Crops Programme. Other applied research programmes that are unique to the UFS are genetic resistance to rust diseases of small grain crops and sustainable integrated disease management of field crops,” said Prof Swart.

“Because the expected growth in population will be 80% in 2020 in sub-Saharan Africa, the future demands of food produce in Africa will be influenced. Therefore research will in future be focused on ways to improve food security by employing agricultural systems that are economically viable and environmentally sound,” said Prof Swart.

“Thorough knowledge of the concept of holistic plant health management is crucial to meet the challenge and it is therefore imperative that innovative crop protection and crop production strategies, with particular emphasis on plant health, be adopted. This is why the Department of Plant Sciences initiated the establishment of CePHMA,” he said.

According to Prof Swart there is a shortage of expertise in plant health management. “The UFS has shown the potential to address the demand of the sub-continent of Africa regarding expertise training and CePHMa is the leader in southern Africa to provide in this need,” he said.

The appropriateness and quality of training in plant health management is reflected in the fact that students from Ethiopia, Eritrea, Malawi, Uganda, Zambia, Ghana, Tanzania, Cameroon, Angola, Mozambique and Lesotho have already been trained or are in the process of being trained in at the UFS.

Scientists from CePHMa have forged partnerships with numerous national and international institutions including the Agricultural Research Council (ARC), various community trusts, seed, pesticide and agricultural chemical companies, in addition to overseas universities.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
21 October 2005

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