I started my career at the University of the Free State in 1986 as a first-year BSc student majoring in Botany and Genetics. After completing my BSc Honours in Microbiology (cum laude) in 1989, I was appointed as a Junior Lecturer in Genetics, where I taught Molecular Genetics. My MSc in Plant Molecular Genetics was completed in 1989, and my PhD in 2004. In 2025, I was promoted to full professor at the same institution where I started my career, a wonderful privilege.
I form part of the NRF SARChI chair under Prof MT Labuschagne since 2016, as well as the ARC Chairs Initiative since 2024. I successfully completed a SAWCIA grant between 2023 to 2025 on the implementation of MARPLE technology in South Africa.
I have currently authored or co-authored 58 articles in primarily Q1 and Q2 journals, as well as 14 popular articles in industry magazines. I have reviewed 25 manuscripts for international journals, four NRF project applications and three NRF rating applications.
I authored and co-authored 24 international conference poster presentations, as well as 43 oral presentations at national conferences.
I have a current C1 NRF rating and an H index of 15 on Web of Science.
Publications (Short List)
Visser B, Bender CM, Herselman L, Jacobs R, Park RF, Boshoff WHP and Pretorius ZA, 2026. Reconstructing Puccinia graminis f. sp. tritici genetic diversity in South Africa using herbarium specimens. Plant Disease ___. https://doi.org/10.1094/PDIS-06-25-1302-RE
Visser B, Boshoff WHP and Pretorius ZA, 2025. First report of rust caused by Phakopsora nishidana on Ficus natalensis in South Africa. Plant Disease 109: 2608. https://doi.org/10.1094/PDIS-07-25-1388-PDN
Visser B, Bender CM, Terefe T, Pretorius ZA and Boshoff WHP, 2025. Wheat rust surveillance in South Africa – a molecular approach. South African Journal of Botany 185: 205-212. IF 2.7; Q2. https://doi.org/10.1016/j.sajb.2025.08.008
du Toit I, Visser B, Rothmann LA and Boshoff WHP 2025. Triazole fungicide sensitivity among South African Puccinia graminis f. sp. tritici isolates. South African Journal of Plant and Soil 1-11. IF 1.0; Q3. https://doi.org/10.1080/02571862.2025.2498020
Maphobole LA, Visser B, Meyer W, Bender CM, Pretorius ZA and Boshoff WHP, 2025. Characterization of Puccinia sorghi isolates from South Africa. Plant Disease 109(10): 2070-2079. IF 4.5; Q1. https://doi.org/10.1094/PDIS-12-24-2585-SR
Pretorius ZA, Terefe T, Visser B and Boshoff WHP, 2024. Battling wheat rust in South Africa: Challenges and strategies. In: CABI compendium, Wallingford, UK, CAB International. https://doi.org/10.1079/planthealthcases.2024.0019.
Chiuraise N, Visser B, Maré A, and Boshoff W 2024. Occurrence and characterization of Puccinia triticina in Zimbabwe. Canadian Journal of Plant Pathology 46(5): 509-523. IF 2.08; Q2. https://doi.org/10.1080/07060661.2024.2356192
Visser B, Boshoff WHP and Pretorius ZA 2024. First report of rust caused by Phakopsora nishidana on creeping fig, Ficus pumila, in South Africa. Plant Disease 108(6): 1892. IF 4.5; Q1. https://doi.org/10.1094/PDIS-12-23-2794-PDN
Bryan A, Korolev A, Bergmann S, Boshoff WHP, Flath K, Justesen AF, Schulz P, Visser B and Saunders DGO 2024. Comparative genomics identifies genetic markers linked to structural variations that differentiate Puccinia graminis tritici and secalis formae speciales. Plant Pathology 73: 1542-1552. IF 2.77; Q1. https://doi.org/10.1111/ppa.13890
Hewitt T, Henningsen EC, Pereira D, McElroy K, Nazareno ES, Dugyala S, Nguyen-Phuc H, Li F, Miller ME, Visser B, Pretorius ZA, Boshoff WHP, Sperschneider J, Stuckenbrock E, Kianian SF, Dodds PN and Figueroa M, 2024. Genome-enabled analysis of population dynamics and virulence associated loci in the oat crown rust fungus Puccinia coronata f. sp. avenae. Molecular Plant-Microbe Interactions 37:290-303. IF 3.42; Q1. https://doi.org/10.1094/MPMI-09-23-0126-FI.
Boshoff WHP, Visser B, Bender CM and Pretorius ZA, 2024. Pathogenicity of Puccinia porri on Allium species and varieties in South Africa. Australasian Plant Pathology 53: 15-30. IF 1.4; Q2. doi.org/10.1007/s13313-023-00960-6
Terefe TG, Boshoff WHP, Park RF, Pretorius ZA, and Visser B, 2024. Wheat stem rust surveillance reveals two new races of Puccinia graminis f. sp. tritici in South Africa during 2016 to 2020. Plant Disease 108: 20-29. IF 4.5; Q1. doi.org/10.1094/PDIS-06-23-1120-SR.
Mafa MS, Lebusa N, Gumani TF, Kemp G, Visser B, Boshoff WHP and Castelyn HD, 2023. Accumulation of complex oligosaccharides and CAZymes activity under acid conditions constitute the Thatcher+Lr9 defence responses to Puccinia triticina. Biologia 78: 1929-1941. IF 1.653; Q3. doi.org/10.1007/s11756-023-01405-7
Mafa MS, Visser B, Boshoff WHP, Kemp G, Alexander O and Castelyn HD, 2023. Flagging defensive roles of carbohydrate-active enzymes (CAZymes) and carbohydrates during Puccinia triticina-wheat interactions. Physiological and Molecular Plant Pathology 124: 101947. IF 2.741; Q2. doi.org/10.1016/j.pmpp.2023.101947
Terefe TG, Visser B, Pretorius ZA and Boshoff WHP, 2023. Physiologic races of Puccinia triticina detected on wheat in South Africa from 2017 to 2020. European Journal of Plant Pathology 165: 1-15. IF 2.1; Q1. doi.org/10.1007/s10658-022-02583-x
Szabo LJ, Olivera PD, Wanyera R, Visser B and Yue Jin, 2022. Development of a diagnostic assay for differentiation between genetic groups in clades I, II, III and IV of Puccinia graminis f. sp. tritici. Plant Disease 106: 2211-2220. IF 4.614; Q1. doi.org/10.1094/PDIS-10-21-2161-RE
Spelman Z, Visser B, Terefe T, Pretorius ZA and Boshoff WHP, 2022. Pathogenicity and microsatellite characterization of Puccinia hordei in South Africa. Crop Protection 158: 106014. IF 3.036; Q1. doi.org/10.1016/j.cropro.2022.106014
Boshoff WHP, Visser B, Bender CM, Wood AR, Rothmann L, Wilson K, Hamilton-Attwell VL and Pretorius ZA, 2022. Fig rust caused by Phakopsora nishidana in South Africa. Phytopathologia Mediterranea 61: 283-298. IF 1.788; Q1. doi.org/10.36253/phyto-13034
Boshoff WHP, Wood AR, Visser B, Bender CM, Joubert L, Richter J, Aime MC and Pretorius ZA, 2022. The life cycle of Puccinia digitariae on Digitaria eriantha and Solanum species in South Africa. Mycologia 114: 319-336. IF 2.696; Q1. doi.org/10.1080/00275514.2022.2031493
Combrink HM, Oosthuizen J, Visser B, Chabilal N, Buccimazza I, Foulkes WD and van der Merwe NC, 2021. Mutations in BRCA-related breast and ovarian cancer in the South African Indian population: A descriptive study. Cancer Genetics 15: 258-259. IF 2.523; Q3. doi.org/10.1016/j.cancergen.2021.06.002
Labuschagne R, Venter E, Boshoff WHP, Pretorius ZA, Terefe T and Visser B, 2021. Historical development of the Puccinia triticina population in South Africa. Plant Disease 105: 2445. IF 4.438; Q1. doi.org/10.1094/PDIS-10-20-2301-RE.
Terefe TG, Visser B, Botha W, Kozana A, Roberts R, Thompson GD, Prinsloo G and Read DA, 2021. Detection and molecular characterization of Wheat stripe mosaic virus on wheat in South Africa. Crop Protection 143: 105464. IF 2.49; Q1. doi.org/10.1016/j.cropro.2020.105464
Meyer WB, Boshoff WHP, Minnaar-Ontong A, Young A, Kong G, Thompson S, Pretorius ZA and Visser B, 2021. Phenotypic and genotypic variation of Puccinia helianthi in South Africa. Plant Disease 105: 1482-1489. IF 4.438; Q1. doi.org/10.1094/PDIS-09-20-1903-RE
I am a Plant Molecular Geneticist who specializes in Molecular Plant Pathology. While I am situated within Botany, my primary collaborations are with colleagues in the Division of Plant Pathology at the UFS. In 2007, I started working with Prof Sakkie Pretorius on the Puccinia species causing rust diseases of wheat, barley, oat, sunflower and maize in South Africa. Since his retirement, my collaboration continued with Prof Willem Boshoff, Dr Tarekegn Terefe (ARC-Small Grain, Bethlehem) and Dr Gert Marais.
My primary focus is the study of the population structures of these pathogens in South Africa, as well as the factors that drive changes within. We use both race-typing and genetic analysis to characterise individual field isolates and place them within local populations. Genetic analysis of all populations was initially done using microsatellite markers, but since 2023, we have adopted MARPLE technology for stem and stripe rust of wheat. For sunflower, wheat leaf, and maize rust, Illumina sequencing was used and will be used in the future to describe their population structure.
Results from all these studies suggested that historical genetic lineages within South African populations are frequently replaced by new lineages, all the result of a single founding introduction to the country. The origin of these introductions is most probably mid-Africa. Uredniospores, which are quite hardy, can be carried long distances by high-altitude winds, making their dispersion across international borders unstoppable. Studies of wheat stem rust indicated that southern African isolates crossed the Indian Ocean to Australia, where they, in turn, formed the founding members of at least three different lineages in that country.
In the absence of alternate hosts, Puccinia species reproduce clonally in South Africa. The progenies are genetically identical but have acquired virulence against a particular disease resistance gene. The evolution of virulence is most probably driven by the release of resistant cultivars carrying a single resistance gene.
We also use MARPLE diagnostics to investigate the evolution of fungicide insensitivity in the country. All unknown field isolates pose a potential threat if they exhibit increased tolerance to the commonly used fungicides. By sequencing the genes whose encoded proteins are targeted by the fungicides, variant alleles are identified and characterized to determine their potential to cause insensitivity in their homozygous form.
Finally, my research is branching into several exciting avenues with this group of very special postgraduate students. Should you be interested in joining this group, feel free to contact me.
My primary interest is the genetic interaction between important cereals and their respective rust pathogens. The different aspects that I investigate include:
- Genotyping of cereal rusts, including rusts of wheat, sunflower, oat, and barley using microsatellite markers, NGS and MARPLE diagnostics.
- Analysis of fungicide insensitivity using MARPLE diagnostics.
- Control of cereal urediniospore germination using natural compounds.
- Identification of naturalized Berberis species in South Africa.
- Genetic interaction between wheat and stem rust during the adult plant resistance response.
- Identification of wheat viruses and their associated vectors in South Africa.
I currently teach the following modules:
- BLGY1643 - The Interdependence of Plants and Life On Earth (4 lectures)
- BTNY3754 - Plant Molecular Biotechnology
- BTNC6804 - Advanced Plant Molecular Biotechnology
- BTNY6816 - Literature Review Botany
- BTNY6808 - Research Project Botany
- BTNY8900 - Botany Dissertation
- BTNY9100 - Botany Thesis
I currently supervise the following postgraduate students:
- Ms Tumelo Fantisi (BSc honours supervisor)
- Ms Ann Mogaecho (BSc honours co-supervisor)
- Ms Jaki du Plooy (MSc supervisor)
- Ms Cara Koopman (MSc supervisor)
- Ms Arinao Magwaba (MSc Agric co-supervisor)
- Mr Alfred Ntjabane (MSc co-supervisor)
- Mr Thubelihle Khawula (MSc co-supervisor)
- Ms Isabella du Toit (PhD supervisor)
- Ms Emily Tsotetsi (PhD supervisor)
- Mr Wilku Meyer (PhD supervisor)
- Ms Amy Coetzer (PhD co-supervisor)
- Ms Marisca Hough (PhD co-supervisor)
I have authored of co-authored the following articles in industry magazines:
Boshoff WHP, Visser B, Bender CM en Pretorius ZA, 2025. Rust as a factor in the production of Allium crops. Starke Ayres Seed News: Summer.
Boshoff W, Visser B en Pretorius ZA, 2024. Vyeroes onder die soeklig. Groente en Vrugte – Julie/Augustus.
Du Toit I, Boshoff WHP, Rothmann L en Visser B, 2023. Swamdoder sensitiwiteit by isolate van die stamroesswam op kleingrane. SA-Grain 50 (71), 38-39.
Visser B, Boshoff WHP en Pretorius ZA, 2022. Lesse uit die verlede: die gebruik van herbarium-eksemplare om die ontwikkeling van twee koringroespatogene in Suid-Afrika te ondersoek. KoringFokus November/Desember, p 22-23.
Boshoff WHP, Visser B en Pretorius ZA, 2022. Blaarroes van gars – roesswam onder vergrootglas in navorsing. KoringFokus Julie/Augustus, p 10-11.
Pretorius ZA, Prins R, Bender CM, Visser B en Boshoff WHP, 2021. Koringstreeproes: 25 jaar later. KoringFokus September/Oktober, p 22-24.
Meyer WB, Boshoff WHP, Minnaar-Ontong A en Visser B, 2020. Sonneblomroes – die nuutste inligting rakende die voorkoms van aggressiewer rasse in Suid-Afrika. SA Graan 22: 44-45.
Visser B, Boshoff WHP en Pretorius, ZA, 2020. Internasionale navorsing werp nuwe lig op die langafstandverspreiding van koringstamroes urediniospore. KoringFokus November/Desember, p 26-27.
Boshoff WHP, Visser B en Pretorius, ZA, 2020. Hawerkroonroes – swam bedreig vatbare kultivars vroeg in die seisoen. KoringFokus Julie/Augustus, p 16-18.
Visser B, Boshoff WHP en Pretorius ZA, 2020. Berberis – ‘n onbekende faktor in die stryd teen stam- en geelroes van koring in Suid-Afrika. KoringFokus Maart/April, p 8-10.
Boshoff WHP, Visser B en Pretorius, ZA, 2020. Hawerstamroes - neem ingeligte besluite oor vatbaarheid van kultivars. KoringFokus Januarie/Februarie, p 20-21.
Terefe TG, Prinsloo G, Roberts R, Botha W, Read D, Thompson G, Khozana A and Visser B, 2019. First report of wheat stripe mosaic virus in South Africa. KoringFokus September/Oktober, p 9-11.
Terefe TG, Prinsloo G, Roberts R, Botha W and Visser B, 2017. Detection of Polymyxa graminis, a vector of important soil borne viruses in South Africa. KoringFokus, November/Desember, p 10-12.
Keet J-H, Visser B, du Preez PJ and Cindi D, 2014. Barberry Pirates. Two species of Berberis could become problem invaders in South Africa. Veld and Flora, Desember, p 174-175.
Since 2025, I have served on the Mycotoxin Research Panel of the Maize Trust, evaluating submitted projects.