Prof. Jacquie van der Waals

My main research focus is the epidemiology, diagnosis and control of soil- and seed-borne diseases of potatoes. Diseases currently being investigated in my research programme include powdery scab (Spongospora subterranea f. sp. subterranea), black scurf and stem canker (Rhizoctonia solani), and blackleg and soft rot (Pectobacterium and Dickeya spp.). Soil-borne diseases are one of the most limiting factors in the production of potatoes and thus the main focus of the Potato Pathology Programme @ UP is understanding these pathogens and epidemiology of the diseases in order to improve management in the field. In order to do this, various techniques are combined to better understand disease spread and development in the field, interaction of host and pathogen, and ultimately use this information to provide growers with a risk assessment for the disease under consideration. I am also currently supervising students investigating the role of crop rotation on soil health and the effect thereof on pathogen inoculum in the soil, using a metagenomics approach. 

I have strong collaborations with researchers in Scotland, The Netherlands, Israel, Poland and Zimbabwe and also work closely with numerous South African colleagues at UP, UOFS and the Agricultural Research Council.

Selected publications:

Mbedzi, P.P., van der Hoven, L., Vorster, B.J., van der Waals, J.E. 2019. Screening for Sclerotinia sclerotiorum resistance using detached leaf assays and simple sequence repeat markers in soybean cultivars. Crop Protection doi: https://doi.org/10.1016/j.cropro.2019.104909. 

Muzhinji, N., van der Waals, J.E. 2019. Population biology and genetic variation of Spongospora subterranea f. sp. subterranea, the causal pathogen of powdery scab and root galls on potatoes in South Africa. Phytopathology https://doi.org/10.1094/PHYTO-12-18-0467-R

Jordaan, E., McLaren, N.W., van der Waals, J.E. 2019. Effect of irrigation on charcoal rot severity, yield loss and colonization of soybean and sunflower. Crop Protection 122: 63-69 doi.org/10.1016/j.cropro.2019.04.026

Lekota, M., Muzhinji, N., van der Waals, J.E. 2019. Identification of differentially expressed genes in tolerant and susceptible potato cultivars in response to Spongospora subterranea f. sp. subterranea tuber infection. Plant Pathology doi: 10.1111/ppa.13029

Dube, J.P., Valverde, A., Steyn. J.M., Cowan, D., van der Waals, J.E. 2019. Differences in bacterial diversity, composition and function due to long-term agriculture in soils in the Eastern Free State of South Africa. Diversity 11, 61; doi:10.3390/d11040061

Gush, S.-L., Muzhinji, M., Truter, M., & van der Waals, J.E. 2019. First report of Rhizoctonia solani AG 2-2IIIB causing elephant hide on potato tubers in South Africa. Plant Disease https://doi.org/10.1094/PDIS-10-18-1850-PDN

Kandolo, S.D., Aveling, T.A.S., van der Waals, J.E., Truter, M. & Laurie, S.M. 2018. Effects of wetness duration, inoculum concentration and temperature on the development of Alternaria blight on transplants of sweet potato. Acta Horticulturae 27: 211–217.

Zimudzi, J., van der Waals, J.E., Coutinho, T.A., Cowan, D.A. & Valverde, A. 2018. Temporal shifts of fungal communities in the rhizosphere and on tubers in potato fields. Fungal Biology 122: 928-934.

Muzhinji, M., Woodhall, J.W., Truter, M. & van der Waals, J.E. 2018. Variation in fungicide sensitivity among Rhizoctonia isolates recovered from potatoes in South Africa. Plant Disease  102: 1520-1526.

Shutt, V.M., Shin, G., van der Waals, J.E., Goszczynska, T. & Coutinho, T.A. 2018. Characterization of Ralstonia strains infecting tomato plants in South Africa. Crop Protection 112: 56-62.

Muzhinji, M., Woodhall, J.W., Truter, M. & van der Waals, J.E. 2018. Relative contribution of seed tuber- and soilborne inoculum to potato disease development and changes in the population genetic structure of Rhizoctonia solani AG 3-PT under field conditions in South Africa. Plant Disease 102: 60-66.

Zimudzi, J. Coutinho, T.A. & van der Waals, J.E. 2017. Pathogenicity of fungi isolated from atypical skin blemishes on potatoes in South Africa and Zimbabwe. Potato Research 60: 119-144.

Simango, K. & van der Waals, J.E. 2017. Effects of different soil treatments on the development of Spongospora subterranea f. sp. subterranea in potato roots and tubers in the greenhouse. Potato Research 60:47-60

Muzhinji, M., Woodhall, J.W., Truter, M. & van der Waals, J.E. 2016. Population genetic structure of Rhizoctonia solani AG 3-PT from potatoes in South Africa. Fungal Biology 120: 701-710.

Van der Waals, J.E., Steyn, J.M., Franke, A.C., Haverkort, A.J. 2016. Grower perceptions of biotic and abiotic risks of potato production in South Africa. Crop Protection 84: 44-55

Jordaan, E. & van der Waals, J.E. 2016. Streptomyces species associated with common scab lesions of potatoes in South Africa. European Journal of Plant Pathology 144: 631 - 643.

Du Raan, S., Coutinho, T.A. & van der Waals, J.E. 2016. Cardinal temperature differences, determined in vitro, between closely related species and subspecies of pectinolytic bacteria responsible for blackleg and soft rot on potatoes. European Journal of Plant Pathology 144: 361 - 369.

Muzhinji, M., Woodhall, J.W., Truter, M. & van der Waals, J.E. 2015. Anastomosis groups and pathogenicity of Rhizoctonia solani and binucleate Rhizoctonia from potatoes in South Africa. Plant Disease 99: 1790 - 1802.

Van der Waals, J.E., Franke, A.C., Haverkort, A.J., Krüger, K. & Steyn, J.M. 2013. Climate change and potato production in South Africa. 3. Effects on relative development rates of selected pests and pathogens. Potato Research 56: 67-84

Wright, J., Lees, A.K., van der Waals, J.E. 2012. Detection and eradication of Spongospora subterranea f. sp. subterraneain mini-tuber production tunnels. South African Journal of Science, 108 (5/6) Art #614

Van der Merwe, J.J., Coutinho, T.A., Korsten, L. & van der Waals, J.E. 2010. Pectobacterium carotovorum subsp. brasiliensis causing blackleg on potatoes in South Africa. European Journal of Plant Pathology 126 (2): 175-185.

STUDENTS