An infected potato.
A study by researchers in the Potato Pathology Program at the University of Pretoria’s Forestry and Agricultural Biotechnology Institute identified oat (Avena strigosa) and soybean (Glycine max) as “ideal to be included as trap crops in rotations with potatoes”.
This is a first study in South Africa on alternative weed and cultivated hosts of the cercozoan Spongospora subterranea, which causes the potato disease powdery scab.
Outcomes from this study appear in an article in the European Journal of Plant Pathology. Researchers in the program conducted greenhouse trials to determine the host status of 14 weed species and 12 cultivated crop species commonly found in potato growing regions in southern Africa.
Spongospora subterranea is an obligate parasite that threatens the economic viability of potato production in Southern Africa. It is the causal agent of powdery scab on potato tubers and galls on the root of potato plants. The pathogen has proven difficult to manage, partly because it is adaptable and can survive under different environmental conditions.
Crop rotation reduces the amount of inoculum in the soil and is one of the strategies used by potato producers to manage the parasite.
“Trapping crops and non-hosts could be used in rotation with potatoes, as they may reduce or leave inoculum levels in the soil unchanged,” wrote the authors.
Professor Jacquie van der Waals leads the Potato Pathology Program, whose research focus is the epidemiology, diagnosis and control of soil- and seed-borne diseases of potatoes. Diseases of interest include powdery scab, black scurf and stem canker caused by Rhizoctonia solanias well as blackleg and soft rot caused by Pectobacterium and Dickeya species respectively.