Pathogens threatening agriculture and biodiversity in South Africa: A horizon scanning approach

Abstract There is mounting evidence that invasive alien species (IAS) have adverse effects on plant health and the global economy, posing a significant threat to biodiversity and ecosystem functioning. Identifying and assessing emerging IAS, such as plant pathogens, is a proactive approach that might assist in prioritising potential pathogen threats before they become established or widespread, negatively affecting plant health, crop production, animal production, animal health by affecting pastures and food security in South Africa. We collected information from the CABI Invasive Species Compendium and Crop Protection Compendium on plant pathogens that are present in neighbouring countries and are likely to be introduced throughout the Republic of South Africa using an expert-elicitation horizon scanning study. Pathogens with the highest score were determined based on their strong capability on the chance of entry, establishment, economic impact, and biodiversity destruction. The current study revealed that only 17 pathogens (6 fungi, 7 viruses, 2 bacteria and 2 phytoplasma) had been prioritised due to their potential to enter the country and have been reported in the neighbouring countries. Maize lethal necrosis disease, Candidatus Liberibacter asiaticus , Candidatus Phytoplasma palmae, Fusarium oxysporum f.sp . cubens e tropical race 4, and Maize chlorotic mottle virus have the highest potential to enter and establish in the country. The most effective phytosanitary actions for the high scoring pathogen were to conduct surveillance for their potential presence in South Africa and risk analysis, especially for organisms recorded in neighbouring countries.