DIVISION:
Disease Management
PROGRAMME COORDINATOR:
Prof. Jacquie van der Waals
COLLABORATING RESEARCHERS:
Dr. Elma Carstens (CRI), Dr. Wilma du Plooy (CRI), Prof. Paul Fourie (CRI), Dr. Providence Moyo (CRI), Dr. Jan van Niekerk (CRI), Prof. Jacquie van der Waals (CRI), Prof. Lizel Mostert, Dr. Lindy Rose (Stellenbosch University), Dr. Khumbuzile Bophela-Dimpe, Prof. Teresa Coutinho, Prof. Quenton Kritzinger, Dr. David Nsibo (Univeristy of Pretoria), Dr. Chris Spies, Dr. Minette Havenga (Agricultural Research Council), Prof. Vladimiro Guarnaccia (University of Torino)
The main emphasis of the preharvest disease program is the sustainable management of fruit, foliar, and soilborne diseases in citrus. This involves seeking and evaluating greener, alternative management methods, optimising chemical control strategies to deter resistance development, improving spray technology, and researching the epidemiology of various pathogens to improve management.
CRI remains at the forefront of citrus black spot (CBS) research, as the disease continues to be a major challenge for the South African citrus industry. Other important pre-harvest diseases on which we focus are: Alternaria Brown Spot (ABS), caused by Alternaria alternata, affecting tangerines and their hybrids in South Africa; rind distortions and blossom blight on lemons; anthracnose and twig dieback caused by Colletotrichum spp., and soilborne pathogens (Phytophthora nicotianae, P. citrophthora, and nematodes).
Market Access
• Adherence to permitted MRL levels
• Communication of local and international research findings to facilitate market access negotiations
Etiology & Diagnosis
• Develop and optimise assays for rapid detection of pathogens and diagnosis of diseases
• Characterise variability in pathogen populations in South African citrus orchards
• Improve awareness of new invasive pathogens to ensure early detection
Epidemiology
• Increase the understanding of disease epidemiology to facilitate improvement of management strategies
• Validate and improve disease prediction models using climatic variables (CBS, ABS and Botrytis grey mould)
Disease Management
• Evaluate and optimise conventional and novel spray application technologies to ensure effective residue loading without exceeding permitted MRLs
• Evaluate novel and GRAS chemical compounds and biocontrol agents for disease control
• Structure spray programmes to improve control, adhere to MRLs and limit fungicide resistance development
Inoculum Management
• Formulation and evaluation of products to reduce primary inoculum
Phytosecurity
• Support of Citrus Improvement Scheme