HOLISTIC HEALTH MANAGEMENT IN CACTUS PEAR ORCHARDS IN SOUTH AFRICA - W. J. Swart

New Crop Pathology Programme (NCPP), Centre for Plant Health Management, University of the Free State, Bloemfontein 9300, South Africa

Diseases are important constraints of crop production worldwide and the manner in which they are addressed will have a significant influence on yield.  Cactus pear (Opuntia ficus-indica) is no exception and the increasingly intensive cultivation of this crop in South Africa will inevitably result in the appearance of numerous disease problems which can negatively influence the growth of the local industry, if not properly managed.  A holistic plant health management programme is therefore being developed whereby the most important diseases in South Africa are being recorded and various options to control them investigated.  Biocontrol tactics employing antagonistic yeasts have been formulated by the NCPP and are showing promise for controlling post harvest diseases of cactus pear.  Significant differences have been recorded between cultivars with regard to their susceptibility to certain important fungal pathogens.  The cultivars Nudosa and Algerian were consistently found to be the most susceptible cultivars, while Malta and Zastron are the most resistant.  Genotypic characterization of cactus pear cultivars using biotechnology techniques will facilitate breeding strategies for disease and pest resistance and yield improvement.  Studies conducted by the NCPP have also demonstrated a clear association between vinegar flies (Drosophila spp.) and many fungi that are potentially pathogenic to cactus pear fruit.  By controlling these insects in orchards further sources of infection could be eliminated.  These findings emphasize the need for an integrated approach to managing diseases of cactus pear in South Africa. The focus will have to be on understanding all biotic and abiotic sources of stress that can affect the overall health and productivity of cactus pear orchards.  Within this holistic approach, emphasis will be placed on the interaction of all forms of stress, rather than on any single source of stress.

Diseases are important constraints of crop production worldwide and the manner in which they are addressed will have a significant influence on yield.  Cactus pear (Opuntia ficus-indica) is no exception and the increasingly intensive cultivation of this crop in South Africa will inevitably result in the appearance of numerous disease problems which can negatively influence the growth of the local industry, if not properly managed.  A holistic plant health management programme is therefore being developed whereby the most important diseases in South Africa are being recorded and various options to control them investigated.  Biocontrol tactics employing antagonistic yeasts have been formulated by the NCPP and are showing promise for controlling post harvest diseases of cactus pear.  Significant differences have been recorded between cultivars with regard to their susceptibility to certain important fungal pathogens.  The cultivars Nudosa and Algerian were consistently found to be the most susceptible cultivars, while Malta and Zastron are the most resistant.  Genotypic characterization of cactus pear cultivars using biotechnology techniques will facilitate breeding strategies for disease and pest resistance and yield improvement.  Studies conducted by the NCPP have also demonstrated a clear association between vinegar flies (Drosophila spp.) and many fungi that are potentially pathogenic to cactus pear fruit.  By controlling these insects in orchards further sources of infection could be eliminated.  These findings emphasize the need for an integrated approach to managing diseases of cactus pear in South Africa. The focus will have to be on understanding all biotic and abiotic sources of stress that can affect the overall health and productivity of cactus pear orchards.  Within this holistic approach, emphasis will be placed on the interaction of all forms of stress, rather than on any single source of stress.