A DIAGNOSTIC PROCEDURE FOR THE MANAGEMENT OF PESTS AND DISEASES OCCURRING ON CACTUS PEAR - W. J. Swart1 & S. vdM. Louw2

1New Crop Pathology Programme and 2Insects on New Crops Programme, Centre for Plant Health Management, University of the Free State,
Bloemfontein 9300, South Africa

Traditionally, the prevention of a plant disease epidemic or pest infestation would require an inquisitive, investigative approach to defining the problem and then solving it.  One must know ‘what is causing the problem?’, before the correct therapeutic measures can be taken.  Detection and accurate diagnosis are therefore the first crucial steps towards achieving this objective.  The very fact that the ecological interaction in question is approached as a ‘problem’, which must be defined and understood before it can be solved, implies a reactive approach, which, as such, is prone to gross miscalculation and misinterpretation.  The burning issue which always surrounds the diagnosis of a pest or disease problem is whether it suffices to have obtained an indication as to, ‘what organism is causing it?’ in order that therapeutic measures can be taken to eliminate it.  We argue for the necessity of questions such as: ‘Why is the organism causing damage?’; ‘How did the organism arrive in the system and why did it establish in the system?’; ‘Why did the parasite-predator complex fail to control the pest or disease?’  The answers to these questions can only be found by ‘looking beyond the pest/pathogen’ - an action that will provide us with a better understanding of the problem so that we can manage it and hopefully provide stronger, substantiated solutions.  However, when considering the incredible number of interactions that constantly take place between plants, insects, pathogens and human activities within an ever-changing environment over a relatively short period of time, it becomes obvious why a holistic or total system approach is the most sustainable way to ensure that our crops achieve their true genetic potential.