Management strategies for controlling pests and diseases in glasshouse crops

Pest and disease control strategy is influenced by (i) the market demand for blemish-free produce, (ii) the sources of pests and diseases, (iii) the availability of crop cultivars with genetic resistance to pests and diseases, (iv) the presence and availability of beneficial animals in the crop production system, (v) the lack of biological control agents for diseases and (vi) costs of Integrated Pest Management (IPM) and Integrated Disease Control (IDC) programmes. Although only 14000 ha of the potential world area of 75000 ha of protected crops employs IPM, this technique is likely to expand in future, and food and plants produced under IPM regimes will become the norm. During IPM, multiple introductions (MI) of natural enemies can be made regularly at affordable rates, whether pests are seen or not, to ensure that particular pests do not cause crop damage. In this manner, growers are better able to deal with circumstances beyond their control; better use will be made of any effective pesticides, and problems with statutory pest control will be easier to solve. IDC in protected crops involves skillful manipulation and deployment of factors affecting the outcome of host-pathogen interactions. The most important of these are genetic resistance, control of the aerial and root environments, nursery hygiene, the health status of planting material and appropriate use of fungicides. The precise combination of factors used may vary with crop, time of year, the target spectrum of diseases to be controlled, the economics of alternative actions and between nurseries growing the same crop. Any action should have minimal effects on biological pest control agents. Unlike IPM, where introduction of predators and parasites is a major part of successful pest management strategies, the introduction of micro-organisms for disease control is often less reliable and, with a few exceptions, rarely practiced at present. Strategies for integrated control of both pests and diseases can be improved by research to increase knowledge on the culture of crops, optimum glasshouse environments, thresholds of pests and diseases and the biology of pests, diseases and their natural enemies. Integration of pesticides with natural enemies has greater potential than is utilised at present and could help to prolong the life of some chemical pesticides.