A greenhouse without pesticides : fact or fantasy ?

Crop protection in European greenhouses became strongly chemically oriented shortly after the Second World War in the 1950s. But an excellent climate for fast reproduction of pests and diseases demanded high spray frequencies and, thus, resulted in quick development of resistance against pesticides. This initiated a search for alternatives of chemical pesticides. The first natural enemies for control of pests in European greenhouse vegetables became available in the 1960s. A change from chemical control to very advanced integrated pest management programs (IPM) took place in a time span of about 20 years. Nowadays, growers worldwide annually introduce millions of natural enemies for pest control. About 100 species of beneficial organisms are commercially available for control of all important insect and mite pests. In the main vegetable crops in northern Europe, most if not all insect problems can now be solved without the use of insecticides. The change to IPM was not based on idealism about a cleaner or healthier environment, but was rooted on clear advantages for the grower. Development of biological control of diseases has started recently, and the first practical successes have been obtained. Integrated management of pests and diseases without conventional chemical pesticides is a goal that will be realised for most of the important vegetables in Europe within a decade. IPM is not limited to greenhouse vegetables, but is increasingly used in ornamentals. New activities in plant breeding research aim at combining aspects of host-plant resistance with biological control, selecting plant cultivars that are able to attract natural enemies after they have been attacked by pest organisms, and selecting plant cultivars that produce a better "working environment"for biological control agents. Because of specific advantages of biological control for the growers, greenhouse crops will be produced without the need to use convrntional pesticides in the very near future. At the same time, this result in a cleaner environment, in staisfaying the demand of consumers for pesticide-free food, and in sustainable crop protection."