摘要 : The intensification of ornamental production, increase in protected crop acreage, introduction of contaminated propagation material and outbreaks of new insect biotypes, may all play a role in the establishment and distribution of... 展开 The intensification of ornamental production, increase in protected crop acreage, introduction of contaminated propagation material and outbreaks of new insect biotypes, may all play a role in the establishment and distribution of new viral diseases. In Israel, virus diseases are economically important due to crop rotation practices. Viruses with a wide host range are well adapted to survive in successive crops of the same plant grown throughout the year. The use of plastic houses favours the introduction of viruses more adapted to tropical and subtropical climates. Many incidences of new virus diseases of ornamentals have been observed in Israel during the past 5 years. In some cases, previously unknown viruses were identified as the causal agents. In other cases, viruses which were known from other ornamental or non-ornamental plants were detected for the first time in new ornamental hosts. The principal propagators in Israel have in recent years employed a variety of techniques to maintain small populations of protected plants that are propagated in large numbers and serve as the principal source of supply for the industry. Many high value crops are produced entirely in plastic houses from propagation to final sale. In spite of the quarantineregulations in Israel, the process of dispersal of pathogens by man continues, especially because it started before virologists could investigate and record events. Intensive research which enables the early recognition of potential dangers, close international cooperation among scientists, advice to growers and traders and governmental measures are necessary in order to recognize potential dangers early and to develop efficient measures for the prevention of major damage. A strict quarantine policy should be followed to prevent the establishment and distribution of new viral pests in the country. Some of the viral diseases affecting ornamental crops in Israel are described. 收起