NEW AND EMERGING VIRUS DISEASES IN ORNAMENTAL CROPS
The growing demand for high-quality and disease-free propagation material, the increasing international trade and the high sanitary standards imposed by many countries for importing propagation material, have highlighted the significance of virus diseases in ornamental crops. A large number of ornamental plant species, of high economical value, are propagated vegetatively, based on building up stocks from source plants. Consequently, viral diseases are a major threat to the production and especially quality of the crop. Viruses usually enter a propagation system at the breeding or germplasm level and are transmitted vertically down the propagation chain. The ultimate outcome of this process is virus-infected progeny. In the last decade many cases of previously undescribed viruses and phytoplasma diseases have been reported from several countries. In some cases previously unknown viruses were identified as the causal agents. In the other cases, viruses which were known from other ornamental or non-ornamental plants were detected for the first time in new ornamental crops that are becoming increasingly economically important. The intensification of ornamental production, introduction of contaminated propagation plant material, and outbreaks of insects, may all play a role in the establishment and distribution of new viral diseases. Most, if not all crop diseases and pests are man-made, and new problems arise as a corollary of agricultural modernization via man's interference with agroecosystems and his role as a "long-distance vector" of viruses in plant propagation material. Disease outbreaks reinforce the notion that viral diseases respect no national boundaries. The ability to effectively deal with emerging viral diseases depends on expertise, capacity and will to address those threats, locally and globally. Improving and coordinating viral disease surveillance systems, enhancing global response capacity, and educating and training a multidisciplinary workforce are needed to adequately address new and emerging infectious diseases. This review will describe some of the new viral diseases affecting ornamental crops and old viruses in new hosts that have been found and identified.
Gera, A. and Zeidan, M. (2006). NEW AND EMERGING VIRUS DISEASES IN ORNAMENTAL CROPS. Acta Hortic. 722, 175-180