ISHS Acta Horticulturae 164: VI International Symposium on Virus Diseases of Ornamental Plants
RECENTLY DISCOVERED VIRUS OR VIRUSLIKE DISEASES OF ORNAMENTALS AND THEIR EPIDEMIOLOGICAL SIGNIFICANCE |
| Author: | R. Koenig |
| Abstract:
More than 80 incidences of new virus diseases of ornamentals have been observed during the past five years. In about 50% of the cases previously unknown virus or viruslike pathogens were identified as causal agents, in the remaining 50% viruses which were known from other ornamental or non-ornamental plants were detected for the first time in new ornamental hosts. A number of virus or viruslike pathogens which at least under certain conditions causes no or only mild symptoms have been found to spread unnoticed in stocks of ornamental plants. Under altered conditions such plants may show obvious disease symptoms (e.g. tobacco mosaic virus infected gesneriads, bean yellow mosaic virus infected masdevallias) or they may serve as a potential source of inoculum for other more sensitively reacting plants (e.g. tomato ringspot virus infected Pentas lanceolata or viroid infected Columnea erythrophae). Viruses which have been thought to be restricted to one or a few closely related plant species in which they produce no conspicuous symptoms have been found to cause or to be able to cause severe diseases in other ornamental plants, e.g. caration mottle virus in Begonias or Helenium virus S in Impatiens. 'Narrow host range viruses' from agricultural crops have recently found to cause diseases in ornamentals, e.g. potato virus X in tulips and clover yellow mosaic virus in Begonias. It is a general experience that most epidemics caused by plant viruses are in some way man-made. Intensive research which enables the early recognition of potential dangers, a close international cooperation among scientists, advise to growers and traders and, if necessary, governmental measures are necessary in order to keep the risks low which may arise from the world-wide trade with ornamentals and the shift of production to warmer countries in which greenhouse propagation of plants is often replaced by open field cultivation. | |
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