DIY orchid virus diagnosis methods

To date, as many asorchidviruses have been recorded, belonging to 9 virus groups (a unit of plant virus classification, each group containing a different number of virus species). Among the 23 viruses harmful toorchids, four have been found in the Taiwan region: Odontoglossum ringspot virus (hereafter referred to as ringspot virus), Cymbidium mosaic virus (hereafter referred to as mosaic virus), Cymbidium bacilliform virus, and Cucumber mosaic virus harmful to Phalaenopsis (the author's unpublished data). According to the author's research, among theorchidviruses occurring in Taiwan, ringspot virus and mosaic virus are the most common. Among 215 virus-infected orchids surveyed, the mosaic virus infection rate was 53.5%, and the ringspot virus rate was 45.1%, which shows how widespread these two viruses are. When orchids are harmed by these two viruses, the quality of theflowersand the growth vigor of the plant itself are often affected, causing obvious symptoms on the floral organs or leaves. Of course, typical symptoms can often directly tell us that an orchid has been infected by a virus, and isolation measures must be taken to avoid infecting other healthy orchids. Unfortunately, however, this is not always the case, because many factors can also cause symptoms similar to those caused by viruses (for example, the fading of floral organs caused by cold damage). If such a situation is regarded as viral infection, then it is unfair to that orchid, and for thegrowerit is even more of a pointless loss of money and time. Think about it: that orchid may have been bought with a lot of money, and you may also have spent several years of time and effort caring for it as a beloved orchid, only for this naked-eye misdiagnosis to sentence it innocently as incurable. Would that not be a great pity! To avoid misdiagnosis, this article will tell you a very simple method with which you can diagnose the two common major orchid viruses yourself. Before introducing the method, there are some matters that must first be understood, and these will help you when diagnosing orchids. Orchids have the largest number of hybrids among all plants, so different varieties infected with the same virus often show differences in symptoms. Some orchids even show no symptoms at all after virus infection, which is very troublesome for diagnostic methods based on symptoms. If symptoms alone are used as the basis for whether a virus infection is present, then in many orchid nurseries there are certainly quite a few orchids that look very healthy on the outside but have in fact already been infected by viruses. If this happens in your orchid nursery, then sooner or later it will be destroyed by these viruses. According to the author's survey, the virus infection rate in some orchid nurseries in the Taiwan region is as high as more than 40%. This number is very frightening, because within a very short period all the orchids in that nursery may become infected by viruses. Division is one way to propagate orchids. When you divide a batch of orchids, if the tool first touches an orchid that looks healthy on the outside but is actually already infected by a virus, then all the remaining healthy orchids have a chance of becoming infected. In addition, you must note that when you buy an orchid from another orchid nursery, if you carry out virus diagnosis, it is very likely that by unintentionally bringing in this "apparently healthy" orchid, you will directly or indirectly infect healthy plants. To avoid causing this kind of pointless loss, it is absolutely necessary to check orchids yourself for virus infection. The equipment required for this method includes double-edged razor blades (used cut in half), carborundum (0.042-0.064 mm), a spray bottle, and indicator plants -- globe amaranth (yuanzaihua) and sickle senna, etc. The carborundum can be placed in a small triangular flask (50 ml or 100 ml), then covered at the mouth with two layers of gauze, and the gauze tied properly so it does not fall off. The spray bottle only needs to be filled with ordinary raw water. During diagnosis, cut open the orchid leaf with a half razor blade, and gently rub the broken tissue surface (the surface cut by the blade) onto the leaves of the indicator plant on which carborundum has been sprinkled. One rub is enough, but the force must be even and rubbed over the entire leaf surface to avoid mechanical injury from rubbing. What must be especially noted here is not to sprinkle too much carborundum; it is enough that its distribution on the surface can be slightly seen with the naked eye. After the diseased leaf has been rubbed onto the indicator plant leaf for about 1 minute, use the spray bottle to wash the carborundum off the leaf. In this way the inoculation work for diagnosis is completed. If globe amaranth is infected by ringspot virus, yellowing lesions appear about 7 days after inoculation, and then become necrotic lesions. If sickle senna is infected by mosaic virus, necrotic lesions can appear about 4 days after inoculation. At this point, you can determine whether your orchid has been infected by the two most frightening orchid viruses. If the traditional biological assay method is used to identify viruses, the required equipment includes a mortar and grinding, carborundum, cotton swabs, phosphate buffer, etc., and the cost is considerable. To save time and expense, based on practical difficulties, the author simplified the traditional biological assay method into the above identification method, making it suitable for ordinary orchidgrowers. This method has already begun to be adopted by orchidgrowersin the United States, and it has also greatly reduced losses caused by mosaic and ringspot viruses. This simple biological assay method may present some difficulties when first used (especially for growers who have not studied plant viruses), but as long as you learn it yourself, you can become proficient in no time. Ke Nanjing