Submitted to: Greenhouse Business
Publication Type: Popular publication
Publication Acceptance Date: 4/1/2005
Publication Date: 4/1/2005
Citation: Daughtrey, M., Adkins, S.T. 2005. If you know one virus, you don't know them all. Greenhouse Business. April Issue, II:4:21-22&27. Interpretive Summary: This popular press article is primarily directed at ornamental growers. In the spring of 2005, numerous questions related to Tobacco mosaic virus (TMV) in petunia and other crops have been fielded from growers. This article relates TMV and its symptoms, transmission and management to Impatiens necrotic spot virus, another well-known pathogen in the ornamental industry. This report represents a mutual research interest of ARS and Cornell University.
Technical Abstract: Growers are encountering questions related to Tobacco mosaic virus (TMV) this season on their petunia, calibrachoa and nemesia crops. Although this is probably the best-known plant virus world-wide, it is not familiar to the average greenhouse grower. Because Impatiens necrotic spot virus (INSV) has been all too common in flower crops since the 1980’s, a grower’s instinctive response to fears of a virus problem is currently to bring all hands on deck to torpedo the Western flower thrips. Although quite appropriate when INSV is the threat at hand, actions that eliminate thrips from the greenhouse would leave TMV virtually unscathed. These two viruses are moved around the greenhouse in totally different ways. INSV is not distributed by people, except within infected plant material. If you handle an INSV-infected plant, you can touch other plants subsequently with virtually no danger of transferring the virus to them. It takes a thrips to spread INSV: it must first feed on an infected plant as a youngster, and then it can (and will!) disseminate INSV as an adult. TMV, however, is notoriously easy to spread: after handling a TMV-infected plant, the plants that you touch afterwards are very likely to become infected. Sap on your clothing from infected plants can inoculate healthy plants as you brush against them. Even time isn’t in your favor: TMV is very persistent on surfaces, so that until hands, tools or clothing are cleaned appropriately, the virus will remain infectious and continue to be spread. And, unfortunately, the one thing that INSV and TMV have in common is a very wide host range. You can never be confident that TMV will not visibly affect other plants in your greenhouse, but it is smart to focus most of your effort on preventing introduction and transmission within the solanaceous plants. To reduce panic in the future, we propose a special handling procedure for vegetatively propagated solanaceous plants, in order to reduce the spread of TMV within these highly vulnerable crops.