Recently, tobacco mosaic virus (TMV) has become a problem in crops such as Petunia, Nicotiana and Impatiens. Although well studied, this virus but has the potential to be very destructive, particularly if it escapes early detection in the host crop. Growers need to know what types of symptoms to look for and more importantly what to do with the infected plants and infested greenhouse after TMV has been confirmed. The primary way that TMV moves form plant to plant is via mechanical transmission. This means that via handling infected plants, pruning implements or watering lances TMV can spread from plant to plant. Insects are not of major concern with TMV. There are a few common symptoms of infection. One of the most common is leaf mosaic and flower break. Leaf mosaic is usually accompanied with leaf distortion In most cases the infected plants are stunted and may become yellow.

The best way to control TMV is through prevention. Growers need to keep the virus out of the greenhouse. If plants are started from seed, it is imperative that the seed guaranteed to be viral pathogens. If plants are to be started from cuttings, the cuttings should be certified virus-free. Most cutting producers go to great lengths to make sure the mother stock from which the cuttings are produced is free of all pathogens. If any semi-finished material is brought into the greenhouse it should be quarantined and randomly tested prior to mixing it in with the rest of the stock in the greenhouse. If there are any suspicions of infection, plants should be tested for TMV.

If detected inside the greenhouse, infected material needs to be immediately removed and destroyed. Employees that are handling the infected plants will need to wash their hands prior to reentering the greenhouse. If at all possible workers need to wear gloves when handling infected plants. Even clothing that comes in contact with infected plants has the potential to move the virus from plant to plant. This virus spreads from plant to plant easier than any other plant virus. All surfaces where the TMV-infected plants were sitting or surfaces to which infected material has come in contact should be washed-down with a surface disinfestant such as GreenShield, Physan, Zerotol or TSP (trisodium phosphate). Once the greenhouse is empty, the entire facility should be sprayed down with a disinfestant before any new plant material enters the facility for the following growing season. Ohio State University. Dr. S.G.P. Nameth. www.flori.ag.ohio-state.edu