Tobacco mosaic virus (tmv) can infect a wide range of hosts, and losses of up to 20% have been reported in infected tomatoes. Phillip mphuthi of the agricultural research council’s (arc) industrial crops unit in rustenburg discusses tmv detection, prevention and management.
Tobacco mosaic virus (TMV) was the first virus discovered. In 1889, Martinus Beijerinck, found that ‘tobacco mosaic disease’ was caused by a pathogen able to reproduce and multiply in the host cells of the plant. He called it ‘virus’ (from the Latin virus, meaning poison) to differentiate this form of disease from those caused by bacteria.
Tobacco yield losses due to TMV are currently estimated at only 1%, because resistant tobacco varieties are routinely grown. However, TMV affects other crops, and losses of up to 20% have been reported in tomatoes.
TMV can be a major problem because, unlike most other viruses, it does not die when the host plant dies and can withstand high temperatures. Thus, the virus can survive on implements, trellis wires, stakes, greenhouse benches, containers and contaminated clothing for many months.
It can also survive in crop debris on the soil surface and infect a new crop planted on contaminated land.
Tobacco products, particularly those containing aircured tobacco, may carry TMV too.
The virus cannot be transmitted in the smoke of burning tobacco, but smokers, especially those who roll their own cigarettes, could possibly carry the virus on their hands and transmit it to healthy plants.
Sap-feeding insects such as aphids cannot transmit TMV. However, chewing insects such as grasshoppers and caterpillars do occasionally transmit the virus. They are not considered important vectors, however.
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