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Protection Methods


- During cultivation
 
There is no curative control method to effectively control tobacco vein mottling virus (TVMV) during cultivation. Generally, an infected plant will remain infected during its lifecycle.

If attacks occur in nurseries and are detected early, the few plants showing TVMV symptoms should be quickly eliminated and in no case transplanted later.

Treatments with aphicide are necessary to control aphid populations on tobacco.

Unfortunately, these treatments are often ineffective in controlling virus outbreaks. In fact, the aphids that vector the virus often come from outside the field and transmit the virus during short punctures, even before the aphicide has time to act. In some countries the current difficulties in controlling aphids on tobacco are sometimes linked to insecticide resistance, which does not improve the situation.

 
- Next crop
 
In the case of TVMV, the use of resistant varieties would be the most effective manner in controlling the virus, particularly in production areas where the virus incidence is severe. Similar to TEV, some varieties of Burley such as Kentucky 10 and Kentucky 14, show some field tolerance to TVMV. This is partial resistance and is not comparable to the level of resistance found in variety TN 86. Two other genotypes (Virgin A Mutant = VAM and Havana 307) may have a resistance similar to that of TN 86. To our knowledge, a few breeding programs in the United States are currently using  Havana 307 as a source of resistance.

Consider all the measures that tend to prevent or at least, minimise the introduction of TVMV and its spread in tobacco fields. 
 
In countries where contaminations occur very early, nurseries and young plants should  be protected with use of agrotextiles (unwoven fabrics, mesh ...). The mechanical barrier would delay the contamination.
 
It has been shown that in tobacco fields planted next to rows of grains, outbreaks of viral complexes were reduced. In addition the epidemiological aspects of the outbreak, it seems to fluctuate from one field to another, depending on the micro-environment of a given field. Avoid to plant tobacco in fields with a previous history of a severe outbreak of this virus.

Last change : 02/25/13
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Figure 1