EFFECT OF TOBACCO ETCH VIRUS ON THE SEASONAL GROWTH OF FLUE-CURED TOBACCO

The effect of tobacco etch virus (TEV) infection on flue-cured tobacco (Nicotiana tabacum L.) plant growth was investigated under field cond itions in 1985 and 1986. Natural field infection of TEV was allowed to develop a patchy distribution of healthy plants and plants infected a t various times of the season. Plants showing symptoms of TEV infectio n early in the season had significantly less leaf area by season's end (2 weeks after topping) than healthy plants or plants infected late i n the season. Significant stunting was evident in plants first showing symptoms as late as 7 weeks after transplantation. Harvestable green leaf weight was not correlated with time of first TEV symptom expressi on. However, leaf weight per unit area was significantly correlated wi th time of plant infections, with earlier-infected plants having great er weight per unit area than later-infected plants or healthy plants. Yield, quality and value of the harvested tobacco were not correlated with number of infected plants per plot, however, probably because of compensation by neighbouring plants.