Determination of Economic Threshold Level (ETL) of Tobacco Mosaic and Leaf Curl Viruses

Experiments were conducted for the determination of economic threshold of Tobacco Mosaic and Leaf Curl viruses of tobacco. Infection of tobacco plants occurred naturally in the field. Mean values of yield were obtained after curing of tobacco leaves which varied significantly with incidence of disease. Yield loss assessment of tobacco caused by Tobacco Mosaic Virus and Tobacco Leaf Curl Virus was considered first. Grade index values of tobacco that influence market value and support price of flue-cured tobacco were also considered. Economic threshold values were determined from economic analysis and regression analysis and those were found to be at 4.5% and 4% disease incidence in NC 95 and K326 for Tobacco mosaic Virus and 4% and 4.5% for Tobacco Leaf Curl Virus respectively