Abstract
The effect of potato virus Y (PVY) on growth, yield and chemical composition of flue-cured tobacco cultivars Coker 86 and NC-744 was primarily determined by the time of inoculation. On Coker 86, early inoculations (15 and 28 days after transplanting) caused height reductions of 37.0 and 34.7% and yield reductions of 71.5 and 74.8%, respectively. Effects were less detrimental on NC-744, suggesting this cultivar possesses a degree of tolerance to the Chilean necrotic strain of PVY. Nevertheless, plant height and dry weight were reduced 9.9 and 16.3% and 36.9 and 38.9%, respectively, by inoculations 15 and 28 days after transplanting. PVY also modified the chemical composition of cured leaves. Total nicotine content was always higher in cured leaves from diseased plants than in those from healthy controls. Because early inoculations caused the most detrimental effects, the 1st mo. after transplanting should be considered the most critical period for PVY infection.