Potato virus Y (PVY) is one of the main tobacco pathogens in the world. The main aim of this study was to determine the effect of weather conditions (temperature, humidity, precipitation, insolation) on infection of tobacco plants with PVY. To determine the relationship between results of field observations and meteorological data, Spearman's rank correlation coefficient was used. Only temperature had a statistically significant effect on PVY infection of tobacco. The number of infected plants do not depend directly on the maximum or minimum temperature, but the duration of the time period with high temperature. Only in the case of the temperature range T>20 °C, statistically significant result R² = -0.561487 was obtained (α = 0.05), which means that the long period with average temperature above 20 °C is negatively correlated with the level of PVY infections. In the years 2003, 2006 and 2010, there were low levels of PVY infections (below 30%), as there were limited by high temperatures during the growing season. A different situation was observed in 1996, 2004 and 2009, when the cool summer led to a large increase of PVY infections.

Despite previous assumptions that cold winters can affect the population of aphids – the PVY vector – and thus lower the number of infected tobacco plants, results obtained revealed that there was no significant effect on PVY infections.