The investigations were carried out at Bonin during I 996-1999. The aim of the study was the comparison of PVY, PVS, PVM and PLRV infection pressure in different periods of growing season. The PVY pressure was the greatest. The mean (of 4 years) infection was 32%. Evidently lower infection was observed for PVS (19%) and PVM (7%) and extremely low for PLRV (only O.Ol%). The most intense spread of PVY, PVS and PVM took place from second IO days of July until first ten days of August.