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.

It was confirmed that in the north of Poland winged specimens of Myzus persicae (Sulz.) start to migrate in spring approximately over three weeks later than in the central and sou them regions. It was observed that during the 1981-1990 and 1991-2000 decades, M. persicae started its flights approximately over two weeks earlier than during the 1971-1980 decade. With this respect one may conclude that the changes are permanent. There were also changes in quantity. In some places the M. persicae share in the entire aphid fauna on potato crops was observed to have decreased as the time passed, which, as it seems, may be associated with a decrease in potato crops area in Poland. Such a correlation can also be confirmed by the fact that in the area where M. persicae share increased, the potato crops area also increased extensively.