Yearly change of the infection of Wheat dwarf virus was studied in winter barley during 1996-2010. Surveys were carried out at Kompolt (Rudolf Fleischmann Research Institute, Róbert Károly College), in winter barley breeding lines showing leaf yellowing and stunting symptoms. In 1996, 250 winter barley samples were tested. During the period o
...f 1997–2005, 100 samples were collected in each year. In 2006, 490 winter barley samples were tested. In 2007 and 2008 the number of samples collected was 500 from winter barley. In 2009 year 100, and in 2010 year 100 winter barley samples were collected for virus testing. Virus diagnosis was carried out using DASELISA for the detection of Wheat dwarf virus (WDV), Barley yellow dwarf viruses (BYDV-MAV, BYDV-PAV, BYDV-RMV, BYDV-SGV), and Cereal yellow dwarf virus (CYDV-RPV). During the ten of the last fifteen years, the occurrence of Wheat dwarf virus in infected samples exceeded those of other viruses causing leaf yellowing and dwarfing symptoms. There were years (1997, 2002, 2004, 2007, 2009 and 2010) when only the Wheat dwarf virus played the main role in development of yirus symtoms. A contrasting tendency can be observed between the degrees of infection of WDV and BYDV. With a rise of infection in the WDV, the proportion of BYDV decreased and vice-versa.