Multiple virus infection of wheat in South Hungary.
Incidences of multiple virus infections of wheat genotypes were studied in South Hungary over a five-year period (1994-99). The viruses detected serologically were barley yellow dwarf luteovirus (BYDV), barley stripe mosaic hordeivirus (BSMV), brome mosaic bromovirus (BMV), wheat dwarf bigemovirus (WDV) and wheat streak mosaic tritimovirus (WSMV). Surprisingly, BYDV was found less frequently compared with BRSMV, BSMV and WDV. It suggests that in this area BYDV is economically less important than other viruses infecting cereals. In many individual plants 2-5 different viruses were identified. The abundant multiple infections of several virus species suggest that estimation of natural viral infection cannot be based only on the analysis of a single virus species. On the other hand the development of multiple resistance in wheat seems to be essential to defend the plants against the most important viruses in a given area.