Detection of cereal viruses and study of aphid population in Bulgaria.

The article presents results form a research project directed towards the viruses composing the infectious background of the wheat and barley in Bulgaria. The presence of five new for Bulgaria viruses BaMMV, BaYMV, BStMV, CDV and WDV was registered. During the autumn period in favourable weather conditions Sitobion avenae is the usual harmful agent among the crops of winter barley. The other aphid Schizaphis graminum appears more rarely. Later among the crops of winter barley the share of Rhopalosiphum maidis and Rhopalosiphum padi increase. During the spring period seven ahids species: Metopolophium dirhodum, M. festucae, R. maidis, R. padi, S. graminum, S. avenae and Sipha maydis are found in the crops of wheat, winter and spring barley. Fife of them: M. dirhodum, R. maidis, R. padi, S. avenae and S. graminum are known as vectors of BYDV. S. avenae has the greatest share in the aphid infestation of the wheat, winter and spring barley crops.