Occurrence and characteristics of barley yellow dwarf virus in Switzerland

afidos aphide aphididae aphids barley yellow dwarf virus getreide homoptera hordeum vulgare metopolophium dirhodum rhopalosiphum maidis rhopalosiphum padi schweiz sitobion avenae suisse suiza switzerland vectores vectors virus virus enanismo amarillo de cebada virus jaunisse nanisante de l'orge