Barley yellow dwarf virus

Symptoms include leaf discolouration from tip to base and from margin to centre. The discolouration takes on different colours depending on the plant. In barley, the leaf turns bright yellow; in oat, an orange, red or purple discolouration is seen and in wheat, rye and triticale, the infected leaves are generally yellow and sometimes red. Plants are usually stunted, with a decrease in tiller number and biomass and a weak root system. Suppressed heading, sterility and failure of grains to fill occur in the most severe cases. In the field, symptoms appear usually as yellow or red patches of stunted plants. The disease is most damaging in terms of yield reduction, if it infects a crop at an early stage of growth. The virus is spread by cereal aphids (e.g. Rhopalosiphum padi, R. maidis, Sitobion avenae, etc.). It is neither seed-borne nor mechanically transmitted. It also attacks maize, rice and several grasses.