In cereal crops, Barley yellow dwarf (BYD) is one of the most damaging viral disease in Australia and throughout the world. BYD is a group of several virus species including; Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV). BYD is only transmitted from infected to healthy plants by aphid vectors.

Over 150 plant species within the Poacae family are characterised as hosts of BYD, including food crops such as wheat, barley, oats and corn. BYD has a negative effect on plant growth as it decreases root biomass, diminishes plant vigour and greatly reduces grain yield and quality.

The most common symptoms of BYD are plant stunting and leaf discoloration (depending on the crop; either yellow or red) which starts from the tip of the leaf and spreads towards the base. The severity of this disease largely depends on the inoculation time; plants are at their most vulnerable when they are infected in the early growth stage. In addition, abiotic factors, including drought and heat can intensify severity of this disease. Another important virus of cereal crops is the Wheat streak mosaic virus (WSMV) which is transmitted by the wheat curl mite (Aceria tosichella).