Barley Yellow Dwarf Developing In Winter Wheat

 

Barley yellow dwarf is starting to develop in winter wheat. Barley yellow dwarf is caused by the Barley yellow dwarf virus (BYDV). This disease usually becomes more distinct at flag leaf emergence. A typical symptom of Barley yellow dwarf is the purplish-yellow color of infected leaves, especially the flag leaf (Figure 1). Advanced symptoms include severe yellowing of infected leaves and sometimes the infected leaf may have the top half killed starting from the leaf tip.

 

Figure 1. Typical symptom of Barley yellow dwarf. Notice the yellow symptoms starting from the leaf tip.

 

 

Barley yellow dwarf virus is transmitted by aphids. In South Dakota, BYDV is transmitted by three aphid species: bird cherry oat aphid (Rhopalosiphum padi), English grain aphid (Sitobion avenae), and greenbug (Schizaphis graminum). Because of the different aphid vectors, BYDV can have several strains. There are three main strains transmitted by the three vectors above: BYDV-MAV strain is mainly transmitted by English grain aphid; BYDV-PAV is mainly transmitted by bird cherry oat aphid, while BYDV-SGV is mainly transmitted by the greenbug.