David Owens, Extension Entomologist, email@example.com
Congratulations to Greg Dempsey for correctly identifying this issue as barley yellow dwarf virus. BYDV has been much more prevalent this year than usual, and especially so in malting barley fields. There is an excellent writeup of BYDV put together by researchers in the Southeast a number of years ago: ef150.pdf (uky.edu). This field also had Pythium damage in root system. At this point, we do not know which disease started first. It is important to keep plants well irrigated and fertilized to reduce the stress impact on the plants.
Barley Yellow Dwarf Virus