Potato yellow dwarf virus (PYDV) is a plantvirus of order Mononegavirales, family Rhabdoviridae and genus Nucleorhabdovirus. The virus was first identified in 1922 in the USA by Barrus and Chupp (1922) who reported a new virus that was killing potatoes. The virus is known for its various effects on potato plants including stunted growth, dwarfing and apical yellowing. The virus also affects the tuber as it causes cracking and malformation. The virus is transmitted by the insect vector Agallia constricta. The insect becomes infected upon feeding on an infected plant and transmits the virus to every plant it feeds upon after this event.