Reported the occurrence of potato mop top virus (PMTV) for the first time in Washington State.

Prior to 2011, potato mop top virus (PMTV) had only been officially reported from the states of Maine and North Dakota.  Although it was believed that the virus was indeed in Washington State, this was not confirmed until samples collected from the Columbia Basin of Washington tested positive for the virus.  The photograph below shows the brown arcs typical of PMTV in a Washington grown potato.  This virus is transmitted by a soil-inhabiting fungus and is particularly difficult to control.