Because of low PLRV tolerances in certified seed, intensive measures are taken to limit aphid populations. Due to increasing aphid populations in northern production regions over the past few growing seasons, the incidence of PLVR is becoming a growing concern and net necrosis has threatened producers of processing potatoes. Many times, infection can be seen in a circular pattern in the field, frequently surrounding what was most likely the original source of virus inoculum, an infected seed piece.
Direct damage can also result from aphid feeding.
PLRV travels through the phloem of the plant into tubers, reducing size and causing net necrosis. Net necrosis causes browning of the vascular system extending throughout the entire tuber as opposed to stem end browning which does not penetrate the tuber more than 1 inch from the stem end. Net necrosis is primarily seen when the virus is spread to healthy plants by aphids. Net necrosis may or may not be found prior to harvest, possible developing or becoming more severe in storage. Timing of the development of net necrosis is dependent upon the time in the growing season at which plants become infected.