Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2001
Publication Date: N/A
Interpretive Summary: Infection of potato by the potato learoll virus can cause a serious internal defect in the tuber called net necrosis. This is a brown discoloration often appearing in a net like pattern that progresses slowly from the stem end toward the bud end. Inspectors look for this defect when a lot of potatoes is checked, and only very low amounts can be tolerated. Many varieties are resistant to this symptom of leafroll infection but some of the most important varieties in North America such as Russet Burbank and Shepody are susceptible. Three new varieties developed in the Northwest by USDA-ARS, and the Universities of Idaho, Oregon and Washington, are resistant to this serious problem. These varieties are Bannock Russet, Gem Russet, and Umatilla Russet.
Technical Abstract: Few potato cultivars in commercial production in North America have resistance to leafroll virus (PLRV) infection. However, many are moderately to highly resistant to the net necrosis symptom in tubers. Important cultivars grown in the northwest and advanced breeding selections have been tested for leafroll net necrosis in Idaho. Net necrosis was evaluated in tubers from plants exposed to current season PLRV infection. Reaction in tubers to PLRV infection was summarized over an eleven-year period. The newly released cultivars Bannock Russet and Umatilla Russet and a number of advanced breeding selections showed good resistance to LR net necrosis, similar to Atlantic. Gem Russet, Russet Norkotah, and Ranger Russet were moderately resistant. Russet Burbank and Shepody were susceptible. CalWhite and Russet Legend were the most susceptible. Cultivars with resistance to net necrosis, including those genetically transformed for PLRV resistance, can provide protection from the worst effects of current season PLRV infection to individual commercial growers. However, PLRV management and green peach aphid GPA control programs must take into consideration the threat of viriliferous GPA spreading from cultivars resistant to net necrosis to the substantial acreage of susceptible Russet Burbank destined for long term storage.