Susceptibility of Selected Potato Varieties to Zebra Chip Potato Disease

Zebra chip (ZC), an emerging and serious disease of potato has caused millions of dollars in losses to the potato industry in the United States, Mexico, Central America, and New Zealand. The disease has recently been associated with a previously undescribed species of liberibacter tentatively named Candidatus Liberibacter solanacearum transmitted to potato by the potato psyllid, Bactericera cockerelli (ulc). At present, applications of insecticides targeted against the potato psyllid are the only means to manage ZC. Given the low psyllid density and short inoculation access period required to induce the disease, insecticides may not act fast enough to prevent transmission of liberibacter to potato by the psyllid and development of ZC. Identification and development of ZC-resistant or tolerant varieties may offer the most efficient and sustainable way to manage this potato disease. Susceptibility of selected potato varieties to ZC was evaluated under controlled field cage conditions in 2009 and 2010 in WA by inoculating potato plants with Ca. L. solanacearum using infective potato psyllids and monitoring them for ZC symptom development. All potato varieties evaluated in both years of the study were determined to be very susceptible to the disease, with almost 100% of the inoculated plants developing severe ZC foliar and tuber symptoms. Potato yield in all tested varieties was significantly affected by ZC, with yield losses ranging from 49.9% to 87. 2%. Information from this research suggests that there is an urgent need to develop new potato varieties that are resistant or tolerant to this damaging potato disease.