2012 Annual Report 1a.Objectives (from AD-416): Increasing the understanding of the zebra chip potato disease vector biology, vector-pathogen interaction, and the epidemiology of the disease. 1b.Approach (from AD-416): Assess the role of the potato psyllid in zebra chip potato disease by:. 1)conducting insect transmission studies under laboratory conditions to determine liberibacter acquisition and inoculation access time required for the potato psyllid to effectively transmit the bacterium and induce zebra chip,. 2)determining the impact of zebra chip on different plant growth stages under controlled field cage conditions,. 3)determining density of potato psyllid required for this insect pest to effectively cause zebra chip,. 4)assessing environmental conditions that may influence ZC symptom expression, including temperature, relative humidity, and light intensity, and. 5)screening potato breeding material for zebra chip. Documents Reimbursable with Texas A&M (SCRI). Log 44012. 3.Progress Report: Zebra chip, a new and economically important disease of potato in US, Mexico, Central America, and New Zealand, is associated with a new species of the bacterium liberibacter that is transmitted by the potato psyllid. A series of laboratory and field experiments confirmed that zebra chip-infected potato tubers do not significantly contribute to the disease spread as these tubers generally do not sprout and if they do, produce disease-free potatoes. It was also determined that zebra chip asymptomatic tubers produced by Atlantic potato plants infected with liberibacter late in the season could develop zebra chip symptoms in storage. Information from this research will greatly benefit seed certification agencies and promote national and international trade of potato seed, in addition to development of better methods to store potatoes. The work reported here addresses objectives 2 and 3 of the parent project plan.