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Phillip Nolte Extension Seed Potato Specialist University of Idaho, Idaho Falls, ID. Zebra Chip in North America. a new challenge?. UNECE Seed Potato Meeting, May 31, 2012 , Edinburgh, Scotland, UK. ZC in North America. Photo and source credit. Dr. Neil Gudmestad, NDSU
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Phillip Nolte Extension Seed Potato Specialist University of Idaho, Idaho Falls, ID Zebra Chip in North America a new challenge? UNECE Seed Potato Meeting, May 31, 2012 , Edinburgh, Scotland, UK
ZC in North America Photo and source credit Dr. Neil Gudmestad, NDSU Dr. Andy Jensen, WPC, OPC, IPC
ZC in North America • “Zebra Complex” or “ZC” • Not just chips (crisps) • Fries • Fresh • Seed?
ZC in North America Disease Diagnosis
ZC Symptom variability • Foliar symptoms similar to purple top wilt syndrome and include: • Leaf curl • Leaf chlorosis and scorching • Limited purpling of top leaves • Twisted stems
ZC Symptom variability • Symptoms continued: • Swollen nodes • Aerial tubers • Vascular discoloration and wilt • Plant death
ZC in North America Recent History
Locations where ZC defect has been found in USA North Dakota Montana Washington Minnesota • . South Dakota Oregon Idaho • . Wyoming • . Iowa Nebraska • . • . • . Nevada Colorado Utah Kansas • . Missouri • . California Oklahoma • . Arizona New Mexico • . Arkansas • . Texas • . Louisiana • .
Seed Production 30,000 A SC 75,000 A SE 207,000 A SW 21,000 A
ZC Timeline for PNW - 2011 • September- Columbia Basin of WA/OR • Idaho: Late September/Early October • Norkotah sample from packing shed with symptoms. Found by ISDA inspector. Confirmed ZC. • Leavings in field sampled confirmed ZC. (Jerome Co) • Additional samples found in research plots in Kimberly (Twin Falls county) – 0 to 1.8% • Samples from commercial fields (Twin Falls county)
ZC in Idaho Current situation • Lots of positives at low incidence • Most in Central ID • Much lower in West • Nothing from East as yet • Many potatoes still in storage
CENTRAL 75,000 A SE 207,000 A WEST 21,000 A ?
ZC in North America Tuber Symptoms
Tuber Symptoms G. Secor
Defect of Chips / Crisps • Disease causes browning of chips processed from affected potatoes • ZC leads to load and field rejections • Initially called “Texas defect” and then “Zebra Chip” due to alternating light and dark streaks in finished product • Discoloration ranges from mild to severe
ZC in North America Causal Agent
Causal Agent • “CandidatusLiberibactersolanacearum” (bacterium) • Not culturable • Spread by potato psyllid
ZC in North America Psyllid Vector
ZC in Idaho Much is unknown • Psyllid behavior and capabilities? • Stored potatoes? • Curiosity or long term scourge? • Seed • ???
Importance of infected seed? • ZC has not been reported in any seed production area of Canada or USA • Disease appears to be independent of seed source • ZCfrequently kills eyes, or produces very weak plant • Studies underway to determine importance of seed borne inoculum • ato-tomato psyllidnative to USA west • Host range – prefers Solanaceae: potato, tomato, pepper, nightshades, but can also develop on many other plants • Occurs annually in WA, OR, and ID • May migrate? but may overwinter here? • Can be very difficult to detect in the field