Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2007
Publication Date: 12/28/2007
Citation: Munyaneza, J.E., Goolsby, J., Crosslin, J., Upton, J.E. 2007. Further Evidence that Zebra Chip Potato Disease in the Lower Rio Grande Valley of Texas is Associated with Bactericera cockerelli. Subtropical Plant Science 59:30-37. Interpretive Summary: Zebra chip, a new defect of potato, has recently been documented in southwestern United States and is causing millions of dollars in losses to both potato producers and processors in affected areas, Texas in particular. Scientists at the USDA-ARS at Wapato and Prosser, WA, and Weslaco, TX, conducted field experiments to investigate the role of insect vectors and potential causal agents in the expression of this disease. It was determined that zebra chip in the Lower Rio Grande Valley of Texas was strongly associated with the potato psyllid insect. The information from the present study will make it possible for potato producers in Texas to focus monitoring and controlling efforts on the potato psyllid and should lead to a reduction in the incidence of zebra chip and serious losses that this disease causes to the potato crop.
Technical Abstract: Zebra chip (ZC) is an important and emerging potato disease that is causing millions of dollars in losses to both potato producers and processors in the southwestern United States, Texas in particular. This disease is characterized by symptoms that develop in fried chips from infected potato tubers and that consist of a striped pattern of necrosis in tuber cross-section. Zebra chip plant symptoms resemble those caused by potato purple top and psyllid yellows diseases. To increase the understanding of the role of the potato psyllid (Bactericera cockerelli Sulc) and phytoplasmas in the expression of ZC, controlled exposure field experiments using cages were conducted in the Lower Rio Grande Valley of Texas, where the psyllid is common and abundant and the disease is very damaging. Also, potato tubers exhibiting ZC symptoms were tested for phytoplasmas by PCR. Results indicated that there was a strong association between the potato psyllid and zebra chip. Plants exposed to psyllids developed typical ZC symptoms in both raw tubers and fried chips. At harvest, potato plants exhibiting ZC symptoms in raw tubers averaged 79.2, 37.5, and 48.6% for uncaged plants, caged plants infected with Texas field collected psyllids, and caged plants infected with laboratory-reared psyllids, respectively. Incidence of ZC increased when the harvested tubers were processed into fried chips. No single potato plant in the cages without psyllids (controls) showed ZC symptoms in raw tubers or fried chips, suggesting that the observed ZC symptoms were due to psyllids. No phytoplasmas were detected in tubers with zebra chip symptoms, suggesting that these pathogens are not involved in ZC.