Zebra chip

Zebra chip, also known as papa manchada and papa rayada, is the term for a disease in potatoes putatively caused by an alphaproteobacteria "Candidatus Liberibacter solanacearum", which is vectored by the potato psyllid. When fried, potato tubers from infected plants develop unsightly black lines resembling the stripes of zebras that render the chips unsellable. Additionally, striped sections of chips frequently burn and caramelize, resulting in a bitter flavor. No health risks have been connected with consumption of infected potato chips.

Zebra chip was first identified in 1994 near Saltillo, Mexico, and was originally named papa manchada (stained potato). In the early 1990s, Texas potato farms reported afflictions, though the disease was not identified in the state until 2000. Since then, zebra chip has been reported in the U.S. states of Arizona, California, Colorado, Idaho, Oregon, Kansas, Nebraska, and New Mexico. Since 2000, Guatemala reported a disease known as papa rayada (striped potato), which has been identified as zebra chip.New Zealand's first suspected case of zebra chip occurred in May 2008, when an Auckland greenhouse reported similar symptoms. In October 2012, the Australian government reviewed the importation of potatoes from New Zealand because of the presence of the disease in the country. Eastern Europe and southern Russia may also be currently experiencing the disease.

An experiment carried out by scientists from the USDA Agricultural Research Service's Vegetable and Forage Crops Research Unit indicates that creating chips from infected raw potatoes increases the visibility of zebra chip. The researchers correlated the presence of the tomato potato psyllid Bactericera cockerelli, which infests both potatoes and tomatoes, to the presence of zebra chip. One of the scientists also reported that targeting the suspected hosts, psyllids, with insect control measures proved effective at stopping the disease. Though early reports suggested the cause might be a bacterium, namely Candidatus Liberibacter, studies have not been able to consistently associate any phytoplasmas with the disease.

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