The number of potato psyllids, which spread the crop disease zebra chip, is up sharply in potato fields at the Kimberly Research and Extension Center and in a Twin Falls County grower's field.

According to an Aug. 3 pest alert sent by University of Idaho staff working to control the spread, 16 psyllids were trapped on sticky cards in Kimberly earlier that week, and a pair of psyllids were removed from plants by vacuuming. The alert indicated 54 psyllids were trapped on sticky cards in the Twin Falls County field. One psyllid was trapped at another field in Twin Falls County, and eight psyllids were found on sticky cards in a Jerome County field.

Leaf samples from the fields revealed no immature psyllids. Molecular testing has confirmed zebra chip at three Twin Falls County locations, including the Kimberly facility, and one Minidoka County location.

Zebra chip reduces yields and produces bands in tuber flesh that darken when fried, making potatoes unmarketable.

Symptomatic plants have been found in other locations, with tests pending. Symptoms include leaf scorching, swollen nodes, vascular tissue browning and curled leaves.

Zebra chip was first observed in the Pacific Northwest last season. It poses no health risk to people.

-- John O'Connell

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