Hawaii Island sweet potato growers are struggling to protect their crops from an invasive insect that makes harvests unmarketable. In fact, the level of harm caused by the rough sweet potato weevil is severe enough that some farmers are abandoning their crops altogether.
“One grower had two fairly good-sized fields that he just didn’t harvest … it wasn’t worth his effort to dig out the roots,” said research entomologist Grant McQuate of the U.S. Department of Agriculture Pacific Basin Agricultural Research Center.
Another person, McQuate said, stopped growing sweet potatoes entirely.
“At first, we didn’t know what this pest was — all we knew was we weren’t getting harvestable, marketable yields,” said Susan Miyasaka, an agronomist at the University of Hawaii at Manoa’s College of Tropical Agriculture and Human Resources.
The rough sweet potato weevil is native to Southeast and Eastern Asia, the Philippines, Japan, Tawain and China. It was first collected in 2008 at a farm in Waipio, Oahu.
The insect appeared on Kauai in 2011 and was detected in Pepeekeo in 2014. It’s not known how it got here, or how it got to its first location in Oahu.
The weevil’s larval stage feeds on the outside of the potato. And while a larvae’s eating habits don’t damage the taste of the potato, they create large tracks around the exterior.
The Okinawan sweet potato, known for its bright purple inside, is primarily an export crop. Most farms are along the Hamakua Coast and in the North Hilo district.
In 2013, 12 million pounds of sweet potatoes were exported to the mainland.
