In those potatoes, females will deposit eggs in the eyes. They can lay from 60 to 100 eggs during a lifetime. Once the eggs hatch, tuber worms burrow into plant stems to feed on the cavities. They also feed on potato leaves, leaving telltale mines.
The real damage is caused when the worms burrow into tubers, leaving dirty tunnels and rendering the spuds unmarketable. The holes also provide entryways for secondary disease organisms, such as fungi.
An early-warning network
For the past three years, Washington and Oregon researchers and Extension agents have maintained a series of delta pheromone traps, which attract male moths, within the Columbia River basin to monitor tuber moth populations.
Oregon State University posts its trap count online weekly at http://oregonstate.edu/Dept/hermiston/TrapReports.php to keep growers abreast. In addition, university Extension entomologist Silvia Rondon recommends growers put one delta trapper field for detection or four traps per field to monitor the pest’s phenology and see how populations fluctuate during the season.
Dorseth and his colleagues at Aberdeen have been conducting grower educational sessions on the importance of this new foundpest.
"We hope to get more growers involved with this survey, as well as [educate] people about identifying these things,” Dotseth says. “There are characteristics about them you can see with a microscope. I still see situations where I have been training Extension educators, who are looking with a hand lens, and they may have a question. I tell them, ‘If you think you may have it, send it to us for confirmation.’”
Throughout the Columbia Basin this year, the number of moths trapped is fewer than at the same time last year. But Andy Jensen, research director for the Washington Potato Commission in Moses Lake, says he can’t explain the population decrease.
“The trap catches were down dramatically last fall, so you would expect trap catches to be down this spring as well,” Jensen says. “It’s totally different than what happened the previous fall when we had large trap catches.”
Rondon, who maintains traps around the Hermiston research station where she works, agrees. During the 2004-05 season, each trap in the Hermiston region averaged 80 moths per week, she says. Even in 2003-04, traps were picking up moths in December, when most insects hibernate.