Apple Maggot Quarantine Slows, Not Stops, Infestation

As the owner of Walter’s Fruit Ranch in Green Bluff, Mark Morrell has seasonal responsibilities. Right now, he’s got apples on his mind.

But one thing he doesn’t have to worry about is apple maggots.

“I have a clean orchard,” he said, walking through tidy rows of gala and golden delicious apple trees. “I don’t worry about (apple maggots) because I don’t have a problem with it.”

Morrell attributes his clean orchards to hard work and integrated pest management. But another, more-silent helper could be the apple maggot quarantine.

The Spokane County quarantine began in 1984 when officials realized they needed to do something to prevent - or at least slow - the spread of the pest. Signs throughout the county warn motorists: Do not transport home-grown fruit.

“Scientists recognized apple maggots would spread through man’s help,” said Michael W. Klaus, project entomologist for the Washington State Department of Agriculture. “They don’t fly very far on their own.”

Spokane is the only quarantined county in eastern Washington. The nearest others are Klickitat and Skamania in central Washington.

In Spokane County, officials’ main concern is keeping Green Bluff free of the pest. So far, Green Bluff’s natural barriers of pine forests and wheat fields, in addition to the farmers’ pest management practices, have successfully kept apple maggots from invading the orchards. The closest they have been found to Green Bluff is 1-1/2 miles away.

The Department of Agriculture helps local growers by acting as an apple maggot monitor. About 50 sticky, yellow traps hang in apple trees throughout Spokane to help scientists determine if the apple maggot is spreading.

Klaus said it is.

“The eradication program helped slow the spread of the fly, but now it’s starting to rebound,” he said.

One fly was recently caught in a trap in the Greenacres area near Liberty Lake - the farthest east an apple maggot has been trapped in Washington.

“The site is one we’ve monitored for many years. It’s nothing we didn’t expect,” Klaus said.

Though maggots have also been caught in areas throughout the Valley near Altamont this year, there are no plans to start spraying pesticides again throughout Spokane County, Klaus said. Widespread spraying stopped in 1986.

Now, it is up to individual counties to come up with the resources to spray infected areas if they choose to do so. If Green Bluff were threatened with infestation, local growers would likely form a pest board and decide how to deal with it then, Klaus said.

The apple maggot is black with clear wings. It’s slightly smaller than a housefly. Adult females deposit eggs under the apple skin. When the larvae burrow and feed on the fruit, the apple begins to turn brown and rot.

Agriculture officials hope area quarantines will keep the apple maggot from spreading to other parts of the country. Currently the pest plagues not only parts of Washington, but areas in California, Oregon, Utah, Idaho, Colorado and portions of states east of the Mississippi River. If it continues to spread, the apple maggot could disrupt the marketing of fruit nationally and worldwide.

“Foreign countries and some states have restrictions on (receiving fruit from) states with apple maggot,” Klaus said.

Though he knows of people who brought infected fruit to officials for inspection, not knowing it contained apple maggot, Klaus said he has never heard of anyone who intentionally broke the quarantine. It is considered a misdemeanor for people to knowingly carry home-grown fruit into a quarantine area, he added.

Apple maggot trapping season runs through late September, but Klaus stressed the importance of always keeping home-grown fruit at home.

“If you get apples from the back yard, make the pies right there,” he said. “But especially during this time of year, don’t move noncommercial fruit out of Spokane.”