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Apple, pear growers fight fire blight outbreak

It’s the worst spring in recent memory in Central Washington for fire blight, which withers apple and pear trees. Growers are cutting limbs and whole trees to keep the disease from spreading. Crop loss could be offset by new plantings coming into production, one orchard consultant says.
Dan Wheat

Capital Press

Published on June 12, 2018 8:29AM

Last changed on June 12, 2018 8:30AM

Fire blight bacteria oozes from the branch of an apple tree in an Omak, Wash., orchard on June 6. Insects, birds, wind and water can spread infectious spores.

Dan Wheat/Capital Press

Fire blight bacteria oozes from the branch of an apple tree in an Omak, Wash., orchard on June 6. Insects, birds, wind and water can spread infectious spores.

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Limbs are piled on the ground as workers prune fire blight infections from apple trees in a Foreman Fruit Co. orchard near Omak on June 6. The limbs are often hauled away and burned.

Dan Wheat/Capital Press

Limbs are piled on the ground as workers prune fire blight infections from apple trees in a Foreman Fruit Co. orchard near Omak on June 6. The limbs are often hauled away and burned.

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The tip of an apple tree limb withered by fire blight in an Omak, Wash., orchard on June 6. Fire blight in apple and pear trees has been progressively worse during the last three springs in Central Washington.

Dan Wheat/Capital Press

The tip of an apple tree limb withered by fire blight in an Omak, Wash., orchard on June 6. Fire blight in apple and pear trees has been progressively worse during the last three springs in Central Washington.

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WENATCHEE, Wash. — Fire blight, a bacteria that kills apple and pear trees, is more widespread throughout Central Washington this year than during any spring in recent memory, growers say.

“I fly a lot. I look down and see the funeral pyres burning. It’s substantial and extreme on the eastern side of Royal Slope. Winchester to Ephrata seems pretty substantial and Quincy not so bad,” said Mike Robinson, general manager of Double Diamond Fruit Co. in Quincy.

“Mattawa doesn’t appear as bad but I’ve never seen this much this widespread. I’ve never seen this many good farmers get this much. Usually they’re on top of their sprays and focused,” Robinson said.

It appears worse in some areas than others but all areas have more than usual, he said.

From his airplane, Robinson said he’s looked down and seen holes in orchards where trees have been removed.

On any given day in the past three weeks, he said he’s seen seven to nine columns of smoke from orchards burning limbs after cutting them from trees to keep the bacteria spores from spreading. They can spread by wind, water, birds and insects. Nicholas Stephens, owner of agricultural consulting firm Columbia IPM in East Wenatchee, said he’s talked with growers from Hood River, Tri-Cities, Yakima, Quincy, Wenatchee, Bridgeport, Brewster and Okanogan.

“I would say in 28 years doing this, I’ve never seen anything like it. It’s really widespread. A lot of orchards are in grave danger, young orchards, old orchards,” Stephens said.

It’s a “snowball effect,” a build-up of inoculum from the previous two years of perfect conditions, like this year, for fire blight, he said.

Once only a concern in pears trees, fire blight has been known since 1993 to damage apple trees. The years 1997 and 2012 were bad years, Tim Smith, Washington State University Extension tree fruit specialist emeritus, has said.

Fire blight over winters in trees and reactivates in oozing cankers around blossom time. It is exacerbated by extreme heat followed quickly by rain during bloom. It attracts flies and other insects that spread it to blossoms. Within a week or two, infection is ahead of portions of trees that show withering.

Antibiotics, copper fungicides, lime sulfur, other minerals and biological controls are applied before, during and after bloom but at best are 80 percent effective, Robinson said.

“Probably the biggest difference in recent years is that it’s pretty evident sprays 24 hours before the infection period are better than after,” he said.

A WSU Tree Fruit website post says this is the third year of “multiple severe fire blight infection periods during bloom.”

Cutting 12 to 18 inches back from withered foliage is recommended, but whole limb removal is recommended for more susceptible varieties and young, vigorous trees. Whole trees should be removed if they have multiple strikes.

“If I have a 5-foot limb with a strike at the tip, I take the whole limb,” Robinson said. “If you’re super aggressive on day one usually you can get in front of the problem.”

Stephens said production for individual growers will be affected but that overall crop loss may be offset by new plantings coming into production.

Cutting limbs, cankers and trees and replanting is laborious, he said.

It’s unusual to have three years in a row of progressively worse conditions, he said.

James Foreman, manager of Foreman Fruit Co. in Wenatchee, said company orchards from Sunnyside to Omak have been impacted. On June 6, crews were trimming infected limbs from trees in a Foreman orchard off Pogue Road near Omak.

Meanwhile, hail damaged about 200 acres of Oneonta Starr Ranch Growers Golden Delicious and Honeycrisp apples near Quincy on May 17, Jim Thomas, company co-owner, said.

Robinson said it was not widespread.





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