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Temperature swings throw ‘curveball’ at SW Oregon tree fruit

January’s temperatures were slightly warmer than normal and early February featured eight days of spring-like weather that was followed by a hard freeze.

By CRAIG REED

For the Capital Press

Published on April 20, 2018 6:40AM

Mark Brosi, left, owner of Sugar Tree Farms near Winston, Ore., and Steve Renquist, Oregon State Extension horticulturalist, talk about the impact of temperature swings earlier this year on fruit trees. Brosi says he won’t have much of an apricot crop and that his peach trees only look “halfway good.”

Craig Reed/For the Capital Press

Mark Brosi, left, owner of Sugar Tree Farms near Winston, Ore., and Steve Renquist, Oregon State Extension horticulturalist, talk about the impact of temperature swings earlier this year on fruit trees. Brosi says he won’t have much of an apricot crop and that his peach trees only look “halfway good.”

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ROSEBURG, Ore. — The roller coaster weather temperatures of earlier this year has had a negative effect on some fruit orchards in southwestern Oregon.

According to growers in both the Rogue and Umpqua basins, apricot trees were severely impacted. Some peach varieties may have also suffered, but growers are remaining optimistic that those trees will still produce some fruit.

What led up to this situation were severe temperature swings. January’s temperatures were slightly warmer than normal and early February featured eight days of spring-like weather with high temperatures ranging from 55 to 66 degrees.

Fruit buds on apricot and some nectarine and peach trees were already slightly advanced because of January’s warmth and then February’s “false spring” increased that advancement into the mid-bloom stage.

But then in the Umpqua Basin area, a morning low of 22 degrees was recorded on Feb. 13. Some more temperatures down into the 20s followed with the average low being 34 degrees and the average high being 49 for the next 11 days. The result was that sap stopped flowing in some of the fruit trees.

With buds halfway through the bloom cycle and no sap flowing, it is possible the partially developed pollen in the buds died. There was then nothing in the blossoms to attract bees so pollination did not take place.

“Mother Nature threw us a real curveball this year with some beautiful days in January and February and then the stone fruits got hammered by several mid- to upper 20-degree days,” said Steve Renquist, the Oregon State Extension horticulturalist for Douglas County. “The cold damages the ovary on the flower and then the ovary is not receptive to being pollinated and it dies.”

Mark Brosi, the owner of Sugar Tree Farms near Winston, Ore., said he wouldn’t have much of an apricot crop.

“There are only a couple buds per tree,” he said.

Kathy O’Leary, who owns Valley View Orchard near Ashland, Ore., said she probably lost her apricot crop.

Dave Belzberg, owner of Rolling Hills Farm near Medford, Ore., said he removed his apricot trees several years ago “because they were always getting frosted.”

When it comes to peaches and nectarines, the growers are taking a wait-and-see approach.

Brosi said his nectarines don’t look all that great and his peaches only look “halfway good.” O’Leary said she is not sure how much the weather impacted her future peach crop, but Belzberg, whose orchard is on a west slope, said his peach trees look “healthy and happy.” He said west sites tend to be cooler than east sites and he added that his trees weren’t flowering during the cold spell so he didn’t anticipate any loss.

Evan Kruse, co-owner of Kruse Farms near Roseburg, said it was too early to tell how his peach trees handled the cold.

“This is definitely a situation where micro-climates played a factor,” he said. “There can be 3- to 4-degree temperature swings so there may or may not be damage to a crop depending on its location.”

Both Kruse and Brosi said there could be a silver lining for the stone fruit orchards that did suffer some damage and subsequent crop loss. That would mean less thinning of fruit would be needed at a later time.

“To lose a few is not a drastic deal,” Brosi said. “Thinning is expensive. It could almost be a good thing.”

“A lighter fruit set would mean less hand labor for thinning and that’s a major cost in peaches and apples,” Kruse said.

Renquist, however, explained that a tree will put more energy into its vegetative growth when it is not growing fruit. That will mean more pruning will eventually be needed.

Because fruit buds on pear and apple trees bloom about a month later than stone fruits, those trees were not advanced enough to be impacted by the extreme temperature changes. The growers also said their cherry trees were not affected.

“I don’t think it does us any good to be pessimists regarding the weather conditions,” Kruse said. “If we were, it wouldn’t do us any good to even put a seed in the ground. You just have to have a little bit of faith and some optimism.”



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