Fungus strikes area peach orchards

Peach leaf curl fungus, pictured next to healthy leaves, can be mistaken for insect damage.

Peaches and nectarines could be scarce this summer, thanks to wet weather that has made conditions perfect for peach leaf curl fungus.

According to Melody Young of Young's Orchard, close to 75 percent of her peach crop is gone. Young said much of the loss has been due to freezing this year during an unusually cool spring. In addition to temperature problems, however, a high rate of peach leaf curl has occurred.

“It's bad,” Young said. “It's probably worse than I've seen it. I think everybody's had that problem.”

Peach leaf curl typically affects orchards in areas with high rainfall, and according to Phil Hamm, plant pathologist for the Oregon State University Extension Service, it is rare in Hermiston.

“This is an abnormal situation in our area,” Hamm said, pointing out peach leaf curl on a peach tree in his back yard. “I've never seen it like this. In the Willamette Valley, if you had this problem you would lose the tree.”

In Hermiston, trees typically dry out too fast, leaving fungus little time to get established. With warm weather on the way, Hamm said the affected leaves, which look gnarly and feel waxy, will likely fall off and new leaves will grow back.

Trees will use more energy to produce leaves, according to Hamm, and fruit size and density could be affected.

“You'll have the potential to have smaller fruit,” Hamm said.

According to Young, the fungus can cause fruit loss as well.

“Sometimes it will weaken the tree and the peaches will fall off,” Young said.

The biggest problem with peach leaf curl is that by the time you know a tree has the fungus, it's too late to treat it. According to Hamm, preventative measures are the only way to address peach leaf curl.

Hamm said the key is to treat the trees with a lime-sulfur dormant spray three times: once in the fall, once in mid-winter and again in early spring. Hamm added that using a good fungicide is important.

Some residential shade trees have been hit with fungus this year as well, most significantly sycamore trees. Sycamore blight damages leafing twigs, forcing the tree to sprout new twigs in order to grow leaves.

Trees plagued by the fungus can be identified by a profusion of short twigs throughout the tree and a lack of leaves in the spring once other trees have leaved out. Hamm said the sycamores affected by blight will eventually grow leaves later in the season.

Hamm also advised that not all sycamores are susceptible to the fungus, and anyone wanting to plant a sycamore should plant blight resistant trees.

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