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Iowa’s white oaks dying from mysterious blight, drought
New testing tool will be used as part of pilot project
AMANA — For 10 years now, Iowa foresters have been watching century-old white oaks wither and die in just a few weeks.
Trees with no visible insects or fungus are dying on ravines and ridge tops across the Midwest. Foresters can do little more than cut down the majestic trees and harvest them quickly to beat the rot.
“A lot of the trees we’re seeing it on are 80 to 150 years old,” said Mark Vitosh, Iowa Department of Natural Resources district forester for seven Iowa counties, including Linn, Johnson and Iowa. “It’s very concerning.”
Other Midwest states, including Illinois and Missouri, also are trying to figure out what is killing their white oaks. But a new test kit — not unlike the rapid tests for COVID-19 — may help solve the mystery of the epidemic called rapid white oak mortality.
‘Why are they not more concerned?’
Tim Krauss and Sabrina Keiper are in charge of Iowa’s largest privately-owned timber land, 7,000 acres owned by the Amana Society.
The upland is mostly oak and hickory, the bottomland ruled by silver maple and cottonwood. Many of the trees date to when the Amana Colonies were established in the 1850s by German immigrants seeking religious freedom and communal living.
“When they first started, the whole property was managed by church society,” Krauss said. “They cut wood for firewood and buildings as they needed it.”
The Amana Society hired its first forester in the 1960s and has worked since then to develop forest management plans. But now the plan has gone out the window with the white oak epidemic.
“With this oak decline, we have two to three dead trees almost every other acre,” Krauss said. “We have to harvest the dead trees because we only have a year until they are no good. We can make our budget by just cutting dead trees. The downside is, they are not coming back.”
With the big trees gone, increased sunlight on the forest floor has caused an explosion of invasive species and less-desirable trees, like hackberry and elm, Krauss said.
Krauss led about 20 members of the Iowa chapter of the Society of American Foresters out into the timber Wednesday morning.
“You can tell from the crispier leaves the branches are dying,” he said, pointing up at a stand of white oaks.
Foresters agree climate change has played a role in the rapid decline of white oaks, with drought making the trees more vulnerable to disease or pests. The Amana trees also were hit by the Aug. 10, 2020, derecho.
“The most dominant trees seem to be the ones taking it on the chin,” said Joe Herring, an Iowa DNR forester based in Iowa Falls who visited the Amanas on Wednesday. He has seen dying white oaks in Eldora and other parts of north-central Iowa.
Sarah Bell, a district forester in Onawa, between Sioux City and Omaha, just east of the Missouri River, also is worried about rapid white oak decline.
“Why are they not more concerned?” she asked, referring to the community at large. “Seems like it’s just us.”
New tests a ‘game changer’
Help is on the way.
The U.S. Forest Service in collaboration with the Canadian Council of Forest Ministers is planning a pilot project with a new test kit that quickly can determine if a tree has oak wilt, a fungal disease traditionally hard to diagnose because samples can change by the time they arrive in a lab.
“You drill through the bark to get a little wood,” explained Tivon Feeley, the Iowa DNR’s Forest Health Program leader.
“It’s a DNA test that will tell us within about 5 minutes whether it’s oak wilt or not. If it’s negative, it stays clear or a golden color. But if positive for oak wilt, it turns a bright blue or purplish color.”
Iowa has been chosen to be part of the pilot, which means foresters will get thousands of kits next year to start testing white oaks. With aerial mapping, they can identify areas with a lot of dying trees.
“This really is a game changer for us,” Feeley said.
If oak wilt is confirmed, foresters can cut down that tree and possibly ones nearby to stop the spread. “We do see evidence that as we remove this tree, it does slow down,” he said.
There are remedies to treat oak wilt, but that only would be done at the residential level, not in a 7,000-acre timber land.
While the pilot project tests will be free, Feeley worries they will be costly in the future.
But there is a cost to doing nothing. Not only could the state lose another tree species, but white oaks are much more valuable than the trees taking their places. Krauss used a folding ruler to measure a fallen white oak he hauled out of the timber.
The tree, straight and with few blemishes, could get $5 per board foot for veneer. Some oaks could sell for more than $1,000. This is compared to hackberry, mostly used for pallets.
“Revenue will be good for the next 10 years probably, but once those high quality (white oak) trees are gone, it’s going to be a struggle,” Krauss said.
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