Metroparks Meetup: Battling oak wilt at the Metroparks

Fungal disease can kill 150-year-old trees in as little as 2 weeks
Published: Dec. 11, 2020 at 10:12 PM EST
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TOLEDO, Ohio (WTVG) - Generations of Toledoans have wandered through the towering oaks of the Metroparks, but it takes a lot of work to protect the Oak Openings region’s namesake from being wiped out.

“Oak wilt is a fungal disease that specifically targets oak trees,” says natural resources supervisor LaRae Sprow, “and if an oak tree is infected, it’s a 100% mortality rate.”

Some of these trees are over 150 years old, so it’s all the more impressive -- and sobering -- that certain trees, like red, black or pin oaks, could be killed in a span of weeks: “Anything in the red oak family will die within about two weeks, but mortality in the white oak family takes a bit longer -- usually 2 to 3 years.”

The fungus works fast, but the spread is slow -- either through “grafting” in the root system, or aboveground where beetles end up carrying it from tree to tree. Helicopter surveys are done in August and September, since it’s the best time to tell which trees are infected.

“From the air, we can see these dead oak trees very easily,” says Sprow, “so it’s the easiest way for us to survey the entire Oak Openings region -- we’re not just doing Wildwood Preserve.”

This week at Wildwood, crews have been working to cut away the infection using a “vibratory plow”: “What we have is a blade that goes 5 feet into the ground, and we essentially sever or cut the root system around any of the infected trees.”

Sprow says any scarring on the landscape is both minimal and temporary: “If you look at the plow lines, it’s not digging up the soil... it’s moving around almost like a sewing machine.”

In the springtime, some infected trees have “spore mats” or open cuts which attract beetles to the tree sap, allowing the fungus to hitch a ride.

“Any pruning that you’re doing to an oak tree,” Sprow suggests, “it’s really critical that it happens during the wintertime/dormant season, so we’re not wounding oak trees in the spring or summer.”

You can do your part in helping to preserve nature for future generations in the Glass City.

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