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Oak Tatters in Iowa: What is to blame?

Mark Vitosh

In recent years, many Iowans have noticed something strange happening to the leaves on their oak trees. The leaf tissue becomes brown or purple and shrivels up, making the leaves look ripped or torn. This condition is known as “oak tatters.” 

Oak tatters has been observed since the 1980s and documented since 1995, but the cause remains a mystery.

On this edition of Talk of Iowa, host Charity Nebbe talks with DNR forester Mark Vitosh about the impact of oak tatters on Iowa’s oak trees since 1995. Jesse Randall, Iowa State Extension Forestry specialist, and Bob Hartzler, Agronomy Professor at Iowa State, also join the conversation with their perspectives about what may be behind this condition.

One common theory is that herbicides may play a role. Together, Randall and Hartzler have conducted tests to see whether common herbicide acetochlor may be a cause.

They were able to induce oak tatters using levels of acetochlor commonly found in rainfall. However, while Randall believes that acetochlor is causing oak tatters in oak trees as well as below-ground impact on the roots of several other tree species, Hartzler feels that we need more study to establish definitive proof that this herbicide causes oak tatters.

Moving forward, both Randall and Hartzler hope for more research investigating the potential link between oak tatters and acetochlor.

"There has to be enough push that people realize that this is a serious issue," Hartzler says.

If you've noticed oak tatters in your area, you can share your information through this survey to help track impacted areas.