Iowa's Bur Oak trees under attack - KWWL - Eastern Iowa Breaking News, Weather, Closings

Iowa's Bur Oak trees under attack

DES MOINES (KWWL) -- One of the most identifiable trees in Iowa is being attacked by a newly named disease that the DNR says causes more problems than the emerald ash borer or the gypsy moth.

Bur oak blight, which has been in Iowa since the early 2000's, is already killing trees.

Symptoms include a v-shaped, brown discoloration of leaves and browning veins in July and August.

Trees usually die after the fourth or fifth year, usually from a secondary pest.

Infected bur oaks tend not to drop leaves in the fall like a healthy tree.  The infected leaves stay on the tree and infect the healthy leaves that grow in the spring.  The disease continues to progress slowly until the leaves start browning in late summer.

Bur oak trees are native to all 99 Iowa counties and more than half of the counties have bur oak blight.  It is also killing oaks in southwest Wisconsin, southern Minnesota and eastern Nebraska.

To have leaves tested for the disease, send samples to Iowa State University's Plant and Insect Diagnostic Clinic. Information on how to submit samples is online at

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