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Saturday - June 12, 2010

From: North Liberty, IA
Region: Midwest
Topic: Diseases and Disorders, Trees
Title: Leaf problems on oaks in North Liberty IA
Answered by: Barbara Medford


My oak trees (young and old) are showing leaf problems. Is there a disease or insect causing oak tree disease?


There are whole books written on pests and diseases of oak trees. In our Native Plant Database there are 78 species of the genus Quercus (oak) native to North America, 14 native to Iowa. In Johnson Co., Iowa you are in USDA Hardiness Zone 4b to 5a. Some of the oaks that are native to Iowa would burn up in Texas, and the Texas oaks would likely have freeze damage in Iowa. Without information on what oak, how old it is, what the leaf symptoms are and how long it has been going on, we couldn't even begin to guess. When we googled "pests and diseases of oak trees," we got a lot of results. We are going to send you links to a few of them so you can look at pictures and read descriptions, which might at least give you a start on identifying problems and treatments, if any. The best and most accurate help can come from the Iowa State University Extension Office for Johnson County. Whatever the problem is, it probably won't be the first time they have heard of it, and they may even have printed materials on what to do.

treehelp.com Oak Trees

USDA Forest Service Sudden Oak Death

gardenguides.com Pests and Diseases of Oak Trees

We are going to give you a list of members of the Quercus  genus native to Iowa, and pictures of some of them.  This doesn't necessarily include the trees you have; there are hybrids, the trees sometimes do their own cross-breeding, and you may have trees from another area. 

Members of Quercus Genus Native to Iowa:

Quercus alba (white oak)

Quercus bicolor (swamp white oak) - pictures

Quercus ellipsoidalis (northern pin oak) - pictures

Quercus imbricaria (shingle oak) - photos and more information

Quercus macrocarpa (bur oak)

Quercus marilandica (blackjack oak)

Quercus muehlenbergii (chinkapin oak)

Quercus palustris (pin oak) - photos and more information

Quercus prinoides (dwarf chinkapin oak) - photos and more information

Quercus rubra (northern red oak)

Quercus rubra var. ambigua (northern red oak)

Quercus rubra var. rubra (northern red oak) - photos

Quercus stellata (post oak)

Quercus velutina (black oak)

From our Native Plant Database:

Quercus alba

Quercus macrocarpa

Quercus marilandica

Quercus muehlenbergii

Quercus rubra

Quercus rubra var. ambigua

Quercus stellata

Quercus velutina




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