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Swamp White Oak PDF Print E-mail
Written by Dawn   
Wednesday, 10 February 2010 15:27

Small town, big swamp? 

I recently was out to see an old schoolmate and good friend of mine.  He lives in Clawson, Michigan and he has a mature stand of Swamp White Oak trees.  Clawson is a tiny city, pretty flat and is mostly small residential.  It is cool to find Swamp Oak trees in Clawson.  They are likely evidence of Clawson's old days.   My mom used to tell me that Clawson was built on a big swamp, which I believe is true.   Swamp White Oak trees are adapted to growing in water saturated soils, which contain low oxygen levels.  As their name implies they are found in areas with high levels of soil moisture. In the summer many swampy areas dry out.  This means that the tree has to be good at storing the water while it can to last it though long dry spells. This trait of growing in wet then dry soils gives them amazing adaptablity and allows them to do well in our suburban compacted soils. This is because compacted soils lack the large pore spaces which normally hold oxygen. This is the same effect as soil which has pore space full of water instead of oxygen.  City soil is usally dry because the soil is too compacted to absorb much water.  So you have the same combiniation of oxygen depleted anerobic activity and soil drought conditions.  Essentially the strong and stable Swamp White Oak tree is perfectly suited to swamp and suburban living.  It is one of the few pre-settlement, native tree species capable of adapting and thriving in such an extreme change in growing conditions.  The grouping of trees in Clawson is growing well in compacted soil conditions. I have one on my property - where it is growing in a seasonally flooded woodland with a high water table.  They all look great. 

This got me thinking abou the differences between the White Oak and Red Oak species.

White Oak differ from the Red Oaks in their health in various ways. 

White Oak heartwood is more dense than Red, making the White Oak tree stronger and a little less prone to breakage. 

White Oak are much more toleant than Red Oak species of fatal Oak Wilt disease.  When a Red Oak is infected by the Wilt disease, it is almost always fatal, with death ocurring in the same season as infection.  The White Oak however are often able to compartmentailze (or trap) the infection in that year's growth ring.  The tree can emerge the following year as healthy. 

White Oak are less likely to experience Iron nutrient deficiency.  Red Oak, especially Pin Oak are prone to a nutrient deficiency called Iron Chlorosis.  This clorosis occurs because the soil nutrients are in a molecular form that is unaccessible to the tree roots.   This typically occurs in compacted soils.  White Oak have adapted to growing in compacted soils as already mentioned previoulsy in this article.

White Oak are less susceptible to Oak Anthracnose.  This is a fungal disease which affects the folliage and growth of the tree.  The leaves turn brown and drop early.  The suscetibliy of the Red Oak to anthracnose versus that of the WHite Oak may possibly be related to nutrient deciency and soil pH as mentioned above.

White Oak are more prone to late Spring frost.  The buds are just emerging at this time and a hard frost can injure or kill the new growth.  Leaves may be small, distorted or off color or they may turn withered and black.  The tree must expend a lot of stored energy to put out new growth to replace this damage.  If this occurs year after year it can send the tree into decline.   

The one pest or health concern I did notice with these Clawson mature White Swamp Oak trees is the White Oak borer.  This beetle generally prefers White Oak trees of a small diameter, but my thought is that since there is no White Oak regeneration in Clawson (meaning no young or adolescent age trees) the borers are attacking all that is available - the large trees.  The beetle is not considered to be a major pest of White Oak, however it does cause some damage to the trees vascular system.  Most of the damage is done in the lower 12 feet or so of the trunk.  This document on the White Oak Borer is informative.  The picture of the beetle makes it look greenish - but it's actually light brown and brown. 

Woodpeckers are one of the best natural controls of the borer larva.  Encouraging woodpecker presence is a good natural defense.  I hate to prune out woodpecker homes when we remove the deadwood from Oak trees we are trimming.  I ask my climber to watch out for the nesting holes and retain them when possible.  Woodpeckers like suet and sunflower seend and their presence can be encouraged with bird feeders. 

The acorns from White Oak trees are favored over Reds by wildlife.  Squirrels and Blue Jay love the acorns.  Oak acorns are edible by people too. The taste is descrbed as much less bitter than the Red Oak acorns.  The acorn inviation for these hungry animals helps protect the tree from harmful insects- which are also on the menu.  Juvenal's Duskywing Butterfly

Northern Oak Hairstreak ButterflyThere are literally hundreds of insetcs that feed on Oak trees.  Some of the beneficial insects including various hairstreak butterfly and dusky wing butterfly. Some not so friendly insects that attack Oak trees include the gypsy moth, which can practically defoliate an entire tree and Leucanium Scale which feeds on the tree's sap, which weakens the tree.  The picnic beetle doesn't due too much harm itself, but it caries the pathogen for Oak Wilt disease.
Red and White Oak trees are strong hardy and long lived.  They have adapted in different ways to survive in many adverse environments.  Swamp White Oak is a species I feel deserves more merit and it currently under-utilized in our urban environments.
Understanding the unique needs of each species allows us to successfully chose the right tree for the right place.  Once you know what the tree likes and needs it becomes much easier to care for the tree using natural and organic methods.