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Trouble In Tree City USA: Storms, Disease Hit Suburban Trees

By Don Corrigan

There’s trouble in Tree City USA – and that means Tree with a “T” and that means Kirkwood and that means Webster Groves. And that means oaks, maples, elms, pines – and more.

Residents with mature trees in their yards have learned this summer that they don’t necessarily have it made in the shade. Their trees have taken a trouncing from storms, pests, rot, fungi – and more.

Perhaps the surest sign of this came on a July weekend when a microburst storm took down massive trees in the area. Earlier this spring, residents were sounding the alarm over pin oaks shedding yellow leaves.

“Trees are wonderful community assets, but they require some TLC and regular observation to determine care needs,” said Bill Ruppert, a Kirkwood horticulturalist and owner of National Nursery Products. “Homeowners are wise to invest in trees, but it’s also wise to keep up with your investments.”

Ruppert recommends tree owners have periodic tree health evaluations by a certified consulting arborist. These should check on presence of pests, nutritional needs and safety conditions related to limb and branch structure.

“We are learning so much now about the importance of putting thought into what kind of trees we plant in order to head off a lot of tree problems,” added Ruppert. “It’s important to think about site and diversity when planting trees.”

In regard to site or location, Ruppert said trees like pin oaks natively thrive in moist river valleys. They do not do so well growing in high PH urban soils containing limestone concentrations, a condition common to Webster Groves and Kirkwood.

He said the loss of leaves from pin oaks earlier this year could be an indication of location stress. Or, the loss could be evidence of overactive squirrels that love to chew on leaf stems and branches as they build their nests in the trees.

In regard to diversity, Ruppert said planting a variety of trees can prevent a die-off from becoming a disaster. The recent emerald ash borer attack on ash trees illustrates this.

For example, extensive planting of ash trees in the past on Gateway Arch grounds has proven very problematic with the arrival of ash borers. A diverse stand of trees would have meant less tree damage and rehabbing of the grounds.

Kirkwood’s Greentree Festival

Kirkwood residents may be surprised to learn that their annual Greentree Festival was founded in 1961 in response to an epidemic of Dutch elm disease. Many trees were lost in the city.

Residents were encouraged to plant trees to replace those being lost with trees sold at the fair for $1. Today many of those trees are mature and grace the lawns and streets of Kirkwood.

“We periodically get a wave of tree losses for various reasons: elms lost to DED fungi, pines and spruces lost to pine wilt, needle cast and tip blight diseases, ash trees now being lost to borers,” said Bill Spradley, owner of Trees, Forests and Landscapes in Kirkwood.  “What will be the next wave?”

Spradley said the next wave could be related to climate change. He said Missouri falls are getting warmer and drier because of changes taking place across the American continent.

Warmer, drier periods will be especially hard on pin oaks, because their native habitat involves rich, wet, acidic river bottomlands.  This problem is also apparent for river birch.

Climate change also seems to be bringing more windstorms and microburst storms into the area. These could be especially hard on red maples and are always hard on non-native Bradford pear trees. Some of the larger pin oaks also are vulnerable.

Spradley has a couple of recommendations about trees that are in ill-health because of root decay fungi, beetles such as the Emerald Ash Borer or weather damage: Take them down now.

“It’s always better to take them down when there’s some life left in them,” said Spradley. “It’s dangerous, if not impossible, to climb on a tree and take it down when it’s dead or brittle. That will always cost more as well.”

Spradley also said that when replacing the tree, look for varieties that are native and that will thrive well in the particular location under consideration.

High On Oaks

Spradley, Ruppert and other tree lovers such as Robert Weaver of Glendale’s Gateway Gardener, Carol Davit of Grow Native, Wayne Lovelace of Forrest Keeling Nursery and Guy Sternberg of Starhill Forest Arboretum – are all high on planting oaks.

They have produced a pamphlet entitled: “Plant an Oak! (But not a Pin Oak!).” Oaks native to Missouri are better adapted to the challenging conditions of urban and suburban sites with disturbed soils.

They recommend replacing dying trees with cherrybark oaks, northern red oaks, nutall oaks, overcup oaks, chinkapin oaks and more … but not pin oaks.

They add that in the spirit of planting for diversity, many other tree genera beyond oaks should be considered. However, oaks deserve priority when considering shade trees in this area.

For those residents still encountering yellow leaves dropping from their pin oaks, Spradley recommends sending samples to the experts for diagnosis. This kind of examination is available for many plants sick for various reasons.

The University of Missouri Plant Diagnostic Clinic (PDC) has been serving Missouri since 1965. Clinic staff are available year round to receive leaf samples for identification of insect damage or plant pathologies.

To obtain a Plant Disease Identification Form write Plant Diagnostic Clinic; 28 Mumford Hall; University of Missouri; Columbia, Missouri 656211. More information also is available at http://plantclinic. Missouri.edu.

For a selection of qualified professional arborist talent, consult with the St. Louis Arborists Association, which can be found at http://www.stlouisarborist.org.

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