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Posts Tagged ‘ganoderma’

By Jacob Murphy
Communications Coordinator

“You can always tell a tree person just by the way they walk down the street,” said Dr. William Fountain, Extension Arboriculture Professor at the University of Kentucky, “Most folks are looking down when they walk. They look at their phone, the sidewalk, their feet, etcetera. But a tree person always has their head tilted up towards the tree tops.” 

Dr. William Fountain is the Extension Arboriculture Professor at the University of Kentucky

I’m embarrassed to admit it, but I’ve never really thought in depth about trees.  Sure, I’ve climbed trees, read a book under a tree, raked leaves from a tree, collected firewood from a tree, etc., but until recently I hadn’t taken the time to understand the effects of trees and the impact they have on our lives.  Trees are like people;  they live, they grow, they die… and sometimes, just like people, looks can be deceiving.  I got the opportunity to tag along with Dr. Fountain and the city’s Forestry team during an inspection of trees managed by Metro Parks and it opened my eyes, to say the least.  

 “It looks healthy,” I said naively, “There are no dead limbs and there are even buds starting to appear.”

“Just because it looks healthy, doesn’t mean it is,” said Kevin Bold from the Division of Forestry, “Trees really are like people. They can be ill with a disease and no one would know until they were examined and diagnosed.”

The tree we were looking at had been diagnosed with a disease called Ganoderma. Ganoderma, which is often referred to as “Ganoderma butt rot,” is a tree disease that kills a tree from the inside out.  Once a tree is infected with Ganoderma the fungus begins to digest the wood, making it soft and sponge like.  Over time, the wood – so important for providing the strength necessary to hold the canopy upright – becomes  increasingly likely to fall during any sort of mild to severe weather, meaning high risk for injury to folks or homes that are nearby, in the event the tree would fall.

A parkway tree taken down due to Ganoderma. You can see the lines where the fungus had begun to digest the wood.

Unfortunately, there is no cure for Ganoderma.  It is a disease that we see after trees have been subjected to environmental stress, and we have had plenty of that in recent years, said Fountain. We have had a number of droughts and these are mature trees in confined growing conditions.  Unlike trees growing in a natural environment our urban trees are forced to grow in areas where their roots are confined.  The airborne spores that cause the disease are everywhere and it spreads by infecting any wounds trees may have.

Displayed above is a sample of wood taken from a tree infected with Ganoderma. The wood becomes very weak and spongy.

Fredrick Law Olmsted, often considered the father of American landscape architecture, designed our parks and parkways. The pin oak was the species most commonly used in the Olmsted design and it seemed an obvious choice at the time.  The tree is easy to transplant and grows fast.  It gave a nice canopy cover for carriages and later, automobiles, as they moved through our city.  While lining the parkways with similar tree species of similar age creates an aesthetically pleasing visual, we have learned a lot about tree biology since Olmsted’s day and we now know that it is unwise to landscape with just a single species or with trees of all the same age because, typically, plant diseases spread only between closely related species. 

As with all other living organisms, trees eventually succumb to old age.  This happens a little more quickly when drought and the urban environment cause the trees to become stressed.  As you see trees disappear from our urban landscape, you will notice that they are being replaced with a diversity of different species.  This makes for a healthier urban forest and more interesting city.  This diversity of species will support an even greater number of wildlife species than we currently have.

“We have found 15 pin oaks in the past year that have been infected by Ganoderma,” said Landscape Manager, Dr. Mesude Duyar Ozyurekoglu, “Unfortunately, if a tree doesn’t have 30% or more of dense healthy wood, it has to come down.”

Displayed above is a tool used to measure tree density. A tiny (non-damaging) hole is drilled into the trunk of the tree, and the tool can sense how dense the wood is and indicate the density onto slips of pressure sensitive paper.

“Are we replacing the trees we take down?” I asked.

Mesude replied, “Yes, but not immediately.  The soil takes time to replenish nutrients after tree removal. And while we can take trees down year round, it’s best to plant trees during the dormant season – in the fall after leaf drop or early spring before budbreak.”

Mesude and her forestry team are responsible for over 15,000 trees in the parks and along the parkways in the city.   Metro Parks spends about $600,000 on the maintenance of these trees in an attempt to keep up with the damaging effects of storms, invasive pests, disease, neglect and age.

James Bruggers, environmental writer for the Courier-Journal, wrote an article in October of 2011 about the poor health of Louisville’s trees and the lack of effort there seems to be to protect and preserve the city’s urban canopy.  Bruggers mentions that Margaret Carreiro, a University of Louisville biology professor who has been studying Louisville’s trees with her students for 10 years,  estimates there are still as many as 3 million trees in the city’s residential areas alone. So, if $600,000 is barely enough for every 15,000 trees the city has, what would it take to provide sufficient care for Louisville’s entire urban canopy?

On November 11, 2011, Mayor Fischer announced the creation of the Louisville Metro Tree Advisory Commission with the goal to plant more trees and take better care of existing ones.  This is tremendous for tree health in Louisville, but the tree commission will need support from citizens to be effective.  Louisvillians have to make our city’s tree canopy a priority, or our future won’t have one. 

The Tree Commission will help in:

  • Advising city leaders on issues affecting Louisville’s urban forest;
  • Providing input in the selection and placement of trees on all city-owned property and public developments;
  • Educating the community and departments and agencies of Louisville Metro regarding the value of trees and proper ways to plant, maintain, and remove trees;
  • Serving as an advocate for the ongoing renewal of Louisville’s urban forest;
  • Creating a public tree fund with private donations;
  • Monitoring and gathering data and publishing reports about the status of Louisville’s tree canopy.

With no offense intended for our canine friends, it is often said that a city without trees isn’t fit for a dog.  Trees add scale to our urban infrastructure.  They provide shade on our hot summer days and cool and purify the air that we depend on for life.  We only seem to notice these giants as they begin to decline and leave our city.  The trees that we are losing were a gift to us from previous generations.   The best way for us to thank our great grandparents is to provide our grandchildren and their children with a healthy and beautiful urban forest… and the knowledge that these gentle giants hold must be cared for.  Trees are like people, our companions, and they deserve our appreciation. Have you thanked a tree today?

(It would not have been possible to write this article without the help and support of some kind and talented people, to only some of whom it is possible to give particular mention here. A special thanks goes to Dr. Fountain for his wisdom and guidance. Also, Mesude Duyar Ozyurekoglu for allowing me the opportunity to shadow her Forestry team. I would also like to thank Kevin Bold, Mike Blankenship and the entire Metro Parks Forestry Division for their never-ending hard work.)

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