Oak Wilt

Oak trees are one of the more popular and commonly planted landscaping trees.  This great species is also a staple of the natural American landscape.  However, oaks can easily succumb to a disease known as oak wilt.  In recent years, this disease has destroyed a significant number of oaks in the Central Texas area.  In order to prevent oak wilt, it is important to understand the disease – its origin and how to treat it.

Although it is not the number one disease that kills oaks, oak wilt it is considered the most commonly known.  It is caused by a fungus known as Ceratocystis fagacearum.  The disease manifests itself through fungal spores that invade an oak and clog its water conducting system.

The disease is spread through two primary agents:

One is through beetles which feed on the sap of oaks.  Beetles frequently carry oak wilt spores to non-infected oaks and introduce the pathogen through a fresh wound.  The wounds may be caused by a number of factors, including wind damage or inappropriate trimming.  However they may exist, wounds must be appropriately treated in order to decrease the chances that an oak will succumb to the effects of oak wilt.

Introduction of these spores by insects may also lead to the second agent frequently responsible for spreading the oak wilt.  Once an oak is affected by fungal spores, the possibility for a continued, rapid spread of the disease to other oaks exists through an interconnected root system.  Severing the root system of affected trees from other localized, unaffected trees is the only means by which to prevent the continued spread.

There is no known cure for oak wilt, so prevention is key.  For instance, there are specific times of year when pruning an oak is more ideal.  Pruning during the extremely hot, dry summer months is beneficial, as there is a decreased spore production during this time period.  Conversely, pruning during the extremely cold winter months is equally beneficial due to a reduced amount of insect activity.  Additionally, should an oak have one, immediate treatment of a fresh wound may prevent spore contamination and preserve the life of the tree. This can be accomplished using pruning paint. Taking several, very achievable steps can lessen the chances that an oak becomes affected by the disease.

Oaks are a valuable landscaping commodity in Central Texas. Their value can be maintained through knowledge of oak wilt and some forethought of preventative care.

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