Rapid Decline of Post Oak Trees

Rapid Decline of Post Oak Trees

Post Oak trees arguably have the most sensitive roots of all the native trees I deal with in Robertson County.  I have seen many Post Oak trees dying around the county.  Some in yards some in pasture, some in wooded areas.  With Post Oak trees it is important to know that any root disturbance at all can cause very fast and often irreversible damage that most often leads to death.  Most often the death is rapid, but in some cases, it may drag on for several years.

Another form of stress in Post Oak trees is caused by extreme dry and extreme wet conditions.  This year was a historically wet year.  Once the rain shut of the end of June it has been followed by one of the driest July and August on record.  Remember Post Oak roots are easily damaged.  So, the extreme wet weakened the roots and the extreme dry conditions just add to the problem.  Post Oak trees do not like to have wet feet for a prolonged time.

We also have a fungal pathogen called Hypoxylon Canker that attacks weakened Post Oak trees.  When these Post Oak trees with weakened roots are attacked by the Hypoxalon Canker the tree will quickly turn yellow then within a few days turn brown.  At this point nothing can be done to save your tree.  The fungus is very fast moving when it hits an area.  You will normally see several trees in an area affected.  People often say it was green one day and brown the next.

You may ask “What can I do to save my trees?”  The unfortunate answer is once you see the tree turn yellow it is too late.  Currently there is no cure for the disease.  The only prevention measure available is to water the trees if possible, during drought conditions.  Especially when going from very wet to very dry.

Watering the stressed trees properly is very important as well.  A good deep watering over several hours is the suggested method.  Do not water every day but rather a deep slow watering once a week to ten days.  The watering can be done in yards but unfortunately is near impossible in pastures and heavily wooded areas.  I wish there was more that could be done but unfortunately there is not.

 

Additional information: EPLP-033 – Rapid decline of Post Oaks in Texas

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