Sunday, May 20, 2012

Hardwood Trees after the Drought

Some parts of Texas remain under an extreme drought, but here in Southeast Texas, we in The Woodlands Texas are only "dry". After several years of low rainfalls and extreme summer heat, our trees have been severely stressed. Under stress, the trees are vulnerable to disease. One such disease that takes advantage of this opportunity is a fungus called  Hypoxylon canker1. I had three trees alive with this disease for 14 years in my yard. In the 14th year, we had our severe 2011 drought, which killed all three trees. One hardwood, a Sweetgum, was killed from the disease 5 years ago. One killed in 2011 was a Red Oak (probably from Oak Wilt disease) and another was a Sweetgum. Now in 2012 another Sweetgum has died. All these hardwoods first lost top branches and decay set in at the top, gradually killing from the top down. After the trees die, the condition continues in the wood and behind the bark, revealing itself with obvious signs as in the photo below. Treating this condition is very difficult. Preventing the disease from continual advancement is accomplished by plenty of water. So extreme drought accompanied by extreme heat, creates just the right conditions to cause this fungal disease to thrive.
Note the black condition inside the bark 

Bark falling off the tree about a year later after the kill
The Texas Forestry Service predicts a loss between 100 million and 500 million trees in Texas from the 2011 drought2. That is a lot of trees! The impact from disease remains unknown. We will experience that this year and beyond! Certainly I am an example of the consequences of the drought on our hardwoods.

1 Hypoxylon Canker and Oaks, East Texas Gardening
2 Texas Forestry Service - Second phase of Drought Assessment