Drought killing native trees
Foresters say the best ways to take care of trees is to water them weekly and use mulch.
By Miguel Liscano
AMERICAN-STATESMAN STAFF
Monday, August 31, 2009
When Sharon Drinkwine and her husband, Bob, moved into their new Sunset Valley home in October, she noticed the leaves on a large live oak tree in their backyard were looking a bit brown.
After a few days, she called a local forester who said the problem might be oak wilt, a fungus that blocks a tree's water conducting system. Within months, the oak was dead.
Though she consulted with seven different tree experts, none could say conclusively what killed the tree, Drinkwine said. But they did agree on one thing.
"The tree was definitely weakened by the drought," Drinkwine said. "We have other trees on the property and they're not looking all that great either."
Drinkwine's dead tree isn't alone.
Arborists and foresters say trees throughout Central Texas, even native species such as live oak and hackberry, have succumbed after being ravaged by the long drought and intense summer heat.
"I have not seen it to this extent in my lifetime," said Jim Houser of the Texas Forest Service. "We're even seeing cedars (Ashe junipers ) dying. They can exist on sunbaked, rocky plantscapes. And we're seeing them die all over the place."
Walter Passmore, the City of Austin's urban forester, said hundreds of the city's estimated 300,000 trees have died this summer. The city plans to cut down 49 trees in Zilker Park this month that officials say were killed by the drought.
And Don Gardner , an arborist who runs a consulting company in Austin, said he's had so many calls about sick trees that it's difficult to keep up with the work.
"Many of our well-established, well-adapted native trees are dying," Gardner said. "From last year to this year, it's really kicking in."
Houser said the death of a tree is usually attributable to a number of factors, sucha s disease and insects. Stress from the drought and heat is often the fatal blow, he said.
However, he said, many of the trees dying lately appear to have been in good condition.
"Apparently completely healthy, vibrant oaks are going down," Houser said. "There is just absolutely no water in the soil. There's just no water there."
To improve the health of trees, foresters recommend soaking them with about five gallons of water for every inch of trunk diameter each week. Houser said to apply water under the tree's canopy and do it slowly so it will soak in.
They also recommended spreading mulch in the tree's root zone to insulate soil, prevent evaporation and prevent harm from extreme temperatures. The mulch also reduces weeds and grass, so the tree will absorb more nutrients from decomposing organic material in the mulch, the foresters said.
Foresters say residents should look for insect infestations and bark falling off as signs that a tree is sick or dying.
Passmore said trees that die on city property are cut down and turned into mulch. Trees that die on private property in urban areas are typically cut down as well to avoid damage from falling over.
Back in Sunset Valley, Drinkwine said she's installed a rainwater collection system to help save her other trees.
And she said she's letting her dead live oak stand, for now at least.
"We really love the look of it," Drinkwine said. "So, we're going to plant wisteria around it, and vines."
mliscano@statesman.com; 246-1150