City Council passed an ordinance this month that is intended to reduce the spread of oak wilt throughout the city, which is killing thousands of San Antonio trees a year. The initiative, which was proposed by Councilman Joe Krier (D9) and unanimously approved by City Council, changed the brush collection yearly schedule in the part of the city most afflicted by oak wilt in an attempt to reduce the disease’s transmission.
“My concern is about quality of life and property value. If homes lose live oak cover, the value of that investment is substantially reduced,” Krier said. “It’s a potentially devastating economic impact. That also affects property tax rates, which can drop the city’s revenue.”
Between February and June, the disease spreads especially virulently. It primarily contaminates trees through cuts through the bark, so the intent of the ordinance is to make tree trimming more inconvenient during the most dangerous times. Generally, trimmings occur around the time of brush collection to save the landscaper money on transportation.
From now on, the northern part of the city will not have any City brush collection between Feb. 1 and June 30. The areas will still have collection twice each year.
Many of the oaks around the city seem timeless. Scientists say that the trees reach their maximum trunk width around the ripe age of 70, and some trees can live to more than one thousand years old. Oak wilt can end that lifespan in a matter of weeks. Once infected, trees generally die within two months.
San Antonio, which has tree cover of nearly 38% of its area according to American Forests in 2009, has more foliage than many American cities. The San Antonio River and the Edwards Aquifer create the last really lush environment north of the Rio Grande Valley, and live oaks have flourished within the city.
This issue is an unusual of example of environmentalists applauding Krier’s actions, considering his usual reservations because of the effect regulations have on business interests. Recent examples include his opposition to the Coal Tar Sealant Ban and his interest in shutting down the Office of Sustainability. It serves as a good example that when sustainability can combine with business, even usual opponents can become allies.
Krier, who served as president and CEO of San Antonio’s Chamber of Commerce for 20 years, said that oak wilt could reduce business from out-of-town visitors.
“In my role there, I greeted thousands of people who were visiting the city. The comment that was made more than any other was that they were surprised at how green it is,” Krier said. “People who come from out of state or country think of Texas as a John Wayne movie. If we jeopardize our green tree cover, we could also jeopardize our tourism industry.”
“All you have to do is go into the areas where oak wilt is affecting the city and see the canopy, especially the live oaks in the north part of the city,” said Mark Duff, a forester with the Texas A&M Forest Service,Castle Hills. “Hollywood Park, almost all of the trees that were there are oak canopies. The trees go from an asset to a liability because of the cost of removal and electricity to cool houses because of a lack of shade.”
The impacts can be enormous. In some of the subdivisions, up to 80% of their overstory are live oaks. When you lose those, the impact is huge because of the high percentage of live oaks.
The city’s Sustainability Plan formally recommends developing a “Street Tree Strategic Plan” to reduce heat island effects and make the pedestrian experience better,” which includes planting a huge volume of trees. In order to reach that goal, the city must more than account for the guaranteed coming losses from the disease.
The brush collection schedule may marginally help prevent oak wilt from advancing, but the problem shows no signs of abating. Drought, which is becoming more frequent and severe as a result of climate change, makes trees more vulnerable to it.
Homeowners play a larger role in restraining oak wilt’s expansion. Besides avoiding pruning between February and June, Duff recommends painting tree cuts with pruning or latex paint to stop the access point for the disease. Planting other Texas natives like Cedar Elms, Big Toothed Maple, or Mexican Plums are good alternatives. There are even disease resistant varieties of oak.
For more information, please visit the Texas Forest Service’s oak wilt website.