Tree News

Texas tree group issues dire warning to Austin owners of oak trees

Austin would be nothing without its live oaks.

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A nonprofit dedicated to trees is issuing a warning to Texas citizens who own oak trees: Put down the pruning shears.

Homeowners and landscaping types may be tempted to do some spring pruning, but when it comes to oak trees, now is not the time.

The reason: oak wilt, a devastating, incurable fungus that has been slowly spreading over a large part of the U.S. This tree disease is contagious and can kill an oak in as little as two weeks.

This is why Texas Trees Foundation is urging homeowners and business owners to NOT prune oak trees after February 1, and to refrain from pruning them between February 1-June 30. (Technically, this is a Dallas group, but officials helping homeowners in Austin warn of the same issue.)

Do not prune unless there is an emergency, and avoid wounding your oak trees during this time.

Oak wilt is an infectious disease caused by the fungus Bretziella fagacearum, which invades and disables the water-conducting system (xylem) in oaks. Beetles who carry the disease are attracted to bark damage or "wounds" where tree limbs have been removed.

All oaks can be infected. However, some oak species are affected more than others.

Most susceptible oaks
Red oaks: Members of the red oak group, particularly Texas red oak (AKA Spanish oak), shumard oak, blackjack oak, and water oak are most susceptible to the fungus and may play a unique role in the establishment of new oak wilt infections.

Live oak and Texas live oak are intermediate in their susceptibility to oak wilt, but are most seriously affected due to their tendency to grow with vast, interconnected root systems that allow movement of the fungus among adjacent trees.

White oaks: Members of the white oak group include post oak, bur oak, Mexican white oak, white shin oak, durand oak, lacey oak, and chinquapin oak. Although white oaks show some tolerance of the disease, all oaks can be infected by the fungus. White shin oak, lacey oak, and chinquapin oak can grow in stands with interconnected root systems, enabling the fungus to possibly infect adjacent trees that are susceptible to the fungus.

How to detect oak wilt
Foliar symptoms, patterns of tree mortality, and the presence of fungal mats can be used as indicators of oak wilt. However, laboratory isolation of the fungus is recommended to confirm the diagnosis. A certified arborist should be contacted when in doubt.

Foliar (leaf) symptoms on live oaks include:

Yellow veins. Leaves on diseased live oaks often develop chlorotic (yellow) veins that eventually turn necrotic (brown), a symptom called veinal necrosis. The most commonly seen foliar symptom on live oaks infected with oak wilt.
Vein banding. Vein banding is where the leaf vein is a darker green than the rest of the leaf.
Tip burn or margin burn, which turns the edges of the leaf brown.

Defoliation may be rapid, and dead leaves with brown veins often can be found under the tree for months after defoliation.

Patterns of tree mortality: Most live oaks defoliate and die within 3 to 6 months following initial appearance of symptoms. Some live oaks take longer to die, and a few untreated trees may survive many years in various stages of decline. Occasionally, a few live oaks in an oak wilt center may escape infection and remain unaffected by the disease.

Red oaks never survive oak wilt and often die within 4 to 6 weeks following the initial appearance of symptoms. During summer months, diseased red oaks can often be spotted from a distance because of their bright, autumn-like coloration in contrast to the surrounding greenery. This symptom is called flagging. So sad.

How to manage oak wilt
Awareness is important when identifying oak wilt. There are four primary approaches used for oak wilt management in Texas:

Prevent the formation of new oak wilt infection centers by eliminating diseased red oaks, handling firewood properly, proper timing of pruning, and painting wounds on healthy oaks.
Trenching or other measures to disrupt root connections responsible for root transmission of the pathogen.
Injection of the fungicide propiconazole into individual, high-value trees to help reduce crown loss and extend the life of the tree.
Plant other tree species to create diversity in the landscape and to mitigate the impact of oak wilt.

Successful control usually depends on an integrated program incorporating measures from all four approaches. These measures will not cure oak wilt but can significantly reduce tree losses.

How to slow the spread of oak wilt
Regardless of season, immediately paint all pruning cuts and other wounds to oaks. Any kind of wound dressing or paint can be used, and all are equally effective at preventing infections from fungal spores when applied immediately.

To repeat: Avoid pruning or wounding oaks from February 1-June 30.

Debris from diseased red oaks should be immediately chipped, burned, or buried.

When to prune
The least hazardous periods for pruning are during the coldest days in winter and extended hot periods in mid to late summer. The best time to prune oaks is during late fall.

Proper pruning techniques should always be used. These include making proper pruning cuts and avoiding injurious practices such as topping or excessive crown thinning. As a general guideline for pruning, clean all pruning tools with 10 percent bleach solution or Lysol between sites and/or trees.

The Texas Trees Foundation is a nonprofit tree planting organization dedicated to greening North Central Texas. Established in 1982, the Texas Trees Foundation manages the nation’s largest non-profit urban tree farm and plants trees on public property.

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San Antonio leads Texas on ending horse-drawn carriage rides by 2030

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Horses will no longer pull carriages on the streets of downtown San Antonio.

San Antonio has pulled off something that the rest of Texas has yet to do, but it didn't come without some contentious conversations. City Council has unanimously voted (with one abstention) to phase out the use of horse-drawn carriages over the next five years. That means by January 1, 2030, there will be none on the streets at all; instead, there will be electric carriages.

These plans have been in the making since 2022 — if not always at the same level of intensity — when District 2 Councilmember Jalen McKee-Rodriguez and District 3 Councilmember Phyllis Viagran wrote up some concerns about the horses' wellbeing. A special session at the end of October 2024 hinted to San Antonians that the end for this practice was neigh — sorry, nigh — and the final vote was made on December 12. In addition to accepting the plan, it extended its timeframe by two years.

The initial proposal included worries about the horses' exposure to traffic and pollution, as well how their presence might exacerbate those issues for the environment at large by slowing traffic. It also raised concerns about the effects of standing or walking on hard surfaces for too long, or spending time in extreme weather.

At the December 12 meeting, San Antonians gave impassioned speeches about animal welfare — both to call attention to the need for better conditions and to defend the reputations and jobs of current horse drivers — but it wasn't the first time the council heard from the public about the issue.

In a prior city survey, 50,476 respondents weighed in. Of those respondents, 51.98 percent said they liked the idea to "Transition horse-drawn carriages to electric carriages and pedicabs and ban horse drawn carriages completely." There were alternative solutions listed, but respondents were less drawn to them.

A cultural divide emerged in the data and continued in the December meeting: some people avoided the carriages because they worried about the treatment of the horses, while others enjoyed them because of their historical echoes and living legacy. Many speakers in favor of the plan used this to form their argument, raising questions about history versus progress.

More tangible objections to the plan hinged on the businesses — specifically five companies — and jobs that would be lost, which was the main factor behind extending the adjustment period.

Discussions about the particulars of the electric vehicles are still to come, as confirmed in the discussion near the end of the meeting. Councilmember Jalen McKee-Rodriguez addressed concerns about what would happen to the horses, mentioning the Brady Hunter Foundation as a future partner in finding them rescue homes.

Some council members also brought up rhetorical questions about animal exploitation by groups like Sea World, the San Antonio Stock Show & Rodeo, military and police forces, and even various groups in the Fiesta parade, although these did not come with a formal motion to pick the issues up.

This decision could have a ripple effect on other Texas cities. Dallas has recently considered a similar ban, but it appears to have stalled; Austin's attempts at a ban have been unsuccessful, but according to the Austin-American Statesman, only one operator is permitted to bring horses downtown. She declines to do so because the long hours are unfair to her and the horses. Houston does have horse-drawn carriages, and there seems to be little conversation about banning them.

Cities like Chicago and Salt Lake City have led the charge in the United States with some of the most prominent successful bans. Other cities around the world with bans include Brussels and Guadalajara, which both switched to electric models. Bans that have been around for years, like Guadalajara's and Prague's, still aren't out of the woods — people are still pushing back on the decision, so it sounds like San Antonio still has much work cut out for it.

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