Habitable forest under siege as invasive species kill trees


Kate Henderson has been preoccupied for a year. The active gardener and member of the Kingwood Garden Club got worse last summer when she noticed several of her red oleander trees were withering and turning brown and then dying.

“At first I thought it was because of winter frost,” she said, but then noticed it was just one type of tree.

Her angst led her to call Mickey Merritt, the Texas A&M Forest Service’s urban and community forestry program manager, for help.

Merritt visited his one-acre lot in Kingwood and brought in an entomologist from the Austin Forest Service and confirmed it was a fungal disease called laurel wilt.

The news was devastating and not what she had hoped for.

“It’s these tiny little beetles called Asian red oleander beetles, and they carry this pathogen, the fungus. As soon as the beetle enters the tree, biting, chewing its way, it immediately infects the tree,” Henderson said.

The reaction is a kind of scrubbing of the tree so the water can’t move up or down and makes the leaves look like they’re withering, starving the tree until it turns brown and dies as fast as a few weeks, she explained. .

“I had 17 trees cut down, and on Monday they are coming back for 12 more,” she said disappointed with the result.

Henderson said she learned that once they were infected there was no cure to save them.

Merritt had even more devastating news that the fungus could proliferate with mixed root systems infecting nearby red oleanders.

And now she notices that her sassafras tree is also infected with the same fungus, and therefore in the same genus as oleander.

Henderson, who is fully involved in the issue, said it seemed to her that Kingwood Drive was the epicenter right around Kings Forest and spread throughout the Greenbelt.

She holds the dubious honor of being the first reported case in Harris County.

Currently, there is no burning ban in Harris County, although there was one prior to recent rains complicating the eradication effort.

“You shouldn’t remove them from the property because they will spread. The entomologist recommended grinding the trees so that they dry out faster and the beetles dry out. I don’t want to be responsible for spreading it,” she said.

Henderson said during visits to friends she saw him in the Conroe, Liberty and Dayton areas.

“It’s going everywhere now,” she said.

The gardener said she took the shredded wood and spread it along her walkways to help with the drying process.

“Burning would have been ideal, but not that many trees,” she said.

The invasive fungus is native to Asia and was introduced in 2002 to the state of Georgia through packaging materials, according to Merritt.

“It slowly spread throughout the southern United States. Most of our southern states have laurel wilt due to the red ambrosia bark beetle,” Merritt said.

The A&M program manager for the urban and community forestry program said he was considering fungicide injections, as they occasionally use with oak trees.

“I don’t want to say they’re promising, but they do in some trees,” he said.

“The moment the beetle enters the tree, it is very effective at distributing the fungus throughout the tree. With oak wilt, the tree may already be infected. But if you catch it in time, you can prevent it from spreading all over the tree and save the tree. With that, it spreads so quickly that once the beetle is there and it deposits thousands of spores in the tree once it chews it, it’s hard to control it with the fungicide,” said Merritt said.

A pre-systemic injection of the tree to help prevent the beetle from entering the tree, he said, might be something to watch, but not a sure bet it would save the tree. You would also need an arborist to do the job.

Tree removal, chipping and labor can be expensive.

“I think if you suspect something like this is going on with their tree, it’s good to call A&M foresters and they’ll confirm if it’s laurel wilt.” Really any red oleander dying in Kingwood right now is disease related,” she said.

She stressed that this should be done responsibly to prevent the spread.

“I’ve developed good muscles,” she laughs after hauling 241 wheelbarrow loads of wood chips.

Henderson is a member of the Kingwood Garden Club and has held the annual tree sale for 22 years in November.

“He was my baby and it hurts me a little to have lost so many of my people,” she said.

If the loss of nearly 30 trees wasn’t painful enough, the plants in his garden that were once sheltered by the shade provided by the trees are now being ravaged by the setting sun.

“There are more consequences with the sun now burning some of these plants and a higher electricity bill,” she said from the loss of shade on the house.

Henderson hopes the City of Houston will help control these unsightly trees in rights-of-way that are affected by the disease.

“You can see them going up and down Kingwood Drive. Unfortunately, it is Kingwood that is heavily impacted along with 15 other Southeast Texas counties,” Merritt said.

As for prevention, Merritt recommended keeping trees as healthy as possible and monitoring them.

“If they see the disease, the best thing to do is remove the tree as soon as possible to prevent the spread,” he warned.

Merritt said he had not seen any studies showing adverse health effects in humans or animals.

The true beetle is microscopic and only two millimeters long.

“They are so good at spreading disease that it only takes one beetle to bring down the whole tree,” he said.

He also warned that the beetles normally attack stressed trees, but the red ragweed borer will also attack a healthy tree.

“I think they’ve been in Kingwood longer than we think. It’s just that they’ve finally hit numbers that we’re noticing and homeowners are seeing their trees die,” he said.

The shocking reality is that Merritt said they wouldn’t cut down a dozen trees, or even a hundred, but literally thousands in an infected area.

“They have a limited distribution centered along the San Jacinto River and Spring Creek corridor, where red berries are prominent,” he said. Switch to Katy and the probability is considerably less.

“No red oleander there unless they have avocado trees that are in the same oleander family,” he said.

Merritt’s recommendations to owners are to diversify.

“There are a lot of houses with red berries and a strong natural population in the green belt. When people consider planting or replanting, consider a diversity of species, not a majority of one genus or family of trees. With diversity, the damage will be much less,” he suggested.

To learn more about beetles and bay wilt, email Merritt at [email protected] To reach Henderson and hear his advice, email him at [email protected]

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