Megan | ISA Texas Chapter

How vegetation can counter the urban heat island effect
COLLEGE STATION, Texas — Cities across Texas have endured record temperatures this summer, and it’s not solely the weather that’s to blame.
Developed areas often experience higher temperatures than nearby rural areas when green spaces are replaced with roads, parking lots and large buildings that retain more heat during the day than natural landscapes.
Areas in these microclimates of a highly developed city, known as urban heat islands, can be up to 20 degrees warmer than surrounding areas that are more rural, according to Climate Central, a nonprofit news organization that analyzes and reports on climate science.
“This prolonged extreme urban heat is a serious threat to our local environment, our public health and our quality of life,” said Mac Martin, Texas A&M Forest Service Urban and Community Forestry Program Partnership Coordinator.
In addition to air and surface temperatures, contributing factors for urban heat islands include heat generated from vehicles and machinery, buildings, road surfaces and even human bodies.
Even at night, urban heat islands retain the day’s heat.
“Because these surfaces are holding onto that heat during the day, cities are unable to cool off at night, even in the winter,” Martin said. “This prolonged exposure to warmer temperatures, even if it’s not necessarily warm outside, is forcing us to experience what was once considered long-term effects of the urban heat island at a quicker pace.”
Martin said urban heat is the nexus of potential issues within an urban environment, with higher temperatures affecting water quality and human health and comfort.
“It truly is like a trickle-down effect, starting with electricity consumption,” said Martin, noting that as communities rely more on air-conditioners to maintain a comfortable temperature, energy grid operators may be forced to resort to brownouts or blackouts to prevent system overloads.
That increase in energy consumption has a direct relationship to increasing air pollution and greenhouse gas emissions.
“The pollutants are harmful to human health but they also contribute to really complex air quality problems including things like ground-level ozone, fine particulate matter and even acid rain,” Martin said.
Those issues contribute to an increase in asthma and other respiratory problems.
Heat islands promote higher daytime temperatures, reduce nighttime cooling and increase air pollution levels, which all contribute to heat-related deaths and heat-related illnesses. Heat islands also intensify the impact of naturally occurring heat waves.
Older adults, young children, people who work outside and people with health conditions are most likely to suffer health problems related to heat islands, and the impacts are unequally distributed across income levels.
“I don’t think it’s any great secret that low-income housing can be in some of the most environmentally inhospitable places within an urban area, with little to no greenspace and increased exposure to air pollution, flooding and other risks,” Martin said. “Those risks are exacerbated by the urban heat island and are putting these communities at an even higher risk.”
Urban heat islands also have direct negative impacts to water quality.
“High temperatures of pavement and the rooftop surfaces can heat up stormwater runoff, which drains directly from our streets into our storm sewers and is deposited unfiltered into the rivers and streams and even drinking water reservoirs as well,” Martin said.
The warmer runoff impacts the biodiversity of streams by limiting the oxygen available, meaning less capacity for life within our streams.
“Several studies have found that urban streams are hotter on average than streams in rural areas and that temperatures in urban streams can rise over 7 degrees during just small, regular storm events due to the heated runoff from urban materials,” Martin said.
The benefits of trees
The good news is that the solution to some of the effects of urban heat islands may be as close as the nearest tree.
“Truly, one of the best defenses for our existing infrastructure is utilizing our urban forests, trees and vegetation to help cool the environment,” Martin said.
Larger expanses of trees can improve air circulation, creating a communitywide cooling effect while also acting as sinks for harmful pollutants.
“Trees are effective air filters by design,” Martin said, “filtering out not only gases that are harmful to us but that are harmful to the Earth’s ecosystem as a whole.”
Mature trees can release hundreds of gallons of water as vapor every day through their leaves, cooling the air. Shaded areas can be between 20 to 45 degrees cooler than peak temperatures in unshaded areas.
Connor Murnane, Texas A&M Forest Service District Forester who manages the W.G. Jones State Forest, said many visitors to the forest see it as an oasis in the urban setting.
The 1,700-acre property draws about 80,000 visitors to its shaded trails each year. It lies within Montgomery County and is surrounded by the growing cities of Conroe and The Woodlands.
A lot of the development has come in the past 10 to 15 years, Murnane said, creating what he called a “concrete jungle” of neighborhoods, apartment complexes, businesses and retail centers surrounding the forest.
Murnane said the forest helps absorb some of the effects of that growth, including water runoff.
“As these non-permeable surfaces like concrete, asphalt, things like that get built up around the forest, all that water that was once being filtered through the ground … now has to go somewhere else. Typically, the Jones (State Forest) catches most of that,” Murnane said.
Murnane said most of the visitors to the forest come for an escape from the hectic pace of their lives and to reconnect with nature.
“It’s one of the few places like it left within Texas, if not the nation,” Murnane said. “Some of the oldest trees are over 100 years old, contributing to an extensive canopy.”
That canopy creates cool zones in the forest.
“In the shaded areas of the forest, you’re looking at temperature differences of at least 20 degrees cooler underneath the shade than you would be out standing on pavement or in a parking lot somewhere,” Murnane said.
Solutions that work
Murnane said the cities of Conroe and nearby Shenandoah have taken an active role in offsetting the effects of urbanization by committing to planting and maintaining trees. Both cities are certified through the Arbor Day Foundation’s Tree City USA program. Nearly 100 cities across the state participate in the program.
“Embracing that idea of maintaining and preserving and improving their urban tree canopy is critical to offsetting the urban heat island effects. Especially as cities develop and are ever-growing, the most important bit of that being maintaining what they do have,” which includes how they adapt to things such as invasive species, Murnane said.
“I would say that those cities that are making strides to commit to maintaining their urban tree canopy are really doing a good part to help offset the urban heat island effect,” Murnane said.
Jaime González, Houston Healthy Cities Program Director for The Nature Conservancy, said the organization has found success in forming partnerships to use nature-based solutions to work for healthier communities and aid in urban resiliency.
One partnership with a coalition of government agencies and research institutions, including the National Oceanic and Atmospheric Administration, used a group of community scientists equipped with heat sensors attached to their vehicles to collect data for a detailed heat map of parts of Houston and Harris County.
“In particular, we really wanted to showcase disinvested communities and communities of color,” González said. “And now that information is openly available and free for the public to use.”
That heat-mapping project in 2020 identified Gulfton in southwest Houston as the city’s hottest neighborhood.
“It’s a large immigrant community that is perhaps the most diverse community in the state. It is very dense by Texas standards, and it’s a community that has many strengths and leadership and beautiful people, but it has relatively little nature compared to other neighborhoods, particularly tree canopy,” González said.
On the August afternoon the heat-mapping survey was done, Gulfton was 17 degrees hotter than the coolest place measured in the county.
A pilot project to introduce nature-based solutions to the neighborhood will begin in the fall, with tree plantings and a forestry strategy.
The Houston Healthy Cities program is also working with a coalition of groups to try to bring shade to Houston bus stops, and is working with an architecture firm to create a model for a next-generation schoolyard at a preschool in the Alief neighborhood, another disinvested community.
The design includes more than 4 acres of prairie wetlands and over 200 trees.
“The whole campus is designed to absorb more water, to reduce mowing cycles and to be cooler,” González said. “We need to manage whole landscapes differently, including school campuses.”
González emphasized the importance of maintaining the existing tree canopy, along with the thoughtful placement of trees and diversity of species for the best results.
“There are some places where kids gather to play with no shade,” González said. “It makes the whole playground a lot less accessible during the summertime to kids who may not have an opportunity to travel elsewhere. So strategic placement of shade, including trees, is really important in places like bus stops, playgrounds and places where people gather.”
The nonprofit Texas Trees Foundation has also established partnerships with various groups and agencies to help further its mission of planting trees and protecting the urban forest across North Texas.
The 40-year-old group’s programs include initiatives to connect students and teachers to nature while planting trees at Dallas school campuses, transform the Southwestern Medical District’s streetscape into a tree-lined parkway, and provide opportunities for community members, homeowners associations and other organizations to design tree-planting projects for their neighborhoods.
Those programs originated from a 2017 urban heat island management study for the city of Dallas that found the city was getting warmer than every city in the country except Phoenix.
That study identified a lack of tree canopy at Dallas schools and the Southwestern Medical District, said Rachel McGregor, Texas Trees Foundation Urban Forestry Manager.
“It is about putting the right tree in the right place, especially in urban areas,” McGregor said. “You want that tree to make it over time.”
The 2017 study also led to the formation of an urban forest master plan, which was unanimously adopted in 2021 by the Dallas City Council.
Lannie McClelen, Program Manager for the Southwestern Medical District project, said the work isn’t a standard streetscape.
“We want to change things up and create a different model,” McClelen said.
Part of that model relies on data delivered by street-level thermal sensors, which will be used to create models for design solutions that will favor pedestrians.
“They’re going to tell us what’s happening at the pedestrian level,” McClelen said. “We want to be able to influence the microclimate for pedestrians. Where we place benches, where we place food tables will be done based on science and not aesthetics.”
The group’s school campus project, a partnership with Dallas ISD, is about more than trees, McGregor said, and includes walking trails and outdoor classrooms.
“We’re trying to mitigate urban heat while connecting a human health aspect to it,” McGregor said.
McGregor and McClelen said the key to such projects is working in partnerships.
“We’re always having conversations with people in different areas,” McGregor said. “Providing good, research-based information for a successful tree-planting is important.”
McClelen recommended starting with an inventory of existing trees.
“Many, many schoolyards do not have a single tree, and that would be a great place to start,” she said.
For more information about Healthy Trees, Healthy Lives, visit healthytreeshealthylives.org.
For more about Texas Trees Foundation, visit texastrees.org.
For details about the W.G. Jones State Forest, go to tfsweb.tamu.edu/jones-state-forest.

Texas A&M Forest Service contacts:
Mac Martin, Urban and Community Forestry Program Partnership Coordinator, Texas A&M Forest Service, mac.martin@tfs.tamu.edu, (979) 458-6650
Connor Murnane, District Forester, Texas A&M Forest Service, connor.murnane@tfs.tamu.edu, (936) 273-2261
Jaime González, Houston Healthy Cities Program Director for The Nature Conservancy, jaime.gonzalez@tnc.org
Darren Benson, Communications Specialist, Texas A&M Forest Service, darren.benson @tfs.tamu.edu, (979) 458-6649

Only mid-way through June and Texas has already seen extreme heat and very little rain this summer, with the trend predicted to continue. The anticipation of drought can bring many thoughts to mind from water shortages to increased wildfire risk, but what do drought conditions mean for our trees?
Drought is defined by a relatively long duration with substantially below-normal precipitation, usually occurring over a large area, and Texas is no stranger to drought. According to the US Drought Monitor, in 2011 more than 80% of Texas experienced exceptional drought conditions. This drought killed an estimated 300 million trees, 5.6 million being urban shade trees.
According to experts at Texas A&M Forest Service, tree fatalities occur during a drought because drought is a significant stress to trees.
“A stress is anything that reduces the capacity of the tree to function efficiently and grow vigorously,” said Karl Flocke, Texas A&M Forest Service Woodland Ecologist. “Stresses are things that can affect growth, nutrient uptake, the ability of the tree to photosynthesize and ultimately the ability of the tree to defend itself against pathogens – things like heat, cold, predation from animals, insects and diseases – a number of different things.”
Drought alone may not kill your trees, though it could be the tipping domino of tree mortality and should be cause for concern.
“Most trees usually die from a combination of different stresses,” said Courtney Blevins, Texas A&M Forest Service Urban Forester. “One of the biggest stresses we see in Texas is drought. When that happens, stresses build up and secondary pests or diseases can establish in trees.”
Secondary pests and diseases are those that attack a tree that is already stressed by something else, such as a drought or a winter storm. Hypoxylon and most boring insects are considered secondary pests and diseases – with the exception of the Emerald Ash Borer, which attacks both healthy and stressed ash trees.
When a tree is already stressed, then these types of insects and diseases will increase and according to Blevins, these secondary insects and diseases not only increase during the time of drought, but for years after a drought or other large stressor event has ended as it takes time for trees to recover.
Drought-stressed trees
So, what happens to trees during a drought? Ultimately, the lack of water causes trees to photosynthesize less, or make less food, which leads to a lack of nutrients needed to survive.
“Plants generate their own food though photosynthesis and one of the key components of photosynthesis is water,” said Flocke. “Water is necessary for the chemical reactions that create sugars, it’s also necessary to help move the needed materials around in the tree and finally, to utilize those materials.”
Without water, a tree cannot generate sugars and cannot utilize those sugars – a necessary part for the entire process of tree growth. When this happens, trees will start to show physical symptoms of the lack of nutrients. While these symptoms can vary from species to species, most trees will begin to show signs of water stress through their leaves.
“The things to look for on your tree are leaves dropping or wilting, small or malformed leaves, yellowing of the leaves and browning tips of the leaves,” said Blevins. “Some species, like junipers, may totally brown out, losing all of their leaves.”
Just because leaves begin to fall from your tree, does not mean the tree is dead though. For small trees, you can simply use your thumb nail and scrape some of the smaller twigs – if there is still green underneath, then the tree is not dead. Within a few weeks, it may leaf back out. If you are concerned your tree is dead, contact a certified arborist for a professional opinion.
Reducing tree stress
The most helpful way to reduce stress to your tree during drought conditions is to give supplemental water – though the amount and how often you water will depend on your specific tree and area.
“Watering is going to depend on the tree; the size, species and age of the tree as well as the soils you have in your area,” said Flocke. “If you have established trees that are well-adapted to your location, it’s very likely that they might not need supplemental water at all. But I would monitor them to look for signs of stress.”
If you begin to see signs of stress in your trees and the ground under your trees is extremely dry, it’s time to begin watering. To test the dryness of the soil, you can take a long screwdriver and stick it in the ground. If the screwdriver doesn’t go easily six to eight inches into the soil, it’s time to water.
“Start by watering the area around the canopy of the tree,” said Flocke. “Not just at the base of the tree and not just around the edge of the dripline but water the entire area underneath the canopy of the tree until the point where you have water start pooling and running off the surface.”
Watering can be done with a water hose, soaker hose, sprinkler or bucket – each way being efficient so long as the tree is getting the water it needs. A good guideline for the amount of water your tree needs is two to three gallons per one inch trunk diameter. See the video here.
According to Blevins, a general rule of thumb for newly planted trees during the heat of the summer is to water them up to three times per week, in the absence of precipitation. Though, you want to make sure the soil is not completely saturated with water at all times.
Larger, established trees may not need much water at all but extremely high temperatures and lack of precipitation may warrant watering them every couple of weeks.
When watering your trees, adhere to any water use restrictions you may have in your area and try to maximize the water you do give.
“The most important thing is to avoid watering during the heat of the day because much more water is going to be lost in evaporation,” said Flocke. “Either early in the morning or later in the evening is the best time to water.”
An easy tip for watering trees during a drought is to try and mimic what a typical summer looks like for your trees, watering every 10 days to two weeks and knowing that it’s okay to not be on a set schedule – just like normal summer rain.
Another way you can help your trees manage drought stress is by mulching. Mulch is an easy and inexpensive option to help your trees because it conserves water, regulates soil temperatures, reduces competition from other plants and improves soil health.
“In general, apply a layer of mulch no more than two to three inches deep,” said Flocke. “In reality, the entire area under the canopy could be mulched, but mulching out several feet around the base of the tree, being sure not to let the mulch touch the base of the trunk, will help.”

Avoiding tree stress
During times of drought, be extremely cautious not to add additional stresses to your tree, making them more susceptible to secondary insects and diseases. First, do not prune your trees unless absolutely necessary.
“What you’re trying to do is reduce stress to the tree, so pruning, even when you have to, is adding stress because you are wounding the tree,” said Blevins. “If you’re pruning out live branches or live leaf areas of the tree, you’re removing food and the site where the tree’s root growth hormone is developed, affecting root growth and further stressing the tree at a time where it’s already too stressed.”
According to Blevins, the exception to pruning trees during drought is a completely dead branch or one that is a hazard to its surroundings.
Another common mistake that can be harmful to your trees during a drought is putting out fertilizer.
“Just generally applying fertilizers without knowing if there is a deficiency is a really bad idea,” said Blevins. “If there is not a nutrient deficiency then it’s not going to help anything and it can actually hurt things and make the tree worse.”
During the summer heat, and especially when experiencing drought conditions, monitor your trees for stress symptoms, adding supplemental water when necessary, and continue to enjoy the values that trees add to our lives.
“Trees provide an enormous value to us in our landscape,” said Flocke. “Keeping trees, especially near our homes, can help to reduce overall energy bills, keep us healthier and provide shade for the house. If we lose those trees, we potentially lose benefits that have taken decades to accumulate.”
For additional information on caring for your trees during drought conditions, visit https://tfsweb.tamu.edu/afterthestorm/Drought/
Stay informed on drought conditions in your area by visiting https://tfsfrd.tamu.edu/ForestDrought/
To contact a certified arborist, visit http://isatexas.com/for-the-public/find-an-arborist/

COLLEGE STATION, Texas — The presence of the invasive emerald ash borer (EAB) was confirmed this week in Wise County. Wise County will be added to the list of Texas jurisdictions under quarantine by the Texas Department of Agriculture (TDA) – the third county added this year. TDA quarantines are designed to slow the spread of the insect pest by limiting the transportation of ash wood, wood waste and hardwood firewood.

On May 25, Texas A&M Forest Service collected an adult beetle specimen in southern Wise County and tentatively identified it as EAB. The beetle was collected in an EAB trap that is part of a state monitoring program run by Texas A&M Forest Service each year.

The specimen was sent to the USDA Department Animal and Plant Health Inspection Service (APHIS) national lab for confirmation and was confirmed as EAB.

“EAB is an invasive wood-boring pest of ash trees that has caused significant impacts across the eastern United States,” said Demian Gomez, Texas A&M Forest Service Regional Forest Health Coordinator. “The pest is a significant threat to urban, suburban and rural forests as it is very aggressive, killing ash trees within two or three years after they become infested.”

The beetle was first detected in Texas in 2016 in Harrison County. Since then, EAB has been positively confirmed in Bowie, Cass, Dallas, Denton, Marion, Wise, Parker and Tarrant Counties.

Each year, Texas A&M Forest Service sets traps and proactively monitors for the pest.

“Since 2018, we have deployed nearly 500 traps across Central, East and North Texas annually watching for the insect’s presence and movement,” said Gomez. “Early detection of the beetle is the best way to stop the spread and avoid high ash mortality.”

Ash trees with low numbers of EAB often have few, or no external symptoms of infestations. However, residents can look for signs of EAB among their ash trees including dead branches near the top of the tree, leafy shoots sprouting from the trunk, bark splits exposing s-shaped larval galleries, extensive woodpecker activities and D-shaped exit holes.

Once the presence of EAB is confirmed in a county, TDA assumes regulatory responsibility which includes the establishment of quarantines. The state’s mandatory quarantine by TDA, restricts movement of any woody ash material exiting the county or quarantined area.

“Because EAB is transported unintentionally on firewood and wood products, the quarantine helps slow the beetle’s spread by restricting the movement of wood in and out of affected areas,” said Gomez.

Communities and residents can find available resources on identifying EAB infestations and creating a community preparedness plan at: http://texasforestservice.tamu.edu/eab/.

COLLEGE STATION, Texas — The presence of the invasive emerald ash borer (EAB) was confirmed May 2, 2022 in Parker County. Parker County will be added to the list of Texas jurisdictions under quarantine by the Texas Department of Agriculture (TDA). TDA quarantines are designed to slow the spread of the insect pest by limiting the transportation of ash wood, wood waste and hardwood firewood.

On April 26, Texas A&M Forest Service collected two adult beetle specimens from a private residence in Hudson Oaks, Texas and tentatively identified them as being EAB. The specimens were sent to the USDA Department Animal and Plant Health Inspection Service (APHIS) national lab for confirmation.

“EAB is a destructive, non-native wood-boring pest of ash trees,” said Allen Smith, Texas A&M Forest Service Regional Forest Health Coordinator. “The pest is a significant threat to urban, suburban and rural forests as it is very aggressive. Ash trees may die within two or three years after they become infested.”

Native to Asia, forest health experts have been monitoring EAB movement across the United States since 2002. It has spread to more than half the states in America, killing millions of ash trees. The beetle was first detected in Texas in 2016 in Harrison County in northeast Texas. Since then, EAB has been positively confirmed in Bowie, Cass, Denton, Marion, Parker and Tarrant Counties.

Each year, Texas A&M Forest Service sets traps and proactively monitors for the pest.

“Since 2018, we have deployed nearly 500 traps across Central, East and North Texas annually watching for the insect’s presence and movement,” said Smith. “Both healthy and unhealthy ash trees are susceptible to EAB attack and have no natural resistance to the exotic insect. Without proper proactive measures, mortality can be 100% in heavily infested areas, so early detection could improve our chances to manage for the pest.”

Texas A&M Forest Service urban tree canopy inventories estimate that ash trees comprise approximately 5% of the Dallas/Fort Worth urban forest and approximately 1% of the standing inventory forests in East Texas.

“There is no known stop to this epidemic,” said Smith. “But we can help communities minimize loss, diversify their tree species and contribute to the health and resiliency of their urban forests.”

Texas A&M Forest Service works with communities on state quarantines of the movement of wood into and out of impacted areas. There are resources available to help affected communities identify signs of EAB infestation and can assist in making decisions about preventative measures they can take and how to handle tree management and removal.

Texas A&M Forest Service Contacts:
Courtney Blevins, Urban Forester in Fort Worth, 817-879-3974, cblevins@tfs.tamu.edu

Allen Smith, Regional Forest Health Coordinator, 903-297-5094, lasmith@tfs.tamu.edu

Prevention is key to stopping the spread of oak wilt, said Demian Gomez, Texas A&M Forest Service regional forest health coordinator. Any new wound, including from pruning, construction activities, livestock, land or cedar clearing, lawnmowers, string trimmers and storms, can be an entry point for the pathogen that infects trees.

“With wounds being the best entry point for the disease, landowners should avoid pruning or wounding trees from February through June,” Gomez said. “And no matter the time of year, to decrease the attractiveness of fresh wounds to insects, always paint oak tree wounds.”

How it spreads
Oak wilt is caused by the fungus Bretziella fagacearum. The fungus invades the xylem – the water-conducting vessels of the trees – and the tree responds by plugging the tissues, resulting in a lack of water to the leaves, slowly killing the infected tree.

During this time, oak trees that died may produce spore mats under the bark. The fruity smell from these mats attract small, sap-feeding beetles that can later fly to a fresh wound of another oak tree and infect it, starting a new oak wilt center.

The second way oak wilt can spread is underground by traveling through interconnected root systems from tree to tree. Oak wilt spreads an average of 75 feet per year by the root system.

All oaks are susceptible to oak wilt. Red oaks are the most susceptible and can die in as little as one month after being infected.

Live oaks show intermediate susceptibility but can spread the disease easily due to their interconnected root systems. The interconnected root systems in live oaks are responsible for most tree deaths and spread of oak wilt in Central Texas. White oaks are the least susceptible, but they are not immune to infection.

Oak wilt is often recognized in live oaks by yellow and brown veins showing in leaves of infected trees, known as venial necrosis. Currently, it may be difficult to diagnose due to seasonal transitioning of oak leaves in the spring – when evergreen oak trees shed their old leaves while simultaneously growing new leaves.

The signs can be seen on a majority of leaves when a tree is fully infected. Landowners should contact a certified arborist if they are unsure if their tree is infected.

“For red oaks particularly, one of the first symptoms of oak wilt is leaves turning red or brown during the summer,” said Gomez. “While red oaks play a key role in the establishment of new disease centers, live oaks and white oaks move oak wilt through root grafts.”

How to fight
To stop the spread of oak wilt through the root system, trenches can be placed around a group of trees, at least 100 feet away from the dripline of infected trees and at least 4 feet deep, or deeper, to sever all root connections.

Another common management method is fungicide injection. The injections are only a preventative measure to protect individual trees. The best candidates for this treatment are healthy, non-symptomatic oaks up to 100 feet away from symptomatic trees.

Other ways to help prevent oak wilt are to plant other tree species to create tree diversity in the area; avoid moving oak firewood before it is seasoned; and talk with your neighbors about creating a community prevention plan. Infected red oaks that died should be cut down and burned, buried or chipped soon after discovery to prevent fungal mats that may form the following spring.

Not only is saving oak trees important for our ecosystem and health, but oak wilt can also reduce property values by 15-20%.

Some cities and municipalities, including Austin, Lakeway, Dallas, Fort Worth, Houston, San Antonio and Round Rock, have programs in place with municipal foresters dedicated to managing the disease. Texans can also contact their local Texas A&M Forest Service representative with any questions about this devastating disease.

For more information on oak wilt identification and management, visit https://texasoakwilt.org/ or Texas A&M Forest Service’s website at https://tfsweb.tamu.edu/.

By Allen Smith

It’s not a complicated device: just some purple plastic, coated with glue and baited with a clear pouch containing a lure– but this emerald ash borer (EAB) trap is a scientifically-designed instrument and serves as our first line of defense against EAB infestation. Since 2011, Texas A&M Forest Service entomologists have been placing these traps in ash trees across Texas looking for the emerald ash borer. The trap is known as a purple prism trap and is designed to catch adult EAB after they emerge in the spring. A specific shade of purple is used as it has been proven to be effective in attracting female buprestid beetles. The female EAB equate the purple color with the appearance of an ash tree trunk where they lay eggs. Male buprestids, including EAB, are more attracted to a green color which is something that these visual insects would except to see in a tree canopy.

Traps are held in the open position by a pot metal spreader to which raising/lowering lines are affixed as well as the EAB lure. Emerald ash borers, being visual creatures, do not use pheromones to locate mates as extensively as other insects such as bark beetles for example. EAB lures are clear pouches containing z-3 Hexenol, an alcohol compound used to mimic the volatile smells given off by ash foliage.

Traps are coated with a very sticky glue that persists the length of the 120-day trapping season. Swarming, aggregating, and mating EAB become entangled in the glue and cannot escape. Traps are hung in ash trees throughout the target county and checked after 60 days to see if any EAB have been caught. At this time, a new hexenol lure is attached and trapping resumes for another 60 days. After 120 total days of trapping, the traps are checked again for EAB and then removed from the locations. Traps in counties where EAB has been reported, are checked weekly. All caught EAB are removed and labelled with date of collection and trap name. Collected samples are then sexed to determine the emergence timing of males vs. females and the opening and closing of the adult flight period window.

Since the confirmation of the emerald ash borer, Agrilus plannipennis, in Tarrant County (2018) and Denton County (2020), interest in EAB management in the Metroplex has increased. The Texas A&M Forest Service has been on the lookout for this most destructive forest pest since 2011 when 300 EAB traps were deployed in areas of east Texas with notable ash populations. This year, approximately 500 EAB traps will deployed across Texas to provide a measure of early detection. Most of the traps will be scattered throughout east Texas with almost 40 traps covering the Conroe/Houston/Galveston area. Traps are already deployed for 2022 along the I-35 corridor from San Antonio to the Metroplex. Dallas, Denton, Tarrant and surrounding Metroplex counties will host approximately 100 EAB traps. Traps will be located in parks, cemeteries, natural areas, and on rural private lands that contain a sizable ash tree population.

If you have any questions about emerald ash borers, EAB trapping or EAB management, please contact your local Texas A&M Forest Service office.

As a homeowner, it’s your job to care for and protect your property, but home insurance companies offer policies that can help you with the protection part. Tree damage may not be the first thing that comes to mind when choosing coverage levels for your homeowner’s insurance, but if a tree falls on your home, it can damage your house and your possessions and cause financial devastation. The endless ‘what if’ scenarios can feel overwhelming, but as far as tree damage is concerned, it’s best to pick coverage rooted in caution and practicality.

Much like the Lorax speaks for the trees, we’ve outlined preventative measures you can take to care for or remove trees and protect your property from tree damage. We’ve also outlined scenarios where your home insurance might or might not cover damage caused by trees. Understanding the nuances of a standard homeowners insurance policy could help ensure you know what is covered if a tree wreaks havoc on your property and what damage you might be responsible for out of pocket.

Does homeowners insurance cover tree damage?

Whether or not a homeowners insurance policy covers tree damage depends on the situation. In order for the damage to be covered, the cause of the tree falling must be due to a covered peril. Many homeowners know they can usually file a claim if a tree damages a covered structure, but you may not know that many home insurance policies also cover at least some portion of damage to the actual trees, shrubs or plants, as long as the damage was caused by a covered peril.

So if a tree falls in your yard but does not damage your home or any other structure on your property, some portion of it may be covered by your home insurance policy. According to the Triple-I, this type of coverage will generally be capped at a certain percentage of your dwelling coverage limits. It’s important to note that most home insurance companies will not pay for tree or shrub removal, except in some cases where it is blocking a driveway or handicap access.

Every policy is different, however, so you should consider speaking with your insurance agent about what is and is not covered in your policy — before tree damage occurs.

Tree damage causes typically covered by home insurance:

Tree damage causes typically not covered by home insurance:

Does homeowners insurance cover tree removal?

Homeowners insurance typically covers the removal of trees if they have fallen due to a covered peril and onto a covered structure, like your house, or if the tree is blocking an access point. Some situations where tree removal may be covered are:

Situations where tree removal is not covered under your insurance policy should be carefully considered. If your home hasn’t been damaged by a fallen tree, but you want to preemptively remove trees on your property, it is unlikely to be covered — and could even have negative consequences.

For example, if the person responsible for removing the tree is injured during the process, you may risk legal repercussions as the property owner. Bodily injury liability is one of the more infrequent causes for insurance claims, but can be one of the most costly. From 2015-2019, according to the Triple-I, bodily injury and property damage was the second severest homeowner’s insurance claim, costing an average of $29,752.

Insurance companies consider your justification for tree removal to determine if it will be covered. They will likely not cover the removal if you’re worried about your yard aesthetic and find the tree unsightly. If an insured structure was hit, insurance providers may reimburse you for tree removal up to a specified dollar amount, usually ranging from $500-$1,000. If a covered structure was not hit, your insurance company is unlikely to pay for its removal, except, possibly, in the circumstances mentioned above. It’s important to check your policy and ask your agent to determine your exact coverage.

What to do when someone else’s tree damages your property

A standard homeowners insurance policy should cover a tree that falls on your house, regardless of who owns the tree.

In some cases, the insurance company may try to collect the money needed to cover the damage from the neighbor’s insurance company in a process called subrogation, which may also cover the deductible for the homeowner whose property was damaged.

However, if your neighbor’s tree has not fallen on your house, but it’s encroaching on your property, do you have the right to cut it?

Usually, it depends on whose yard has the tree trunk. If your neighbor’s tree branches and leaves cover portions of your yard, but the tree trunk is in his yard, it belongs to your neighbor. In that case, your local laws or HOA governance will likely determine whether overgrown trees that encroach on your property must be maintained by their owner.

Tree removal in these cases can lead to disputes between you and your neighbors who have differing opinions on the matter. Your HOA may get involved, or worse — your neighborhood Facebook page could become the battleground for the tree removal debate.

Another risky ‘what if’ is if your tree is damaging your neighbor’s property. It could cost you and your insurance provider to compensate for the damages, not to mention your reputation in the neighborhood. That’s why regular care and maintenance of your trees is typically a good idea.

How much to expect from the insurance company

The payout from your insurance company after tree damage depends on several factors, including what type of property was damaged. If a covered peril causes damage to your house, you may be eligible to receive up to the limit of your policy’s dwelling coverage, depending on how much damage was done.

You can usually also file a claim for your personal belongings, if they were damaged, up to certain limits. Different categories of possessions have individual limits and high-value items may not be covered at all, unless you have added them with scheduled personal property insurance. You can choose to increase these limits, but it will likely cause your homeowners insurance premium to go up.

If the tree itself that caused damage to your home was valuable, you might also be able to file a claim to replace it. As mentioned earlier, not all policies will cover the actual tree, and the ones that do will likely have certain coverage caps in place, so you will need to look at your policy or speak with an agent to see how much is covered.

Once a claims adjuster creates an estimate for each claim category, the insurance company subtracts your policy deductible from the amount you receive. Many homeowners insurance policies also cover some living expenses, such as hotels, up to certain limits if your home is uninhabitable while the damage is repaired.

How to prevent tree damage

It is your responsibility as a homeowner to maintain your trees properly. Damage caused by dead or rotting trees is not likely to be covered by homeowners insurance, and if a tree owned by you causes damage to someone else’s property or person, you might get sued. Here are a few things you can do to prevent trees from causing damage to structures and property:

Frequently asked questions

What is the best home insurance company?

Finding the best home insurance company depends on a lot of factors. It is a good idea to compare quotes from some of the top home insurers in the country using criteria like customer service scores from J.D. Power, financial strength ratings from AM Best and average premiums. Not every homeowner has the same needs, so it is smart to look at several options and speak with a licensed insurance professional.

Does homeowners insurance cover diseased tree removal?

Diseased tree removal is generally considered routine maintenance and is not typically covered by a standard homeowners insurance policy. It is your responsibility to track the health of your trees and treat them when needed.

If a falling tree damages my roof, will that be covered by homeowners insurance?

A roof can be expensive to replace, but most standard policies will cover tree damage to a roof if the following perils caused it:

In most cases, roof damage from a tree felled by floods or earthquakes is not covered. It is a good idea to purchase a separate policy to cover these perils if you live in an area prone to either. Note that insurance companies will typically only cover your roof if it is in good repair. If you are unsure of the specific coverages included in your policy, turn to your agent or insurance company for clarification.

Do trees add value to my home?

Arbor Day Foundation finds that planting trees in residential areas can increase property values anywhere from three to 15 percent. Trees can really spruce up a neighborhood and appeal to potential buyers.

Removing dying or rotting trees can also increase the value of your home by eliminating that risk for future residents, according to Realtor.com. Remember that the cost of removing trees, even if diseased or rotting, is considered routine care and maintenance and is usually not covered by insurance.

What types of trees are the safest?

It’s typically a good best practice to select trees that don’t forget their roots — literally. If you’re considering planting a tree or evaluating the type of tree on a property you’re looking to buy, look for healthy, strong roots. Bonus points if the tree is relatively low-maintenance.

Some of the best trees for this can include oaks, maples, hickories and elm trees, according to Realtor.com. You might want to consult with a landscape expert to determine what trees are the best for your climate and property type.

What types of trees can’t be trusted?

Simply put, trees that ain’t from ‘round these parts are better avoided. Experts advise picking trees best-suited for your environment and considering their native location. For example, non-native tree types like black locusts and box elders, native to the Southeast and Central/East regions, generally wouldn’t thrive in the desert climate of the Western U.S., according to Realtor.com.

It’s also usually a good idea to avoid trees that attract invasive species of insects or trees with invasive roots. These types of trees can bring unwelcome visitors to your home or shift the foundation of your house entirely.

Again, speaking with an ISA Certified Arborist or landscape professional might be the best idea to determine what trees are right for your home.

Oak wilt is one of the deadliest tree diseases in the United States, killing millions of trees in 76 counties of Central, North and West Texas, and we can help prevent it from spreading.

Prevention is key to stopping the spread of oak wilt. Any new wound can be an entry point for infection including those produced by pruning, construction activities, livestock, land or “cedar” clearing, lawnmowers, string trimmers and storms.

“With wounds being the best entry point for the disease, landowners should avoid pruning or wounding trees from February through June,” said Demian Gomez, Texas A&M Forest Service Regional Forest Health Coordinator. “And no matter the time of year, to decrease the attractiveness of fresh wounds to insects, always paint oak tree wounds.”

Oak wilt is caused by the fungus Bretziella fagacearum. The fungus invades the xylem – the water-conducting vessels of the trees – and the tree responds by plugging the tissues, resulting in a lack of water to the leaves, slowly killing the infected tree.

All oaks are susceptible to oak wilt. Red oaks are the most susceptible and can die in as little as one month after being infected. Live oaks show intermediate susceptibility but can spread the disease easily due to their interconnected root systems. White oaks are the least susceptible, but they are not immune to infection.

Oak wilt can spread two ways – above ground or underground. The disease is spread above ground more rapidly this time of year, in late winter and spring, because of high fungal mat production and high insect populations. During this time, red oaks that died of the disease last summer and fall may produce spore mats under the bark. With a fruity smell, these mats attract small, sap-feeding beetles that can later fly to a fresh wound of any oak tree and infect it, starting a new oak wilt center.

The second way oak wilt can spread is underground by traveling through interconnected root systems from tree to tree. Oak wilt spreads an average of 75 feet per year by the root system. This occurs primarily in live oaks and is responsible for the majority of spread and tree deaths in Central Texas.

Oak wilt is often recognized in live oaks by yellow and brown veins showing in leaves of infected trees, known as venial necrosis. Currently, it may be difficult to diagnose oak wilt due to seasonal transitioning of oak leaves in the spring – when evergreen oak trees shed their old leaves while simultaneously growing new leaves. The signs of oak wilt can be seen on a majority of leaves when a tree is fully infected. Landowners should contact a certified arborist if they are unsure if their tree is infected.

To stop the spread of oak wilt through the root system, trenches can be placed around a group of trees, at least 100 feet away from the dripline of infected trees and at least four feet deep, or deeper, to sever all root connections.

Another common management method for oak wilt is through fungicide injection. The injections only protect individual trees injected and best candidates for this treatment are healthy, non-symptomatic oaks up to 100 feet away from symptomatic trees.

Other ways to help prevent oak wilt are: plant other tree species to create a variety in the area; avoid moving oak firewood before it is seasoned; and talk with your neighbors about creating a community prevention plan for oak wilt. Infected red oaks that died should be cut down and burned, buried or chipped soon after discovery to prevent fungal mats that may form the following spring.

Not only is saving oak trees important for our ecosystem and health, oak wilt can even reduce property values by 15 to 20 percent.

Some cities and municipalities, including Austin, the City of Lakeway, Dallas, Fort Worth, Houston, San Antonio and Round Rock, have oak wilt programs in place with municipal foresters dedicated to managing the disease. Texans can also contact their local Texas A&M Forest Service representative with any questions about this devastating disease.

Demian Gomez, Regional Forest Health Coordinator, Texas A&M Forest Service, 512-339-4589, demian.gomez@tfs.tamu.edu

Red imported fire ants (Solenopsis invicta) have a unique ability to cling together and form a floating raft whenever their underground tunnels flood. This raft can hold together and carry the colony for weeks or until the water recedes. These ants have a hydrophobic cuticle, and the cuticular texture creates an air bubble. These tightly knit bodies create a buoyant, water-resistant foundation for a floating raft. While other species of ant can float on top of water due to their hydrophobic cuticle, Solenopsis invicta is one of few species to exhibit rafting behavior. This behavior is one of many that aid in its successful dispersal.

Ant rafts have a constantly changing shape, and are made up of structural and surface ants. Structural ants are those that pack close together to keep the colony afloat, while surface ants march freely on top of the raft. The queens and eggs are safely tucked in the middle. The everchanging raft shape is caused by a behavior called “treadmilling”, where structural ants circulate to the surface of the raft, while free-walking surface ants burrow into the lower structural levels. Together, this cycle contracts or expands the raft, allowing for the construction of a narrow bridge that branches away from the body of the raft. These extensions are built to help raft riders “feel around” their environment and reach out for land or another such surface where the colony can safely disperse.

There is still a lot left to learn about ant rafting. One study created a series of models in which simulated ant individuals had to follow a simple set of instructions to carry out successful rafting behavior. Researchers hope that understanding rafting behavior and creating successful models will provide inspiration in the design of autonomous active systems such as swarm robotics.

Here is a short video to help you to water your tree.

Don’t wait until the leaves are brown and falling off!