October 30, 2021 New Orleans, La.
The Louisiana Iris Conservation Initiative (LICI) has completed their Chinese tallow tree eradication project for 2021 on the US Fish & Wildlife Services Bayou Sauvage National Wildlife Refuge in New Orleans, La. It is estimated that 3,000 - 4,000 Chinese Tallow trees were killed by a small group of LICI volunteers working throughout 2021 using the "hack and squirt" method.
LICI volunteer, Richard Bosworth, demonstrates the first step in using the hack and squirt application to kill Chinese tallow trees, cutting, or "hacking," a ring around the tree using a hatchet. Only two or three cuts are typically needed on smaller diameter trees.
Hack-and-squirt herbicide applications are one of the least expensive manual herbicide application methods. This method introduces the herbicide into the stem using spaced cuts made at a convenient height, below the last live branch, around the trunk. Using a hatchet or similar device, frill cuts, or downward-angled incisions, are made evenly spaced around the stem, one per inch of diameter.
Removing or killing undesirable trees is a forestry industry-recognized forest management tool. Hack-and-squirt, also known as a frill and spray herbicide application, offers the most target-specific, efficient, and economical means for controlling unwanted trees. In this case, the undesirable tree is the Chinese tallow tree. It is an invasive tree species found throughout Louisiana and many other southern states.
This photo shows the second step of the hack and squirt application, the "squirt."
A small amount of herbicide is sprayed into each cut.
Herbicide applications to this undesirable tree facilitate the regeneration or growth of native trees in the mixed-species stands of live oak, hackberry and cypress trees found on the refuge by eliminating the Chinese tallow tree as competition to these trees.
The Chinese tallow tree can resprout from cut stumps when a herbicide is not applied.
The Chinese tallow is a drought-tolerant tree native to China and Japan. It was first introduced in South Carolina during the 1700s as an ornamental tree and then for making soap from seed oils. It can be found from eastern North Carolina southward to Florida. From Florida, it spread westerly through Louisiana and Arkansas into Texas.
Chinese tallow trees can be identified by broad, waxy-green leaves, which often have an extended tip or “tail.” New growth briefly appears reddish.
In the early 1900's it was used as an ornamental tree in Louisiana because most of Louisiana's native trees do not produce fall-colored leaves. The Chinese tallow tree does.
The Chinese tallow tree can be easily spotted in Louisiana forests when its leaves change color in late fall. Once this happens, the green color starts to fade from the leaves, and then reds, oranges, and yellows become visible. The leaves from most of Louisiana's
native hardwood trees turn brown in color.
The Chinese tallow tree can reach a height of 40 feet and a width of 3 feet in diameter. Its deep taproot allows the tree to hydrate in drought conditions. It will reach its full potential height when located in an area that receives plenty of moisture, like those found along the edges of Louisiana's wetlands. In dryer locations, it is less broad and does not grow as tall.
There are very few large, mature Chinese tallow trees, like the one shown above, in the Bayou Sauvage refuge because they were destroyed along with most of the mature
native trees by Hurricane Katrina's strong winds.
The Chinese tallow’s other common name, “grey popcorn tree,” is based on the form of the mature seed pods, which turn black and open to reveal white, waxy seeds. These seeds develop from greenish fruit, which appears in clusters at branch tips during September and October. The tree is primarily spread through seed dispersal from birds or water.
Chinese tallow tree seeds.
Chinese tallow trees can live up to 100 years old. It can produce seeds when it is only three years old. Each mature tree can put out up to 100,000 seeds per year. Seeds remain viable in the soil for two to five years.
Birds' digestive system will dissolve the waxy outer coating of the Chinese tallow tree's seed, but not the inner seed itself. This allows the birds to spread the seeds far and wide.
The Chinese tallow trees on the refuge took advantage of the vast areas of bare ground that were created by 2005's Hurricane Katrina's destruction to get a head start on the native trees that would have reforested the damaged areas. Since the Chinese tallow trees grow faster than native tree species, they out-competed most of these trees that naturally tried to grow back into these areas.
Before and after Hurricane Katrina, photos of the same section of the Ridge Trail
boardwalk are seen above.
This photo, taken in December of 2021, is of the same area of the Ridge Trail boardwalk shown in the pictures above. It shows how young Chinese tallow trees filled the
spaces between the larger trees that survived Hurricane Katrina.
The Chinese tallow tree grows extremely fast. Growth rates of 7 feet to 13 feet per year have been documented for seedlings. "The tallow trees will out-compete all of the native trees, eventually shading over them and killing them off," says LICI's Gary Salathe. He is LICI's project leader for their tallow tree eradication at the refuge.
LICI started the Chinese tallow tree eradication project at the Bayou Sauvage refuge after receiving a US Fish & Wildlife permit in January of 2021. The refuge supplies the herbicide used to kill the tallow trees. It began as an offshoot of a multi-year project the organization has to introduce the Louisiana iris. Irises once grew in abundance at the refuge. Still, they were thought to have been killed off as another casualty of Hurricane Katrina's salt saltwater storm surge that flooded the refuge for weeks after the storm.
Photo: The Ridge Trail Boardwalk at the US Fish & Wildlife Services Bayou Sauvage
National Wildlife Refuge in New Orleans east.
Salathe says LICI's original plan was to kill off the Chinese tallow trees only along the shoreline of the old Bayou Sauvage within the area of the refuge's Ridge Trail boardwalk to create new places for irises to be planted. He began a one morning each week event for a small number of volunteers to work on killing the tallow trees.
Photo (left to right) Tres Fisher, Richard Bosworth, and Aaron Hunter after coming out of the woods from working 2 1/2 hours on the tallow trees. Along with Gary Salathe, this group worked one day each week through most of 2021, eradicating Chinese Tallow trees using the "hack and squirt" method.
Once work began on the tallow trees, the volunteers quickly discovered young cypress and live oak trees that other volunteers had planted in the past. These trees were located away from the bayou shoreline. Many had died from being shaded out by the tallow trees. The trees that were left were also crowded and shaded by the faster-growing tallow trees, which also threatened their survival. The goal was then expanded into killing off all of the tallow trees in the boardwalk area by the fall of 2022. Some of the trees that LICI's volunteers discovered came from this tree planting in 2015: https://youtu.be/AuOPVE3AtOg
This wintertime photo shows an area of the Bayou Sauvage refuge where a pure stand of Chinese tallow trees canopied over and shaded out native trees trying to grow there.
As more and more of these areas were discovered, it became apparent that a
reforestation effort would be needed once the tallow trees were killed off.
The areas cleared of tallow trees created the need for them to be replanted with native trees. LICI decided in September to embark on a new project to reforest these areas during the winter of 2021/2022 with native trees. "Without planting native trees in these areas, they would just be taken over by tallow trees again," Salathe said. He added that LICI's tallow tree eradication crew plan to go through the areas each year where the new native trees will be planted to kill off any Chinese tallow trees that attempt to grow back. The hope is that the native trees will create a canopy that will shade out any Chinese tallow trees that try to get reestablished in a few years.
LICI's volunteers working on the Chinese tallow tree eradication project found this stand of bald cypress on the refuge planted about nine years ago. The trees were able to grow tall enough to shade out any other competing trees before the Chinese tallow trees
could get established. It's what they hope will happen in a few years to
the new trees they plant this winter.
LICI has plans to start back up a 2022 version of the once-each-week Chinese tallow tree eradication project work-morning as soon as they are finished planting trees this winter.
LICI's Chinese tallow tree eradication project's goals are shown on this map.