Chinese Tallow Tree
|Figure 1. Chinese tallow tree is a once popular ornamental tree that now persists in our natural environments. Photo courtesy of Ronald F. Billings, Texas Forest Service, Bugwood.org.|
Chinese tallow tree (Triadica sebifera (L.) Small) is a short-lived, fast growing tree native to eastern Asia (Figure 1) that has become naturalized through the southeastern U.S. from North Carolina to eastern Texas and in California. It was originally introduced to the U.S. during the 1700’s; an introduction often dubiously credited to Benjamin Franklin, though more likely the work of French botanist Francois Michaux. Evidence indicates that it was brought as a source of oil for the soap industry.
Chinese tallow tree tolerates a wide range of environmental conditions, making it a good choice for ornamental applications. Unfortunately, these same characteristics make it invasive in most of our natural environments. It grows rapidly and is resistant to many pests, so that it quickly dominates sites. It spreads rapidly by producing abundant seeds that are spread by birds and may lay dormant in the soil for up to five years before germinating. Chinese tallow tree also spreads by sprouting from the roots, especially when the original stem is cut or top killed.
Currently Chinese tallow tree is used as an ornamental plant due to its attractive fall coloration, however, several states have placed Chinese tallow tree on their noxious weeds list. The Atlas of the Vascular Plants of Arkansas records Chinese tallow tree in 15 counties in Arkansas, and the USDA Plants Database adds an additional three counties to the list. Chinese tallow tree is called Sapium sebiferum (L.) Roxb. in some references.
The following paragraphs provide detailed information about Chinese tallow tree.
Chinese tallow tree grows as a large shrub or a medium-height but large diameter tree – up to 60 feet (18 meters) tall and 3 feet (90 centimeters) diameter (Figure 2). Bark is light to dark gray and furrowed.
Brittle branches spread and support a crown of simple alternate leaves that range in size from 1.5 to 3.5 inches (3.8 to 8.9 cm) wide and approximately the same length. The leaf stalk is usually at least half as long as the leaf blade. Overall, leaves are nearly round to more or less kite shaped, base of the leaves is rounded, and the tip tapers to a short or long point (Figure 3). Leaves are hairless, medium green on top and slightly lighter green beneath. Leaf veins, especially the mid-vein, are lighter green on the upper surface. Leaf margins are not toothed. The leaves change to yellow, orange, or red in the fall (Figure 4).
|Figure 2. Chinese tallow tree is a large shrub to medium tree with light to dark gray furrowed bark. Photo courtesy of Chris Evans, Illinois Wildlife Action Plan, Bugwood.org.||Figure 3. Leaves of the Chinese tallow tree have a kite-shaped, often mildly asymmetric shape that tapers to a point at the tip of the leaf. Photo courtesy of Chris Evans, Illinois Wildlife Action Plan, Bugwood.org.||Figure 4. Leaves of Chinese tallow tree change color to yellow, orange, or red in the fall. Photo courtesy of James H. Miller, USDA Forest Service, Bugwood.org.|
Chinese tallow tree flowers in the spring – typically April to June. The small greenish yellow flowers of the Chinese tallow tree have no petals, so they don’t look like typical flowers. They develop in catkins 2 to 8 inches (5 to 20 cm) long in the spring. Most trees produce one catkin per branch, but occasional trees produce more. Each catkin has a few separate female flowers, occurring at the base of the catkin with male flowers filling out the remainder (Figure 5).
Fruits develop as a ¾-inch (2 cm) diameter three-lobed capsule which matures in late summer (Figure 6). As the capsule matures and dries out (Figure 7), the outer shell splits open and ultimately falls off at maturity, leaving a cluster of three to four off-white waxy seeds (Figure 8). These seeds remain attached into the winter and give the tree one of its common names – popcorn tree. One tree can produce from 50,000 to 100,000 seeds with high rates of viability. Seeds are dispersed by a variety of birds and by environmental agents such as creeks or floods. Research indicates that they are viable in the soil for at least two years and potentially up to five years.
|Figure 5. Chinese tallow tree flowers develop in catkins with a few female flowers at the base and male flowers filling out the remainder. Photo courtesy of Chuck Bargeron, University of Georgia, Bugwood.org.||Figure 6. Chinese tallow tree produces clusters of ¾-inch (2 cm) diameter green fruits in the fall. Photo courtesy of Chris Evans, Illinois Wildlife Action Plan, Bugwood.org.||Figure 7. As Chinese tallow tree fruits mature, the capsule wall dries and splits, revealing the seeds. Photo courtesy of James H. Miller, USDA Forest Service, Bugwood.org.|
|Figure 8. After the capsule walls fall off, the off-white seeds remain, giving the Chinese tallow tree its alternate name – popcorn tree. Photo courtesy of Joseph LaForest, University of Georgia, Bugwood.org.|
Stop the Spread
Chinese tallow tree is difficult to control because it sprouts freely and produces abundant seed. Given sufficient time, it most likely will escape cultivation.
Chinese tallow tree can be controlled by cutting and removal if one is persistent. When a tallow tree is cut, it will resprout from the stump or roots. Successful removal depends on diligently checking for sprouts and removing those sprouts promptly. Biological control has been investigated, but few pathogens or pests attack the tree.
For most homeowners, herbicides present a better control option. Several herbicides including 2, 4-D, fosamine, hexazinone, imazapyr, metsulfuron, and triclopyr have proven effective. Depending on the herbicide and the size of the individual tree, application can be by basal bark application, cut stump treatment, hack-n-squirt, foliar spray, or soil application. Consult your county extension agent if you have questions about specific herbicide recommendations tailored to your situation.
As with all herbicides, misuse of these chemicals can cause tremendous environmental damage and can harm you. Read and follow all label directions, including personal protective equipment recommendations.
One of the most commonly used treatments for Chinese tallow tree is a basal bark application of the ester formulation of triclopyr. Most trees can be killed with a 15% solution using vegetable oil as a surfactant. This solution should be applied as a 6” (15 cm) wide band sprayed around the tree in the lower 2 feet (60 cm) of the trunk. A 20% solution might be required to kill larger trees.
A basal bark application may not be effective on large trees with thick bark. In those cases the tree may be cut and the stump treated with 50% solution of the ester formulation of triclopyr or a 10% solution of imazapyr. Note that imazapyr is persistent in the soil, so avoid overapplication. Glyphosate applied by hack-n-squirt will also provide good control of larger trees. Use an undiluted 4 lb / gallon (0.48 kg / liter) glyposate solution applied into frills spaced 2 to 3 inches (5 to 8 cm) apart around the tree trunk.
Let’s work together to stop the spread Chinese tallow tree in Arkansas.
Here are some additional resources to learn about Chinese tallow tree.