Chinese Tallow
Chinese tallow, triadica sebifera, is a fast-growing invasive tree that can reach up to 60 feet tall.
The popular, deciduous ornamental tree has broad oval leaves that change colors in the fall. In the spring, dangling yellowish spikes hold small clusters of fruit that later split to reveal seeds that resemble popcorn in the fall and winter, giving it its nickname “popcorn tree.”
Chinese tallow was first introduced to the U.S. in the 1700s and later brought to the Texas Gulf coast in the 1900s to make soap and seed oil.
It is well adapted to wet and dry sites and freshwater and saline soils, and it is shade and flood tolerant.
Ecological threat
Chinese tallow is a prolific seed producer that can reproduce in as little as three years. Seeds are transported by birds and water.
Since it is well adapted to numerous site conditions and has no natural enemies, it can easily outcompete native vegetation, negatively impacting wildlife. This is evident by the large-scale conversion of the upper coastal prairie to woodland and resulting impact to Attwater’s prairie chicken.
Chinese tallow fallen leaves contain chemicals that create poor soil conditions for native vegetation. And leaves and fruit are toxic to humans and cattle.
FIA plot data also shows that Chinese tallow has increased by 38% in East Texas from 2007 to 2017 and is expanding northward from the Gulf Coast. Jasper, Angelina, Liberty, Hardin, and Newton Counties experienced the greatest increase in plots measured with new infestations.
While tallow increased by a greater total amount on private lands during this time, during the survey period, public lands have experienced a much faster rate of increase.
Net volume of Chinese tallow is also increasing, as expected due to its fast growth rate. Over the last ten years, net volume has increased by 44%, at an average rate of 3.3 million cubic feet per year.
Future invasion
Sites that are flat, have low to moderate site productivity, and are not actively managed are at greatest risk of invasion.
The greatest potential for new infestations are in Southeast Texas between Interstate-10 and Highway 190, though there are susceptible sites all the way to the Red River. Southeast Texas is also frequently at risk to hurricanes, which increases this region’s vulnerability to Chinese tallow colonization.
The presence and density of Chinese tallow seedlings can also indicate regeneration and spread potential. Fortunately, the overall number of Chinese tallow seedlings declined 32% between 2007 and 2017 in Texas. However, there are still a total of 497 million seedlings in East Texas, and this decline was only realized on private land. Public land experienced a 103% increase in the number of seedlings in just five years (2012 to 2017).
Management
Prevention is an important control option for Chinese tallow.
Foliar applied herbicides can provide control for smaller trees, though basal bark applications are needed for larger trees.
Prescribed fire can help reduce regeneration potential, especially if Chinese tallow has been known to occur in the area. Artificial, not natural, regeneration of forest lands is also associated with Chinese tallow control.
Chemical control depends on the site and size and density of trees.
On grass pastures and fields where concern with drift and water contamination is minimal, pre-mixed herbicide products with picloram plus 2,4-D (e.g., Grazon P+D) have proven to be effective with broadcast, directed, and individual plant treatment (IPT) foliar applications.
On forest sites, where damage to hardwood and pine species is a concern, IPT treatments may be more desirable than broadcast treatments.
- If trees are less than 5 inches in diameter, basal bark applications using the ester derivative of triclopyr (e.g., Garlon 4, Pathfinder II) at a 20 – 30% solution and appropriate adjuvants have proven to be effective. Triclopyr has little to no soil activity and is safe to surrounding, non-target, desired trees. However, triclopyr-ester products should not be used on aquatic sites where Chinese tallow are prone.
- If trees are greater than 5 inches in diameter, bark tends to be too thick for basal spray and IPT treatment using some type of cut surface (e.g., Hack-N-Squirt, Cut Stump) application is preferred. Several products are available. For example, products with the chemical imazapyr (e.g., Arsenal, Habitat) at 20-40% solution show effective and can safely be used on aquatic sites. However, imazapyr is soil active and could damage non-target, desired hardwoods (pines are generally resistant) through root uptake. An alternative is to use an amine derivative of triclopyr product (e.g, Garlon 3A) or the newer choline derivative of triclopyr (e.g., Vastlan) for cut surface IPTs. Both are suitable for aquatic sites and have no soil activity that could damage non-target trees.
The above lists only a few chemical options for Chinese tallow. Several other products are effective. For example, products with liquid formulation of imazamox (e.g., Clearcast) has shown to be effective, have no residual soil activity, and may not harm other hardwood species if applied properly.
All treatments are most effective when applied from late summer to early fall when trees are actively growing. Cut-surface treatments are effective and easiest applied in the late fall.