For eight days at the end of March, six intrepid workers from the Lady Bird Johnson Wildflower Center (JWC) worked to map invasive plants at Big Thicket National Preserve, northeast of Houston, TX. Under contract with the National Park Service (NPS) and led by Invasive Species Programs Coordinator Dr. Hans Landel of the JWC, the team was continuing its effort to map invasive plants in six national parks in the area managed by the NPS’s Gulf Region Exotic Plant Management Team. They have already mapped species in San Antonio Missions National Historical Park, and will be visiting Jean Lafitte National Historical Park and Preserve, Vicksburg National Military Park, Gulf Islands National Seashore, and Natchez Trace Parkway later in the year. The team is developing the protocol for mapping using computer tablets with geographical information system (GIS) software. The protocol will be used by NPS, and the data will enter the National Invasive Species Information System (NISIMS). NISIMS is the standard database system used by two other agencies in the Department of the Interior.

While at Big Thicket, the team braved snakes, mud, mosquitoes, spiny and thorny plants, and alligators while mapping trifoliate (or hardy) orange (Procirus trifoliata), golden bamboo (Phyllostachus aurea), common and giant salvinia (Salvinia minima and S. molesta), and water hyacinth (Eichhornia crassipes). Of these, trifoliate orange had the largest infestations. They found large patches of it, some covering more than a quarter of an acre, along the few miles of Big Sandy Creek they surveyed. Nothing was growing under the thickets. See the Invasive Species Highlight below for more information on this noxious species. While searching the backwaters along the Neches River, they were pleased to find that the recent flooding had swept the infestations of salvinia and hyacinth out to sea.

Other invasives they came across incuded Japanese climbing fern (Lygodium japonicum), Chinaberry (Melia azedarach) and Chinese tallow (Triadica sebifera). It was discouraging to see Chinese tallow in so many locations. In fact, there is so much of it that the Preserve staff must rate it as a low priority, even though within a few decades the Big Thicket's very character will have changed because of the widespread infestation.

The team really enjoyed the Preserve, even with the hard work, and thanks the Preserve’s staff for their help and support. They highly recommend you visit the preserve. Be prepared to see Chinese tallow in most places, though!

Keep track of the team on the Texasinvasives.org Facebook page as they survey the other parks.

Mapping trifoliate orange.

Mapping golden bamboo.

Forcing through a thicket of trifoliate orange.

Searching for aquatic invasives.
Photo credits: Hans Landel, Lady Bird Johnson Wildflower Center

Trifoliate orange, also known as hardy orange, is a deciduous shrub or small tree that invades woodlands, forest edges, fence rows and urban green spaces. It can grow into large thickets, crowding out all other plants. Its large thorns make it especially problematic.

It grows from 8 to 30 ft. (2.4-9.1 m) high. The leaves are alternate, compound with three leaflets (trifoliate), up to 2 in. (5.1 cm) long and have a winged petiole. The twigs are green with stout, 1 in. (2.5 cm) or more long thorns. The bark is conspicuously green-striped. Spring flowers are white, 5-petaled, 1-2 in. (2.5-5.1 cm) in diameter and showy. Its fruit looks like a dull miniature orange, 1.5-2 in. (3.8-5.1 cm) in diameter, with a downy skin.

Hardy orange spreads mainly by dispersal of the fruit, which contain several seeds. Fruit can be carried downstream, where they come to rest in bottomlands; the several seeds then sprout, creating a new population.

Trifoliate orange was introduced from northern China as an ornamental due to its unique form and green color, beauty when flowering, and interest provided when fruiting. It was likely also planted as impenetrable hedges. Due to its hardy nature it is often used as rootstock for citrus trees.

Trifoliate orange needs to be watched closely since it can easily become established and create even more competition for desirable trees in forest settings. To prevent the spread of trifoliate orange, do not plant it; choose alternative plants, and eradicate the plants you find outside of a landscaped setting. Control can be achieved by hand pulling seedlings or, for larger specimens, the cut-stump application of an herbicide. Contact your local Texas A&M Forest Service or AgriLife office for specific recommendation and as always follow label directions. To be safe use basic precautions like gardening gloves, long pants & long sleeved shirts, and eye protection.

In Texas this invasive plant is found in mainly in the eastern woods.  It is found throughout the sourthern United States and up into Pennsylvania. 

(Some information for this article comes from this link)

Follow this link for more information on hardy orange.

Texas Is Ramping Up Efforts to Control Aquatic Invasive Species
The last Texas legislative session saw an unprecedented $6.6 million commitment to statewide aquatic invasive species management. Texas Parks and Wildlife will receive five new employee positions, allowing them and their partners to increase the treatment areas, expand biocontrol capacity, enhance early detection programs, implement control strategies for riparian areas, perform critical research and increase outreach and awareness campaigns. Read about partners and proposed projects.

Using Isotopes to Track Invasive Beetles
Well established in the eastern United States, Japanese beetles (Popillia japonica) have begun making their way westward via airports despite tighter control efforts. A new technique, however, offers invasive pest managers insight into the origins of a beetle invasion and allowing for a more informed control plan. Researchers can pinpoint the beetles’ birthplace by comparing the levels of deuterium, a stable hydrogen isotope present in water found in their tissues to an original water source. Learn more about deuterium and how invasive pest managers can use it to track Japanese beetle movements.

Resistance to White-nose Syndrome Found in Asian Bat Species
Researchers sampled five bat species from both North America and China to understand why some bats survive white-nose syndrome (endemic to Europe and Asia) and some do not. Tests show that Chinese species do not carry the same fungal loads as some of their North American counterparts, thus showing a greater resistance to infection. Researchers also found evidence that some North American bat species could become resistant as well. Read more .

The Giant Reed: Not Your Average Grass
The giant reed, Arundo donax, isn’t like other warm­weather grasses of the world. The giant reed, also known as Carrizo cane, uses a less efficient type of photosynthesis called C3 that occurs in crop plants like soybeans and peanuts. This makes the giant reed an unusual grass. Most prolific warm­weather grasses like switchgrass and sugarcane use a more highly efficient photosynthesis type called C4. Researchers found that the giant reed utilizes high levels of both chlorophyll and a major enzyme of photosynthesis, Rubisco, to boost efficiency. Learn more.

Robots vs. Lionfish
By next spring, the red lionfish (Pterois volitans) could finally meet its match. Researchers from Lamar University are hoping that a semi­autonomous aquatic robot from OpenROV will be the newest tool in the battle against the lionfish. Researchers are setting out to create a set of robots, controlled by users wearing virtual reality headsets, that can identify and kill lionfish. The first phase of trials are set to begin mid­summer and will test the robot’s ability to identify a toy lionfish. Read more about the robot.

Bringing Flame Weeding Back
Before World War II and the subsequent expansion of chemical research, flame weeding was the go-to method of weed removal. Now as concern over the widespread use of glyphosate grows, some people like biologist Meghan Fellows are returning to flame weeding in an effort to finally gain control over the aggressive lesser celandine (Ficaria verna), a small but highly invasive perennial flower. She is quick to point out that the goal is to wilt the plant, not burn it. Fellows’ test plots in Maryland are showing promise for the return of flame weeding. Learn more about the technique and her results.

City Fights the Emerald Ash Borer Without Cutting Trees
While many municipalities are opting for tree removal to control infestations of emerald ash borer (Agrilus planipennis) , Mount Vernon, Iowa, decided to try chemical treatment. The city has treated 211 trees with the chemical TREE­age and while many areas are experiencing ash tree decline, Mount Vernon Horticulturist Mike Wehde claims the treatment is working. The victory comes at a cost, however. Roughly $30,000 will be spent every three years for chemical treatment to keep the trees larva-free. Learn more.

Beating Back the Snakehead
The snakehead fish (Channa argus) first appeared in Maryland in 2002. Since then, it has begun to spread, with a firmly established population in the Potomac River. They are now poised to threaten Chesapeake Bay. To combat the spread of the invasive snakehead, authorities are looking to fishermen. It turns out that snakeheads are pretty tasty. On May 21st, a snakehead derby will take place in the hopes of raising awareness while also reducing their numbers. Read more about the snakehead and its impact on Maryland and Virginia river systems.

If you would like your invasive species event or news listed in the next iWire, please send the details to iwire@texasinvasives.org

Sentinel Pest Network and Invaders of Texas Species Workshops

Invaders of Texas workshops train volunteers to become citizen scientists to detect and report invasive species. Workshops, which are free, include information on the Sentinel Pest Network, which serves to increase the awareness and early detection of the Emerald Ash Borer, Cactus Moth, Asian Longhorned Beetle, and other pests of regulatory significance.

Workshops are tailored to meet the interests of your volunteer group, and supplementary session examples include an introduction to the TX Invaders mobile application and the Eradicator Calculator, a feature on Texasinvasives.org designed to help organize and track volunteer-based eradication efforts.

Saturday, April 2, 2016
Location: Jesse H. Jones Park & Nature Center (Humble, TX)
Contact: Rosanne Belzung


For more information or to register to attend a free workshop, please visit the Workshop Page.