Austin Chapter of the Native Plant Society of Texas Title: Unnatural Texas: Invasive Species Dilemma    Matt Turner and Robin Doughty, authors of Unnatural Texas? The Invasive Species Dilemma, discussed the problems posed by invasive species at the Feb. 19, 2019, meeting of the Austin Chapter of the Native Plant Society.    Matt Warnock Turner, a fifth-generation Texan, is a naturalist, teacher, and free-lance writer who works as a market researcher at UT’s McCombs School of Business. Son of a well-known botanist, he applies his humanities training (PhD in literature from Yale) to enrich our understanding of the plant kingdom around us. He has published both scientific and popular works, including the award-winning, Remarkable Plants of Texas (2009). He’s twice appeared as a guest on PBS’s “Central Texas Gardener” and starred in the PBS documentary, “Wildflowers: Seeds of History.”    Robin W. Doughty, a Yorkshire-born Geographer, who received his PhD from University of California Berkeley, has been on the UT faculty for more than 40 years. Robin has a longstanding professional and personal interest in wild animals, environmental change, and conservation. He has authored over 10 books on such subjects as the feather trade, the recovery of the endangered whooping crane, the mockingbird, the purple martin, the armadillo, the eucalyptus tree, and more recently the international steps being made to conserve albatrosses. He continues to travel the world extensively and lecture on physical geography, cultural history, and wildlife.

Matt Turner Robin Doughty

Feral Pigs

Feral pigs    Feral pigs were first introduced to Haiti by Columbus on this second voyage. He brought them from the Canary Islands. Hernando do Soto brought them to Florida and helped spread them across the south.    The sows are extremely attentive to their young which helps the population increase. The population increase is currently about 20 percent a year. There are an estimated 1-3 million feral pigs in Texas. Texas has about half the feral pig population in the United States.    The pigs have become a big problem on Texas Highway 130. With the toll road 's 85 mph speed limit and wild pigs crossing the roadway, you get what you expect: crashes.    All kinds of methods of hunting the pigs is going on with dogs and with helicopters.    Feral pigs can be captured in corrals. But so far control has been mediocre.    One way to capture them is the Judas trap. A single feral pig is caught and a radio tracker collar is placed on the animal. It is then let go and it makes its way back to the herd. Then the herd can be captured or killed all together.    Sodium nitrite is being used as a poison on the pigs. The sodium nitrite reduces the amount of oxygen in the animal’s blood. The animal eats the chemical in a bait, grows faint, and dies.    Another poison is warfarin. The bait food is laced with warfarin (a rodenticide used to kill rodents).    Problem: other desirable animals (mammals) may eat the bait food and thus the chemical and die.    The estimated 2.5 million feral pigs that are in Texas cause about $50 million in agriculture damage per year.    Hunters put out a lot of deer feeders to attract deer. Problem: feral pigs find the feeder and like the food and eat it, too.

Water Hyacinths mass together Water Hyacinths have pretty flowers

Water Hyacinth    The water hyacinth is a free-floating perennial aquatic plant that takes up space on the surface of the water and has roots that float in the water below it. The plant, with a pretty purple flower, was introduced at the 1884 World’s Fair in New Orleans. Of course, it got passed around and within seven years, there were so many of the aquatic plants in the waterways that Congress authorized control management because it was interfering with boat traffic.    The plant originally came from Brazil.    The plant can reproduce so much and its colonies can cover the water so completely, the colony of the plants look like solid ground.    The plant is basically a giant sponge. The plants double in number every two weeks and the colony impedes water flow and navigation. They can clog pipes.    Water hyacinths pull in water and then that water is lost from the lake by transpiration (water loss through the leaves). The invasive plant blocks sunlight to phytoplankton and underwater plants so the native vegetation in the lake dies.    The plants deplete oxygen in the water when their leaves decay. They turn lakes into marshes. Their colonies just keep getting bigger and the plants more numerous. Finally they get so packed together they can support the weight of a man when they are two feet thick.    The control of water hyacinths can be done with a mechanical harvester but the plants grow as fast as the harvester can crunch them. Chemical spray is partially effective in controlling them.    Another control is using the rodent nutria. The mammal eats hyacinths. But of course that plan has a problem. The animal prefers plant stems of good plants that are in the lake. Therefore the nutria themselves are a pest.    Other potential controls are water hyacinth weevil and water hyacinth moth. Both show promise as a control.    Water hyacinths are useful for waste water treatment. They suck up nitrogen, chloroform, and heavy metals. Hopefully, that's a promise that may work out.    In small amounts hyacinths shade out algae and provide homes for snails and other algae grazers.

Chinese Tallow Photographer: Chris Evans Source: The University of Georgia, Bugwood.org

Chinese Tallow    Chinese tallow, an ornamental tree, was introduced by Benjamin Franklin. The seeds make useful oils. But they are still invasive.    The US Agriculture Department was pushing Chinese tallow as a good crop for the Southern US after the Civil War. It was planted as a potential crop. The Texas Department of Transportation planted Chinese tallow as shade trees for the highways.    The trees don't grow well in low rainfall areas, so they only go as far west as Austin. They are not in West Texas.    Chinese tallow grows like crazy. It can grow nine feet in two years.    Chinese tallow is free of predators in the US. There are predators for Chinese Tallow in China where it came from.    One out of four trees in Houston are Chinese tallow. Where there used to be a field in Houston, there is now a forest of Chinese tallow.    You can burn Chinese tallow to get rid of it, but there’s not enough fuel in the tree to burn it all the way out. So the next option is bulldozing it. Problem: you have to keep bulldozing it as it comes back.    There is no biological control, though a flea beetle is being researched. Flea beetles will not kill mature Chinese tallow trees, but stress the plants so that native species can successfully compete in the environment. It is one tool, along with herbicides and physical removal, to control this highly invasive species.    Wild birds do feed on tallow seeds, but it’s more like junk food to the birds. Caterpillars and moss don’t grow on tallow trees so the trees are not that attractive to birds as a food source.    However, Chinese tallow is a big nectar plant, so the beekeepers like it.    Tallow seeds are the most productive oil seeds. We might actually be able to get biodiesel out of the seeds.    Chinese tallow can grow on marginal land so it doesn’t compete with crops. It is cultivable but may not be economically so.    Bottom line: there is no easy way to control Chinese tallow.

Saltcedar Photographer: Steve Dewey Source: Utah State University, Bugwood.org

Saltcedar    The saltcedar tree is a spreading plant characterized as a shrub or tree with a height of 5-20 feet. The saltcedar tree is distinguished by petals and sepals arranged in groups of four or five with white to pale-pink coloring. There are eight species in the United States.    It started out as an ornamental. Then it was thought it would be good for erosion control. Another possibility was to use it for shade where the usual shade trees don’t grow.    It is also drought tolerant. It can be used to keep back water in floods. The roots are deep so when the trees are destroyed by floods, they can come back from the roots.    Saltcedar is flammable even when its green so fire can be more frequent.    Cottonwood and willows will outcompete saltcedar, but we might have to change how/when water is released from dams to allow the trees we want to grow better.    There is a larva that eats saltcedar leaves and hence the saltcedar starve to death.    But now they are finding out that the endangered Southwestern Willow Flycatcher is using the saltcedar to nest so we probably can't get rid of it.

   For more information about the Austin Chapter of the Native Plant Society of Texas please go to their web site at www.npsot.org/austin.

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