September 2017
Update on Use of Poison to Control Wild Hogs in Texas

In April, Scimetrics, the company behind the only EPA-approved pesticide for feral hogs, withdrew its request for registration in Texas. The company has "discontinued [its] attempts to provide this resource in Texas at this time," according to a news release. Scimetrics was worried about the potential for lawsuits over the use of its product, Kaput.

The news came a week after a bill that would require state agency or university research before the use of lethal pesticides on wild pigs overwhelmingly passed the Texas House. The Texas legislature eventually included a rider in the state budget that prevents the Agriculture Department from taking action to permit the use of Kaput.

Meanwhile, USDA-APHIS Wildlife Services is researching the use of sodium nitrite, which is a chemical used in food preparation such as to cure bacon, as a control measure. Sodium nitrite causes feral hogs to fall unconscious and die within three hours. They hope to have it registered with the EPA in four years, according to an article in the September/October issue of The Wildlife Professional, published by The Wildlife Society.

feral hog
Credit: Texas Department of Agriculture

feral hog damage
Credit: Billy Higginbotham, Texas AgriLife Extension Service,

USGS Develops Preliminary Web Tool to Show Potential Spread of Aquatic Non-native Species Due to Hurricane Harvey Flooding

In addition to the tremendous difficulties faced by victims of Hurricane Harvey as a result of flooding, natural resource managers are facing the potential spread of aquatic invasive species. Flooding can connect normally separated drainages, which can spread invasives from one body of water to another. To help explore this possibility, the U.S. Geological Survey has produced an on-line mapping tool that illustrates the potential for aquatic invasive species to spread as a result of the flooding due to Hurricane Harvey.

While preliminary, the tool allows one to investigate the potential spread of over 80 non-native species, from a water flea (Daphnia lumholtzi) to bighead carp (Hypophthalmichthys nobilis) to giant salvinia (Salvinia molesta). It uses the HUC (hydrologic unit code) system to identify watershed units, and classifies units as either already possessing the specific species or potentially having the species spread to it.

Dr. Hans Landel, the manager of and editor of this e-newsletter, has seen the effects flooding can have on the distribution of aquatic invasive plants, although the effects he saw were positive. In the Fall of 2016 he led a team to Big Thicket National Preserve north of Beaumont to map invasive plants, including giant salvinia and water hyacinth (Eichhornia crassipes). A few weeks before they arrived, heavy flooding had occurred. As a result, when they made their way by kayak into the bayous, they found that the populations of hyacinth and salvinia that had previously been present had been washed out to the Neches River and, presumably, on to the Gulf.

Go to for an article on the USGS' new on-line tool.

USGS Hurricane potential spread website

USGS Hurricane potential spread map

North American Ash Tree Species Face Extinction

The continued existence of North America's most widespread and valuable ash tree species is now being questioned. Due to the huge impact of the emerald ash borer (Agrilus planipennis), five of the six most prominent ash tree species in North America have been listed on the International Union for Conservation of Nature's Red List as "Critically Endangered" -- only one step from going extinct, and the sixth species is assessed as "Endangered". The IUCN Red List of Threatened Species™ "is widely recognized as the most comprehensive, objective global approach for evaluating the [risk of extinction] of plant and animal species".

The IUCN Global Tree Specialist Group states, "Taking all of [the available information] into account, it is clear that EAB will rapidly kill all living F. pennsylvanica trees greater than 2 cm dbh that it encounters across the vast majority of the species' range. Furthermore, EAB can survive at low densities in infested forests of decimated ash populations, on alternative host plants, ready to infest any regenerating Green Ash sprouts until the trees finally die off and the seed bank is depleted. Therefore, until there is convincing evidence that EAB will be stopped before wiping out the entirety of the ash population in North America, it must be considered an imminent and all-encompassing threat."

"[The ash trees'] decline, which is likely to affect over 80 percent of the trees, will dramatically change the composition of both wild and urban forests. Due to the great ecological and economic value of ash trees, and because removing dead ash trees is extremely costly, much research is currently underway across sectors to halt their devastating decline. This brings hope for the survival of the species," says Murphy Westwood, member of the IUCN Global Tree Specialist Group who led the assessment.

You can read the full Red List entry for Green Ash, and access the entries for the other ashes.

ash tree
Credit: David Cappaert,

Credit: David Cappaert,

IUCN_Red_List logo

2017 NAISMA Annual Meeting

The 2017 North American Invasive Species Management Association Annual Meeting will be held October 23-26, 2017 at the Nugget Hotel and Casino located in Sparks, NV. The meeting provides one of the best professional development opportunities for invasive species professionals in North America. Come ready to learn, recharge, get a new perspective on your challenges and opportunities, and leave energized to boost your invasive species management capabilities. Early Registration ends September 1. More information and registration


Microbes in Sediments Determine Success of Invasive Marine Alga

More and more, researchers are illuminating the role soil microbes are playing in the processes leading to the establishment of invasive plants. In a recently published study by researchers in Australia, and published in the journal Scientific Reports, differences were found between the microbial communities in marine sediments associated with a native seagrass, Zostera capricorni, and those associated with an alga ("seaweed"), Caulerpa taxifolia, which is one of the 100 most invasive species in the world. Another study, noted below, also found differences in soil microbial communities between the native and the invasive strains of Phragmites.

Microbial communities in marine sediments control ecological processes, affecting the availability of nutrients and the chemistry of the soil. In this case, the algal sediments had a higher proportion of microbes that produce sulphides, which can be extremely toxic to seagrasses, under low oxygen conditions.

The researchers also tested the effects of the different sediments on the growth of the alga. They found the sediments associated with the seagrass reduced algal growth, while the sediments associated with the alga had a positive effect on its growth. "Our results shed light on why intact, dense beds of seagrass are resistant to colonization by this alga," says Associate Professor Gribben. "However, the balance of the microbes in the soil can be disturbed when seagrass beds start to decline due to other pressures, helping the alga invade new areas."

Learn more at

Seagrass. Credit: Malcolm Francis, National Institute of Water and Atmospheric Research

Caulerpa taxifolia
Caulerpa taxifolia. Credit: Rachel Woodfield, Merkel & Associates, Inc.,

Invasive Spotlight:
Japanese Honeysuckle
(Lonicera japonica)

Japanese honeysuckle is a semi-evergreen woody vine that produces lovely white fragrant flowers and black berries, and that has few natural enemies. While this makes it an attractive garden plant, it also makes this import from East Asia an invasive plant. Shrubs and young trees can be killed by girdling when vines twist tightly around stems and trunks, cutting off the flow of nutrients through the plant. Dense growths of honeysuckle covering vegetation, even high into the canopy, can gradually kill plants by blocking sunlight.

It produces long vegetative runners that develop roots where stem and leaf junctions (nodes) come in contact with moist soil. Underground stems (rhizomes) help to establish and spread the plant locally. Long distance dispersal is by birds and other wildlife that readily consume the fruits and defecate the seeds at various distances from the parent plant.

It can occur as dense infestations along forest margins and right-of-ways and, being shade tolerant, under dense canopies. It will also grow high in canopies.

Japanese honeysuckle is a semi-evergreen to evergreen woody vine that branches and can climb and trail up to 80 feet (24 m) long. It forms long woody rhizomes that sprout frequently. Its simple oval leaves are opposite, 3–8 cm (1.2–3.1 in) long and 2–3 cm (0.79–1.18 in) broad. The flowers bloom in pairs along the vine, unlike the native honeysuckles that produce a bunch of flowers at the end of stems. The flowers are double-tongued, opening white and fading to yellow, and sweetly vanilla scented.

Follow this link to learn more about Japanese honeysuckle.

Japanese honeysuckle flowers and leaves
Credit: Sheldon Navie, Weeds of Australia

Credit: Qwert1234, Wikipedia

More News

Hunting Wild Hog from Hot Air Balloon Now Legal in Texas
In June, the Texas legislature passed and Gov. Greg Abbott signed into law legislation that permits a landowner to "participate as a hinter or observer in using a hot air balloon to take depredating feral hogs or coyotes under the authority of a permit…" This law went into effect September 1. See this video for more information.

New Citrus Planting Method Stops Bugs, Yields Additional Benefits
A planting design developed in 2009 that outwitted the Diaprepes root weevil in Texas citrus groves has turned out to yield numerous other benefits for growers and brought better quality oranges and grapefruits to consumers, experts say. Read more in this AgriLife article at

Fungal Spore 'Death Clouds' Key in Gypsy Moth Fight
A fungus (Entomophaga maimaiga) known to decimate populations of gypsy moths (Lymantria dispar) creates 'death clouds' of spores that can travel more than 40 miles to potentially infect populations of invasive moths, according to a new study. [The gypsy moth is one of the Sentinel Pest Network watchlist species.] Learn more from

How Invasive Species Threaten Bats
A new review is the first to describe the scope of threats to bats by invasive species. The review summarizes the threats according to four categories: predation, disease, competition, and indirect interactions. The investigators identified threats of 37 invasive species to 40 bat species. Learn more from

Invasive Plants Change Ecosystems from the Bottom Up
Even when two different Phragmites australis lineages are grown side-by-side in the same ecosystem, the bacterial communities in the soil differ dramatically. This is a discovery that will aid in understanding how plant invasions get started and the conditions necessary for their success. Learn more from See also this account.

Scientists and Farmers Work Together to Wipe Out African Lovegrass
New research and collaboration could lead to the eventual eradication of the highly invasive African lovegrass (Eragrostis curvula) threatening pastures and native grasslands across Australia. What they discovered is that local knowledge is the key to a successful management approach. Learn more from


If you would like to highlight a successful invasive species project or nominate a special person to be highlighted in an upcoming iWire, please send the details to

Sentinel Pest Network and Invaders of Texas 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 designed to help organize and track volunteer-based eradication efforts.

Upcoming Workshops:

Monday, October 16, 2017
Location: Hill Country Youth Events Center (Kerrville, TX)
Contact: Kerr County Extension Office, 830-257-6568

Saturday, November 18, 2017
Sentinel Pest Network Workshop
Location: Houston Advanced Research Center (The Woodlands, TX)
Contact: Teri MacArthur

Saturday, January 20, 2018
Location: Headwaters of the Incarnate Word (San Antonio, TX)
Contact: Pamela Ball

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