At war with Agave Americana: tenacious plant resists chainsaw, digging, fire

“When the pups pop, get them out while they’re little.”

That’s good advice from Mr. Smarty Plants, a collective of volunteers who’ve answered thousands of questions posed to the Ladybird Johnson Wildflower Center over the years. The guidance would have come in handy before I planted several Agave americana more than a decade ago around our ranch house along the Llano River. Their blue-green fleshy leaves, exotic profile and reputation for low maintenance in brutal Texas summers seemed a perfect match for the rocky caliche soil and lack of water at the ranch.

Dr. Kelly Lyons, a grass expert and biology professor at Trinity University, stands victorious over an Agave americana. Brisket Rivard (left) assists. Photo by Monika Maeckle

But since we only visit the property every other weekend, some times less, my agaves became a nuisance. Too often I was absent. I failed at plant management. As Mr. Smarty Plants advises, thinning the pups early, while they’re manageable and have shallow roots, is imperative to avoiding an ornery agave cluster. I ignored the agaves entirely for more than a decade. The result? Several mean agave forests that pricked and poked anyone who dared approach.

Let there be no mistake: Agave Americana deserves our respect. The plant is a case study in self-reliance, asking for NOTHING in exchange for its reliable growth and eventual stunning presence. It demands no supplemental water, no fertilizer, no pruning, no prissing. It lives a dramatic semelparous life–that is, it enjoys a singular episode of reproduction. Then it dies.

Agave americana blooms only once in its lifetime. Photo via Ladybird Johnson Wildflower Center

With a lifespan between 10 and 30 years, the agave shoots one dramatic stalk yards into the sky. The resulting candelabra-like branchlets sport clusters of yellow flowers. Hummingbirds and bats love this pollen trove. Agave americana, technically native to Mexico, also is found in South Texas. Climate change inevitably will extend its range north.

Dr. Kelly Lyons, a grass expert at Trinity University, suggests the plant be put on the “watch list” as potentially invasive. It’s already been labeled unwelcome and invasive in sand dunes, where it overwhelms all competitors.  Left to its own devices, the plant dominates, its rhizomes and pups forming dense communities around the mother plant. Each one has its own set of needle-tipped leaves and serrated blade-like fronds.

I stupidly imported Agave americana to our ranch a dozen years ago. I planted one each on either side of our front gate, thinking they would “welcome” visitors with their dramatic poise. Others I plugged in around the house, some along a much-used trail and a couple along our switchbacked main dirt road.

Good luck getting your shovel through this. Photo by Monika Maeckle

Quiet and understated in their youth, the mature agaves seemed daunting. Their passel of pups defended each mother plant like a thorny army. Nothing could be less welcoming at our front gate than getting stabbed by these mean-spirited cacti. Needle-nosed agave fronds prickled and poked whoever was assigned to lock or unlock the gate; their barbed leaves snagged on your shirt and skin, often leaving a sticker behind.

I had been stabbed one too many times. I decided to tackle the out-of-control succulents, which by this time, stood taller than my five-foot-six-inch frame. Leather

Fleshy Agave leaves

Some of the agave leaves are almost a half-foot thick at their base. Photo by Monika Maeckle

gloves, long sleeves, thick jeans, a sturdy hat and glasses became my agave fighting uniform.

I started with a shovel on one four-foot specimen behind the house. Approaching the plant was practically impossible. The gnarly agave colony fended me off, aggressively protecting its mama with their intertwined roots and serrated leaves. As Mr. Smarty Plants says, agaves self propagate via rhizomes, sending shallow-rooted baby plants all around the base rosette. This helps absorb water in the dry climate in which it thrives. The roots become intertwined, knitted together like an impenetrable quilt. As dead agave blades die and dry out atop them, a sinewy mulch results. A shovel cannot penetrate the fibrous mass.

If you take on an agave, be sure to cut off the black needle-like tip from the Agave leaves before you start working.  Photo by Monika Maeckle

Intrigued by this seeming fortress surrounding the agaves, I researched and learned that the thick agave leaves, plump with water, also contain stringy sisal fiber that native peoples and later Westerners used to weave baskets, rugs, ropes and blankets. Cutting these sinewy leaves to gain access to the soil to dig up the root becomes a separate challenge requiring sharp shears, a knife, nippers or a coba, a special tool from Mexico that a cactus grower friend supplied to us. Some of the fleshy leaves approach a half-foot girth at their base.

Frustrated, one day I convinced my older son Nicolas to get out the chainsaw. Even though we both wore long sleeves, hats and sun glasses, the agave juice spattered on exposed skin and caused painful welts and blisters that lingered for weeks. Nicolas had an allergic reaction that also caused a rash.

The leaves of Agave Americana are barbed and ornery. #watchout Photo by Monika Maeckle

Then I tried setting the agave on fire using kindling and later charcoal fire starter. Keeping the fire alive was a challenge given the agave’s high moisture content–like burning a watermelon. Eventually, the flame caught. The plant literally shed tears as water drooled down the sides of its sword like leaves. A sad sight, but I still had to dig the root rosette up with a shovel.

I even considered herbicides, but the mass of the plants would require such enormous doses, that just seemed wrong.

Finally, an experienced landscaper suggested I wrap a chain or towing strap around the plant’s base, attach it to a trailer hitch or truck axle and pull it out by its tap-root. This seemed like a brilliant idea. After clearing as many baby agaves as we could to gain access to the base, my friend Kelly and I wrapped a chain around the rosette and attached it to my Toyota 4Runner. With four-wheel drive engaged, I stepped on the

AGave graveyard

Agave graveyard: Discarded Agaves lay on the rocky watershed where they can’t make contact with soil and resprout. Photo by Monika Maeckle

gas and the agave released its grip on the rocks and earth holding it in place. We dragged the plant to the “agave graveyard’ on the karst watershed where it could not make contact with soil. Like its thorny sibling prickly pear, agave is famous for resprouting if any of its greenery touches the earth. Experts caution not to add it to the compost pile, either. It will quickly take root.

My husband Robert Rivard with his Coba, a tool provided from a horticulturist friend in Mexico to keep the agaves under control. Photo by Monika Maeckle

As a gesture of my respect for this plant, we’ve allowed two specimens to remain on site. We await their century plant spurt, the year when these mighty agaves will shoot their reproductive stalks skyward and grace us with pollen powdered yellow flowers that will attract bats and hummingbirds. In the meantime, we manage the plant aggressively, snipping its hefty mature leaves with the coba, and clearing the pups regularly.

Once these agaves springs their seeds, we’ll shut down agave production on the ranch.

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Trinity students continue battle with Johnson grass–Goldenrod winning

Biology students from Trinity University returned to the Texas Butterfly Ranch last week to continue battle with invasive species–specifically, Johnson grass. Four students arrived last Friday to take stock of an ongoing experiment that began last April on the banks of the Llano River and will continue through next year. The goal: figure out which methods are most effective in killing Johnson grass.

Johnson grass experiment

Levanya Hospeti and Molly Lenihan assist Dr. Kelly Lyons  in collecting data for a Trinity University biology experiment. Foreground: Johnson grass. Photo by Monika Maeckle

“We successfully reduced Johnson grass abundance using both grubbing and herbicide,” said biology professor Dr. Kelly Lyons, a restoration ecologist and invasive plant expert who organized the experiment for her students. While it’s too soon to say whether grubbing (physically removing the Johnson grass) or herbicide (aquatic-safe glyphosate) is more effective, preliminary data suggest that where Johnson grass was reduced, biodiversity increased.

“We also found that in these rainy seasons, Goldenrod competes well with Johnson grass, albeit to the exclusion of most other species,” said Dr. Lyons.

That’s good news for migrating Monarch butterflies who use the late season bloomer as a nectar stop as they move through the Texas Funnel each fall on their way to Mexico.

Goldenrod Llano River

Goldenrod, a favorite nectar source for Monarch butterflies during the fall migration, competes will with Johnson grass and shields Swamp milkweed from harsh sun and flooding. Llano River, Texas Hill Country. Photo by Monika Maeckle

The project began last April as part of Trinity University’s ongoing research funded by the University, Texas Ecolab, and the National Science Foundation. Last spring, a team of students arrived at the ranch to set up plots and gather baseline data on plant density and diversity. Students established four 15- x 2-meter plots were established and applied  different forms of Johnson grass control–grubbing, weedwhackjng, and herbicides, in various combinations.

On this visit, Levanya Hospeti, Molly Lenihan, Austin Philippe and Olivia Roybal joined Dr. Lyons to collect data and plant plugs of native Eastern gamagrass, Tripsicum dactyloides, a boisterous grower that Dr. Lyons believes can compete heftily with the rambunctious Johnson grass. Students planted 20 Eastern gamamgrass plugs and will continue monitoring the site over the course of the next year.

EEG

Olivia Roybel watches as Austin Phillipe drills a hole to plant Eastern gamagrass plugs. Photo by Monika Maeckle

Texas Invasives cites Johnson grass as one of the Top 10 Most Noxious weeds in the world. It arrived from the Mediterranean in the 1800s when it was imported as a supplementary foraging crop–even though when stressed, it can produce toxic amounts of hydrocyanic acid that makes it poisonous to livestock. The super aggressive grass spreads through rhizomes and seeds, hogs space and resources, and crowds out natives that provide food, fodder and shelter to local wildlife.

monarchsonfrostweed

Monarch butterflies nectar on Frostweed along the Llano River in 2012. Now the native nectar source has to compete with Johnson grass. Photo by Monika Maeckle

For years we’ve enjoyed lovely stands of Goldenrod and Frosted on the Llano in the fall when the Monarchs pass through. Solidago altissima and Verbesina virginica, beautiful yellow and white late season nectar sources, respectively, serve as important fuel and resting stops for migrating Monarch butterflies and other creatures. But ever since a road project disrupted our stream bank and hauled in uninvited Johnson grass, we’ve been fighting the battle to win back our native nectar plants.

Eastern gamma grass

On the Llano River: Eastern gamagrass, a lovely native and host to the bunchgrass skipper.  Photo by Monika Maeckle

Dr. Lyons thinks that the Goldenrod and Eastern gamagrass, a lovely, large bunchgrass related to corn that grows two – 10-feet tall, are up to the task.

Dr. Kelly Lyons

Dr. Kelly Lyons

“The species is already present in high abundance and provides high quality habitat,” said Dr. Lyons, adding that Eastern gamagrass also works as a great soil stabilizer in river ecosystems. “Restoration ecologists often refer to it as ‘riparian rebar’ since its rhizomes are even more substantial than Johnson grass,” she said.

So the battle continues.  No surprise that we’re rooting–pardon the pun–for Eastern gamagrass. It offers multiple benefits to our local creatures, including service as a host plant to the Bunchgrass skipper. It also appears to be a steady companion to our Llano River Swamp milkweed, Asclepias incarnata, host plant to Monarch butterflies. Tall mounds of Eastern gamagrass already occur naturally all along the Llano, providing shade for late season milkweed from harsh summer sun.

Bunchgrasss skipper hosts on Easern gamma grasss and other bunch grasses. Photo by Charles T. and John R. Bryson, Bugwood.org -

Bunchgrasss skipper hosts on Eastern gamagrass and other bunch grasses. Photo by Charles T. and John R. Bryson, Bugwood.org –

We spend a lot of time and energy talking about restoring native milkweeds and other pollinator plants to the prairies that we’ve lost. It’s equally important to manage and combat the advances of invasive species that infect our wildscapes. Johnson grass is just one interloper. Check out the Texas Invasives website for more information.   We’ll keep you posted on the progress of the project.

 

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Trinity Students Tackle Invasive Johnson grass on Llano River

There was a fine lady from Lampasas
Who waged battle with invasive grasses
When a root so immense
of that Sorghum halepense
Knocked her and her friends on their Johnson grasses.

                          –Chris Best, Texas State Botanist
                             U.S. Fish and Wildlife Service

monarchsonfrostweed

Monarch butterflies nectar on Frostweed along the Llano River in 2012. Now the native nectar source has to compete with Johnson grass. Photo by Monika Maeckle

On the Llano River, we’ve always enjoyed lovely stands of Goldenrod and Frostweed in the fall when the Monarchs pass through. Solidago altissima and Verbesina virginica, beautiful yellow and white fall bloomers, respectively, serve as important nectar and resting stops for migrating Monarch butterflies and other creatures.

Until recently.

In the last two years, we’ve noticed our uninterrupted stands of fall nectar plants persistently punctuated by invasive Johnson grass. A recent road project that busted the crust on our river frontage opened the gate for germination, and the record rains and floods have put our nectar rest stop for pollinators at risk. Where once stood a solid stand of fall blooms for migrating Monarch butterflies, local Swallowtails and native bees, now presides an uninvited patch of Johnson grass.

The pesky invasive, Sorghum halepense, first arrived in the U.S. from the Mediterranean in the 1800s when it was imported as a supplementary foraging crop.   We all know how that turned out.

Eastern gamma grass

On the Llano River: Eastern gamagrass, a lovely native and host to the bunchgrass skipper.  Photo by Monika Maeckle

Now, Johnson grass is one of the Top 10 Most Noxious weeds in the world, according to the educational website Texasinvasives.org, a public-private partnership of state and federal agencies, conservation organizations, green industry businesses, academia and others organized to protect Texas from the threat of invasive species.  Johnson grass is super aggressive, spreads through rhizomes and seeds, hogs space and resources, and crowds out natives that provide food, fodder and shelter to local wildlife.

Johnson grass has nasty rhizomes
Creeping through the clastic loams
The bunches measure three feet wide
And their leaves are stuffed with cyanide.

                                            –Chris Best

When stressed by drought, frost or herbicides, Johnson grass can produce toxic amounts of hydrocyanic acid that makes it poisonous to livestock–not a trait you typically seek in a grass meant for cattle grazing.  The seeds are also especially well protected by their casings and can survive the digestive tracts of birds and others that might eat them.

Oh, and Johnson grass likes moist conditions.  Like riversides.  After floods.   Are you getting the picture here?

austinjohnsoneeggrass

Trinity biology student Austin Phillipe lets us know what he thinks of Johnson grass on the Llano. That’s Johnson grass on the left. Eastern gamagrass on the right. Photo by Monika Maeckle

Trinity University students to the rescue.   Last week, five students accompanied their biology professor, Dr. Kelly Lyons, a restoration ecologist and expert in invasive plants, to the Texas Butterfly Ranch to assist in a Johnson grass eradication project as part of Trinity University’s summer research program funded by the University, Texas Ecolab, and the National Science Foundation.

The project began in April when a team of students arrived at the ranch to set up plots and gather baseline data on plant density and diversity.   Four 15- x 2-meter plots were established and will be treated with different forms of Johnson grass control–grubbing, weedwhacking, herbicides, and fire in various combinations.

Last week, students Ann Adams, Cassandra Alvarado, Avva Bassiri-Gharb, Kendall Kotara and Austin Phillipe returned to check the effect floods had on the site and begin control treatments.  The messy job of reestablishing the plots started Thursday, as super-sized mosquitoes dogged the students.  “Wear a hazmat suit,” quipped Avva Bassiri-Gharb. Said Phillipe:  “A bad day in the field beats a good one in the lab. But we had a great day in the field so you can’t beat that!”

More data collection and Johnson grass removal continued Friday in the aftermath of yet another inch-plus of rain and two overnight tornado warnings.  Grubbing and herbicide applications followed, with herbicide applied via makeshift wand–actually barbecue tongs wrapped in towels–that kept the product from escaping to desirable plants.

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Later this year we’ll test fire as a control method, and plant Eastern gamagrass, Tripsicum dactyloides, as a native replacement.   The project will continue into 2016.

Eastern gamagrass, a lovely, large bunchgrass related to corn that grows two – 10-feet tall, is well suited to the Llano River’s unpredictable moods of famine and flooding.

Dr. Kelly Lyons

Dr. Kelly Lyons

“The species is already present in high abundance and provides high quality habitat,” said Dr. Lyons, adding that Eastern gamagrass also works as a great soil stabilizer in river ecosystems. “Restoration ecologists often refer to it as ‘riparian rebar’ since its rhizomes are even more substantial than Johnson grass,” she said.

Eastern gamagrass also competes well with overzealous Johnson grass and uses niche space in a similar way, said Dr. Lyons. “We hypothesize that it will hold its own when Johnson grass tries to reinvade.”

So the war is on.  No surprise that we’re rooting–pardon the pun–for Eastern gamagrass.  It offers multiple benefits to our local creatures, including service as a host plant to the Bunchgrass skipper.   It also appears to be a steady companion to our Llano River Swamp milkweed, Asclepias incarnata, which is a host plant to Monarch butterflies.  The tall  mounds of Eastern gamagrass provide shade for late season milkweed from harsh summer sun and shield it from flooding.

Bunchgrasss skipper hosts on Easern gamma grasss and other bunch grasses.  Photo by Charles T. and John R. Bryson,  Bugwood.org -

Bunchgrasss skipper hosts on Eastern gamagrass and other bunch grasses. Photo by Charles T. and John R. Bryson, Bugwood.org –

We spend a lot of time and energy talking about restoring native milkweeds and other pollinator plants to the prairies that we’ve lost.   It’s equally important to manage and combat the deluge of invasive species that infect our wildscapes.  Johnson grass is just one interloper.    Check out the Texas Invasives website for more information.   We’ll keep you posted on the progress of the project.

 

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Like what you’re reading? Follow butterfly and native plant news at the Texas Butterfly Ranch. Sign up for email delivery, like us on Facebook, or follow us on Twitter, @monikam