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Why planting tenacious tamarisk seemed like a good idea until it wasn’t, and other harrowing tales of Colorado’s invasive species

For scientists, preserving nature’s balance can mean love-hate-love relationships with everything from Dalmatian toadflax to horny beetles and jumping carp.

In this July 12, 2012 photo, dead, browned tamarisk lines the banks of the Colorado River as efforts to eliminate the invasive species appeared to be working. The small tamarisk leaf beetle, used to control the nonnative and invasive tamarisk plant, was released in 2004 along the Colorado River in Grand County. (AP Photo/The Salt Lake Tribune, Francisco Kjolseth)
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Tamarisk was brought to the U.S. from Kazakhstan in the early 1800s to shore up riverbanks and railroad beds.

It worked.

Left to itself, tamarisk multiplies.

Left to itself in America, 6,000 miles from natural predators on the Asian steppes, tamarisk goes nuts.

Tamarisk is a tenacious shrub whose pinkish flowers look good just enough of the year to just enough people to have spared its collective life through this point in time. 

Tamarisk spreads through its roots. Cut one stalk, another is happy to pop up a few inches away.

Tamarisk spreads through seeds. All year. From its watery perch, tamarisk seeds spread downstream through floods and upstream on the wind.

Tamarisk is also known as salt cedar. Bite the feathery leaves and you’ll know why. The leaves suck salt up from Western sand. The leaves fall and decompose. The ground gets saltier. Cottonwoods and willows don’t like the salt. So they quit.

Chop the tamarisk, and it giggles. Paint a stump with herbicide and another stump says, “Nice try, yoo-hoo, over here!” Tie an old tire around its neck and light it on fire — it’s been tried — and you have tamarisk and melted, salty rubber.

Tamarisk can grow 12 feet in one summer. Tamarisk can hold its breath underwater for 70 days.

By the late 1990s, tamarisk had oversalted the food of native species on 1.6 million acres in the West, and counting. It was a most wanted plant in Colorado and the Four Corners.

Wanted, as in dead, not alive.

Headlines said the insatiable tamarisk, thirstier than a new subdivision, would drink the West dry.

There’s a beetle. Diorhabda carinulata. Rhymes with “hakuna matata,” as in, the ladybug-size beetle espouses the problem-free philosophy of eating acres of tamarisk dead, dead, dead.

A tamarisk beetle, diorhabda carinulata, feeding on tamarisk tree leaves. (Ed Kosmicki, Special to The Colorado Sun)

Because this beetle eats only one thing, it also resides in and around Kazakhstan. So some U.S. scientists deployed butterfly nets in Genghis Khan country, flew home, threw some diorhabda into cushy lockdown in laboratories across the West, and then started filing paperwork.

This is not 1832. It takes a long time to legally release a new predator onto U.S. soil. Think years, and then think more than that.

It took a decade after immigration for the beetles to see wild U.S. tamarisk. It took another four years after that for Dan Bean, director of the Palisade Insectary for the Colorado Department of Agriculture, to get a permit to release them at a Colorado River boat ramp outside of Fruita.

Why does it take so long for a federal government “yes”? Asian carp, cane toads, lionfish, brown tree snakes. All things that seemed like a good idea at the time.

Georgians once paid each other $8 an acre to plant kudzu as a soil binder in the 1930s. Now they pay each other $1,200 an acre to scrape it out with a Bobcat loader.

That’s why.

Also: Norwegian rats.

Even if you get approval for a new invasive predator, you’ve got to go very, very slow.

First you have to remind them that breeding on a storm-tossed Colorado River bank is harder than the cushy laboratory life of laying eggs on a cage floor lined with paper towels.

Then you have to make absolute double-secret probation sure they don’t eat anything else but what you hired them to eat. 

Diorhabda did not eat anything else. They consistently demonstrated glorious, gluttonous monogamy.

From indoors at Palisade, the diorhabda went to a screen porch. For a year. Finally, in a wave of releases happening for years from California to Colorado and Utah to Mexico, they got their predator license.

It worked.

Diorhabda chased tamarisk from miles of riverbank in a matter of weeks.

Colorado was happy.

Utah was happy.

Texas was happy.

California was happy.

New Mexico was happy.

Arizona? Not so much.

Arizonans love a bird called the Southwestern willow flycatcher. The bird’s song is described as “sneezy.”

As anyone knows who has ever seen Phoenix, Arizona is not exactly pristine wilderness.

As cattle wandered, as malls multiplied, as dams proliferated, as wetlands were paved over by pickleball courts, the increasingly homeless flycatcher sought refuge.

In tamarisk.

Southwestern willow flycatcher (National Park Service)

The Southwestern willow flycatcher is officially endangered.

It would be better if the willow flycatcher didn’t like to build nests in non-native tamarisk. But with as few as 900 breeding pairs of the flycatchers left across what amounts to about a third of the lower 48, who’s going to tell them?

So Arizonans sued. About the beetles. Specifically about the people dedicating their lives to releasing beetles that in turn dedicated their lives to wiping out tamarisk. The tamarisk the little birds loved.

This field, of trekking to the Shelek River and waving a net around checking beetles in your luggage for 6,000 miles and raising bugs under your bed for a decade and suing for permission while others sue you for cease and desist, is called biocontrol.

You’d think the biocontrollers who know how to spell all four sibling species of diorhabda would throw up their hands in despair at this point.

They have not.

Biocontrollers seem to love it. The arguments are the point. Species have been on the move since Adam walked out of Eden with an apple core.

Who’s up? Who’s down? Who’s out of control? Who’s about to disappear? What idiot brought it here? Who has the right to do anything about it?

That’s the point.

“You can’t ever say it will never, ever cause another problem. You have that no matter what you do in resources management,” says Bean. “We were certain the beetles would behave themselves, and stay on tamarisk. But there’s always that question.”

In this Tuesday, July 9, 2019 photo Northern Arizona University researcher Matt Johnson sweeps tamarisk trees along the Verde River in Clarkdale, Ariz., in search of beetles that feed on the leaves. The beetles were brought to the U.S. from Asia to devour invasive tamarisk, or salt cedar, trees. (AP Photo/Felicia Fonseca)

The Arizona lawsuits killed federal beetle catch-and-release funding.

The feds had been thisclose to quitting anyway, still po’d about an unauthorized beetle release in southwestern Utah.

Seems that while one federal agency was rethinking the whole beetle thing, another federal agency still promoting the bug gave a nudge-nudge-wink-wink PowerPoint talk to county weed officials. No one can ignore a good PowerPoint. 

Other biocontrollers took the pause caused by this tiff to question everything they ever assumed about tamarisk.

Turns out it’s not really that thirsty.

“Tamarisk Will Kill Us All” headlines were all based on a 1987 paper that said each plant drank 200 gallons a day. Turns out the authors never showed their math.

A thoroughly-vetted paper in 2007 put the actual number at 32 gallons.

Guess what a cottonwood drinks in a day?

32 gallons.

So tamarisk in the West has been downgraded from a floating felon to an overhyped jaywalker.

And god-like species patrollers of the West seem OK with that.

“My thoughts have changed on the tamarisk,” said Steve Anthony, weed control manager for Garfield County, sliced through by the Colorado and a lot of salt cedar.

Anthony now calls tamarisk “a dull roar.”

He’s got a few other dull roars on his list of county weed threats. The list runs to 156 pages.

Garfield County pays a bounty for the noxious weed myrtle spurge pulled from the ground. (Renee Savickas, Garfield County)

The list describes how Garfield County has a bounty program.

For myrtle spurge. 

Myrtle spurge was brought to the U.S. from the Balkans as an ornamental. In biocontrol, “ornamental” is spelled “disaster waiting to happen.”

Myrtle spurge does not play well with plants or humans. It doesn’t let anything grow next to it. Break a leaf of the succulent and your hands will be covered in an irritating, milky discharge.

Bounty hunters in Garfield County should wear gloves. And then find Anthony when they have filled a 13-gallon garbage bag with myrtle spurge.

Give or take. Anthony is a generous broker for myrtle spurge.

For this 13-gallon bag of poisonous succulent, Steve Anthony will pay you a $20 voucher to a local nursery supply.

Record High for Myrtle Spurge Bounty Payoff: 56 bags in 2010. 

Current Average for Myrtle Spurge Bounty Payoff: A dozen. Give or take. 

“Tamarisk” does not appear in the 156-page Garfield County weed control plan until page 14. 

It sits right next to Steve Anthony’s current big problem: Russian olive.

Garfield County has federal money to help landowners remove exactly two of dozens of designated noxious weeds. One is tamarisk. The other is Russian olive.

Jim Bair has both.

Jim owns a horse grazing property that he’s trying to revive, a couple of miles upstream from Rifle’s Garfield County Airport. He calls it Bair Landing.

The airport is where Anthony has his proudest tamarisk victories. Release beetles swarmed it. Chainsaw-wielding crews of day-release inmates from Rifle Correctional Center also swarmed it.

They won. 

Insulted but not vanquished, tamarisk moved on. That’s what it does. Some reached Bair Landing.

But Bair’s worst problem is Russian olive colonizing south from the Colorado River bank to clog his pastures.

A dense thicket of Russian olive trees on his neighbor’s property stands in stark contrast to Joe Bair’s cleared grassy land east of the fenceline. Bair received help from Garfield County’s tamarisk/Russian olive removal program in getting rid of hundreds of the invasive trees growing on the banks of his land along the Colorado River. (Gretel Daugherty, Special to the Sun)

On Google Satellite View, the opportunistic gray-green trees look like someone attacked Bair Landing with the dullest Crayon in the box.

Bair bought his Landing after 27 years in Glenwood Springs. Taking possession, he realized he couldn’t even get to water’s edge. More than 300 Russian olives were putting two of his seven grazing acres off limits to hungry horses.

Bair’s application for public Russian olive eradication funds went to the Weed Advisory Board.

If you want to be on the Weed Advisory Board, it helps to own 40 acres or more of Garfield County land. And to live on it.

Submit your application to Sarah LaRose. There are usually openings.

Work crews at Bair Landing cleared some tamarisk but spent the most time felling and chipping Russian olive for a hundred feet in from the river. Bair hauled the sawdust to the dump. Sawdust crowds out the horse grass.

“When I bought this place I didn’t realize how big a problem I had,” Bair said.

The long-term plan for Russian olive in Colorado involves birth control, not genocide.

Because Russian olive is still an ornamental in some states. Just like you can buy “weed” in Colorado but can’t ship it to, say, North Dakota, you can buy weed called Russian olive in North Dakota but you can’t ship it to Colorado. Or New Mexico. Or New York, Montana, Illinois or Washington state.

Since some people love Russian olives, Bean and his colleagues can’t just kill them all. But they can sterilize them.

A Russian olive tree is pictured in Lafayette on May 26, 2020. Photo by Andy Colwell, Special to The Colorado Sun

The Swiss and the Iranians found a mite that eats the shoot tips and flowers of Russian olive. The Swiss and Iranians say aceria angustifoliae is “likely” to eat only Russian olive.

“Likely” is doing a lot of work there.

Nevertheless, Bean is eager to unleash aceria angustifoliae on Colorado as soon as he gets permits. Which could take years.

In the meantime, Bean’s other big battle in Colorado is against Dalmatian toadflax.

Dalmatian Toadflax would make a great name for a band.

Much better than Milky Discharge.

Anyway.

Dalmatian toadflax came from — wait for it — Dalmatia. In Dalmatia it is spelled “ornamental.”

Here, it invades burned-over areas and grows chest high. After the 2012 Hewlett Gulch and High Park wildfires near Fort Collins scorched 90,000 acres, Dalmatian toadflax left showy yellow flowers on rolling hills and bullied out every other species.

There’s a Dalmatian toadflax weevil. Mecinis janthiniformis.

Dalmatian toadflax. (Gary Stone, University of Nebraska Lincoln)

If you name your band Dalmatian toadflax, then Dalmatian toadflax weevils are the ones following you all over the country in RVs wearing tiny tie-dye T-shirts.

The weevils overwinter inside dried toadflax stems and come out in spring for binge breakfast. Bean and others collect dried stems in the fall, guard them in Palisade, and hand them out to landowners in the spring.

At High Park, Bean said, “the density of toadflax declined by 90% without any spraying.”

Tamarisk control is subdued, but not dead. Front Rangers associate tamarisk with Moab and Grand Junction. The bathroom wall you duck behind on a raft trip. But tamarisk plagues the Arkansas basin in Colorado, too. All the way to Kansas.

There’s a tougher version of diorhabda. 

Released in Texas, by way of Uzbekistan. Likes the heat. Don’t tell Arizona.

Estimated release approval date in Colorado?

The over-under is on “never.”

So for a few summers, Bean and his friends drove southeast, to where Oklahoma sticks a finger under Colorado and a tiny, highly unreliable portion of the Cimarron River flows northeast through a corner of the state.

For the record, before the Cimarron makes up its mind, it starts in New Mexico, tries Oklahoma and thinks better of it, flirts with Colorado, auditions for Kansas, gives Oklahoma a second chance, gets a Kansas callback and then finally hits a groove back in Oklahoma in search of the Arkansas River. The Cimarron also dries up completely more often than is friendly to wetlands biologists.

Texas beetles have been seen in Kansas, headed upriver, and in Oklahoma, headed downriver. The feds have had enough of entomological squabbling in the Four Corners and forbid scientists like Bean from crossing state lines to capture beetles.

But there’s nothing that says you can’t stand at the border and hand out flyers for all-season clothing-optional beetle raves. 

So Bean’s crew stands amid Colorado tamarisk, where the Cimarron flees Oklahoma and where the Arkansas begins subjecting itself to Kansas. They wave nets and pray for diorhabda carinata.

There’s also beetle pheromone, because of course there is.

Take an empty jar. Scoop the air over a churning mass of male diorhabda that are in close touch with their reproductive feelings. Slap a cap on the jar and send it to Montana State.

Montana State will sort the chemicals by levels of horniness and reproduce them synthetically. They’ll send you back a vial of the good stuff.

Dripping a drop on some tamarisk is like dropping a pizza box in a frat house. Except that the male diorhabda pheromone attracts both females and males.

Finally, a point in biological history where the male is doing more than its share.

Landowners still feeling plagued by tamarisk should call their local extension agent. They might get a box of beetles. They might get a spritzer of beetle musk. They might get a busload of minimum-security felons carrying sharp tools. But they will get something.

And if you’re willing to wait a while, Montana State is working on embedding that good pheromone stuff in a wax so that it lasts longer on the leaf.

To sum up: Tamarisk was our friend until it wasn’t and we couldn’t kill it with knives or poison or tire fires or chain gangs so we got denuding beetles from Kazakhstan or was it Turkmenistan who only eat one thing and they work great but then sneezy songbirds had a sad and Arizona made friends with tamarisk and hired a bunch of lawyers and we had to stop and maybe tamarisk really could be our friend too but not really so now we stand at the border waving butterfly nets and loading diorhabda sex wax into a caulking gun.

Now. About those Asian carp. Some are here and some are on the way. 

Asian grass carp were invited here to eat an invasive species, European watermilfoil. 

Unlike tamarisk beetles, grass carp order the buffet, not a la carte. They eat everything that’s green. 

Grass carp can eat their weight every day or two. 

The record grass carp in Colorado weighed 57 pounds, 13 ounces. 

Colorado put grass carp on a diet by dividing the state: East of the Continental Divide, stocked grass carp could be fertile. West of the divide, they had to be sterile. 

Party on the plains, business on the plateau. 

It didn’t work. Now every single grass carp released in Colorado has to be the last of its family line. 

Colorado claims silver carp are not here. 

Yet.

Google some silver carp videos. Especially if you want to swear off ever boating in the Midwest again. 

Scores of fish jumped into the air inside Western Kentucky’s Barkley Lock. (Chattanooga Times Free Press)

Nebraska has silver carp. They are headed west. 

Colorado says diversion dams will slow the silver carp’s wandering. 

Try not to think about floods like 2013 when dams across Colorado and Nebraska were overrun and whole counties became a big soup for two-way swimming. 

Silver carp weigh up to 100 pounds. They jump 10 feet out of the water. They jump out of the water at the sound of a boat engine.

In places they have colonized — basically everywhere — this tends to dampen enthusiasm for water skiing.

Everything’s fine.


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