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Dr. Dan Bean, the state’s top expert in using insects to control invasive plant species like tamarisk, came to Southern Colorado last week to help local conservation officials and biologists continue to wage war on the plant that threatens nearly every major waterway in the region.
Bean manages the Colorado State Department of Agriculture’s Plant Industry Division Insectary at Palisade. He spent three days, July 7-9, working along the Apishipa and Purgatoire rivers in Las Animas County to release beetles that will devour tamarisk, also known as salt cedar.
Patty Knupp, a private land and wildlife biologist, said 1,000 beetles were released July 7 in two locations along Chacuco Creek, a tributary of the Purgatoire River. On July 8, four more releases of beetles were conducted along the Purgatoire River and two releases were made on the Apishipa River. Then, on July 9, the tamarisk eating beetles were released on the main stem of the Arkansas River near Fowler.
“If we don’t control the upper reaches of these tributaries to the Arkansas, then why would we want to start on the main stem of the river?” Knupp said, replying to a question about why certain locations were selected.
Knupp, who works under contract with the U.S. Department of Agriculture’s Natural Resources Conservation Service, the Colorado Division of Wildlife and the Rocky Mountain Bird Observatory, said private land owners have partnered with government agencies to wage war on tamarisk, primarily through aerial spraying with helicopters, since 2005.
The partners in this case included the Branson-Trinchera and Spanish Peaks-Purgatorie River Conservation Districts, NRCS, the Colorado State Forest Service (represented by Shelly VanLandingham from the State Forestry Service office in La Junta, plus the agencies and groups that contract with Knapp.
For decades, farmers, ranchers and many other people across the West thought the plague that tamarisk had visited upon streams and rivers was simply unsolvable. But times are changing, in part because people like Bean have discovered insects that devour the plant. Other scientists have developed an herbicide called Habitat, that can be applied by hand-held sprayers, or better yet, with helicopters, to kill tamarisk. Knupp said its only drawback in terms of application is that it can’t be applied with fixed-wing aircraft, such as crop dusters.
People in the business of combating tamarisk speak almost with reverence about the success Bean has accomplished along the Dolores River and Colorado River on the Western Slope. The beetles released along the Apishipa and Purgatoire rivers last week were almost certainly offspring of beetles that had been part of successful control projects along the Dolores and Colorado river basins.
One of Bean’s primary concerns has been to determine if the tamarisk beetles feed on other beneficial insects. Knupp said another of the state insectary’s challenges has been to find out how to make the insects more hardy.
“It has been kind of tough to get them established,” she explained. For example, beetles that were released last year along Fountain Creek and other places in Pueblo County were nowhere to be found when Knapp and others went searching for them or their offspring this year.
Ants and Asian ladybugs are natural predators of tamarisk beetles and can be particularly tough on a population.
“We’ve found that the beetles don’t do especially well below the 38th parallel,” she noted. “The number of daylight hours have an impact on whether they flourish.”
But there have been some fairly significant success stories, especially with aerial application of herbicide. Since 2005, more than 2,000 acres along the Apishipa River drainage have been sprayed. That figure represents about 30 miles of river. Knupp said the private landowner who first allowed spraying tamarisk on his land in 2005 has seen about 90 percent of the plant killed, and he has realized his goal of seeing more water flow down the river.
Tamarisk is particularly hard on riparian zones. A mature plant can consume nearly 200 gallons of water per day. When multiplied by the 67,000 acres of tamarisk growing in the Arkansas drainage alone, it’s easy to see why people who are concerned with developing water resources want to wipe it out.
Tamarisk is not native to America. It was imported to the U.S. as an ornamental shrub as far back as the early 1800s. During the Great Depression and the Dust Bowl days of the 1930s, millions of tamarisk plants were planted as a means to control erosion.
It not only consumes a lot of water from a river or stream, tamarisk also produces a lot of salt, Knupp said, which makes it difficult to establish native plants like willows, cottonwood trees, natural grasses and forbes after the tamarisk has been eradicated.
The cost of eradication can vary greatly, too. Aerial spraying of herbicide can cost as much as $200 per acre. That pales in comparison to the cost of going in with tractors, chainsaws or other mechanical devices to wipe out areas. In that case, the cost can reach $1,000 or more.
Those costs have made waging war against tamarisk big business. This year, the NRCS pooled $1 million for groups that would apply for funding programs to eradicate the plant. Applications were due in February for the initial NRCS Environmental Quality Incntive Program contracts. In the past four years, Knupp reported the NRCS has spent the following amounts on tamarisk eradication: 2006, 13 projects, $950,000; 2007, 18 projects, $500,000; 2008, 10 projects, $492,000; and this year, 11 projects, $861,000.
The need to help eradicate invasive species like tamarisk and Russian olive trees in order to improve both quantity and quality of water sources, has elevated the subject to even higher levels in the federal government. President Barack Obama even made such programs part of the American Resources and Recover Act funding, known as the stimulus bill, channelling money for such projects through the U.S. Fish and Wildlife Service.
In most cases, if NRCS EQIP funds are granted to help a landowner with a project, they involve cost-sharing and the landowner ends up paying part of the cost, Knupp explained. Also, in most casts technical Integrated Pest Management planning and invasive weed species control prescriptins are provided by county weed control departments, personnel from conservation districts or private contractors with the know-how to control the invasive species and get native plants growing again.
All of this is information that Bean and others at the Plant Industry Division Insectary have known for years.
Their level of expertise on the beetle alone is a biological lesson in itself. For example, here is how Bean describes the beetle: “The tamarisk leaf beetle, “Diorhabda elongata,” is found throughout the range of tamarisk in Eurasia and North Africa. The beetles that we have in Colorado were originally from the northwestern part of China, near the town of Fukang, or from Kazakhstan, near the town of Chilik. For all practical purposes beetles from these two origins are identical; they cannot be distinguished by taxonomists and they behave in exactly the same manner regarding host plant preference. We call them the Central Asian strain of D. elongata. There are other strains currently in use in the U.S. including the Mediterranean strain from Crete and mainland Greece, the North African strain from Tunisia and the Uzbek strain from Uzbekistan. We have these strains in culture at the Palisade Insectary but they are currently not permitted in Colorado, so all work in our state is with the Central Asian strain.
The tamarisk leaf beetle feeds on the scale-like leaves of the tamarisk plant. Beetles feed as adults but about 90 percet of the damage comes from feeding as larvae. Adult beetles can fly and are attracted to plants by the smell of the leaves (host pant volatiles) and by a pheromone emitted by the males after they begin feeding. This combination of odors brings in large numbers of males and females and in a few days the tamarisk plant is covered with eggs. These hatch into small black caterpillar-like larvae that feed voraciously on the foliage. When the larvae complete feeding (in about two weeks) they drop to the ground and pupate in the leaf litter or soil beneath the plant. After two weeks they emerge as adults. Adults that emerges later in the season feed then enter a dormant state known as diapause and they spend the fall and winter beneath the tamarisk plants as adults waiting for the spring flush of foliage.
Beetle larvae can defoliate a plant in a matter of days. The plants turn from bright green to straw brown following defoliation and a healthy plant will then send out new foliage within weeks. After several cycles of defoliation plants begin to die back and they can be killed by several years of defoliation. Even before they are dead the tamarisk plants lose vigor and the canopy opens, allowing other plants, such as willows, cottonwoods and grasses, to return.
That is the scientific aspect. But Bean goes on to write that this year the Insectary is particularly interested in releasing beetles in the Arkansas Basin, especially in tributaries like the Purgatoire and Apishipa river basins, that empty into the Arkansas near Fowler and Las Animas respectively, and in the Fountain Creek and Four-Mile Creek drainages, that meet with the Arkansas in Pueblo and Fremont counties.
It’s a war here, but then Colorado might not be the focal point of the attack either. Knupp said she believes the problem with tamarisk might be even worse in New Mexico. The plant has spread throughout the West.
In Colorado, though, officials estimate that 69 percent of the area invade already by tamarisk lies within the Arkansas River Basin, making it ground zero for the war here.
Dr. Dan Bean, the state’s top expert in using insects to control invasive plant species like tamarisk, came to Southern Colorado last week to help local conservation officials and biologists continue to wage war on the plant that threatens nearly every major waterway in the region.
Bean manages the Colorado State Department of Agriculture’s Plant Industry Division Insectary at Palisade. He spent three days, July 7-9, working along the Apishipa and Purgatoire rivers in Las Animas County to release beetles that will devour tamarisk, also known as salt cedar.
Patty Knupp, a private land and wildlife biologist, said 1,000 beetles were released July 7 in two locations along Chacuco Creek, a tributary of the Purgatoire River. On July 8, four more releases of beetles were conducted along the Purgatoire River and two releases were made on the Apishipa River. Then, on July 9, the tamarisk eating beetles were released on the main stem of the Arkansas River near Fowler.
“If we don’t control the upper reaches of these tributaries to the Arkansas, then why would we want to start on the main stem of the river?” Knupp said, replying to a question about why certain locations were selected.
Knupp, who works under contract with the U.S. Department of Agriculture’s Natural Resources Conservation Service, the Colorado Division of Wildlife and the Rocky Mountain Bird Observatory, said private land owners have partnered with government agencies to wage war on tamarisk, primarily through aerial spraying with helicopters, since 2005.
The partners in this case included the Branson-Trinchera and Spanish Peaks-Purgatorie River Conservation Districts, NRCS, the Colorado State Forest Service (represented by Shelly VanLandingham from the State Forestry Service office in La Junta, plus the agencies and groups that contract with Knapp.
For decades, farmers, ranchers and many other people across the West thought the plague that tamarisk had visited upon streams and rivers was simply unsolvable. But times are changing, in part because people like Bean have discovered insects that devour the plant. Other scientists have developed an herbicide called Habitat, that can be applied by hand-held sprayers, or better yet, with helicopters, to kill tamarisk. Knupp said its only drawback in terms of application is that it can’t be applied with fixed-wing aircraft, such as crop dusters.
People in the business of combating tamarisk speak almost with reverence about the success Bean has accomplished along the Dolores River and Colorado River on the Western Slope. The beetles released along the Apishipa and Purgatoire rivers last week were almost certainly offspring of beetles that had been part of successful control projects along the Dolores and Colorado river basins.
One of Bean’s primary concerns has been to determine if the tamarisk beetles feed on other beneficial insects. Knupp said another of the state insectary’s challenges has been to find out how to make the insects more hardy.
“It has been kind of tough to get them established,” she explained. For example, beetles that were released last year along Fountain Creek and other places in Pueblo County were nowhere to be found when Knapp and others went searching for them or their offspring this year.
Ants and Asian ladybugs are natural predators of tamarisk beetles and can be particularly tough on a population.
“We’ve found that the beetles don’t do especially well below the 38th parallel,” she noted. “The number of daylight hours have an impact on whether they flourish.”
But there have been some fairly significant success stories, especially with aerial application of herbicide. Since 2005, more than 2,000 acres along the Apishipa River drainage have been sprayed. That figure represents about 30 miles of river. Knupp said the private landowner who first allowed spraying tamarisk on his land in 2005 has seen about 90 percent of the plant killed, and he has realized his goal of seeing more water flow down the river.
Tamarisk is particularly hard on riparian zones. A mature plant can consume nearly 200 gallons of water per day. When multiplied by the 67,000 acres of tamarisk growing in the Arkansas drainage alone, it’s easy to see why people who are concerned with developing water resources want to wipe it out.
Tamarisk is not native to America. It was imported to the U.S. as an ornamental shrub as far back as the early 1800s. During the Great Depression and the Dust Bowl days of the 1930s, millions of tamarisk plants were planted as a means to control erosion.
It not only consumes a lot of water from a river or stream, tamarisk also produces a lot of salt, Knupp said, which makes it difficult to establish native plants like willows, cottonwood trees, natural grasses and forbes after the tamarisk has been eradicated.
The cost of eradication can vary greatly, too. Aerial spraying of herbicide can cost as much as $200 per acre. That pales in comparison to the cost of going in with tractors, chainsaws or other mechanical devices to wipe out areas. In that case, the cost can reach $1,000 or more.
Those costs have made waging war against tamarisk big business. This year, the NRCS pooled $1 million for groups that would apply for funding programs to eradicate the plant. Applications were due in February for the initial NRCS Environmental Quality Incntive Program contracts. In the past four years, Knupp reported the NRCS has spent the following amounts on tamarisk eradication: 2006, 13 projects, $950,000; 2007, 18 projects, $500,000; 2008, 10 projects, $492,000; and this year, 11 projects, $861,000.
The need to help eradicate invasive species like tamarisk and Russian olive trees in order to improve both quantity and quality of water sources, has elevated the subject to even higher levels in the federal government. President Barack Obama even made such programs part of the American Resources and Recover Act funding, known as the stimulus bill, channelling money for such projects through the U.S. Fish and Wildlife Service.
In most cases, if NRCS EQIP funds are granted to help a landowner with a project, they involve cost-sharing and the landowner ends up paying part of the cost, Knupp explained. Also, in most casts technical Integrated Pest Management planning and invasive weed species control prescriptins are provided by county weed control departments, personnel from conservation districts or private contractors with the know-how to control the invasive species and get native plants growing again.
All of this is information that Bean and others at the Plant Industry Division Insectary have known for years.
Their level of expertise on the beetle alone is a biological lesson in itself. For example, here is how Bean describes the beetle: “The tamarisk leaf beetle, “Diorhabda elongata,” is found throughout the range of tamarisk in Eurasia and North Africa. The beetles that we have in Colorado were originally from the northwestern part of China, near the town of Fukang, or from Kazakhstan, near the town of Chilik. For all practical purposes beetles from these two origins are identical; they cannot be distinguished by taxonomists and they behave in exactly the same manner regarding host plant preference. We call them the Central Asian strain of D. elongata. There are other strains currently in use in the U.S. including the Mediterranean strain from Crete and mainland Greece, the North African strain from Tunisia and the Uzbek strain from Uzbekistan. We have these strains in culture at the Palisade Insectary but they are currently not permitted in Colorado, so all work in our state is with the Central Asian strain.
The tamarisk leaf beetle feeds on the scale-like leaves of the tamarisk plant. Beetles feed as adults but about 90 percet of the damage comes from feeding as larvae. Adult beetles can fly and are attracted to plants by the smell of the leaves (host pant volatiles) and by a pheromone emitted by the males after they begin feeding. This combination of odors brings in large numbers of males and females and in a few days the tamarisk plant is covered with eggs. These hatch into small black caterpillar-like larvae that feed voraciously on the foliage. When the larvae complete feeding (in about two weeks) they drop to the ground and pupate in the leaf litter or soil beneath the plant. After two weeks they emerge as adults. Adults that emerges later in the season feed then enter a dormant state known as diapause and they spend the fall and winter beneath the tamarisk plants as adults waiting for the spring flush of foliage.
Beetle larvae can defoliate a plant in a matter of days. The plants turn from bright green to straw brown following defoliation and a healthy plant will then send out new foliage within weeks. After several cycles of defoliation plants begin to die back and they can be killed by several years of defoliation. Even before they are dead the tamarisk plants lose vigor and the canopy opens, allowing other plants, such as willows, cottonwoods and grasses, to return.
That is the scientific aspect. But Bean goes on to write that this year the Insectary is particularly interested in releasing beetles in the Arkansas Basin, especially in tributaries like the Purgatoire and Apishipa river basins, that empty into the Arkansas near Fowler and Las Animas respectively, and in the Fountain Creek and Four-Mile Creek drainages, that meet with the Arkansas in Pueblo and Fremont counties.
It’s a war here, but then Colorado might not be the focal point of the attack either. Knupp said she believes the problem with tamarisk might be even worse in New Mexico. The plant has spread throughout the West.
In Colorado, though, officials estimate that 69 percent of the area invade already by tamarisk lies within the Arkansas River Basin, making it ground zero for the war here.
