Invasive Plant Control in our Farms and Forests

Both forests and farms require management of invasive plant species—and they make use of the same proven methods

To drivers speeding down the interstate, green expanses of forest and farm may seem unalike. After all, rows of cultivated crops appear quite different than the expanses of wild forest located just a few miles away. However, farmers and forest managers may have more in common than you might suspect. For example, both use some of the same tools to safeguard landscapes and biodiversity while minimizing environmental impact.

 

But how exactly do the practices used in farming help protect our forests? Many of us have heard about how forest management can reduce the threats of fire and drought, but the issues caused by invasive plants are also a major challenge for forest stewards. To the untrained eye, what may appear as an unremarkable, or even beautiful blooming plant, may actually be starving native flora of sunlight and nutrients and disrupting ecosystems.

 

Luckily, most of the non-native plants introduced to the United States, either accidentally or deliberately, are relatively harmless to the environment. But a few hardy, persistent varieties are doing serious damage in some areas. The worst offenders grow quickly, and have prolific seeds. They can also eliminate valuable food sources and habitats for native birds, fish, and other animals, widening the scope of their damage. By outcompeting indigenous species, invasives can stress entire ecosystems and even contribute to extinction.

 

Invasive plants can also disrupt the flow of water bodies and contribute to drought. For example, the tamarisk or salt cedar tree, which has infested 3.3 million acres of the American West, guzzles precious water and alters the habitats of local wildlife. Native to eastern Europe and central Asia, the tree was first introduced in the West in the 1820’s for its ornamental properties. Its hardiness and tolerance for salinity in water helps it flourish in hot western climates, and it’s now displacing iconic native flora like mesquite and cottonwood trees.

Crop Field Landscape
Crop Field Landscape

To drivers speeding down the interstate, green expanses of forest and farm may seem unalike. After all, rows of cultivated crops appear quite different than the expanses of wild forest located just a few miles away. However, farmers and forest managers may have more in common than you might suspect. For example, both use some of the same tools to safeguard landscapes and biodiversity while minimizing environmental impact.

 

But how exactly do the practices used in farming help protect our forests? Many of us have heard about how forest management can reduce the threats of fire and drought, but the issues caused by invasive plants are also a major challenge for forest stewards. To the untrained eye, what may appear as an unremarkable, or even beautiful blooming plant, may actually be starving native flora of sunlight and nutrients and disrupting ecosystems.

 

Luckily, most of the non-native plants introduced to the United States, either accidentally or deliberately, are relatively harmless to the environment. But a few hardy, persistent varieties are doing serious damage in some areas. The worst offenders grow quickly, and have prolific seeds. They can also eliminate valuable food sources and habitats for native birds, fish, and other animals, widening the scope of their damage. By outcompeting indigenous species, invasives can stress entire ecosystems and even contribute to extinction.

 

Invasive plants can also disrupt the flow of water bodies and contribute to drought. For example, the tamarisk or salt cedar tree, which has infested 3.3 million acres of the American West, guzzles precious water and alters the habitats of local wildlife. Native to eastern Europe and central Asia, the tree was first introduced in the West in the 1820’s for its ornamental properties. Its hardiness and tolerance for salinity in water helps it flourish in hot western climates, and it’s now displacing iconic native flora like mesquite and cottonwood trees.

And in the Sierra National Forest, a pristine protected landscape of 1.3 million acres, Centaurea solstitialis, or yellow star thistle, and Carduus pycnocephalus, or Italian thistle, are two especially aggressive interlopers. The thistles were first introduced into the area in the mid-1800’s as a contaminant in hay and seed, and have now infested millions of acres with their dense thickets, choking out native plants and making large tracts of land impassable to humans and animals.

 

Farmers, however, are all too familiar with the problem of invasive plant species as they protect their crops from weeds. So, it’s not too surprising that forest managers have adopted many of their practices and tools. Some practices for forest management include grinding, mowing, submergence, light starvation, or grazing animals to eradicate certain invasive plants. But with precise application, herbicides can be the best option, especially when plants are well established, and mechanically removing them is difficult or could trigger erosion.

 

Using herbicides correctly, and according to their labels, is an effective and safe way to help manage our forests and guard them against these invasive species. And each herbicide approved for forest use comes with decades of research and testing prior to being authorized. A 2015 report from the U.S. Forest Service explains, “Though the use of herbicides is permitted on national forests, each herbicide must be field-tested, and an environmental analysis must be completed and approved before the herbicide can be included in the Integrated Weed/Pest Management Plan established.

 

Joanna Clines, a botanist with the U.S. Forest Service, has been battling invasives for more than 30 years. Recently, she’s had good success with targeted applications of herbicides. The seasoned forest steward notes that "invasive weed spread is kind of like a wildfire- if you find and put the fire out when it’s still small, like an abandoned campfire, you can prevent it from growing. Finding the first plant or small patch of invasive weeds before they produce seeds and treating or removing them promptly is similar."

 

Clines takes a no-nonsense approach to her work eradicating invasive plants, saying, “I am now completely convinced we can’t win this battle against invasives damaging the land without the full toolbox. We need herbicides in the toolbox.” Clines takes a methodical approach when it comes to protecting the treasured Sierra landscape, with its pristine alpine lakes and thriving animal populations. When it comes to using herbicides, she stresses, “It’s a science and an art. You have to pay attention to what you’re doing. I take it seriously that herbicides need to be respected, label instructions must be read and followed, and pesticide laws and regulations understood and followed.”

plant close up
plant close up

And in the Sierra National Forest, a pristine protected landscape of 1.3 million acres, Centaurea solstitialis, or yellow star thistle, and Carduus pycnocephalus, or Italian thistle, are two especially aggressive interlopers. The thistles were first introduced into the area in the mid-1800’s as a contaminant in hay and seed, and have now infested millions of acres with their dense thickets, choking out native plants and making large tracts of land impassable to humans and animals.

 

Farmers, however, are all too familiar with the problem of invasive plant species as they protect their crops from weeds. So, it’s not too surprising that forest managers have adopted many of their practices and tools. Some practices for forest management include grinding, mowing, submergence, light starvation, or grazing animals to eradicate certain invasive plants. But with precise application, herbicides can be the best option, especially when plants are well established, and mechanically removing them is difficult or could trigger erosion.

 

Using herbicides correctly, and according to their labels, is an effective and safe way to help manage our forests and guard them against these invasive species. And each herbicide approved for forest use comes with decades of research and testing prior to being authorized. A 2015 report from the U.S. Forest Service explains, “Though the use of herbicides is permitted on national forests, each herbicide must be field-tested, and an environmental analysis must be completed and approved before the herbicide can be included in the Integrated Weed/Pest Management Plan established.

 

Joanna Clines, a botanist with the U.S. Forest Service, has been battling invasives for more than 30 years. Recently, she’s had good success with targeted applications of herbicides. The seasoned forest steward notes that "invasive weed spread is kind of like a wildfire- if you find and put the fire out when it’s still small, like an abandoned campfire, you can prevent it from growing. Finding the first plant or small patch of invasive weeds before they produce seeds and treating or removing them promptly is similar."

 

Clines takes a no-nonsense approach to her work eradicating invasive plants, saying, “I am now completely convinced we can’t win this battle against invasives damaging the land without the full toolbox. We need herbicides in the toolbox.” Clines takes a methodical approach when it comes to protecting the treasured Sierra landscape, with its pristine alpine lakes and thriving animal populations. When it comes to using herbicides, she stresses, “It’s a science and an art. You have to pay attention to what you’re doing. I take it seriously that herbicides need to be respected, label instructions must be read and followed, and pesticide laws and regulations understood and followed.”

With all this in mind, Clines partnered with Corteva AgriscienceTM to treat about four acres of Italian thistle and Klamath weed with Milestone herbicide at the U.S. Forest Service office compound in the Sierra National Forest in 2021. While it may seem surprising to some, these maintenance and administrative locales are important sites of treatment, since heavy vehicle traffic can disperse seeds throughout the parks.

 

The thistles aren’t the only invasives plaguing the Sierras. The U.S. Forest Service reports that approximately 25 percent of the 1,400 vascular plants documented in the Sierras are not native. Of these, about 100 are so aggressive and damaging to ecosystems that they are classified as noxious weeds or invasive non-native plants.

 

When farmers and forest managers share tools and information, the critical work of protecting our land gets easier. That’s bad news for invasive species, and great news for the rest of us.

autumn scene with lake in the foreground, trees with autumn colors, and mountains in the background
autumn scene with lake in the foreground, trees with autumn colors, and mountains in the background

With all this in mind, Clines partnered with Corteva AgriscienceTM to treat about four acres of Italian thistle and Klamath weed with Milestone herbicide at the U.S. Forest Service office compound in the Sierra National Forest in 2021. While it may seem surprising to some, these maintenance and administrative locales are important sites of treatment, since heavy vehicle traffic can disperse seeds throughout the parks.

 

The thistles aren’t the only invasives plaguing the Sierras. The U.S. Forest Service reports that approximately 25 percent of the 1,400 vascular plants documented in the Sierras are not native. Of these, about 100 are so aggressive and damaging to ecosystems that they are classified as noxious weeds or invasive non-native plants.

 

When farmers and forest managers share tools and information, the critical work of protecting our land gets easier. That’s bad news for invasive species, and great news for the rest of us.

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