Gardeners Have Hand in Invasive Species Control

  • Centaurea diffusa a.k.a. Spotted knapweed. Introduced in the late 1800's, knapweed can reduce diversity in the region's prairies. (Photo courtesy of the USDA)

Gardeners have been ordering new plants and digging in the dirt this spring, but if they’re not careful, they could be introducing plants that can cause havoc with forests, lakes, and other natural areas. Gardeners can’t count on their suppliers to warn them about plants that can damage the local ecosystems. In another report in the series, “Your Choice; Your Planet,” the Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

Gardeners have been ordering new plants and digging in the dirt this spring, but, if
they’re not careful, they could be introducing plants that can cause havoc with forests,
lakes, and other natural areas. Gardeners can’t count on their suppliers to warn them
about plants that can damage the local ecosystems. In another report in the series “Your
Choice; Your Planet,” the Great Lakes Radio Consortium’s Lester Graham reports:


Gardening, especially flower gardening, seems to get more popular all the time. Maybe
it’s because the baby-boomers have all reached that age where they’re beginning to
appreciate stopping for a moment to smell the roses.


That’s fine. In fact if gardeners plant the right kinds of plants… it can be great for
wildlife. There are all kinds of guides for backyard natural areas.


But… in some cases… gardeners can unleash plant pests on the environment.


Katherine Kennedy is with the Center for Plant Conservation. She says almost all of the
problem plants that damage the native ecosystems were planted with good intentions…


“I don’t believe that any invasive species has ever been introduced into the United States
on purpose by someone who willingly said, ‘Oh yeah, this is going to be a problem, but I
don’t care.’ They’ve almost all been inadvertent problems that were introduced by
someone who thought they were doing something good or who thought they were
bringing in something beautiful.”


English ivy, a decorative ground cover, is now killing forests in the Pacific Northwest…
kudzu is doing the same in the southeast… and in the Great Lakes region and the
Midwest… pretty flowering plants such as purple loosestrife and water plants such as
Eurasian watermilfoil are causing damage to wetlands, crowding out native plants and
disturbing the habitat that many wildlife species need to survive.


Bob Wilson works in the Michigan Senate Majority policy office. Like many other
states, Michigan is looking at legislation to ban certain problem plants. Wilson agrees
that these plant pests are generally not intentional… but they do show that people seem to
unaware of the problems that they’re causing…


“The two most common vectors for bringing in these kinds of plants are typically
landscapers, who bring it in as a way of decorating yards and lawns, and then aquarium
dumpers, people who inadvertently dump their aquarium, thinking that there’s no
consequence to that. Before you know it, something that was contained is now spread.”


But stopping the import of pest plants is a lot harder than just passing laws that ban them.
With mail order and Internet orders from large nurseries so common, the plants can get
shipped to a local nursery, landscaper or local gardener without the government ever
knowing about it.


Recently, botanists, garden clubs, and plant nursery industry groups put together some
codes of conducts. Called the St. Louis Protocol or the St. Louis Declaration… the
document set out voluntary guidelines for the industry and gardeners to follow to avoid
sending plants to areas where they can cause damage.


Sarah Reichard is a botanist with the University of Washington. She helped put the St.
Louis Protocol together. She says if a nursery signs on to the protocol, it will help stop
invasive plant species from being shipped to the wrong places….


“And it’s up to each of the nursery owners, particularly those who sell mail order or
Internet, to go and find out which species are banned in each state.” LG: And is that
happening?
“Uh, I think most nursery people are pretty responsible and are trying to
do the best that they can. I’m sure that they’re very frustrated and understandably so
because the tools aren’t really out there for them and it is very difficult to find the
information. So, it’s a frustrating situation for them.”


But in preparing this report, we found that some of the biggest mail-order nurseries had
never heard of the St. Louis protocol. And many of the smaller nurseries don’t have the
staff or resources to check out the potential damage of newly imported plants… or even
to check out each state to make sure that banned plants aren’t being sent inadvertently.


Sarah Reichard says that means gardeners… you… need to do some homework before
ordering that pretty flowering vine. Is it banned in your state? Is it a nuisance that could
cause damage? Reichard says if enough gardeners care, they can make a difference…


“You know, gardeners have tremendous power. We, you know, the people that are
buying the plants at the nurseries – that’s what it’s all about. I mean, the nurseries are
there to provide a service to provide plants to those people and if those people have
certain tastes and demands such as not wanting to buy and plant invasive species, the
nurseries are going to respond to it. So, we’re all part of one team.”


Reichard and others concerned about the problem say although agencies are working on
it… the federal government has not yet done enough to effectively stop invasives from
being imported and shipped to the wrong areas. They say it’s up to the nurseries, the
botanists, and the gardeners to stop them. If not, we’ll all pay in tax money as
government agencies react to invasives with expensive eradication programs to try to get
rid of the plants invading parks, preserves, and other natural areas.


For the Great Lakes Radio Consortium, this is Lester Graham.

Related Links

GARDENERS HAVE HAND IN INVASIVE SPECIES CONTROL (Short Version)

  • Centaurea diffusa a.k.a. Spotted knapweed. Introduced in the late 1800's, knapweed can reduce diversity in the region's prairies. (Photo courtesy of the USDA)

Gardeners are being asked to be careful about what they plant. Invasive species that cause damage to natural areas often start as a pretty plant in someone’s yard. The Great Lakes Radio Consortium’s Lester Graham reports:

http://environmentreport.org/wp-content/uploads/2004/05/graham2_053104.mp3

Transcript

Gardeners are being asked to be careful about what they plant. Invasive species that
cause damage to natural areas often start as a pretty plant in someone’s yard. The Great
Lakes Radio Consortium’s Lester Graham reports:


Botanists, plant nurseries and gardeners are all being asked to do a little more homework
before importing, selling, or planting new kinds of plants. Katherine Kennedy is with the
Center for Plant Conservation. She says some of the plants you mail order from the
nursery can end up being invasive kinds of plants that damage the local ecosystem…


“We are actually at a point where these invasions crowd out the native community, not
just a species or two, but the entire community. And the wildlife value falls and the
native plants are displaced. And, so, the destructive potential for a species that becomes
truly invasive is more immense than I think many people realize.”


Kennedy says you can’t count on the nursery to warn you when you order plants. She
says gardeners have to make sure the plants they’re ordering won’t hurt the surrounding
landscape.


For the Great Lakes Radio Consortium, this is Lester Graham.

Related Links

Bugs Released to Munch on Invasive Plant

  • Purple loosestrife's looks are deceiving. It's a beautiful plant, but researchers say it has caused enormous damage in many parts of the country. An imported beetle has now shown significant signs of controlling the plant.

Purple loosestrife is a beautiful plant. It’s tall… and each cone-shaped stem produces hundreds of flowers. When the plants bloom in mid-summer they can create a sea of purple in wetlands throughout the region, but the ability of the plant to spread and reproduce in great numbers is what concerns scientists and land managers. Over the years they have been working to control it. The Great Lakes Radio Consortium’s Mark Brush says one way they’re trying to control it is by releasing a bug to eat the plant:

Transcript

Purple Loosestrife is a beautiful plant. It’s tall… and each cone-shaped
stem produces hundreds of flowers. When the plants bloom
in mid-summer they can create a sea of purple in wetlands
throughout the region… but the ability of the plant to spread and
reproduce in great numbers is what concerns scientists and land
managers. Over the years, they have been working to control it.
The Great Lakes Radio Consortium’s Mark Brush says one way
they’re trying to control it is by releasing a bug to eat the plant:


Roger Sutherland has lived next to this wetland for more than 35
years.

He helped build a boardwalk over the soggy marsh so that he can
get a close-up view of some of his favorite plants:


“You see that plant with the big green flower? Yep. That… and
there’s more along here… that’s a pitcher plant. These are insect
eating plants and there’s another one called sundew here… here’s
some right in here…”

(sound under)


But like many wetlands throughout the country, this wetland has
been invaded by a plant originally found in Europe and Asia.


Purple Loosestrife was introduced as an ornamental plant.
It was a
beautiful addition to gardens, but once it took
hold in the environment,
it out-competed native plants.

Frogs, birds, and insects have relied on these native plants for
thousands of years. Purple Loosestrife is crowding out their habitat.


“We’re going to get a lot more shade with this loosestrife.. and so
these plants that are on these hummocks here…
these little insect
eating plants and so on… just can’t tolerate that shade, so we’ll
probably lose ’em unless I can keep it open here… and I am trying
to keep some of it open.”


The plant spreads quickly… that’s because one plant can produce
more than two million seeds that spread with the wind, like dust.

So when it moves into an area, it often takes over creating a thicket
of purple with a dense root system.

Land managers have seen populations of ducks, and turtles
disappear when loosestrife takes over…

And research has shown that the plant can reduce some frog and
salamander populations by as much as half.


So land managers wondered what to do to stop the spread of this
weed.

They initially tried to control the plant by digging it up… or by
applying herbicide to each plant.

Trying to kill the plants one by one is hard work… especially
considering how abundant purple loosestrife is.

But researchers have hope because of a bug.


(Sound of volunteers planting loosestrife)

Volunteers have gathered here in Ann Arbor, Michigan to plant
purple loosestrife.

They’re putting dormant loosestrife roots into potting containers and
adding fertilizer.


(more sound)


When the plants leaf out they’ll be covered with a fine mesh net and
become home to a leaf-eating beetle known as galerucella.

And galerucella loves to munch on purple loosestrife.

The volunteers are creating a nursery to raise more beetles.

Once they’ve got a bunch of beetles growing on the plant… they’ll
take it to a nearby wetland… and the bugs will be released into the
wild…


(sound up)


Linda Coughenour is a member of the Audubon Society.

Her group is working with state and local agencies to raise and
release these beetles.

She says tackling purple loosestrife invasions is a big task – and
governments need help from volunteers to deal with the problem:


“This is a serious problem throughout the entire Great Lakes
wetlands… it has migrated from the East Coast to the Midwest…
so, uh.. the problem’s just too big – so they thought up doing this
volunteer project and they’ve enlisted people all over the state… and
we’re just one of those.”


Volunteers have have been releasing their beetles into this wetland
for few years now and they’re beginning to see progress:


“It’s going really well… for a while we got off to a slow start, but for two
years now we’ve found evidence that the beetles are reproducing on their
own. We see little egg masses, we see larva that are starting to eat
the plants, we see adult beetles on the plants that have wintered
over. And that’s the thing, to get them to do it on their own.”


But releasing a foreign species into the wild is always a concern.

There are a number of examples of bugs released into the wild to
eliminate a pest, but ended up causing a problem themselves.

But before importing a bug that will prey on plants – the federal
government requires testing to make sure it won’t eat other plants.


The tests have been done.


And researchers feel that this is an extremely finicky bug…


Berndt Blossey is a specialist on invasive plants and ways to control
them.

He says the beetles were tested on native plants before they were
allowed to import the bugs:


“And it was shown there that they will not be able to feed and
develop on the plants. They will occasionally nibble on them, but
they will not be able to develop on them and they usually move off
after they have taken a bite, and they move off to other plants.”


The leaf beetle is not the only bug researchers are importing.

They’re also importing two other beetles known as “weevils.”

One that feeds on loosestrife flowers, and one that feeds on its root
system.

Blossey says more than one bug is needed to keep the plant from
growing back:


“Loosestrife will rebound from resources in the root stock. If you
have the root feeder in the system as well, these fluctuations will be
dampened, so loosestrife will not be allowed to comeback to higher
levels.”


(sound of wetland up)


People who admire the diversity of plants and animals in wetlands
like the idea of keeping purple loosestrife in check.


Roger Sutherland welcomes the bugs.

He believes they’ll help him keep this wetland open for the plants,
birds, and insects he’s come to know over the years:


“We know that the purple loosestrife will probably always be here.
But if we can bring it down to a manageable level, where you’re going
to have a pocket here and a pocket there… and you can kind of
maintain the integrity of this wetland system… then you can’t ask for
anything more than that.”


And researchers say that’s the goal.

To help these wetlands reach a balance… so that plants and animals
that have evolved to rely on these wetlands for thousands of years…
can continue to do so.

For the Great Lakes Radio Consortium, I’m Mark Brush.

Related Links

New Ballast Treatment on Display

The state of Michigan is trying a new approach to stop the spread of foreign aquatic species in the Great Lakes – using a new system to clean ships’ ballast water. The Great Lakes Radio Consortium’s Quinn Klinefelter has more:

Transcript

The state of Michigan is trying a new approach to stop the spread of foreign aquatic species in the Great Lakes – using a new system to clean ship’s ballast water. The Great Lakes Radio Consortium’s Quinn Klinefelter has more.


A generator deep in the bowels of the Canadian freighter “Federal Yukon” spits copper ion particles at a cargo hold filled with ballast water. The particles poison any creatures living in the water…a second process cleanses the ballast before it’s drained into the Detroit River. It’s a test designed to find – and hopefully eliminate – any species carried in the water that is NOT native to the Great Lakes. Michigan Lt. Governor Dick Posthumous warned the threat from foreign species like zebra mussels is very real.


“Like an uninvited house guest…they come in uninvited…they eat all your food…and then they leave the house all messed-up.”


Posthumous says the Great Lakes Governor’s Association will meet with Canadian leaders this fall in Chicago to try and find ways to prevent the spread of foreign aquatic species. For the Great Lakes Radio Consortium, I’m Quinn Klinefelter.

Tackling an Invasive Beetle

Foresters think they might be on the verge of eradicating a pest that destroys trees. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

Foresters think they might be on the verge of eradicating a pest that destroys trees. The Great Lakes Radio Consortium’s Lester Graham reports.


The Asian long horned beetle attacks maples and elms. The bug first appeared in 1996, after wood crates infested with the beetle were shipped to New York from China. A second infestation appeared in the Chicago area in 1998. Stan Smith is a manager of the tree nursery program for the Illinois Department of Agriculture. He says the Asian long horned beetle might be under control around Chicago.


“Our population, we feel, is small enough that it might be getting to the point where it might not be able to reproduce very well. Hopefully within four to five years we’ll have everything pretty well cleaned up. At least that’s what we think can happen.”


The beetle is more widespread in New York, but fortunately the insect can’t fly very far. That means it can’t spread quickly, giving foresters a better chance at eliminating the pest.

Foreign Wasp Flying Westward

A foreign wasp from Europe has made its way to several Great Lakes states this summer. The European Paper Wasp was first detected on the Eastern seaboard in 1980. But as the Great Lakes Radio Consortium’s Gina Carrier reports, it’s now being sighted in greater numbers in the Midwest:

Transcript

A foreign wasp from Europe has made its way to several Great Lakes states this summer. The European Paper Wasp was first detected on the Eastern seaboard in 1980. Now it is being sited in greater numbers in the Midwest. The Great Lakes Radio Consortium’s Gina Carrier reports.


The European Paper Wasp looks very similar to our native yellow jacket. But it’s not as aggressive and can actually help Midwest gardeners because it likes to feed on certain pesky caterpillars. Tom Ellis is an entomologist at Michigan State University. He says the European paper wasp can be found in central and southeastern Michigan, Indiana, and Ohio and the Chicago area.


“The things that it became accustom to and fed on the eastern seaboard are pretty much similar if not the same to what we have in Michigan and throughout the Great Lakes states certainly.”


He says it’s unknown whether the wasp will continue to move westward. There’s no effort to stop its spread because Ellis says the wasp isn’t destroying crops or foliage. For the Great Lakes Radio Consortium, I’m Gina Carrier.

Native Lake Species Fighting Back

  • Alewives washed up on Lake Michigan shores after the invaders' populations exploded, then crashed. Researchers have a difficult time predicting how invasive species will affect the balance of nature in the Great Lakes.

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders:

Transcript

Ever since the Great Lakes were opened to shipping, exotic species of aquatic animals have invaded the lakes. Nearly always it’s been bad news for the region’s native fish and wildlife. The Great Lakes Radio Consortium’s Lester Graham reports on the latest effects of the invaders.


Some of the exotic species that have caused major problems in the Great
Lakes have been around since the 1940’s and ’50s. For example, the sea lamprey found its way into the lakes through manmade channels. It’s a parasite that attacks lake trout and other large game fish. It devastated the lake trout fisheries. Only recently have efforts gotten the lamprey under control. It’s still out there, but it’s not decimating the lake trout population as it once was.


More recently, a big concern has been the zebra mussel. It hitchhiked its way to the Great Lakes in the ballast water of cargo ships. In the last couple of decades the zebra mussel has caused major changes in all the lakes except for Superior where it seems limited to the shallow and warmer bays.


David Jude is a researcher with the University of Michigan’s Center for
Great Lakes and Aquatic Sciences. He says the huge numbers of zebra mussels siphon through lake water like a giant network of filters. There are so many of them that water in the lakes is actually clearer.


“I think people tend to hear about the water clarity increases. ‘Ah, the water’s clearer,’ you know, ‘That’s great!’ But it’s not great, because there’s a lot of things going on in the water column.”


Things such as, algae converting the sun’s energy into more phytoplankton.
Small fish and tiny invertebrate animals called zooplankton eat the phytoplankton and then they become food for fish. But, the zebra mussels filter out a lot of the phytoplankton, stealing food from the native zooplankton.


David Jude says a couple of other invaders are also causing havoc at the base of the food chain in the Great Lakes. Instead of eating just the green phytoplankton, zooplankton invaders from the Black and Caspian Seas also eat their North American cousins.


“These are predators. And they feed on the zooplankton, our native zooplankton that is out there already. So, not only do we have the impact of zebra mussels removing algae which is a food for these zooplankton, now we’ve got two predators that have been introduced and both of those will eat zooplankton which would have been food for fish to eat.”


Besides the zooplankton floating around in the water column, a major food source for fish is in the sediment at the bottom of the lakes, and it’s disappearing. James Kitchell is with the University of Wisconsin – Madison. He says many different kinds of fish depend on a little creature called diaporeia, which have become scarce in many areas.


“It appears to correlate in general with an increases in zebra mussels. So, there’s the prospect that diaporeia is literally starving to death as a consequence of zebra mussels eating the available food, but when you look at the diaporeia, they appear to be healthy. They’re not skinny and look to be starving. So that doesn’t explain it.”


It’s a big concern because a lot of fish that anglers like, such as yellow perch, depend on diaporeia for food.


Besides the zebra mussels and the two zooplankton predators, a fourth invader is causing problems. Populations of the round goby, an ugly, aggressive feeding little fish from Eastern Europe, have exploded in the Great Lakes. The round goby scours the bottom, eating the eggs and larvae of native fish. The University of Michigan’s David Jude says as big of a problem as the invasive fish has been over the last several years. The round goby’s future might soon be curtailed a bit.


“We did SCUBA dives in Lake Erie, for example, we’d turn over rocks. Round gobys would tear out from under the rocks and we’d have small mouth bass following us around and they would ignore the round gobys. They didn’t know how to catch a round goby. But, because there’s so many round gobys now, they had to learn how to eat them or die. So, the predators are definitely learning how to eat round gobys.”


Other native fish are beginning to eat the exotics. The silver chub, which once nearly disappeared from the Great Lakes, is making a bit of a comeback feasting on zebra mussels. With each invader, the lakes ecosystems go through upheaval, and then find a new balance. But make no mistake. It’s a different balance. Nicholas Mandrak is a researcher at Youngstown State University. He says exotic species invading the Great Lakes will mean continued changes, and for people who fish the lakes, not many of the changes will be good.


“You’re not going to be able to catch as many species that you’re used to catching. You know, the native species are going to decline. The walleye are going to decline. So, I think the bottom line is the recreational and commercial fisheries are going to change in a manner that is negative to most people.”


Researchers, though, have learned to be careful about predicting how invasive species will affect the lakes. They’re often surprised by the intricacies of the food web and the ecosystems that support it. Throwing an exotic invader into the mix makes it that much more unpredictable, and it will likely get worse. Mandrak says they’ve been studying how global warming might affect the lakes. One scenario suggests 30 to 40 new exotic species from the South will make their way through manmade canals as temperatures rise. For the biologists, it’s a worrisome concept. For the Great Lakes Radio Consortium, this is Lester Graham.

NATIVE LAKE SPECIES FIGHTING BACK (Short Version)

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports:

Transcript

It appears that fish native to the Great Lakes are beginning to prey on some of the alien species that have invaded the lakes. The Great Lakes Radio Consortium’s Lester Graham reports.


Aquatic Species from Europe and elsewhere have hitchhiked to the Great Lakes in the ballasts of cargo ships for many years. A lot of them have upset the natural ecosystems of the lakes. Lately, though, some native fish are taking advantage of the invaders. Nicholas Mandrak is a researcher at Youngstown State University. He says a Great Lakes minnow that was once thought to have died out has recently re-emerged.


“And they’re eating zebra mussels. So, it looks like the increase
in silver chub is related to zebra mussels, so we finally found a native
fish that is benefiting from the zebra mussel.”


Other researchers say small mouth bass are beginning to prey on another invasive species, the round goby, which eats the eggs and larvae of fish native to the Great Lakes. The researchers say the benefits don’t outweigh the negative affects on native species. But it evens the score a little. For the Great Lakes Radio Consortium, this is Lester Graham.