P
Paul J. Berg
Guest
~
Portland, Oregon is poised to declare war on a foreign invader, a tasty
but invasive weed known as garlic mustard.
The seedy, saw-toothed herb grows in shady forests and spreads rapidly,
crowding out native plants such as sword fern.
"It's kind of like the next English ivy," said Jennifer Goodridge, who
oversees the Portland Bureau of Environmental Services' effort to fight
invasive plants. "Potentially, even worse."
By fall, Portland hopes to wipe out the weed, pulling some by hand and
killing some through chemical warfare, probably using the herbicides
glyphosate or triclopyr.
Pesticides may seem contradictory in Portland, which aims to be green as
Forest Park in May. This is a city that throws parades for electric cars
while asking residents not to wash their cars in the driveway. And the
city does use a combination of non-chemical weapons in its war on weeds,
from planting native species to burning some plants with a tool called a
flame weeder.
But sometimes, city horticulturists say, you have to go the RoundUp
route -- especially when weeds could damage native trees and plants.
Take garlic mustard, already a plague in the Northeast and Midwest. The
European native has established beachheads in Portland sites including
Forest Park, Oaks Bottom, the Terwilliger corridor and Johnson Creek.
On Wednesday, the City Council agreed to join in the hunt to destroy
garlic mustard, led by the nonprofit Three Rivers Land Conservancy. The
conservancy will seek a roughly $50,000 grant from the Oregon State Weed
Board, which has declared the herb to be "a menace to public welfare."
Portland would get about $12,000, some of it to pay for pesticides.
"People are always assuming that spraying is going to have loads of
negatives," said John Reed, pest management program coordinator for
Portland Parks & Recreation. "It does have some. . . . But if we want to
keep garlic mustard out of all our natural areas, well, it's going to
take spraying."
Not everyone likes that conclusion. Chris Johnson has lodged several
complaints with the city about herbicide spraying on parks land along
Errol Creek, next to his Southeast Portland home. Johnson said he can
sometimes smell the chemical indoors, worries what it does to his land
and animals and is "against the whole idea of spraying." He wishes the
city would use goats for plant control.
The Eugene-based Northwest Coalition for Alternatives to Pesticides also
"would like to see all of Portland's parks pesticide-free," said Megan
Kemple, the nonprofit group's pesticide-free parks program coordinator.
"Pesticides are harmful to the health of pets and children and our
environment."
Limited chemical use
Chemicals play a key but limited role in Portland's pest-killing
campaigns, as spelled out in an 81-page Integrated Pest Management (IPM)
plan followed by several city bureaus. The plan mixes strategies from
careful plant selection and maintenance (such as mowing and mulching) to
chemicals, stating that "judicious use of carefully selected pesticides
can be an important tool."
Reed said chemicals sometimes are the best choice for removing plants,
though "we always want to ensure that our herbicide choice is
well-researched and our use is environmentally sound, carefully done,
minimal and well-justified."
That means knowing which weeds need pesticide, such as Japanese
knotweed, whose roots spread so widely that hand pulling can't control
the plant.
Portland parks only use state-licensed applicators and put up signs to
warn of spraying. And horticulturists carefully choose which of the
dozens of city-approved pesticides to use, Reed said. A popular choice
is glyphosate, sold as RoundUp and other brands. Compared to other
pesticides, RoundUp stays where you spray it, breaks down fairly quickly
and poses a low threat to the health of people and other animals.
Pesticide-free experiment
Portland's pesticide use has fallen over recent decades, driven by
safety and environmental concerns and a desire to work efficiently.
In the 1980s, workers annually sprayed hundreds of acres of city park
grass to keep it weed-free. In the '90s, the parks bureau decided to
tolerate more weeds and step up other weed-control methods, such as
overseeding, or sprinkling more seed on established turf.
In the past 10 years, the bureau has put herbicide on "only a few acres
per year" of turf, Reed said. Similarly, he said, spraying pesticide in
the canopy of city trees has almost disappeared.
In all, workers used 405 gallons of weed-killer concentrate in
Portland's 10,000 acres of parks in 2006, along with enough solid
herbicide to equal 35 pounds of active ingredient, Reed said.
This fall, Portland finishes a three-year test that made three parks
pesticide-free: Arbor Lodge Park in North Portland, Lair Hill Park in
Southwest and Sewallcrest Park in Southeast.
Kemple's coalition pushed then-Parks Commissioner Jim Francesconi to
approve the trial as he ran for mayor in 2004. The city initially
resisted the idea, she said, because it takes more money and staff time
to weed instead of spray. But the coalition and other community groups
organized volunteers who weed land, which used to be sprayed, at monthly
work parties.
The hand-weeding takes at least 400 volunteer hours a year, plus extra
time from parks staff supporting the effort. The program has worked well
in two parks, city staff said; it's been tougher maintaining Arbor
Lodge, which has two ball fields, half the program's 16.7 acres and
fewer volunteers living nearby. The city is now reviewing the trial,
which Kemple hopes can continue and expand to five parks.
Garlic mustard must go
The parks test all but proves that it is practically impossible for
Portland to stop spraying pesticides entirely.
Before 2004, crews spent about $250 a year putting two to five pints of
RoundUp herbicide on the three test parks combined, Reed said. Replacing
that with hand work took thousands of dollars' worth of staff and
volunteer time and expenses for signs and tools -- just for three small,
neighborhood parks.
Expanding into, say, Forest Park's urban wilderness would take more time
and money than the city could offer. Even Kemple said it would be "very
difficult" to wipe out pesticides in Portland, though it remains her
group's goal.
"Any time you get into a situation where you're dealing with invasive
weeds, (hand weeding) is really not a feasible option because of the
massive amount of volunteer time required," said Martin Nicholson, a
horticulturist overseeing the pesticide-free parks for the city.
But back to garlic mustard, a plant that makes a delicious pesto but a
terrible neighbor.
Unlike many weeds, garlic mustard (Alliaria petiolata) can grow in the
shade of forests. The plant produces seeds prodigiously, spreading
quickly. Once it hits an area, garlic mustard can easily win more than
its fair share of light, water, food and dirt, crowding out native
plants.
Scientists think garlic mustard may even kill tree seedlings through its
own chemicals: The plant's roots seem to emit a chemical that poisons
fungi that normally help protect and nurture seedling trees.
That explains why Portland wants to destroy garlic mustard, along with
false brome and other herbal interlopers that have no natural predators
to stop them from occupying land used by native plants, animals and
people.
"There's nothing to stop them," Reed said. Absent human work, including
herbicides, "you're going to end up with a wildland that's not
particularly rich or unique to our area."
~
Portland, Oregon is poised to declare war on a foreign invader, a tasty
but invasive weed known as garlic mustard.
The seedy, saw-toothed herb grows in shady forests and spreads rapidly,
crowding out native plants such as sword fern.
"It's kind of like the next English ivy," said Jennifer Goodridge, who
oversees the Portland Bureau of Environmental Services' effort to fight
invasive plants. "Potentially, even worse."
By fall, Portland hopes to wipe out the weed, pulling some by hand and
killing some through chemical warfare, probably using the herbicides
glyphosate or triclopyr.
Pesticides may seem contradictory in Portland, which aims to be green as
Forest Park in May. This is a city that throws parades for electric cars
while asking residents not to wash their cars in the driveway. And the
city does use a combination of non-chemical weapons in its war on weeds,
from planting native species to burning some plants with a tool called a
flame weeder.
But sometimes, city horticulturists say, you have to go the RoundUp
route -- especially when weeds could damage native trees and plants.
Take garlic mustard, already a plague in the Northeast and Midwest. The
European native has established beachheads in Portland sites including
Forest Park, Oaks Bottom, the Terwilliger corridor and Johnson Creek.
On Wednesday, the City Council agreed to join in the hunt to destroy
garlic mustard, led by the nonprofit Three Rivers Land Conservancy. The
conservancy will seek a roughly $50,000 grant from the Oregon State Weed
Board, which has declared the herb to be "a menace to public welfare."
Portland would get about $12,000, some of it to pay for pesticides.
"People are always assuming that spraying is going to have loads of
negatives," said John Reed, pest management program coordinator for
Portland Parks & Recreation. "It does have some. . . . But if we want to
keep garlic mustard out of all our natural areas, well, it's going to
take spraying."
Not everyone likes that conclusion. Chris Johnson has lodged several
complaints with the city about herbicide spraying on parks land along
Errol Creek, next to his Southeast Portland home. Johnson said he can
sometimes smell the chemical indoors, worries what it does to his land
and animals and is "against the whole idea of spraying." He wishes the
city would use goats for plant control.
The Eugene-based Northwest Coalition for Alternatives to Pesticides also
"would like to see all of Portland's parks pesticide-free," said Megan
Kemple, the nonprofit group's pesticide-free parks program coordinator.
"Pesticides are harmful to the health of pets and children and our
environment."
Limited chemical use
Chemicals play a key but limited role in Portland's pest-killing
campaigns, as spelled out in an 81-page Integrated Pest Management (IPM)
plan followed by several city bureaus. The plan mixes strategies from
careful plant selection and maintenance (such as mowing and mulching) to
chemicals, stating that "judicious use of carefully selected pesticides
can be an important tool."
Reed said chemicals sometimes are the best choice for removing plants,
though "we always want to ensure that our herbicide choice is
well-researched and our use is environmentally sound, carefully done,
minimal and well-justified."
That means knowing which weeds need pesticide, such as Japanese
knotweed, whose roots spread so widely that hand pulling can't control
the plant.
Portland parks only use state-licensed applicators and put up signs to
warn of spraying. And horticulturists carefully choose which of the
dozens of city-approved pesticides to use, Reed said. A popular choice
is glyphosate, sold as RoundUp and other brands. Compared to other
pesticides, RoundUp stays where you spray it, breaks down fairly quickly
and poses a low threat to the health of people and other animals.
Pesticide-free experiment
Portland's pesticide use has fallen over recent decades, driven by
safety and environmental concerns and a desire to work efficiently.
In the 1980s, workers annually sprayed hundreds of acres of city park
grass to keep it weed-free. In the '90s, the parks bureau decided to
tolerate more weeds and step up other weed-control methods, such as
overseeding, or sprinkling more seed on established turf.
In the past 10 years, the bureau has put herbicide on "only a few acres
per year" of turf, Reed said. Similarly, he said, spraying pesticide in
the canopy of city trees has almost disappeared.
In all, workers used 405 gallons of weed-killer concentrate in
Portland's 10,000 acres of parks in 2006, along with enough solid
herbicide to equal 35 pounds of active ingredient, Reed said.
This fall, Portland finishes a three-year test that made three parks
pesticide-free: Arbor Lodge Park in North Portland, Lair Hill Park in
Southwest and Sewallcrest Park in Southeast.
Kemple's coalition pushed then-Parks Commissioner Jim Francesconi to
approve the trial as he ran for mayor in 2004. The city initially
resisted the idea, she said, because it takes more money and staff time
to weed instead of spray. But the coalition and other community groups
organized volunteers who weed land, which used to be sprayed, at monthly
work parties.
The hand-weeding takes at least 400 volunteer hours a year, plus extra
time from parks staff supporting the effort. The program has worked well
in two parks, city staff said; it's been tougher maintaining Arbor
Lodge, which has two ball fields, half the program's 16.7 acres and
fewer volunteers living nearby. The city is now reviewing the trial,
which Kemple hopes can continue and expand to five parks.
Garlic mustard must go
The parks test all but proves that it is practically impossible for
Portland to stop spraying pesticides entirely.
Before 2004, crews spent about $250 a year putting two to five pints of
RoundUp herbicide on the three test parks combined, Reed said. Replacing
that with hand work took thousands of dollars' worth of staff and
volunteer time and expenses for signs and tools -- just for three small,
neighborhood parks.
Expanding into, say, Forest Park's urban wilderness would take more time
and money than the city could offer. Even Kemple said it would be "very
difficult" to wipe out pesticides in Portland, though it remains her
group's goal.
"Any time you get into a situation where you're dealing with invasive
weeds, (hand weeding) is really not a feasible option because of the
massive amount of volunteer time required," said Martin Nicholson, a
horticulturist overseeing the pesticide-free parks for the city.
But back to garlic mustard, a plant that makes a delicious pesto but a
terrible neighbor.
Unlike many weeds, garlic mustard (Alliaria petiolata) can grow in the
shade of forests. The plant produces seeds prodigiously, spreading
quickly. Once it hits an area, garlic mustard can easily win more than
its fair share of light, water, food and dirt, crowding out native
plants.
Scientists think garlic mustard may even kill tree seedlings through its
own chemicals: The plant's roots seem to emit a chemical that poisons
fungi that normally help protect and nurture seedling trees.
That explains why Portland wants to destroy garlic mustard, along with
false brome and other herbal interlopers that have no natural predators
to stop them from occupying land used by native plants, animals and
people.
"There's nothing to stop them," Reed said. Absent human work, including
herbicides, "you're going to end up with a wildland that's not
particularly rich or unique to our area."
~
