“Over time, an invasive plant [Garlic Mustard] loses its toxic edge”

9/1/09 | Diana Yates, Life Sciences Editor | 217-333-5802; diya@illinois.edu

CHAMPAIGN, lll. – “Like most invasive plants introduced to the U.S. from Europe and other places, garlic mustard first found it easy to dominate the natives. A new study indicates that eventually, however, its primary weapon – a fungus-killing toxin injected into the soil – becomes less potent.

Garlic mustard produces glucosinolates, pungent compounds that leach into the soil and kill off many soil fungi, especially those native to North America. | Photo by L. Brian Stauffer

The study, in Proceedings of the National Academy of Sciences, is one of the first to show that evolutionary forces can alter the very attributes that give an invasive plant its advantage. In fact, the study suggests the plant’s defenses are undermined by its own success.

Garlic mustard comes from a family of smelly, sharp-tasting plants that includes cabbage, radish, horseradish and wasabi. Unlike most plants, which rely on soil fungi to supplement them with phosphorous, nitrogen and water, garlic mustard gets by without the extra help, said Richard Lankau, a postdoctoral researcher at the Illinois Natural History Survey (INHS) at the University of Illinois. Lankau led the study with INHS plant ecologist Greg Spyreas.

“For whatever reason, these plants just don’t hook up with the soil fungus,” Lankau said. Instead, garlic mustard produces glucosinolates, pungent compounds that leach into the soil and kill off many soil fungi, especially those native to North America. This weakens the native plants. As a result, garlic mustard now grows in dense patches in many North American woodlands, its preferred habitat. Those patches are often devoid of native plants.

Lankau began the new study with a seemingly obvious question: Once garlic mustard has vanquished most of its competitors, why would it invest as much in maintaining its toxic arsenal? He predicted – correctly, it turns out – that levels of glucosinolates in the plant would diminish over time.

“When you’re in a situation where the only thing you’re competing with is other garlic mustard, it may be that making lots of this chemical is not a very good idea,” he said.

Thanks to a study of historic herbarium records conducted by co-author Victoria Nuzzo, of Natural Area Consultants, N.Y., the researchers had access to a 140-year record of the age of garlic mustard populations across the eastern half of the U.S. The team collected garlic mustard seeds from 44 locations, grew them in a greenhouse and tested glucosinolate levels in each. Those tests found that older populations – those that have been present in an area for more than 30 years – produced lower levels of the fungicidal compounds than those that got their start less than two decades ago, Lankau said.

Genetic studies suggested that these patterns were the result of natural selection. That is, the plants that produced less of the toxin were more likely to survive and reproduce in older populations. 

The researchers then grew the garlic mustard in soil from native woodlands. After a time, they removed these plants and potted native trees in the same soil. The trees did best in pots that had held plants from older populations of garlic mustard, indicating, again, that the plants’ toxin output had diminished over time, killing less of the fungus on which the native plants relied.

To determine if the decline in glucosinolate production was allowing native plants to return to areas previously dominated by garlic mustard in the wild, the researchers turned to a unique data set available in Illinois. The Critical Trends Assessment Program (CTAP) is a
long-term initiative funded by the state Department of Natural Resources and administered by the INHS that monitors the status of plants, birds and insects across the state every five years. The CTAP began in 1997, and so data from the first two sampling periods were used (1997-2001 and 2002-2007)

Because CTAP includes data on plant abundance, including garlic mustard and native plants from across the state, the researchers were able to determine if native plants were declining or advancing in the presence of garlic mustard. Again, they found that older populations of garlic mustard – though still problematic – posed less of a threat to native plants than the newer ones did.

While this study focused on only one plant, the results indicate that some invasive plants evolve in ways that may make them more manageable over time, Spyreas said. This suggests that conservation efforts might be more effective if they focus on the most recently invaded areas, which – in the case of garlic mustard, at least – is probably where the most damage occurs.

This study was funded by the Agriculture and Food Research Initiative at the U.S. Department of Agriculture and by the Illinois Department of Natural Resources. The research team also included Adam Davis, of the Agricultural Research Service at the USDA.”

For more on this story, please click here to check out the News Bureau Website from Illinois University

Editor’s note: To contact Rick Lankau, e-mail ralankau@illinois.edu. To reach Greg Spyreas, call 217-819-2059; e-mail spyreas@illinois.edu. The paper, “Evolutionary limits ameliorate the negative impact of an invasive plant,” is available online.

Garlic Mustard a real-life Sci-Fi Story?

Need to fight off the back-at-work blues?  Read this article about little green aliens… and then think about all of the good we are collectively doing across the region fighting back!

“Baby-boomers and twenty-something sci-fi freaks may remember the 60s cult-classic film, The Day of the Triffids, about an invasion of flesh-eating plants from outer space.

In truth, Benzie County [Michigan] could create its own reality show with an invasive alien species from the flora world Garlic Mustard. The tenacious immigrant from Europe, Garlic Mustard, Alliaria petiolata, poses a serious threat to our North American woods, including some of its beloved plants such as the trillium and trout lily.

If we like this area and wild flowers in it, something has to be done to get rid of the garlic mustard plant, says park ranger Bill Herd of Sleeping Bear Dunes National Lakeshore. Right now, it is biggest threat to the park.

Herd says it showed up in this region about five years ago. What makes this unique is it’s the one invasive plant that thrives in the shade of the forest floor. It is green under the snow, giving it a head start in the spring. It replaces native plants before they come up, and is even a threat to tree seedlings, threatening future forests. It’s conceivable that morel hunting will only be a story this generation tells their children of something they did before garlic mustard wiped out the northern Michigan’s favorite mushroom.

Just how concerned should we be? What is the prognosis for eliminating this plant? Herd says there are now nature preserves in several New England States that are now more than 80% garlic mustard. There are forests with no natural plants-just dense colonies of garlic mustard.

Plant biologists agree this plant could be one of the most harmful and difficult to control of all the invasive plants in the region. The seeds germinate easily. Its presence and infestation means a drastic ecological impact for native species. It changes the soil composition of the forest floor. Morels and tree-seedlings will have a hard time sprouting and growing as this plant inserts itself on the forest floor. The plant was first documented in North American around 1868. Although, it was used as a cooking herb because of its garlic-like scent, it is unclear if was deliberately or accidentally introduced by its seeds from European travelers. Now it is found in 30 U.S. states and at least three Canadian provinces. The seeds are easily spread by humans, birds, rodents and deer.

The battle is being lost to regional area infestations, including Benzie, Lake and Wexford Counties. The insidious take-over may be breeding in those back forty acres that are seldom hiked on.

Hand-pulling, herbicides and fire are the management techniques used. The simplest and most effective is hand-pulling, which could turn the losing battle around if all citizens were aware of the situation and assumed a vigilante force against this “alien flesh-eating” plant of our forest floors.

We’re aware of this problem and we’re going to do everything we can, says Josh Mills, Frankfort City Superintendent. But it’s going to take a lot of community effort. Mary Schmitt, Frankfort resident, is a perfect example of the community effort initiative that Mills was referring to. After attending a meeting at the township hall in Benzonia last month, she learned about the seriousness of the problem. She met the presenter, Jerry Solanics, who is another citizen police, who works with Manistee and Benzie counties on educating others about identification and how to participate in management. I appointed myself block captain Schmitt says, and I went up and down Leelanau Avenue with Jerry and knocked on doors and handed out flyers with information and photographs of the plant. Schmitt says most people know about it but don’t know what to do about it. And, she points out that some people just aren’t physically able to get out and pull it. She says she spent an afternoon with three students from Benzie High School pulling the invader from neighbors yards who weren’t able. I thanked them for taking the time to come and do this, she said, and one of the young men replied that it was better than staying home and watching.” -Great Lakes Wiki

Nearly 2 Billion Seeds Saved from Being Spread 2010 Field Season

Ok, so I want to preface this by saying, these are rough numbers, there are SO many factors and variables that would go into producing a completely accurate number.  But I just wanted to give you some scope on the difference that we are all making.  Here was my attempt at calculating just how many garlic mustard seeds we have all prevented from being spread during the 2010 Garlic Mutard Challenge so far…2,064,239,100 seeds!

That seems like an insance number, right?  Well it is!  To make this number seem even more magnanimous, imagine this-

Keep in mind that many seeds don’t even make it to seedlings or then rosettes in the first place, and only 60-90% of seedlings make it through summer droughts.  So, using conservative numbers, from what we’ve all pulled this year, we have collecitvely saved a potential 2,554,495,786,250 seeds from spreading in 2011!

Yikes, all that math is making my brain hurt!   But all of that math should make you think twice about overlooking a patch of garlic mustard or not stopping for the 2 seconds it takes to brush off your boots when entering or leaving a natural area. 

I’m usually the first one to start running the other way when the idea of math is brought up- but I really wanted to bring home the difference that we are all making! Think about the impact that your action of just pulling one stalk or just one bag or a 1/2 bag or 50 bags of garlic mustard is having on natural areas for future generations!

Garlic Mustard Free, It’s the Way to Be!

Last year we compiled a list of Garlic Mustard “Free” locations across the region at the end of the Challenge.  These are locations that have been monitored to some extent and have been found to have zero second year garlic mustard plants!  And we’re doing it again this year- tell us about your Garlic Mustard “Free” property!

During the Stewardship Network’s Garlic Mustard Challenge, one of our goals obviously was to pull 150,000 lbs of garlic mustard- and then once we shattered that goal, see just how much we could collectively pull before July 9th!

But, the goal doesn’t end at however many pounds of garlic mustard we can pull- it’s the idea that getting rid of garlic mustard makes way for the return of beloved native wildflowers and plants, brings the local ecosystem closer into balance, and increases the overall quality of the natural area for everyone.

That’s where the Garlic Mustard Free locations come in.  Not only do we want to see how many pounds of garlic mustard we can collectively pull, but how many natural areas near and dear to our hearts we can win back from the clutches of garlic mustard and other invasive species.  How many acres can we reclaim from the degrading biological and aesthetic effects of monocultures?  

Big or small, every piece of garlic mustard ‘free’ land is another step towards brining the Great Lakes Region- and beyond- back into balance.

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Join the list below!  To join the list, email the property name, approximate location (county or city), and estimated acreage to staff@stewardshipnetwork.org

Berberian Woods, Oakland County, MI (Six Rivers Regional Land Conservancy)

Bradford Dickinson White Preserve, Kent County, MI (Land Conservancy of West Michigan)

Castle Park Preserve, Allegan County, MI (Land Conservancy of West Michigan)

Coldwater River, Kent County, MI (Michigan Nature Association)

DePersia South Highlands, Ottawa County, MI (Land Conservancy of West Michigan)

Dunes Pines Nature Preserve, Allegan County, MI (Land Conservancy of West Michigan)

Frances Broehl Memorial #1, Lenawee County, MI (Michigan Nature Association)

Maas Family Nature Preserve, Kent County, MI (Land Conservancy of West Michigan)

Minnie Swarek Nature Preserve, Ottawa County, MI (Land Conservancy of West Michigan)

Prairie Ronde Savanna, St. Joseph County,MI (Michigan Nature Association)

Tippy Dam, Manistee County, MI

Trillium Ravine, Berrien County, MI (Michigan Nature Association)

Wege Natural Area, Kent County, MI (Land Conservancy of West Michigan)

Between Maple Road and Liberty Road, surrounded by Pine Lake Co-Op, Ann Arbor, MI

Garlic Mustard that’s too old to pull…

Wondering what garlic mustard looks like when it’s too ripe to pull?  Well, City of Ann Arbor Natural Area Preservation was generous enough to provide us with some pictures of garlic mustard that is too old and ripe to pull, and should be left alone. 

Participate in Global Field Survey of garlic mustard

For those of you out in the field managing against garlic mustard, please check out this opportunity:

I would like to draw your attention to the world’s largest collaborative project on invasive species; it may be of particular interest to educators, conservation groups, and resource managers.
 
Do you want to be part of the world’s largest scientific research project on invasive species? The ‘Global Garlic Mustard Field Survey’ is an international collaboration aimed at obtaining much-needed data on the abundance and distribution of Garlic Mustard (Alliaria petiolata) across its native and introduced ranges. In our first field season last year, we received measurements and seed samples from 65 populations, with a majority from Europe – already one of the largest systematic field surveys of an invasive species. Our goal for this summer is 150 or more, with a stronger emphasis on the southern and mid-west to western United States.
 
This year we are hoping to increase participation among educators, as well as land managers and ‘citizen-scientists’ who may not have much formal science training. The survey involves a simple protocol that can be followed directly or incorporated into field courses and nature surveys. A population takes two people about 2-4 hours to measure. We are also planning to develop internet-based teaching modules and tools to aid with monitoring and managing this invasive plant. The sampling protocol, along with contact information is available at the Global Garlic Mustard Field Survey website: www.GarlicMustard.org (note that you do not need to log in to the site to participate).
 
Ideal sampling time is 2-4 weeks after flowering finishes and ranges from early June in southern states (e.g. OK, AR, AL, GA, SC) and lower altitudes to mid to late July in northern states (e.g. OR, WA, ID, ND, MN, WI, MI, VT, ME), higher altitudes and Canada.
 
Please contact me if you would like to participate.
 
North American Coordinator
Dr. Robert Colautti
Biology Department
Duke University
rob.colautti@duke.edu

“To pull or not to pull, that is the question”

All of this wonderful summer weather we’ve had this past week and a half has been great, getting geared up for 4 months of baseball, cookouts, trips to the pool and the beach, and many other summer shenanigans.

However, this summer weather has hastened the point at which many people in many places across the Great Lakes region should STOP pulling garlic mustard.  A good rule to follow- if there are no blossoms left on your garlic mustard, please think twice and let it be.  Disturbing garlic mustard while trying to remove it is going to more harm than good.  The dried seed pods (also known as siliques) pop like popcorn, spreading the seeds up to 3 meters from the original stalk. 

Check out this link for more information on the garlic mustard life-cycle

Please use your own good judgement when deciding to pull or not to pull!  There are still many areas north of approximately Lansing, Michigan that still have a few good weeks to pull.  But latitude isn’t everything and there are many more factors in play (rainfall, amount of sun, etc.), so it’s best to check your garlic mustard before diving right in to remove them.

The 2010 Challenge still has several weeks (it runs April 14th- July 9th) in order to give folks Up North a fair chance to participate… so, if you can, keep on pulling!!

Mmmm… Garlic Mustard Recipes!

Now that we’ve pulled over 86,000 lbs of garlic mustard- what are we going to do with all that garlic mustard!?  Well, if you can’t bear to part with your piles and piles of garlic mustard, you can eat it!!

In the Kalamazoo Nature Center’s “From Pest to Pesto” Cookbook you can find recipes for garlic mustard ranging from hummus to wonton cups to soups and salads to shrimp to ravioli to dumplings! 
Click here to order KNC’s $5 cookbook

For appetizers, entrees, egg dishes, and even desserts involving garlic mustard, the Mid-Atlantic Exotic Pest Plant Council (or, the MA-EPPC) has its own creative list of recipes! 
Click here to view list of MA-EPPC’s recipes

Bon appetit!

Video on garlic mustard mobilizes group

Barbara Lucas and Wisconsin Family Funding are making waves with their Garlic Mustard Video!  Available on the Stewardship Network website and our 2010 Challenge blog, it can also be found on a Liberty Township online flyer and the USDA National Agriculture Library website.

The Pfeiffer Nature Center in New York found the video on the Stewardship Network website, found it incredibly information and useful, and used it for community mobilization– pulling the weed and educating others about garlic mustard!

Click here to see Barbara Lucas’ (Wisconsin Family Farms) video on Garlic Mustard!

Overwhelmed by your garlic mustard patch? Try these tips

Sometimes deciding how to attack your patch of garlic mustard can be tricky, and overwhelming!  Read on below for tips on how to approach your garlic mustard:

First, instead going right into the thickest cover of garlic mustard, search for outlier populations, or small fringe populations of garlic mustard.  You should always try to get those first so that the garlic mustard can’t become well established in that area.

Second, cutting basal rosettes with a lawn mower or weed whacker will prevent or slow those from blooming and making seeds.  Don’t waste your time though hand pulling rosettes as it is very unefficient and many won’t make it through the winter anyways.

Third, in areas with a monoculture or very high percentage of garlic mustard cover, where hand pulling is virtually impossible, there is the option of spraying with herbicide.  However, this option must be approached with much caution as you may need to sacrifice some non-target plants (i.e. the native flowers you want to keep) — and herbicide spraying should always be approached with caution anyways.  Spraying the monoculture will help prevent seed production and distribution for that season.

For more information, please visit the Michigan State University Extension webpage on garlic mustard.  There, you can find a wealth of more indepth information on garlic mustard control and current and ongoing research.