Good Oak News

Sunday, October 27, 2013

American Pokeweed: Feast or Foe?

Popping up out of nowhere

We've been working with the Village of Shorewood Hills for a couple years now on rehabilitating a slope that they have set aside as a stormwater control area within the village. By the time we got there in the fall of 2010 it was an area of weedy trees and invasive brush, dominated by a canopy of black locust, with mostly bare soil on the ground. The ground layer plants that were present were mostly invasive species such as burdock, canada thistle, reed canary grass, garlic mustard and dames rocket, but a few scattered patches of native plants remained from the original seeding done in 2000. One thing we did not see when we first started working on the site was American pokeweed (Phytolacca americana).

We've done some regular but limited management work on this slope in the past few years. A prescribed burn, some brush removal, annual control of garlic mustard, dames rocket and other weeds, and a couple rounds of interseeding. Overall the site looks a lot better today, but it's still a work in progress.

The one plant that has responded best to all this treatment is the American pokeweed. It has gone from being absent, or perhaps a small, trivial population, to covering more area on the slope than any other species. It clearly dominates the entire lower 1/3rd of the slope.

This leaves us to wonder, is it healthy to have this much pokeweed? Should we begin to manage pokeweed alongside summer weeds like bull thistle and burdock at this site? I personally have always admired pokeweed as a resilient pioneer species. Its large size, colorful stem and tropical appearance make it an interesting find on any site. But land-managers around southern Wisconsin are becoming concerned about the rapid increase in abundance of this species in their natural areas. I decided to do a little more research on this species to develop an informed decision on how we should approach managing it... as a weed or a native warrior, and I found out some interesting things.

Poison, meal, medicine and dye

It turns out pokeweed is a poison, a medicine, and an edible wild plant, all in one.

The roots, stems, and leaves of this plant contain high amounts of toxic compounds such as phytolaccine, phytolaccatoxin formic acid, tannin, and resin acid. The berries also contain trace amounts of these compounds, which cause diarrhea, colic, bloody stools, possible anemia, and occasionally death. The young leaves contain less toxin and were used as food by Native Americans and early settlers.

Some people still eat this "poke sallet" today by choosing leaves from the plant when the stems are still green (before they turn purple) and boiling them twice, dumping out the water from the first boiling to remove the toxic compounds. The stems can also be cut, covered in cornmeal, and fried like okra (I assume after being boiled once first). According to the site, Eat the Weeds, "Nutritionally, pokeweed is a powerhouse: A half cup of the greens provides 35 calories (10 from fat), no cholesterol, three grams dietary fiber, and 90% of your daily need for vitamin A, 60% of vitamin C, 8% calcium, and 6% of iron." Eat the Weeds has a really good write up about the edibility and cultural impacts of pokeweed consumption so the above link is a worthwhile side trip.

Pokeweed was even sold as a canned vegetable in the southern US until recently. And the popular song from the 1950's, Poke Salad Annie, was written about a poor girl who gathered and ate this plant.

The compounds produced by this plant don't just make the plant difficult to eat, they also have potential use as medicines. Native Americans discovered the medicinal effects of this plant early on and used it to stimulate the heart and to treat cancer, rheumatism, itching, and syphillis. It was also effective as a laxative and to induce vomiting. Compounds found in the pokeweed plant are being examined by modern medical science; particularly the 'pokeweed antiviral protein' (PAP) is being explored for the medicinal value at treating cancer, herpes and HIV. Other compounds in this plant may enhance the immune system and have additional anti-cancer effects. See for more fascinating medical info.

On top of all of that, the juice from the berries was once used to make ink and dye, and is still used today to make red food coloring. This pokeweed ink was used by Thomas Jefferson to scribe the Declaration of Independence.

An Ecologically Valuable Plant? Just ask the birds.

The brightly colored berries are an important food source for many songbirds including eastern bluebirds, rose-breasted grosebeaks, cedar waxwings, northern cardinals, hermit thrush and many other birds which typically consume berries, (including, but not limited to these listed on Illinois Wildflowers) as well as small mammals. We noted a pair of cardinals and woodpeckers feeding on the pokeweed at our last visit to the slope.

So What's the Prognosis?

Pokeweed is considered by some to be just a big weed. But its clear that the plant has value feeding wildlife, perhaps on our own dinner plates, and in our medicine. However, it can get overpopulated at times and shade out other more conservative native speices and may need control work to balance the system. It can be particularly overwhelming in small areas. On the other hand, considering the alternatives in such sites are often invasive weeds such as garlic mustard, dames rocket, burdock and thistles, the pokeweed is often a better option than the alternative.

I think the key to this issue in southern Wisconsin is the below image:
Image courtesy: Kartesz, J.T., The Biota of North America Program (BONAP). 2013. Taxonomic Data Center. ( Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2013. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]

Southern Wisconsin is on the very northern edge of the range of this plant, it thrives in warmer, more moist climates to the south and east of here. It's only in the past decade or so that we've been finding it in abundance in southern Wisconsin. It is likely that this insurgence of pokeweed is a result of global warming altering our local weather patterns in such a way that benefits pokeweed. Consider also that the species responds positively to disturbance, and you have a species that we can expect to be common on natural sites into the future. Perhaps there are various parasites and pests that curb the growth and abundance of pokeweed where it is more common further south that will slowly move their way north to slow this species down in our area. Or perhaps due to habitat fragmentation, these potential control agents won't be able to make the trip.

As a point of comparison, American pokeweed has become an invasive plant in some areas of China. According to this study, it is a sucessful invader in forests composed of black locust. Black locust is an invasive plant in Wisconsin. Though native to the southern US, it must have been imported to China for its timber value. It is interesting to note that our work site also has a canopy of black locust, so there appears to be some association between these species. Perhaps pokeweed is immune to the allelopoathic toxins that black locust releases? This would make sense since they evolved in the same environment. The other interesting thing about this study is that they found that where indigo bush, a native leguminous shrub, was found it was able to exclude the pokeweed, though it's not clear why.

So my advice would be to consider doing control work on pokeweed carefully. If you have a lot of other weeds in the area, it appears to be very effective at suppressing plants of shorter stature. There is no garlic mustard under the dense pokeweed patches on our slope in Shorewood. There's nothing else under there either though. So if you have it taking up a lot of space in a habitat surrounded by a lot of more conservative species, then you might want to control it, to speed the process of ecological sucession up a little bit. However, I suspect that a careful inspection of most sites where pokeweed occurs will reveal that pokeweed is the best plant among a list of awful alternatives. I'd speculate that pokeweed wouldn't compete well in more intact habitats against more conservative natives.

My other thought is that if you have a smallish garden, whether it be vegetable, perennial, or both, this species could be a bit too much for your landscape, so removing some or all of the plants makes sense.

If it Must be Done

If you're going to try to control this species, you'll need to know that it forms a large, deep taproot from which it can resprout if cut or only the upper portion of the root is removed. However, if removed when they are still small plants then it's possible to dig them out. The other organic option for control is mowing. However, studies have shown that mowing will knock it back for a growing season, but it will resprout at full strength the next year. So repeated mowing 2-3 times per year for 2-3 years would probably be needed for permanent control.

Glyphosate, the active ingredient in Round-Up® and other common herbicides, has been shown to be effective at controlling this species. But because of the large size of pokeweed it will have to be applied with caution. For a foliar application, the best bet is to get it while the plant is still relatively small in spring to avoid overspray. The other option would be to use a "stump treatment" method, similar to what is used on brush where a 50/50 mix of the glyphosate concentrate and water are mixed and applied directly to a stump immediately after it is cut. This is time consuming but will nearly eliminate any potential for collateral damage. See the label of the herbicide bottle for specific instructions.

Monday, October 7, 2013

Job Opening: Ecological Restoration Manager

Good Oak Ecological Services is looking for qualified candidates to fill our Ecological Restoration Manager position here at our Madison location. This position is responsible for supervising all aspects of Good Oak's ecological restoration projects, including meeting with clients and educating them about the ecological health of their property, formulating feasible adaptive management plans, developing estimates and proposals, leading the crew conducting field work, and invoicing completed projects. Our restoration work includes: brush removal, prescribed burning, mechanical and chemical weed control, prairie establishment, shoreline and slope restoration, and erosion control.

For more information see the job announcement on our website:

Wednesday, August 28, 2013

Native Thistles: Pillars of the (Natural) Community

A great spangled(?) fritillary butterfly enjoying some nectar from a native pasture thistle.

Yesterday I took the crew out for a field day to some great natural areas so they could learn some plants and see what real, healthy, managed prairies and savannas look like. Along the way we were fortunate enough to see a lot of native thistles in bloom. We saw many butterflies and bees feeding on these thistles, and I explained to them that, in addition to being excellent pollinator plants, the seeds were valuable food sources for small birds (goldfinches love thistles) and that the fluff from thistle seeds is used by hummingbirds and other small birds for nesting materials. Later, researching online I found that goldfinches are so enamored with thistles that seeing them actually has an effect on their hormone levels.

Then last night I read this article about the reintroduction of the rare swamp metalmark butterfly into a restored wetland in the Chicago area. It turns out the swamp metal mark caterpillars can only eat our native swamp thistle and pasture thistle. These valuable members of our local natural community have a lot to offer, but unfortunately they have suffered not only from habitat loss that effects all of our native species, but also from persecution due to their similarity to the weedy exotic thistles.

Exotic Thistles: America's Least Wanted

Most people think of thistles only as weeds. And it's true that some of most common, troublesome and difficult to eradicate weeds include Canada thistle, plumeless thistle, bull thistle, and musk thistle. These are all exotic species, introduced accidentally as agricultural weeds which are now problems in cultivated and natural areas alike. There are a few more exotic, weedy thistles too, such as European marsh thistle, but they are less common in this part of the state. In any event, these weedy thistles have long been recognized as pests and are on top of many noxious weed lists. There are only 3 plant species listed under Wisconsin's noxious weed law and one of them is Canada thistle.

In Illinois, both Canada thistle and musk thistle are listed as noxious weeds (not sure why they skipped the more common bull thistle), and they only bothered to put 7 other plant species on this list. Canada thistle is in fact listed as a noxious weed in 43 states!

When we at Good Oak are managing natural areas we always make controlling thistles a priority. Every farmer has a deep seated hatred of thistles, and we don't want people thinking our prairies are just 'weed patches'. Because of this common disdain for thistles, and some local weed laws (more on this later) native thistles are rarely included in commercial prairie seed mixes, despite the many benefits they can offer to wildlife.

Native Thistles: Rare Natural Gems

Wisconsin has five native thistles. Let me introduce you to them:

Pasture thistle (Cirsium discolor) is found in mesic prairie remnants, and sometimes more disturbed sites like woodland edges and yes, even pastures. You will occasionally find it in some better quality restored prairies.

Pasture thistle flower.
Pasture thistle.
The pale underside of the leaf on pasture thistle.

It looks a little like bull thistle at first glance, but the underside of the leaf is distinctively white, which is where this species gets its scientific name. A lot of overlapping silvery hairs create this bright white appearance. Bull thistle can be pale on the underside, but if you're looking at pasture thistle you will definitely think "whoa, that's white!"

Tall thistle (Cirsium altissimum) is a plant of open woodland and savannas. Note that the leaves aren't very thistle like with only small thorns. In fact, without the flowers you might not think it was a thistle at all. They have more surface area to gather more light in these semi-shade environments. The stems are covered in fine hairs, and tall thistle shares the white leaf undersides with its cousin pasture thistle.
Tall thistle.
Pasture thistle and tall thistle are the only two species that you have any chance of finding outside of a high-quality natural area. If you simply remember to look for the white underside to the leaves, you can always differentiate these two native thistles from the various weedy exotic species. These two species also bloom later than the exotic thistles. Bull thistle and Canada thistle for example, bloom from late-June through July, whereas tall and pasture thistle bloom from late July through August.

Swamp thistle (Cirsium muticum) grows only in good quality wetlands. The flowers are a darker, more vivid magenta color compared to most other thistles.
Swamp thistle.
Swamp thistle flower.

Hill's thistle (Cirsium hillii) is a state threatened species which you which you will only find in dry sandy prairies in the upper midwest. It's our shortest native thistle, typically around 18". It's also densely hairy to help it retain moisture in its dry sand-prairie habitat. The flower color is more of a true pink rather than magenta, even reddish.... unfortunately my poor-quality cell-phone photo below is not color accurate.
Hill's thistle.

Dune thistle (Cirsium pitcheri) is our rarest thistle, so rare in fact that it is Federally Threatened. It only grows on a handful of sites in Wisconsin, on stabilized sand dunes on the Lake Michigan shoreline. Its range is limited to the Great Lake shorelines of Wisconsin, Illinois, Indiana and Michigan, within a few-hundred feet from the shore. Its flowers are a pale pink, and its foliage looks nothing like other thistles with hardly a thorn to be seen. In fact the frosted-grey looking leaves look more like sage than any thistle.
Dune thistle flower.
Dune thistle's basal rossette (foliage).

Thistles: Nature's Grocery Store

As it turns out, thistles are extremely valuable plants to wildlife. Most of us think of flowers and we think of pollinators, and thistles are extremely attractive flowers to many kinds of bees, butterflies, hummingbirds, hawk moths, and many, many other small creatures. Spiders, assassin bugs and other predators set up shop on thistle flowers; pollinators can't resist the flowers so they are great spots to ambush prey.

Two species of bumble bee and dozens of small green beetles collect nectar and pollen from a pasture thistle.

As much as it pains me to admit it, this Delaware skipper is enjoying a nectar drink from a Canada thistle. Even the exotic invasive thistles can provide some value for wildlife.
Butterflies love thistles. Fritillary butterflies like this one seem to be particularly enamored by flowers in this genus.

In addition to pollinators and the predators who love them, many insects feed on the foliage of thistles, such as the above mentioned swamp metal mark butterfly. Some of these insects are specialists that can only feed on thistles and no other food source. Others are more generalist and can feed on other, similar plants. John Hilty from Illinois Wildflower has put together this list of insects that feed on thistles on his amazing website.

With at least 23 species of insects that feed on the foliage and (I don't think I'm going out on a limb here to say) hundreds of insects (and one bird) that feed on the nectar and pollen, you can see they play an important role in our ecosystem. Even more so if you consider all the insects, spiders, amphibians, reptiles, mammals and especially birds that in turn feed on the insects that feed on the thistles. Thistles aren't only a pillar of the natural community, they are a big part of the foundation of the natural food pyramid.

Separating Good from Bad: 

Our noxious weeds laws are put in place for a reason. These weeds cause economic and ecological damage. Canada thistle in particular is extremely difficult to eliminate requiring an expert, targeted approach for success. But to be absolutely clear, none of our native thistles are aggressive, weedy species. They will not spread rapidly like Canada thistle or infest over-grazed pastures like bull thistle or plumeless thistle. They really can't tolerate the heavy disturbance associated with modern agriculture and dairy production and pose no threat of economic loss to farmers. Unfortunately, many weed laws treat all thistles the same, outlawing the exotic weeds and the already imperiled native thistles alike.

For example, the City of Madison's weed ordinances which can be found in Chapter 23, section 29, paragraph 2 states that “The term 'noxious weeds' as used in this section includes the following: Canada or other thistles...” while leaving out many more harmful weeds such as, oh, I don't know, just about everything listed on the state of Wisconsin's invasive species rule NR-40.

The state of Iowa lists any and all all plants in the Cirsium and Carduus genera (what we might call all of the true thistles) as noxious weeds, regardless of origin. At least Iowa is thorough in its noxious weed list to include harmful invasive plants like purple loosestrife, common buckthorn and poison hemlock among others. By comparison Madison's weed ordinance seems somewhat haphazard.

I don't have much say in Iowa or in other municipalities around the midwest that throw a blanket ban on any thistle of any kind, but I would like to help make an effort to improve Madison's noxious weed law. If we can be clear about what plants are an economic, ecological and/or health threat to our citizens then we come up with a sound list of plants that should be banned in our community. The state's NR-40 list is a good place to start. Throw in a few hazardous plants that are already on the list such as poison ivy and the ragweeds, throw in a special request for reed canary grass which has some economic value, but is an ecological horror show, and I think we would have a good law. Then if only we could get the city to enforce it...

Wednesday, August 21, 2013

Critical review of management of natural right-of-ways in Madison

Last week a small urban prairie that had been painstakingly maintained by dedicated for over 15 years was mowed down by City of Madison staff, for no apparent reason at all. The prairie will recover, next year, but this year we have lost habitat for pollinator (with honey bees, native bees and monarch butterflies all seeing dramatic population crashes in recent years), winter cover and resources for birds (songbird populations have dropped by 50% in the past 50 years in the US), we lost the prairie in peak bloom(!) and we'll never get to see what this unique growing season had in store for us for fall display of asters and goldenrods. Furthermore mowing down the native perennials may leave growing space for a variety of weeds and invasive plants... I'm most concerned about the exotic cool-season grasses that we've been struggling to control in the prairie.

Below is a letter that I wrote and sent as an email attachment to my alderperson, the alderperson who's district contains the Atwood Community Prairie, city engineering staff, the Atwood prairie volunteers and members of Madison's Wild Ones chapter. Mayor Soglin will be getting a hand-delivered letter this afternoon. I thought I would share it here on my blog for all to see.

I have been angry about this subject for a while, which I am sure is evident in the text of the letter. But in retrospect, I really want to add that I really appreciate that the City of Madison is trying to add native plants to our urban landscape. "Green" efforts like these are truthfully going to be critical for the survival of our local flora and micro-fauna in the long term, and they also create an opportunity for people to come in contact with beautiful native wildflowers in their everyday life. Not to mention the psychological boost contact with nature gives people the urban air pollution these plants can help reduce and the erosion control and water filtering work they can do if property employed. Unfortunately, they're doing an extremely poor job implementing these projects, and in most cases, failing completely. So here is what I had to say.

Frank Hassler
President/Chief Ecologist
Good Oak Ecological Services
205 Walter St.
Madison, WI 53714
(608) 209-0607

August 21st, 2013

To: Mayor Paul Soglin
Alder David Ahrens
Alder Marsha A. Rummel
City of Madison Engineering Staff

Cc: Atwood Community Prairie volunteers
select members of the Madison Chapter of Wild-Ones
Russ Hefty, Conservation Resources Director

I am spurred to write to you today by the misguided mowing of the Atwood Community Prairie. I want to be clear that that action is only a single incident in what I believe has been years of mismanagement of natural areas along our City of Madison bike paths and stream corridors. You can consider this letter to be an angry letter from a citizen or a free, independent consultation. As I will explain in this letter, with the neglect of these natural areas the city violates both state law and City ordinances, and wastes a significant amount of taxpayer money on projects that are regularly failures. Some of these projects further promote the spread of invasive plants and noxious weeds in our community. Because I live on the east side of the city I will focus on sites near my home which will provide more than enough examples of the issues about which I am concerned.

The way these areas are (mis)managed causes significant ecological harm, but with changes to management strategies I believe theses areas can provide significant benefits to our ‘endangered’ local wildlife and plants, provide educational and recreational opportunities to city residents and naturally beautify our city. Madison can be a model for how other communities in our region should manage their right-of-ways.

Volunteers arrived at the prairie on Tuesday, August 13th for a workday and late-season social gathering only to find this.

The Mowing of Atwood Prairie

The Atwood Community Prairie was established in the mid-90’s with seed mix provided by the city, and has been dutifully managed by volunteers ever since. From what I can tell, the original seed mix was cheap and of low quality. However, the volunteers worked hard over the years weeding and spending their own money on plants and seeds to enhance the prairie.

Even in the past 6 years that I have lived in Madison I have noticed great improvement in the prairie. As of early last week, it was at peak bloom and absolutely full of native flowers. Then it was mowed.

So far communications between the prairie volunteers and city staff seem to indicate that it was mowed for visibility reasons. As you can see from the photos above, with sidewalks and several feet of mowed grass on either end of the prairie (up to 10’ total), there is no reason to think that there is a safety hazard associated with the prairie vegetation at this site.

Another reason given for the mowing was to control the growth of woody plants and to facilitate snow removal along the bike path. However, prescribed burning and regular maintenance by volunteers prevents tree saplings from getting established. The herbaceous vegetation here easily collapses under the weight of snow that has fallen or been plowed onto it, making mowing unnecessary for these reasons.

According to the DNR, Wisconsin has lost 99% of its original prairie habitat and 99.93% of its oak savanna. Small urban prairies like this one are critical habitat for pollinators, winter habitat for songbirds and other wildlife, and they are an overwintering site for for many beneficial insects such as solitary bees. Mowing this prairie in the middle of the peak season not only robs the public of this beautiful amenity along the bike path, it also takes critical resources away from our already imperiled local wildlife.

South and north ends of Atwood Community Prairie, respectively after mowing. Note that the vegetation at the ends of the prairie where it could plausibly cause visibility issues has been left standing.

Noxious weeds and invasive plants commonly allowed to persist and reproduce in stream and bike path right of ways, despite state laws and City ordinances demanding that they should be “destroyed”:

- All three species listed as noxious weeds by the state, Canadian thistle, hedge bindweed and leafy spurge can be commonly found flowering, reproducing and spreading along Madison bike paths and stream corridors. State law (66.0407) requires that “The person having immediate charge of any public lands shall destroy all noxious weeds on the lands.” (

Leafy spurge is allowed to spread both by roots and by seed along the Capitol City Trail immediately south of Livingston Ave.

Canadian thistle and reed canary grass go to seed on this section of bike path between Dixon St. and Milwaukee St.

Hedge bindweed blooming along the Southwest Commuter Path immediately east of Doty St.

- Additionally, species prohibited as noxious weeds by the City of Madison’s own ordinances, including common ragweed, giant ragweed and stinging nettle are commonly found along bike paths and stream corridors. City ordinance 23.29, paragraph 2 states that “Every person shall destroy all of such noxious weeds on land which he shall own, occupy or control...” (

Giant Ragweed and stinging nettle are both common along the Capitol City Trail, see here together behind Olbrich Park. There are many, many more examples of these noxious weeds on trail and stream sides.

- Many plants listed as Restricted under NR-40, Wisconsin’s invasive species rule, are common along the bike paths ( Additionally, reed canary grass, which is not yet listed on NR-40 (for economic reasons), but is arguably the most destructive invasive species in the state, is abundant, and dominates most stream corridor areas and is common along bike paths. (Examples too numerous to provide photographs of them all).

- If mowing is intended to control weeds, it should be noted that doing so this time of year has very little impact on the majority of weeds found along the bike paths, and likely increases their spread by seed, and in the cases of some of our most difficult weeds to manage like Japanese knotweed and leafy spurge, by vegetative cuttings moved around the city on mowing equipment.

- In my summation, not only is the city failing to “destroy” these noxious weeds, but in fact they have spread and increased in abundance during the past 6 years that I have lived in Madison. I believe the city is causing significant ecological harm by allowing these invasive plants to persist and spread to destroy the native plantings that the city has invested significant funds into establishing.

Recent projects to establish ‘natural’ buffer zones along shorelines have been nearly complete failures:

The shoreline restoration along Starkweather Creek from Milwaukee Street to MATC campus shows the following faults:

- less than 10% coverage by desirably native plants (that were part of the original seed mix), the entire stretch is dominated by reed canary grass and canada goldenrod.

- This is clearly the result of poor site prep and limited/poor quality maintenance that were inadequate to meet the goals of the project.

- Once established, these natural areas should stabilize and require only light regular maintenance. Unfortunately these areas are never allowed to reach this state due to a lack of proper oversight.

- In order to rectify this situation now, the area will need an intensive effort over several years to control weeds and get good quality vegetation established. This will cost many times what it would have cost if the area had been prepared, installed and maintained correctly in the first place. Good results could have been achieved with much less effort.

- Poor planning and accepting low bids for maintenance contracts from firms that were not qualified to do the work will leave the city either with this failed project or great expense being put into rectifying the situation.

Though a few native big bluestem grasses can be seen in this photo, almost every plant in this photo taken along Starkweather Creek, just north of Milwaulkee St. is either reed canary grass or Canadian goldenrod.

- Similarly, the Olbrich Park shoreline on Lake Monona has less than 10% coverage by desirable native plants. There is certainly more coverage by noxious weeds than by the plants that were seeded into the area. The reasons for the failure of this planting, and the work required to rectify the situation are similar to the above.

- Establishing prairies is indeed a challenging activity, requiring experienced land managers and an adaptive approach to managment. However, a few ‘rules’ of successful prairie establishment are that thorough site preparation to eliminate weeds before seeding is critical to success, and that careful monitoring and aggressive weed management are necessary during the first few years of establishment.

The vegetation establishment of the slope erosion control project along the bike path Starkweather Creek spur behind Olbrich Park is off to an extremely poor start, and destined to fail if action is not taken immediately:

-Though I was initially pleased to see the tangle of invasive brush removed from this area and the rampant erosion issues here addressed, it is clear that poor site preparation and a complete lack of vegetation maintenance on this slope will result in a failure to establish the native prairie plants that were seeded here, and the site will end up dominated by noxious weeds and invasive plants if corrective actions are not taken within the next few days.

- It is clear from abundant weeds including barnyard grass, foxtail grasses, velvet leaf, common ragweed, giant ragweed, and others, that the topsoil used for this project was not “clean”, but instead was dense with weed seeds.

- Since seeding has been completed here, no maintenance work has been done. Annual weeds up to 6’ fall now dominate the seeded area. Typically one would plan on doing 2-4 mowings in the first growing season of a planting like this. The shade produced by the dense annual weeds has undoubtedly killed many prairie seedlings which only grow a few inches above ground in their first growing season and require direct sunlight for growth.

- The edge of this slope along the bike path has since been mowed. However, the dead plant material is so thick it completely covers the ground, smothering all vegetation below. Also, most of these weeds have already developed seeds. Mowing at this stage does nothing to control the reproduction of these weeds, and may in fact increase the amount of viable weed seeds that reach the soil.

- At this stage the only possible course of action to prevent a complete failure of this planting would be to cut down existing vegetation, and remove it all from the site so as to limit the amount of weed seeds that are able to drop on site. I strongly urge that this work take place within the next few days.

- I strongly urge that this area be re-seeded, be covered with fresh erosion matting in spring of 2014 and that a regular maintenance regime (including regular mowing of annual and biennial weeds and spot herbicide treatment of perennial weeds) be carried out for the first several growing seasons in order to promote good establishment of native plants in this area.

This area, seeded in the spring of 2013 is completely dominated by annual weeds. The only plants that are visible in the area which were part of the intended seed mix are the annual oats (brown in color, center of photo).

Extremely poor maintenance of most rain gardens:

The City of Madison proudly touts its rain garden program, and continues to expand the number of rain gardens around the city. While this program is well intentioned, many of the rain gardens are poorly maintained, if at all. Many critics of rain gardens consider them ‘weed gardens’ and by not maintaining the rain gardens properly, especially in the first few years of growth, the city is proving these critics right. I find this particularly frustrating because I believe that the establishment of rain gardens and other methods to cut run-off into our lakes and streams is critical if we are to improve the quality of our waters. Below are a few (among many) examples of poor rain gardens that need to be rectified:

- Goodman rain garden has weedy trees (boxelder, hackberry, walnut) 4-5 years old. Meaning that the contractor hired to maintain this rain garden has failed to do an adequate job for many years in a row. Crown vetch, reed canary grass and other invasive plants have gone unmanaged at this site for 3-4 years, despite the fact that I alerted city staff to this issue about 3 years ago. Ragweed (the pollen of which causes hay-fever allergies) has been allowed to bloom every year for at least the past 5 years (these would have probably been eliminated from the site by now if they had been managed early on). Lack of care is obvious and embarrassing, especially considering the interpretive sign describing rain gardens at this site.

Above: Many weedy trees displace native perennials in the Goodman rain garden. Removing these trees should be a simple, basic part of maintaining the site, which has been neglected.

The invasive crown vetch persists in the Goodman rain garden just beyond the mower’s reach, and has spread significantly over the past several years with no effort made to control it.

- Similarly the rain gardens at the end of Ivy Street, across from Sherry Park, are in very poor condition. The rain gardens were dug too deep and with very steep sides, which would have to result in instability and erosion on the sides of the rain gardens. Even though they were only planted about 3 years ago, it appears that they have received almost no maintenance and have many more weeds in them than native plants.

Though native plants are still present in one of the Ivy St. rain gardens, noxious weeds such as Canadian thistle and stinging nettle are pushing them out, with no effort taken to control them.

Though common ironweed (purple flowers) is prominent in the other Ivy St. rain garden, the bulk of the area is covered by various weeds and not the native plants which were planted there.

- A few rain gardens in the city seem to be in fairly good shape. For example, those located in Brittingham Park are fine examples - I suspect because they were installed and managed by qualified professional ecologists during their first several years of existence. Also their larger size may promote ecological stability. I suggest examining what has gone right in some rain gardens and wrong in others to develop a plan of action going forward to maintain existing rain gardens and establish new ones.


- More careful planning, preparation and maintenance needs to be done to insure success of various “natural” plantings on shorelines and right-a-ways around the city. The city should expect to invest more up front for more thorough site preparation, better seed mixes, and more intensive maintenance for the first few years of a planting in order to see a successful planting with lower maintenance costs down the road.

- Concerted efforts must be made to eliminate noxious weeds and invasive plants on public property.

- All field staff should learn to identify noxious weeds and invasive plants and be trained in targeted control methods. They should also learn to identify native prairie plants that are commonly included in seeding mixes around the city. Being able to identify a couple dozen weeds and a couple dozen prairie plants should be a basic qualification for anyone managing vegetation for the City, even if it’s just running a riding mower.

- The City continues to hire under-qualified landscapers to conduct installation and maintenance work in these natural areas within the city. The Goodman rain garden is a prime example. The City needs to develop a process to screen for qualified contractors to bid on natural areas management activities. With well over a dozen firms (including Good Oak Ecological Services) that specialize in invasive species control and natural areas management servicing Madison, there is no lack of qualified experts in this field in our region that could do good quality work for the city.

- City engineers seem quite competent in the field of civil engineering, but vegetation management is an entirely different field of expertise. The city should consider the following options: 1) Hire a consultant to help develop the vegetation management aspects of the RFP and to monitor the site preparation and maintenance work. 2) Hire additional staff with expertise in natural areas management and weed control specifically to plan and manage these reconstructed natural areas around the city. 3) Increase the funding and man-power available to the Parks Division’s Conservation Resources Director so that qualified personnel already working for the city can take charge of managing these areas. Please note that the Conservation Resource crew currently has insufficient resources to manage the natural areas they are already tasked managing. As such, the increase in resources to this group would need to more than compensate for the increase in responsibility.

- The city should get existing rain garden and natural corridors on track before attempting to add additional management units.


Frank Hassler
Concerned Citizen
Professional Ecologist

Saturday, June 29, 2013

What Sustainable Landscaping Means to Us

A question worth asking yourself from time to time.
At Good Oak, we are trying to promote Aldo Leopold’s “Land Ethic” across the landscape both on
wild rural properties and smaller urban lots. Leopold stated this philosophy, perhaps most succinctly, when he wrote in The Sand County Almanac that “A thing is right when it tends to preserve the stability and integrity of a biotic community; it is wrong when it tends otherwise.”

Unfortunately, most landscaping practices “tend to do otherwise.” The work practices of the so called 'green industry' makes it one of the most wasteful and polluting industries in our nation. The traditional landscape that has developed over the past 60 or so years consumes copious amounts of water and natural resources, produces significant quantities of air and water pollution, and offers little wildlife habitat while continuing to destroy and fragment existing habitat. In short, traditional landscaping degrades the health of our biotic communities, and ultimately quality of life for people as well.

So our alternative to this deleterious paradigm is what is being called Sustainable Landscaping. There are many aspects of sustainable landscaping and being sustainable in a particular landscape type means slightly different things around the country and around the world. I want to take a few minutes to explain what we at Good Oak think are key points to sustainable landscaping for sites in the beautiful Midwestern United States.

Native Plants: The plants that have been living in the Midwest for thousands of years are ideally suited to our local climate, even climatic extremes, and are co-evolved with local wildlife to provide the resources they need to thrive. Right plant, right place.

Edible Plants: Buying local foods is gaining in popularity as people realize the benefits to the environment and the community. There’s nothing more local than your own yard, so we like to incorporate fruit trees, raspberry beds, and even veggie gardens in our designs as much as possible.

Reusing Materials On-Site: It's quite upsetting to see traditional landscapers taking plants, stone, and soil from a job site and taking them straight to the landfill only to replace these with “new” quarried stone, scrapped topsoil, and mass-produced plants. We subscribe to the environmentalists Three R’s: Reduce, Reuse and Recycle! We choose to rebuild an old stone wall with existing stone, clean and move decorative gravel from an outdated foundation planting into a new ‘dry stream bed’ feature, compost the plants that we remove from a site and replace them with plants that are suited to the soil conditions that already exist on site.

Local Materials: In the traditional nursery system, massive nurseries in the southern US supply all the plant material for garden centers and landscapers in the East and Midwest. These plants are grown in warm climates and shipped many hundreds and in some cases nearly 1,000 miles to local resellers. Landscaping stone can come from anywhere. Red lava rock for example is shipped halfway across the country! All of the materials we use come from about 1/10th that distance, with over 95% of the plant and stone material we use being produced or quarried within 100 miles of our Madison headquarters. In the future we hope to halve this distance. Using local materials not only supports our local economy, it also allows us to create landscapes which celebrate the unique beauty of our region.

Quality Materials: I have seen too many decomposing concrete wall blocks and too much torn and shredded plastic edging to use these materials in our projects. The initial cost of these materials may be lower, but you pay more in the end having to replace plants that were unhealthy or not hardy and materials that break down too soon and become trash. We use only natural stone and quality brick for hardscaping and healthy native perennial plants for our softscaping, creating durable and beautiful landscapes.

Respecting Rain Water as a Resource: The high coverage of impermeable surfaces in our urban landscape creates water flow issues ranging from wet basements to erosion on slopes or other sensitive areas. Traditional landscapers treat this water as a waste product and try to shunt it away to ditches, sewers ands streams as quickly as possible, often carrying pollutants into our streams and lakes along with it. At Good Oak we realize that water is one of our most precious resources. We find ways to reuse rain water such as in rain barrels or develop decorative landscape features such as rain gardens, swales, and other structures that capture rain water near where it falls so it can recharge our groundwater stores. In the future we’d like to offer permeable options to replace hard surfaces such as green roofs (featuring native plants of course!) and permeable pavers.

Reducing Emissions and Pollution While We Work: Most power equipment produces copious amount of air pollution, not to mention noise pollution. Sometimes these power tools can save a lot of time and thus save our clients lots of money. But whenever manual labor is cost competitive, we’ll always choose the broom over the leaf blower and the mattock over the stump-grinder. Fuel-thirsty trucks are necessary tools to move materials and our crew, but we do the best we can to reduce our fuel consumption. We train our staff in hyper-miling driving techniques and offer our staff a Sustainable Transportation stipend for using human-powered or public transportation to get to work.

Smart and Limited Use of Pesticides: We always try to use as little herbicide as is necessary when controlling weeds and preparing a site for planting and offer clients the “organic option" to manage weeds manually or mechanically whenever we think these are viable options. However, certain tasks, such as controlling difficult weeds like Canada thistle and leafy spurge, just cannot be accomplished without the skilled application of herbicides. When we do use herbicides, we always select the least toxic options available. Compared to the highly toxic 2,4-D that many people spray on their lawns multiple times per year, we’re making good progress. We flat out do not use insecticides of any kind. These chemicals have a higher toxicity to humans and other animals. Native plants tend to be little harmed by insect damage and there are always non-toxic options for keeping pests off our edible food crops.

Quality Work and Smart Solutions: Simply put: doing good work the first time saves time, money, and resources.

Saturday, April 6, 2013

Eradicating Garlic Mustard Requires A Holistic Approach

Garlic Mustard: flowering second-year plants above, young first year plants below.
UPDATE (3/3/17): I'm continually updating this post over the years as new information comes to light, we develop new techniques, and as I find new typos! You can consider this an up-to-date, thourough guide to garlic mustard control.

Doing some research online for herbicide rates recently, I ran across a lot of incorrect and misleading information on controlling garlic mustard (Alliaria petiolata). So I was inspired to write this post. A lot of people don't realized that fall and early spring are actually the best times to manage garlic mustard, so if you think you have more garlic mustard than you can handle, get out there and get ahead of it!

Each garlic mustard plant can produce hundreds, even thousands of seeds. This allows there population to increase rapidly and establish a lot of seeds in the seed bank. The seeds don't generally move far from the parent plant, most fall or are flung just 2'-5' away. Often you can see small patches of garlic mustard in rough circles around 4' in diameter where an adult plant was able to go to seed the previous year. Only a few seeds will travel further, carried in flowing water, on animal fir, or in mud on animals' feet (including your shoes!), and vehicle tire treads.

From a technical standpoint, garlic mustard is among the easiest invasive species to control in our region. Despite the large number of seeds they produce, garlic mustard is a biennial, they only live for 2 years. The first year they remain a low rosette and gather energy. The second year they bolt, flower, produce seed and die. So all you have to do is prevent them from developing seeds before their time is up. Garlic mustard is susceptible to a variety of herbicides, it's shallow-rooted, and has a low fire tolerance. It stays green at times of year when most native plants are dormant. This gives us a lot of management tools that we can wield against this otherwise rapidly reproducing pest.

The two most important factors in control garlic mustard are: 1) Determination: to completely exterminate every plant each year so there is no seed production, and 2) Patience: since the seeds can live for up to 7 years in the soil, you have to figure that this battle is going to take a decade to win. Below is a 'battle plan' for the year-round management of this invasive pest.

Don't Spread the Seeds!:

 You can't do much to kill off the garlic mustard seeds in the soil. You have to wait for them to sprout so you can do something about them. But you can prevent their spread! If you have been walking or driving through an area that has garlic mustard, thoroughly clean your boots' treads to avoid moving these seeds to other sites. This goes for vehicle tires and the feet of animal companions too. If you're moving through an area where there are upright dead stalks from last year's plants, be sure to clean out your socks and pant cuffs too.

Garlic mustard seeds are black, cigar shaped and just over 1/8th inch long. Photo courtesy www.

Prescribed Burns: 

The garlic mustard seedlings look a lot like the sprouts you buy from the health food store, but often carpet the woodland floor almost as thick as moss. I have seen them sprouting as early as mid-February. They are delightfully easy to kill. Prescribed fire can wipe them out en-mass.

Freshly sprouted garlic mustard seedlings. These can be hard to differentiate from the seedlings of other plants visually, but they have the characteristic garlic mustard smell when crushed. Photo courtesy of The Buckthorn Blaster.

Prescribed burns will also negatively impact the second-year rosettes to a greater or lesser extent depending on the intensity of the fire and the health of the individual plants. I have seen hot burns kill over 50% of the mature garlic mustard plants in a woodland, whereas other times it seems like it's 0%.

We feel that prescribed burns are a critical tool for controlling garlic mustard, particularly the seedlings. Considering the many other benefits of prescribed burns in woodlands, repeated spring burns during the early years of your garlic mustard control work will improve the health of your woodland greatly.

A prescribed fire like this one can be the most efficient tool in your garlic mustard control arsenal.

Time the burn for early-to-mid spring (typically this is in late-March or early-April) after a lot of them have come up, but be aware of any early sprouting native plants, particularly spring ephemeral wildflowers that might be in the area. If you spring ephemerals in your woods, you will need to get the burn completed before these wonderful woodland wildflowers sprout. These spring ephemerals are perennials, and will survive a fire, but repeated burns will weaken them and delay or prevent flowering for the year.

Flame Weeding of Seedlings: 

Not able to do a full-out prescribed burn? A propane torch like those sold by the Red Dragon company works very well at killing off seedlings. The fire will only top-kill any mature plants (the roots will survive to resprout). So it won't kill second year garlic-mustard rosettes. On the other hand any native perennials that might literally get in the line of fire will also readily resprout from the roots as well.

Flame weeding is a little slower than an herbicide spray application, but has a very low risk for collateral damage and no residual impact that some herbicides may have. It is an extremely satisfying control method as you watch hundreds of them wilt and die immediately. It makes me laugh like a mad scientist every time. With a flame-thrower in my hand and a propane tank on my back, I'm sure I look like one too.

Torching garlic mustard seeds should work very well from the early seedling stage when they just have a pair of their cotyledons (baby leaves) up until their first set of real leaves are about the size of a quarter. After that the kill rate may go down slightly, but it's probably worth doing until mid-May.

These more mature seedlings have developed their first true leaves, but are still vulnerable to prescribed fires, flame weeding and organic herbicides.

Most people try a little too hard with the flame weeder. It only takes a little heat and you will see a slight color change to the plant, they may wilt slightly. That's all you need. When you come back in a few minutes you will see that they have wilted and are goners. Usually I sweep through an area torching them lightly and when I'm done, go back over it for any spots that didn't quite get hot enough.

An important note here is that you want to be careful not to accidentally start a little wildfire. Avoid days of low humidity and high wind.  Its safest if the humidity is above 50% and the leaves are NOT dry and crinkly. If there is little or no leaf litter or dead plant material in there area, you're probably ok. Test it out in a small area first to see if the burning leaves fizzle-out or if the fire spreads on its own. Remember that conditions can and will change as the day goes-on, so even though a fire might not carry in leaf litter in the morning, that doesn't mean it won't flare up and take off in the afternoon. Always keep a hose or portable water sprayer on hand just in case. Also, have a phone in your pocket ready to call the fire department. Better safe than sorry.

Treating Seedlings with Organic Herbicides: 

If running around your property with a flame thrower seems a little extreme to you, another option for killing seedlings is to use an organic herbicide such as Phydura or Nature's Avenger. Both of these herbicides are mild, naturally derived acids that dissolve the waxy cuticle layer on a plant's leaf causing them to dry out and die. Like fire, these organic herbicides only top-kill plants, but that's enough to wipe out little garlic mustard seedlings that haven't developed much of a root yet. Its not nearly as much fun as flame weeding, but Smokey The Bear would prefer you use this method.

Is Treating Seedlings Worth It?: 

There is some debate about weather its worth the effort to conduct control work on the first-year seedlings, there are a several key talking points:

First, is a little thing called "intraspecific competition", which basically means that the seedlings of the same species all compete with each other for survival, and only a small fraction, perhaps 1 in 10, 1 in 100, or less,  make it to adulthood. So any seedlings that you fail to treat or kill will have an easier go of it, with plenty of growing space since you've taken out the competition, and they no longer to compete with their siblings for resources.

Because of this, some people will argue that treating seedlings is a waste of resources. If you have the time to do it, curtailing the raw numbers of plants make later management much easier. It also eliminates the effect that a "carpet" of garlic mustard can have on the native woodland flora, giving our wildflowers some growing space back so they can reclaim some of the woodland floor that had previously been lost.

UPDATE (4/11/16): I don't talk a lot about the ecological impacts of garlic mustard in this blog post, its long enough just covering the topic of control! However, I think its worth pointing out that garlic mustard has an allelopathic impact on soil fungi, that is to say, it releases chemicals into the soil that kill our native soil fungi. Many native plants are dependent on, or strongly benefit from a symbiotic relationship with these soil fungi. The plants provide carbohydrates from photosyntasis to the fungi. In return, the fungi absorb various nutrients from the soil through their fine mycelium, which they pass on to the plant.
As a result, the garlic mustard can have a very dramatic impact on the ground layer flora, strongly reducing the species diversity and abundance of native plants, more from this chemical warefare than from direct competition. And it appears that the impacts to the soil biotic community are significant and potentially permanent. It stands to reason the loss of these soil fungi will negatively impact tree health as well.
Considering these impacts, I'd recommend trying to control garlic mustard seedlings if you have the time and resources to do so. Working to preventing them from getting established in the first place can reduce or prevent harm to soil micro and macro-organisms, wildflowers and potentially trees that live in your woodland.

The second issue to consider when tackling garlic mustard in the seedling stage is that by killing off this first wave, you've effectively recruited their reinforcements. New seedlings will often immediately germinate to take their place. This may seem discouraging, but I believe that it's better to flush as many of these seeds out of the seed bank, so we can start killing them too. Bring them on! The second wave of seedlings is rarely as dense as the first, so either way you're better off.

Dormant Season Herbicide Treatment of Rosettes:

The real key to controlling garlic mustard is targeted herbicide applications when most of our native plants are dormant. This works both in late fall and in early spring. In spring, you can begin shortly after the snow has melted away. In order for this method to be effective the air temperature needs to be above 35 degrees (often we'll wait until it's above 40 just to be sure). At these times of year the garlic mustard is easy to find since they are just about the only thing that is green. Try to get it done before the native woodland wildflowers come out, or else you will have to be very careful to spray around them.

The herbicides we use to spray garlic mustard includes glyphosate-based herbicides (same active ingredient as Round-Up®) since glyphosate breaks down fairly quickly in the environment and has no residual activity as it binds strongly to clay particles in the soil upon hitting the ground and is broken down by bacteria within a few weeks. Other glyphosate-based herbicides include Accord®, Razor® Pro, Makaze® and Glypho-Star. If you're working near wetlands of any kind, use an aquatic-approved formulation such as Rodeo®, Aquaneat®, or AquaMaster®.

A Note On Recent Glyphosate Research:
There have been some studies recently that correlated the use of glyphosate-based herbicides by farmers to an increased risk of certain forms of cancer. Bear in mind that this group of people is at a very high exposure level to the chemical, often using handling concentrated pesticides and applying it with no personal protective equipment, day-in, day-out for decades. They also have a very high exposure to many other agro-chemicals. Also remember that correlation does not imply causation. More research needs to be done to determine if there really is a causative link here here, and what the mechanism of pathogenesis might be. For the time being, many, many other studies indicate that glyphosate is very safe for animals (less toxic than salt-water!) and that it breaks down fairly quickly in the environment so there's no risk of long-term contamination. We will update our practices and recommendations if future research suggests a greater risk.

If there is a risk of harming native grasses or sedges nearby, many of which also stay green pretty late into the fall and green up early in the spring, then we will use a triclopyr-based herbicide such as Garlon® 3A or Vastlan®. Triclopyr takes longer to break down, roughly 3 months, and has some residual activity, so it may kill any broadleaf seedlings that try to sprout in the treated area during this time. On the other hand, triclopyr is "practically non-toxic" to animals (though you always have to wonder about the unspecified "inactive" ingredients in the herbicide solution as they constitute 55% of the mix!)

Tryclopyr herbicides seem to be harder to find, but you should be able to find Garlon 3A at Ben Meadows, Forestry Suppliers or your local farm co-op should be able to order it for you. We like to work with Rick Schulte of Crop Production Services in DeForest as he is highly knowledgeable about the safe use of pesticides to control invasive plants.

Which herbicide to use and at what application rates are a bit of a contentious subject among land managers. One mistake we often see is people mixing their herbicide with tap water, which is often alkaline (a mild base) in our region. This can partially de-active some herbicides, such as glyphosate, which are mild acids. Its best to use rain water or use a water condition such as Choice or Watersoft to neutralize your water before mixing in the herbicide.

We also add a dye to our herbicide mix, such as Hi-Lite Blue to help us keep track of what's been sprayed and what hasn't. I like to use 1 oz of this dye per gallon of water to allow us to see which plants were sprayed and which weren't even a week or more later.

Before I recommend herbicide application rates, I need to say that my recommendations are not a substitute for the pesticide label. The label is the law; read it and follow the instructions before applying any pesticide. 

I also want to add that you should always wear the personal protective equipment (PPE) as recommended on the label. I would go above-and beyond to recommend anyone applying herbicides should be wearing long pants, long sleeves, waterproof boots, "rubber" gloves (we like disposable nitrile gloves) eye protection and a hat or other head covering, to reduce the risk of direct exposure. If there is a breeze, always spray down-wind of yourself and use extra caution when mixing or otherwise handling concentrated herbicides.

For early-spring or fall application when there is a relatively low leaf area compared to the root mass we like to have a higher concentration of active ingredient in the mix. For glyphosate-based, terrestrial herbicides, we recommend using 6 oz of concentrate per gallon of water. The aquatic-approved formulations of glyphosate have a higher concentration of active ingredient, so use those at around 5 oz/gallon. For triclypyr-based herbicides like Garlon 3A, we recommend using between 4 and 5 oz/ga for this dormant-season application.

As the plants mature and grow they have more leaf surface area to absorb herbicide, so you can dial down the concentration of active ingredient a bit: 3-4 oz/ga of terrestrial glyphosate, 2.5-3 oz/ga of aquatic-approved glyphosate or 2.5-3 oz/ga of triclopyr.

Though its best to apply herbicide as early as possible in the spring before native plants come up (or even in the fall), provided that you take care not to get any overspray on native plants, you can continue to apply herbicide to garlic mustard until it starts to flower and still expect the plant to die before it sets seed.

As for application technique, we use backpack sprayers like this one or for smaller jobs, hand sprayers like this or this. We cruse through the woods in teams in a systematic grid pattern to be sure we traverse the entire area. If time is limited, I recommend focusing on areas with the least garlic mustard so you can cover the most area per time allotted. Then work your way into the more dense areas as time allows. Hopefully this will allow you to push the garlic mustard back further and further to the core of the population each year.

Dormant season spraying does a very good job at killing most of the garlic mustard. Still, we find that roughly 5-10% survive this treatment. Either the herbicide wasn't entirely effective on a plant or we simply miss them among the hundreds of others as we walk through. As a result, pulling is a necessary step to follow-up after dormant season spraying. The early season spraying reduces the hand-pulling workload considerably, making managing large sites or dense patches of garlic mustard manageable.

Pulling during the Flowering Stage: 

This is when most people start treating garlic mustard, when really, it should be the final stage in the management process. If you wait until late-April or May to start working on garlic mustard, you've waited too long. If you're dealing with a small area and just a few dozen or hundred plants, then pulling them can be effective. But hand pulling is labor-intensive and time-consuming, so it's critical to start early when dealing with sites larger than an acre in size, or dense patches of garlic mustard in smaller areas.
Pulling garlic mustard can be a big job!

The technique here is fairly simple. Grab the plant firmly at the base and pull steadily. If the plant breaks off leaving the root in the ground, try again to get the root out. A small weeding tool, or even a dinner folk can be helpful here. If you don't get the root, you don't kill the plant!

Once the plant is out of the soil and in your hands, I recommend shaking the dirt off the roots and snapping the stem below the flower head and/or above the root. This prevent the plant from moving nutrients and water up from its roots to the flower heads. You don't actually need to break them into multiple pieces, just bend the stem back on itself until you feel it snap. This is especially important for plants that are well into the flowering stage, and we have often see pulled garlic mustard plants that are thrown back on the ground turn their flower head up and continue flowering! It only takes a split-second to snap the plant and it makes for good insurance, just in case. Now repeat this process until you have removed every last garlic mustard in the area. If even a single plant is allowed to successfully reproduce, the result could be hundreds or thousands of seeds, most of which will develop into plants that you will need to pull in years to come.

I like to start pulling-season just before the garlic mustard starts to bloom. At this point the roots have gotten weak and the plants pull out easier. If you get to this task early enough you can simply snap the stems and drop the plants where you pull them and move on or even put them in the compost bin. If you wait until well into the flowering season and you'll have to bag them out and get them in the trash, which is a lot more work. How do you know when it's safe to leave the pulled plants just laying on the ground? Our general rule of thumb is that once petals start to fall off the flowers, that means those flowers have been pollinated and are starting the process of producing seeds. Bag 'em.

Notice how the petals have fallen off the lower flowers on this stalk and they are beginning to elongate into seed pods. At this point, you definitely need to be bagging the plants out of the site and disposing of them in the landfill.
For late-season pulling, you will have to collect the garlic mustard in garbage bags and send it to the landfill so that it does not develop seeds. They should not be composted or put on the curb with other lawn waste. As long as you bag out the dead plants, you can continue this work into mid-summer up until the seed pods start to open up and release seed.

Mowing, a Last Resort: 

Often times we get a call from a new client, asking us to control the garlic mustard in their woods. Unfortunately, they wait until May to call us and when we get there, their woods look something like this:

There's more garlic mustard here than can be pulled in a reasonable amount of time. It's too late to herbicide. Though it will kill the plants, they will be able to develop seeds as it dies anyway. So what to do?

Mowing or weed whipping garlic mustard isn't a perfect solution, but it can cut the reproduction rate down dramatically. We know it doesn't prevent seed production entirely, but we suspect it cuts it by about 90%. And we always say that 90% control is better than 0% control. Timing is critical though. You need to wait until there are just a few flowers left blooming per plant. At this stage most of the seeds will have started to develop, but will not be mature enough to be viable, and the plant is near-enough to the end of its life that it won't have the resources to put much of an effort into resprouting from the roots once cut.

We call the technique "obliteration mowing" because it involves complete obliteration of the plant. It uses a string trimmer, aka weed whip, to mince up those seed heads so that the little bits of plant can no longer provide nutrients to the developing seed. You also want to be sure that you cut it all the way to the ground so that the roots have as little reserves left as possible from which to resprout.

For individual plants or small clusters, we often start at the top of the plant and mow down the stalk to the ground. This technique is more targeted and reduced damage to neighboring 'good plants'.

For larger patches, we sweep the string trimmer head with the machine held so that the cutting strings are spinning perpendicular to the ground through the patch of garlic mustard at the height of the flowers/seed-heads. This first step minces up the seed heads preventing further development. The second step is to sweep back through with a couple horizontal swipes to cut the plant stalk as low to the ground as possible.

Be warned that you will get little bits of garlic mustard all over you. It's a bit like an outdoor food processor if you're doing it right.

With a mower, you may need to go over each area two or three times to be sure the plants are minced up enough. If you're just cutting and knocking them to the ground with the mower deck, then it's not going to do much good. A heavy-duty field and brush mower is good for this task, our you can take your standard push mower and rear it up on hind wheels for the first pass.

If you get any resprouts you will need to go back and mow it all again, or pull the few straggling survivors. Fortunately its a lot less work the second time around.

Spraying Garlic Mustard Over the Summer?: 

We usually allow first-year garlic mustard plants to grow and fester over the summer since we don't want to do any harm to the native plants that live next to them. But if you have some really bad areas that are nothing but garlic mustard, it wouldn't hurt to spray these patches over the summer.

While you're out there, control these other invasive plants too!

Garlic mustard isn't the only invasive plant in the woods that overwinters green and sprouts early. Take a look at the linked Weed Identification and Control Sheets and get to know them, its critical to control these right along side of the garlic mustard, or they may take over your woods as well:

Healthy Woodlands Resist Garlic Mustard: 

Just like a healthy person is less likely to get pneumonia, a healthy woodland is going to be much more resistant to garlic mustard invasion. The reason garlic mustard is such a prolific pest is because virtually all of the woodlands in our region are in really, really poor health.

Derek here is standing in a sick woodland. In this case we have a "sugar maple deadzone" blocking out all light to the ground, where there should be a proliferation of woodland wildflowers. Its easy for garlic mustard to thrive if there is no ground-layer competition!

Garlic mustard is a bit of a cheater. It greens up early in the spring, and stays green late into the fall. It can even be photosynthesizing during snow-free periods in the middle of the winter! This gives it a big advantage over our native flora in capturing energy from the sun.

Historically, regular ground fires in our woodlands kept tree seedlings and shrubs in check, creating an environment where a fair amount of sun can hit the ground under an open tree canopy. Our native woodland plants are therefore accustomed to more sunlight. They are also adapted to going dormant in the fall, because naturally wildfires occurred in our region in late fall and early spring. If they had stayed green all winter they would have often lost tissue, and the energy needed to create it, to the regular fires.

Garlic mustard on the other hand evolved in an environment free of fire, and with a dense forest canopy. So it developed adaptations to allow it to gather more light in the off-season.

Decades of abuse in the form of overgrazing by cattle, irresponsible logging practices such as high-grading, and more recently grazing by overpopulated deer, has decimated the plant communities in most woodlands. We have introduced exotic shrub species such as buckthorn and honeysuckle which have spread rapidly in these disturbed woodlands and crowded out native flora. Even trees native to the region that were once rarely or never found in our woodlands due to their intolerance of fire (often including box elder, among others), now crowd the woodland canopy, creating dense shade. Once our woodlands contained hundreds of species of wildflowers and grasses that grew vigorously and bloomed all through the growing season. Today most woodlands have only a handful of ground-layer plants in them, most of which bloom early in the spring and disappear by mid summer, leaving a lot of growing space available for garlic mustard.

Our Midwestern woodlands are now too shaded for our native plants, but just right for garlic mustard. So in order to control garlic mustard in the long term, we must return our woodlands to health. Remove exotic brush. Thin out weedy, fire-intolerant "canopy invading" trees to let more light reach the ground. Re-establish native woodland wildflowers and grasses by seeding and planting. In a healthy woodland, garlic mustard won't have a chance against our hardy native perennials.

Vestal Grove at Somme Prairie Grove is a rare example of a healthy oak woodland (photographed in August, during the height of the 2012 drought!). Notice how much sunlight reaches the ground layer plants in this woodland. How could a four-inch tall garlic mustard rosette ever survive with this dense competition from native wildflowers!?