Tag: invasive

Tree of Heck

We have about 3000 sq ft of mixed border surrounding (in multiple layers) our 1500 sq ft home.  We take care of everything ourselves, in our spare time (ha!!).  Thus, our maintenance schedule BARELY includes cutting back perennials and ornamental grasses Feb-March, plus any pruning needed for woodies…then some fits of weeding throughout the growing season.

Most of this stuff has been in the ground for five to eight years, and we have a high tolerance for nature taking its course.  We’re surrounded by deciduous forest, so of course trees pop up where they’re not supposed to, especially oaks and the occasional hickory, which I dearly love and hate to remove. But I do. Because seedling trees are about impossible to just yank out like a weed – a whip just a few feet tall will have a taproot as long.   With our stringent maintenance regime, they’re usually tall enough to poke up over the Panicum or loom over the Leucanthemum by the time I notice, so then digging becomes the only option.

Or, wait, maybe just cut it back really hard, like below the soil line.  That’ll kill it, right? Nope?  Back again? Chop, chop, hack, hack.  Most saplings will give up after a few years. Except this one:

Ailanthus altissima a.k.a. “Tree of Heaven.”

Most of you know this is a totally invasive doody-head of a tree.  Google for details if not familiar.  I thankfully have not had much experience with it, until the past few years – there must be a mature one in the area.  It would pop up here and there in our borders and blueberry field, but I didn’t think much of it. Grab the loppers, cut it back.  BIG mistake.

Behold, the most ridiculous root:shoot ratio ever:

ailanthusrootBunny, our pensive 40 lb whippet, for scale. 

I had lopped this individual back three years in a row. All I could see were the pale, unbranched shoots, not very imposing at all, so chop, chop.   But finally, after a heroic effort last evening, it was successfully ripped from the heart of our main perennial border. Joel had to use our John Deere 950 tractor with a brush grabber chain to get this out of the ground, even after 20 minutes of his digging around the root to get the chain attached.

Like some kind of sea monster, my repeated attempts to kill it apparently just made it angry.  And stronger.

It’s still out there, on our burn pile.
A dog barks in the night.
0_o.

 

 

 

 

 

 

Can Permaculture and Good Science Coexist

Several years ago I posted a four-part discussion about permaculture and my concerns with the blend of philosophy, science and pseudoscience that it contains. (Here are links to Parts 1,  2, 3 and 4.) So I was pleased to be part of an Extension tour group that visited an established permaculture farm in the San Juan Islands earlier this spring. This gave me an opportunity to see whether there was any perceptible shift in the permaculture community towards practices based on applied plant and soil sciences. Specifically, I chose to look for invasive species identified as noxious weeds that many permaculturists cultivate rather than eradicate.

Bamboo may not be a listed noxious weed in Washington State, but the yellow archangel beneath it is.
Bamboo may not be a listed noxious weed in Washington State, but the yellow archangel beneath it is.

Our spring came early this year, and the islands were blindingly yellow with the Scots broom that runs rampant there (and throughout the West). This species is a Class B listed noxious weed in Washington State and has been mandated for control by San Juan County. So I was surprised and disappointed to see it and other related broom species not only present at this farm but used actively as nitrogen fixing species.

Other brooms were actively blooming and setting seed.
Other brooms were actively blooming and setting seed.

The practice here is to plant broom or some other nitrogen fixing species right next to a fruit tree as a “companion plant.” While the idea is logical, the choice of species is not. There are many other plants, including legumes and alders, which grow well in our area and would provide the same benefit.

Scots broom (a class B listed noxious weed in Washington state) used as a “companion plant” for a fruit tree (both are encased in wire).
Scots broom (a class B listed noxious weed in Washington state) used as a “companion plant” for a fruit tree (both are encased in wire).

There is nothing that can excuse the deliberate use of a listed noxious weed that’s mandated for control by local government. Permaculturists should endeavor to be good citizens and not infringe on the rights of their neighbors who don’t share their philosophy.

English holly is on the noxious weed monitor list for possible listing.
English holly is on the noxious weed monitor list for possible listing.

 

WSDA noxious weed listings for species mentioned in this post:

Scots broom
French broom
Spanish broom
Yellow archangel
English holly

Spec errors mount

For years I subscribed to Consumer Reports. I appreciated their objective approach to product testing and lack of advertising. In their own words, their policy is to “maintain our independence and impartiality… [so that] CU has no agenda other than the interests of consumers.” But recently they’ve veered off the science-based trail – at least the one running through our gardens. Their approach to plant and soil sciences is more pseudo than science. And last year, after 30+ years of loyal membership, I quit my subscription when Consumer Reports began partnering with Dr. Oz (see here for instance ).

So until today I’ve been blissfully unaware of whatever CR has published on gardening and garden products. Then this post appeared on our Garden Professors blog group page ). I’ve included some of the article below along with my italicized comments in brackets.

“Lawn care without the chemicals: rid your yard of weeds and pests with these mostly organic solutions”
“…Here are 10 common weeds and pests that plague homeowners nationwide, along with chemical-free measures [“chemical-free?” Well, we shall see.] that should be effective in bringing them under control. For more information, go to the websites of Beyond Pesticides and the Great Healthy Yard Project. [Neither of these two sites is remotely scientific or objective.]

“Dandelion – what is it? A perennial weed whose common yellow flowers turn to windblown seed. Telltale signs. Though a handful of dandelions is no big deal, a lawn that’s ablaze in yellow has underlying problems that need to be addressed. How to treat. Like many broadleaf weeds, dandelions prefer compacted soil, so going over the lawn with a core aerator (available for rent at home centers) might eradicate them. [Like many broadleaf weeds, dandelions will grow anywhere. That’s why they’re called weeds.] It also helps to correct soil imbalances, especially low calcium.” [I’m curious how CR determined a “soil imbalance.” And did they test their hypothesis experimentally?]

Dandelions obviously suffering in a calcium rich soil

“Barberry – what is it? An invasive shrub with green leaves and yellow flowers, often found in yards near wooded areas. Telltale signs. Left unchecked, the shrub’s dense thickets will start to choke off native trees and plants. How to treat. Cut back the stems and paint their tips with horticultural vinegar or clove oil (repeated -applications may be needed). Burning the tips with a weed torch might also work.” [Yes! Chemical free vinegar and clove oil! By the way, clove oil has NO demonstrated efficacy for this application. And I’m sorry, but “burning the tips” of barberry is just going to stimulate lots of new growth below the damage. Just out of curiosity, how many people have problems with barberry in their lawn?]

I think you’d notice this in your lawn…

“Crabgrass – what is it? An annual weed with a spreading growth habit. It’s common in the Northeast, in lawns with poor soil conditions. Telltale signs. Lots of bald spots, especially after the first freeze, when crabgrass dies off. How to treat. Have your soil tested. Lime or sulfur may be needed to adjust the pH. Aeration is also recommended. Corn-gluten meal, applied in early spring, can be an effective natural pre-emergent herbicide. [Corn gluten meal, applied in early spring in climates where it rains, is an effective fertilizer for crab grass.]

Crabgrass with increasing levels of corn gluten meal.
Courtesy of Tom Cook, Oregon State University.

“Kudzu – what is it? An aggressive climbing vine that’s common in parts of the Southeast and the Midwest. Telltale signs. The thick vine forms a canopy over trees and shrubs, killing them by blocking out sunlight. How to treat. Pull out the vine and, if possible, its taproot. Be sure to bag and destroy the plant or its vines will regerminate. If the root is too thick, paint the stump with horticultural vinegar or clove oil repeatedly, or burn it with a weed torch.” [Ditto the comments for barberry.]

Have fun painting stumps. (Wikimedia)

“Canadian Thistle – what is it? An aggressive creeping perennial weed that’s found throughout the U.S. Telltale signs. Look for outbreaks in vegetable gardens, particularly those with peas and beans. [I have no idea where this little nugget of nonsense came from. It’s a weed! It will grow ANYWHERE! It doesn’t need peas and beans!] How to treat. Repeated hand weeding and tilling of the soil will weaken its extensive root system. [Because tilling the soil is such a great way of suppressing weed seed germination. And it’s really good for your lawn, too.] Planting competitive crops, such as alfalfa and forage grasses, will keep it from returning.” [Yes, do replace your lawn with alfalfa and forage grasses.]

Your new, improved lawn (Wikimedia)

“Fig Buttercup – what is it? A perennial weed with yellow flowers and shiny, dark green leaves. It’s common in many parts of the East, Midwest, and Pacific Northwest. Telltale signs. The weed will start to crowd out other spring-flowering plants. It can also spread rapidly over a lawn, forming a solid blanket in place of your turfgrass. How to treat. Remove small infestations by hand, taking up the entire plant and tubers. For larger outbreaks, apply lemongrass oil or horticultural vinegar once per week when the weeds first emerge. It might take up to six weeks to eradicate.” [Now in addition to pouring vinegar on your lawn, we’ll try lemongrass oil instead of clove oil. Another unsubstantiated application – maybe lemongrass because buttercups are yellow? Makes about as much sense as anything else. It smells nice though.]

Color coordinated weed control

“Phragmites – what is it? An invasive grass species found nationwide, especially in coastal wetlands [where so many of us have lawns]. Telltale signs. Dense weeds can crowd out other plant species without providing value to wildlife. How to treat. Cut back the stalks and cover the area with clear plastic tarps, a process known as solarizing. Then replant the area with native grasses.” [Solarizing pretty much nukes everything that’s covered – not just the weeds. In fact, the rhizomes of this weed are so pernicious I’m not sure that solarization would work. Am still waiting for CR to test their hypothesis in an objective and scientific manner.]

Phragmites rhizome (Wikimedia)

So, Consumer Reports, I’d love to come back to you. But until you start applying your own standard of objective rigor to everything you cover, I’ll have to pass.

Go ahead, weed, make my day…

Ridding an ecosystem of invasive plants is never easy. We can bring in goats to munch on offending plants or force armies of schoolchildren into slavery to pull them out; but, in all likelihood the sneaky little devils (the invasive plants, not the schoolkids) will be re-sprouting and back with a vengeance before we can turn around. For many invasive plant infestations the most practical long-term solution is chemical control – in other words, herbicides. Of course, herbicides have their issues such as drift and potential impacts on non-target plants. And what do you do when you want to get rid of invasive plants in a remote, sensitive ecosystem with limited access? Enter Herbicide Ballistic Technology (HBT). The HBT system uses the same technology as a recreational paint-ball gun but instead of filling the projectiles with paint, the balls are filled with triclopyr, which is commonly used in homeowner products for brush and poison ivy control.
hbt

Dr. James Leary at the University of Hawaii has been exploring the use of HBT to control invasive plants in various ecosystems in Hawaii. Most of the time Dr. Leary and his colleague use the standard paintball HBT system, but for the big jobs they call in the heavy artillery – literally. Dr. Leary recently presented a seminar here at MSU on work he and his team have conducted in conjunction with the Maui Invasive Species commission to eliminate populations of Miconia calvacens, one of the most problematic invasive trees in Hawaii. According to the seminar abstract, Dr. Leary reports “Our best utility for HBT deployment on a Hughes 500D helicopter platform featuring real-time capabilities in target elimination. …we have conducted 17 tactical search and destroy mission covering a total net area of 3,888 ha and eliminating 7,463 Miconia targets.”

Targeting miconia from a helicopter. Photo: C. Duncan.
Targeting miconia from a helicopter. Photo: C. Duncan.

Clearly the war on invasive has been raised to a different level

Must we continue to bring in exotics?

A couple weeks back I posted about a collaborative research project that I am involved with to identify seed sources of two Mediterranean fir species (Turkish fir and Trojan fir) for use as Christmas trees in various locations around the country.   The post prompted a question from Monta Zengerle who asked, “Must we continue to bring in exotics to satisfy the nursery trade?”  Since our intended purpose is Christmas trees and people move plants around the world for purposes other than nursery stock, I’ve broadened the question to “Must we continue to bring in exotics?” for this discussion.


Not all exotic species introductions are man caused.  This dock washed ashore in Oregon following the Japanese tsunami carrying all kinds of critters with it.

The answer, of course, is “No.”  As human beings the only things we absolutely have to do are eat, sleep, and breathe.  But the reality is much of the food and fiber production around the world, as well as our amenity plantings, are based on exotics plants.  Human agricultural history is largely the story of plant importation and subsequent breeding.  As Thomas Jefferson famously observed, “The greatest service which can be rendered any country is to add a useful plant to its culture.”  However, it is doubtful that Jefferson considered kudzu or purple loosetrife could be among those plants added to our culture.  Today we have a different understanding and realize that along with the economic benefits of plant exploration and importation comes the possibility of unintended and serious ecological consequences.  And we’ve realized this for some time. People that deal with plant introductions on a regular basis talk about ecological errors and economic errors.  If we allow importation of a plant that later turns out to be ‘bad actor’, we’ve made an ecologically harmful decision; if we ban a useful plant that ultimately would have turned out to be non-invasive, we’ve suffered an economic loss.  Fortunately, only a small percentage of exotic species become naturalized and only small percentage of naturalized species become invasive.   The underlying challenge is we cannot predict with 100% certainty which plants will be invasive in a new environment and which won’t.  Ecologists are working on it and we can certainly begin to judge the invasive potential of new introductions.  In the meantime, we are left with the imperfect calculation of whether the potential economic upside outweighs any potential environmental risk.


‘Top-work’ on noble fir in Oregon to maintain a single terminal leader.  Turkish fir typically require less top-work.

So let’s look at our current project as a case study.  What’s the upside?  Christmas tree growers in the U.S. produce roughly 20 million trees annually.  That’s a potential economic impact of hundreds of millions of dollars and seasonal and full-time employment for workers on over 13,000 farms from North Carolina to Washington State.  A major issue for growers in virtually all of the principle growing regions is phytophthora root rot.  Previous work at Oregon State University indicates that Turkish fir is highly resistant to this pathogen.  By identifying seed sources with phytophthora resistance and superior Christmas tree characteristics (tree form, needle color, post-harvest needle retention), we will enable growers to continue or expand production and give consumers an additional choice for their holiday tree.


Native noble fir (left) is highly susceptible to root rot. Turkish fir (right) is much more resistant.

What’s the down side?  As I mentioned, predicting invasiveness is difficult.  That said, firs have several characteristics that make them unlikely invaders.  Most firs have a relatively long juvenility period (age before they produce seed) which means they have a long period between generations.  Secondly, most fir species produce seed crops sporadically as opposed to producing heavy seed crops year after year.  Ecologically, firs are pretty wim
py; growing best on moisture, well-drained sites and unlikely to aggressively colonize disturbed areas.  Lastly, the best predictor of invasiveness is invasiveness – a plant that has become invasive in one location is a candidate to become a repeat offender in a similar environment.  Among conifers, the greatest issues with invasives have been pines (genus Pinus), in the southern hemisphere.  In fact, all of the documented cases of invasives in the pine family (Pinaceae) are Pinus species; none were Abies.  Based on all this, the likelihood of Turkish fir or Trojan fir becoming ecological problems appears very small, while the potential to add a useful plant to our culture is clear.

Exotic giant sequoias at Hoyt arboretum, Portland, OR.

Richardson, D.M. and Rejmánek. 2004. Conifers as invasive aliens: a global survey and predictive framework. Diversity and Distributions 10:321-331.

Helium Makes Kudzu Float Away

As promised — some happy news:  There’s this kid in Valdosta, GA (close to Tifton where I spent a few years as a graduate assistant), who has been experimenting with ways to kill kudzu.  Here’s the video.

To see this kid work on something like this at such a young age is fantastic and gives me hope for the future.  I wish the kid were here so he could come to the University of Minnesota – I think he has a lot to offer and he makes me slightly more optimistic about where horticulture ends up.

For those of you who choose not to view the video, what this kid does is to inject helium into the soil around the root system of a kudzu plant.  After the injection the plant apparently dies.  The exact reason why isn’t known, but one person who was interviewed said he suspected that the helium smothers the plants roots thus killing it.

I’m a little bit suspicious about that explanation, and I’m also a little bit skeptical about how much more economically feasible it would be to use the helium instead of more standard herbicides.  I’m also very interested in any other gasses that he might have tried to kill the kudzu – I wonder, for example, if he tried propane?  It might work, but I’d say it was too dangerous to try.

I’m suspicious about the helium smothering the root system of kudzu because kudzu has such an extensive root system and because the helium should dissipate pretty quickly, especially in sandy soils like they have in Southern Georgia.   It’s also very unlikely that the helium itself is acting as a poison because helium is an inert gas.  It just doesn’t react with anything.  What I think is more likely is that, by finding the site where the kudzu’s stem enters the ground, this kid has found a “weak spot” on the kudzu which is susceptible to damage.  Then I think that the helium acts a refrigerant when it is released and actually freezes the stem of the kudzu.  However it works though, it’s a neat trick!

New Year’s Prediction: Invasive Fire Continues to Burn

Happy New Year!  I hope everyone had restful and enjoyable holidays.  In addition to looking back over the year that just past, a common New Year’s tradition is to make predictions for the coming year.  Without going too far out on a limb, one of my predictions for the upcoming year is that the debate over invasive plants will continue to intensify, especially as it relates to Landscape Horticulture.  Along these lines, a couple of recent articles by Gregorio Gavier-Pizarro and his colleagues at the University of Wisconsin and the USDA Forest Service caught my eye.

 

In both studies; “Housing is positively associated with invasive exotic plant species richness in New England, USA” (Ecological Applications 20:7, 1913-1925) and “Rural housing is related to plant invasions in forests of southern Wisconsin, USA” (Landscape Ecology 25:10, 1505-1518), the investigators conducted on-ground assessments of species richness and density of commonly listed invasive plants  (e.g., Japanese barberry, Autumn olive, Honeysuckle, Common buckthorn, Multiflora rose) in conjunction with spatial analysis of remote sensing data to examine patterns of invasive spread in the urban/wildland interface.  As one would expect, the presence and species richness of the invasives increased with development.  An important ‘take home’ message, however, is that disturbance associated with rural housing development and the creation of edges appears to be the biggest driver of invasive species encroachment.  That is, land clearing, road-building and other development activities create habitats that are more susceptible colonization – a condition referred to as ‘invasibility’.  So whether a particular homeowner plants natives or non-invasive exotics they may still contribute to the expansion of invasive exotic plants in their region by increasing its invisibility.

 

The other thing that makes this work and related studies significant is that I think we will see a continued shift in the efforts to curtail the expansion of invasive exotic plants.  In particular, rural housing development and associated landscape practices will become and increasingly intense front-line in the invasive battle.

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When history and good stewardship collide

One of my colleagues emailed me a couple of pictures last week taken in Puyallup, WA.  As you can see, there’s a trellis supporting a massive old trunk…

…and crown…

of an ancient Hedera helix ‘Baltica,’ a cultivar of English ivy.

For those of you not in Washington or Oregon state, English ivy is a designated noxious weed.  Thousands of dollars and hours of labor are spent on removing this species from forested areas in Washington state, where it crowds out native species and increases tree failure simply through the weight of vegetation.  It is not a well-mannered ornamental in our climate.

So why, you may ask, is this particular English ivy prominently displayed and obviously cultivated?  Chris Pfeiffer (my colleague) found out that it had been planted by Mrs. Ezra Meeker, wife of the founder of Puyallup, over 140 years ago at their original homestead.  It is part of Puyallup’s cultural history and is considered a heritage “tree.”

But as you can see in the second photograph, the ivy is in flower and presumably will set seeds, thus contributing to the invasive problem.  I don’t know enough about the City’s management plan for this specimen, but I doubt it includes removal of the flowers before seed set.

So what should communities do in situations like this?  I think the city needs to remove the flowers, though this would be a labor intensive activity.  But it would only take one person a few hours to hand prune the flowers.

I’ll be curious to hear what you all think, and whether you have seen similar collisions between historical significance and appropriate plant choices.

How to Kill Buckthorn

Last year we completed a small research study on how to kill buckthorn.  If you live in the upper Midwest then you’re familiar with this plant as a shrub which has escaped cultivation, been spread by birds, and generally made a nuisance of itself, particularly at the edges of forested land.

Buckthorn is notoriously difficult to kill after it gets more than about a foot high.  It laughs at single applications of roundup. If it’s pulled out of the ground any roots that don’t come with it have a good chance of sprouting shoots themselves, and it seems to enjoy being treated with organic herbicides like vinegar.  So, to try and kill bucktorn, we used an herbicide which had the active ingredient triclopyr.  This is an active ingredient which is usually great against all manner of weedy vines like poison ivy.  This herbicide is labeled for homeowner use and is available in most garden centers.

We applied this herbicide to buckthorn in the spring, summer and fall, and we used a few different application methods including painting the herbicide onto cut stumps and spraying it onto the leaves of uncut bushes, as well as painting the product onto the lower portion of stems.  Some of these application methods were experimental.  Do not attempt to apply an herbicide in any way besides that which is listed on the label!

That said, we found that the fall was by far the best time to apply the herbicide and that spraying the foliage wasn’t nearly as effective as other application methods, particularly painting the cut stem with the product after cutting it down.