Canadian Thistle

It has been a busy few weeks for me — holiday traveling, Green Expo talks (that’s our regional conference), and getting ready for a semester leave this year — I’ll be working on a project investigating how professors transfer information to the public.  But during this time I have, for some unexplainable reason, been thinking about Canadian Thistle.  And do you know what I’ve come up with?  This: 

It’s a colossal waste of time and money to worry about Canadian thistle. 

Despite its name Canadian thistle is not native to North America.  It was introduced in the 1600s — probably by accident.  Most parts of the plant are edible and some people even say that it’s tasty.   Though it can be found across the US it is rarely found in such high concentrations that it displaces native species.  Where it does dominate the landscape conditions are usually bad enough (highly disturbed sites) that other plants won’t fare well anyway.  Canadian thistle is known as an early succession plant which means that it will establish in a disturbed site — perhaps even taking it over — but will slowly, over years, be taken over by other plants.

Canadian thistle is considered a noxious weed across the United States, but it is classified that way mostly because of political pressure rather that for what it does (if nothing else it is a very visible, nasty looking plant).  People may get scratched up, but you won’t hear about anyone dying from Canadian thistle poisoning.  As an agricultural weed it can be significant, but usually pales in comparison to other weeds.  Because it is listed as a noxious weed some states and local governments have tried to rein it in, at least over small areas, but this thistle is very resistant to herbicides, and tough to kill just by pulling, and so efforts are often fruitless. 

Should we redouble our efforts and assail this thistle with more energy?  I just can’t bring myself to say yes.  This weed may be undesirable, but to put much money into a losing battle with a weed that has been here for about 400 years and that mostly affects disturbed sites seems like a silly strategy.  In my mind we should be treating this weed as undesirable, but not nearly at the same level as other invasive or noxious plants.</d

A selection of GP posts from 2011 (part 2)

So much good stuff to read back through. The Garden Professors really bring the straight poop on so many topics!


Post:  Podcasts are here! by Linda.

Complete with a pleasant musical intro and background, Linda’s info-packed and professionally-produced podcast “The Informed Gardener” made the rest of us look under-achieving. Take some time this winter and work back through them, if you haven’t had a chance.


Post: Sunday Bloody Sunday by Jeff.

I’m one of those “let me tell you what stupid thing I did yesterday” people, and I really appreciate it when other folks ‘fess up to messing up in an effort to keep you from doing the same. Jeff used a 20% vinegar solution to kill some garden weeds, and ends up killing a little froggy in the process.  He even posts a photo of the wee corpse.  So is “natural” always better?  This post really makes the point of “apparently not”.  


Lots of great posts – Linda’s post and photos of the Bartlett Tree Expert’s research arboretum was fascinating.  I keep meaning to check it out when passing through Charlotte NC. As happens here on occasion, a commenter took exception, this time to photos and descriptions of the research trials; suggesting she was endorsing Bartlett’s entire corporate philosophy/menu of services etc. Lots of back-and-forth ensued. Drama on the GP!

Bert went to a LOT of trouble to get our reader’s input in selecting an upcoming post-transplant tree experiment – Be a Part of History post. Bert notes “Of course, as with any major research project, the first step in the rigorous scientific process is to come up with catchy acronym for the study.  I propose ‘the SOcial MEdia DEsigneD TRansplant ExpErimental Study’ or SOME-DED-TREES for short.”    I have since stolen this idea for my own research (I KNEW something was missing). Good ideas flowed forth from our commenters. 

Bert then set up a survey in October “Vote Early and Often”, the results of which are posted as “The People Have Spoken.


Also in October was the hilarious “Amazing Water Slices” post by Linda.  This was an easy one for her, because, the hilarity was (unintentionally) supplied by quotes and photos from the actual sales information on this purported “best new garden product of 2011”.


I’ll just file this under “live and learn” in regards to blogging.  I believe I failed in stating the importance (“So we’ll just guess from now on…”) of the decision by the USDA/NASS to eliminate several Agriculture survey programs that provide annual reports on the economic impacts of various crops/commodities/sectors. If you really think a fiscal report that states the importance of a particular crop is just B.S. government interference (though most of eliminated crops/sectors are small-farm related), please re-read the “why I care” part.   However…if you WERE concerned and just didn’t say so in the post comments, you’ll be relieved to know several programs were reinstated within 30 days (a big hubbub was apparently raised) including three dear to my heart, the Floriculture report, the Bee and Honey report, and the annual Hops Production report. Note to self: do not mention The Government ever again in a blog post.


Bert’s “Another victory for the politics of destruction” post was clear, concise, non-partisan, and well done.  Unfortunately, he mentioned The Government. Nutshell: a grower-initiated, Christmas tree marketing check-off effort was framed as “Obama’s Christmas Tree Tax” to the point the program was pulled.  I had thought about posting on this very topic, but Bert beat me to it and as someone who actually works with Christmas Tree Growers, he was much more knowledgeable.  Plus he got to enjoy the anti-you-name-it comments (which he responded to very graciously)

Final thoughts regarding 2011…this blog is an old-fashioned, goodness-of-our-heart effort to bring you topics we think are important, provide some entertainment with factoids buried within, untwist our knickers, and generally try to be thought-provoking and/or helpful. Linda has done a terrific job hosting it and riding herd on the rest of us.

Does every post ooze wisdom and revelation? No. But lots of them do, complete with NO annoying advertising.  I noticed a trend reading back through 2011 – many of our “regular” commenters ceased commenting (though several still do – thank you!). The number of posts in 2011 with one or zero comments was greater than in 2010. It’s a challenge to take the time and effort to post something, and then…*crickets.*  I do understand how interest in a particular blog waxes and wanes. There are about one million gardening blogs (only slightly fewer than foodie blogs) vying for your attention; some of you may just be blogged out.  

Hate "Weird Plant Wednesdays"? Want more arguments on root washing? Can’t get enough mulch, compost tea, or Christmas trees? Need more feedback on your feedback? Please take this opportunity to tell us what you think at Linda’s survey. And thank you for your patronage.


Want healthier babies? Plant trees!

NOTE: Linda and I switched places this week so we could get the Garden Professors survey up on Monday – See Linda’s post for the link – please take a minute to give us your feedback!

I recently received a copy of a newsletter from the USDA Forest Service Pacific Northwest Research Station that included a summary of an article recently co-authored by one of the Station’s scientists on the effect of urban tree cover on pregnancy outcomes of new mothers in Portland, OR

According to the summary, researcher Geoffrey Donovan and his colleagues found that babies born to pregnant mothers who lived in neighborhoods with high amounts of tree cover were more likely to have higher birth weights than babies born to mothers living in areas with less tree cover.  Of course, being a skeptical (cynical?) Garden Professor my first reaction was, “Well, duh…expectant mothers that live in areas with more tree cover are probably living in better neighborhoods, are wealthier, better educated, and have lots of other things going for them that we typically associate with better pregnancy outcomes.” 

The summary put out in the PNW Station newsletter was scant on these details so I went on-line and dug out the original paper (citation below).  As I suspected the authors noted that, “Women with greater access to urban trees were more likely to be non-Hispanic white, younger, have fewer previous births, and live in newer, more expensive houses closer to private open space compared to women with less access to urban trees.”  However, they were able to account for these effects in their statistical analysis and still found that birth weight increased with the amount of tree cover near the mothers’ homes.

As we’ve all heard many times, correlation is not causation and it is unclear exactly how tree cover improves pregnancy outcomes.  One of the most likely explanations for the tree cover effect is that having more trees around reduces stress levels, resulting in better birth outcomes.  Trees can also reduce noise and other forms of pollution as well.  Regardless of the mechanism, this study may provide one more bit of ammunition for urban forestry advocates that go to battle for trees in our cities.

Donovan, G.H.; Michael, Y.L.; Butry, D.T.;Sullivan, A.D.; Chase, J.M. 2011. Urban trees and the risk of poor birth outcomes. Health & Place. 17(1): 390–393.

PS: Don’t forget to take our survey!


Happy New Year…and our request to our readers

It’s that time of the year again…annual reports are due to our respective administrations. One thing all of us need to document is impact on our various audiences. So we’ve created a short (10 question) survey to collect your feedback. The questions are mostly multiple choice and a bare-bones response will take you maybe a minute. Of course we’d love as much detail as you care to provide, so don’t feel obligated to speed through!

We’ll keep the survey open for the month of January, but your responses are more likely to be used if you get them in quickly. (For me, that means next Monday. January 9. One short week.)

Thanks in advance – and we look forward to another year of being your Garden Professors!

(If you didn’t see the hot link to the survey in the text, here it is again: