Bridging research and reality

This summer, I’ll be giving a seminar on “Arboriculture Myths” at the ISA conference in Portland, OR. I’ve been quizzing arborist-types for a few months now to find out what myths they would most like to see debunked during my talk. Intermixed with the suggestions of dubious products and questionable practices there was this question: “How often do the results from research with limited scope get over-extrapolated?”

I like the question a lot, because this is the fine line that we Garden Professors walk in bringing you the newest scientific information we can find.  As a rule, I tend to hold back on recommending anything that has only been tested in a lab situation.  I like to see field test results, where environmental variation will quickly swamp anything with marginal effects.  In other words, if something can make it through an experimental, replicated field test, I can get excited about it.

Which brings me to a recent article in Arboriculture and Urban Forestry (2012, Vol. 38, Issue 1, pp. 18-23. And no, I can’t post it on the web). Briefly, the article describes an experiment where water evaporation was measured in pots filled with various substrates, which were either left uncovered or mulched with about 3” of pine bark.  The results showed little difference between the mulched and unmulched containers.

As the authors point out in the discussion, it’s an artificial system that includes no trees, nor any way for water to move through the soil except from the top down.  And I really don’t have a problem with the methodology, or the data generated, or even most of the discussion. What bothers me is a single sentence at the end of the abstract:

“Given the minor reduction in evaporation, and reported disadvantages of mulch application close to the trunk, landscape managers might consider changing mulch application practices for newly planted trees.”

Wow. How did we get from a series of containers with no plants in them to this recommendation?

Every gardener knows the value of mulching – a perception that’s substantiated by hundreds of publications. Since I’ve written about mulches on the blog a number of times I’m not going to belabor the point. But I will refer readers to a short Ecological Restoration article I published a few years ago that most definitively linked mulch application to plant survival in restoration sites; Bert also published an article on the benefits of mulching and lent me a few photos to illustrate. And Jeff has even more data on the topic, including some that may radically change the perception that mulch against tree trunks is a bad thing.

Mulch increases soil moisture


Which plot would you rather have in your garden?

Those of you who read scientific journals probably read the abstract first – I know I do. If it interests me, I’ll read the entire article. But sometimes the abstract is the only thing you can find online. And for this reason, the peer-review process in many of the journals asks whether the contents of the abstract are justified by the results. Honestly, I don’t think this article meets that standard.

Does anyone really know how to handle weather?

Lots of people around the country seemed to take perverse pleasure in the snow and ice storm that paralyzed much of the Pacific Northwest recently.  From Boulder to Boston, northern residents that deal with snowstorms on a regular basis chortled at video clips of cars and buses slip-sliding away in western Washington.  Perhaps it’s just the Northwesterner in me getting a little defensive, but I’ve never understood why people feel the need to gloat over other people’s inability to cope with weather.  At the end of the day we’re all in the same boat.

I’ve lived in the Northwest, the Plains, the South and the Midwest.  And guess what?  Nobody can handle weather they’re not used to or equipped for.  On NPR the other day I heard a former Chicago resident now living in Seattle bragging how his former city dealt with snow and couldn’t understand why everyone was making such a big deal about a little snow.  I used to live in Georgia and people there were similarly perplexed when a few days of 100 degree heat killed hundreds of people in Chicago.  Likewise, I can remember my amazement shortly after I moved to Michigan and saw a scroll at the bottom of the morning TV news announcing 2-hour school delays for fog.  I’d never heard of such a thing.  If we had fog delays in Olympia, we’d have started half our school days at 10:30.

On the eve of the recent Northwest snowstorm I saw an interview on the Weather Channel with Seattle’s transportation manager, who said they had 30 snow plows standing by.  Custer had better odds.  To put things in perspective it would be like the city of Lansing having 6 plows (it has more than 60).  Seattle and western Washington are not equipped for snow, nor does it make any financial sense for them to do so.  Just like it doesn’t make sense for everyone in the Midwest to have central air or to equip every Michigan school bus with fog lamps.  Just remember, when you get ready to gloat over someone else’s weather misfortune, Mother Nature will always have the last laugh. 

New weekend feature: “what I learned from my garden”

While in Connecticut a few weeks ago I met Henry Young (a former horticulture extension agent), who did a guest post on the blog this past week about the important of “negative” results.  He also had another interesting idea for the blog that I’m going to initiate this weekend – the “What I learned from my garden” feature.

I did one of these back in July of 2010, when I worked water into a clay loam soil the same way you might work it into potting mix – with disastrous results.  So to kick off our new weekend feature, here’s another story from my “oops” collection:

Nearly every place we’ve lived we’ve had a wisteria vine – carefully trained and maintained so it wouldn’t get under the shingles and other places it wasn’t welcome.  In Buffalo, we had a second-story open porch off our bedroom with decorative iron fencework around the edge.  How lovely it would be if we planted a wisteria below and trained it along the fence, so that we’d have purple clusters dripping from the black ironwork in the spring!

We got the vine planted and it quickly reached the second story, twining its way around the fencework.  All we did was keep the wild hairs pruned off and waited eagerly for the floral show.

Well, it never bloomed in the four years we had left in that house.  But it did grow vigorously.  The slender vines thickened into bloated things that grasped and pulled at the fencework, pulling it off-kilter in its eagerness to take over the south side of our house.  The fence and the wisteria were becoming one.

Fortunately, we moved before I had to take an ax to the thing, and to this day I have no idea what the new owners did with that unholy alliance of metal and plant.

We learned – our current wisteria is restricted to a sturdy wooden trellis that laughs at its attempts of herbal domination.  But it still hasn’t bloomed…I assume it’s sulking.

Wisteria on the right, along with indestructible trellils

This feature will succeed if YOU contribute!  Send me your stories, with photos if possible, and I’ll post them on weekends.  We’ll all laugh and learn together.

There are papers out there on almost everything!

It amazes me how much information is out there if you really look for it.  This morning I was having a discussion with a couple of friends about how and why asparagus affects the odor of urine (I might or might not be able to let you know why next week — after my administrators decide how much potty humor they’ll let me get away with).  Anyway, I decided to see what I could actually find out about it and found a remarkable number of papers on the topic including this recent one on odor perception.  In a nutshell it says that there are actually differences in the way we produce and smell that characteristic scent that asparagus gives urine.  The introduction is quite interesting — I even pulled this nugget out “Proust wrote more favorably that asparagus “as in a Shakespeare fairy-story transforms my chamber-pot into a flask of perfume” “.  Hmmmm.  Participants in the study had to smell other peoples urine to grade its odor level.  In fact, here’s another quote from the article:  “Some subjects were unable to complete some parts of the testing. For instance, some people could not complete the smelling phase because of unanticipated aversions to urine.” Interesting.  These people had, presumably, been around urine all their life.  Probably even produced some themselves.  How could they not know they were averse to it till now?

Here’s what I want to know:  Is there a market for asparagus that doesn’t result in the odor, and, if so, is it even possible to breed this trait out or is the flavor of asparagus intimately tied to this mildly unpleasant side-effect?  Now there’s a problem for a breeder!

The new Hardiness map’s here! The new Hardiness map’s here!

I probably shouldn’t admit this but one of my all-time favorite movies is Steve Martin’s classic “The Jerk”.  Part of the appeal is that I have an affinity for low-brow humor in general but also because the movie contains some great lines; “I was born a poor black child”, and the classic scene when Martin’s character finds his name in the phonebook for the first time and runs around yelling, “The new phonebook’s here! The new phonebook’s here!”

I wasn’t quite as excited as Navin R. Johnson today, but pretty darn close.  The reason? The USDA (finally) released a new hardiness zone map for the US.
Why is this exciting news?  Well, for several reasons.  The earlier version of the USDA map was released 1990.  The 22-year-old map had several limitations.  First, it was 22 years old.  Secondly, the versions of the map that were available electronically did not reproduce well and had poor resolution when you tried to zoom in on a particular area.  This sometimes made it difficult to identify the hardiness zone for certain locations and limited the utility of the map for presentations and publications. 

There have been persistent rumors for last 6 or 7 years that the USDA would release a better, updated map.  In addition to the shortcomings of the old map in terms of resolution, many felt the map didn’t accurately reflect more recent climatic conditions.  In 2006 the National Arbor Day Foundation released an updated hardiness map using more current climatic data.  This map indicated that many locations were 1 or even 2 hardiness zones warmer than the 1990 USDA map.  In addition, the Arbor Day map was available as a hi-res TIF file suitable for PowerPoint presentations and had a ‘zone-finder’ feature based on zip codes.

I haven’t had a lot of time to work with the new USDA map, but my initial reaction is a thumb’s up.  Like the Arbor Day map, the new USDA map has a zone finder based on zip code that makes it easy to find the zone in your area. The map is interactive, allowing users to zoom in or out.  As with MapQuest and other on-line maps we’ve grown accustomed to, it allows the user to select a roadmap or satellite background and choose different levels of transparency or opacity.

Whenever I discuss hardiness zones, I always include the caveat that these maps are based on average annual minimum temperatures.  That is, they are based low temperatures we are likely to see in an average year.  Not sure about where you live, but I have yet to see an average year in my adult life.  There are many years when we will get below our USDA hardiness zone temperature.  Human nature says we want what we can’t have and gardeners love to push the boundaries of their hardiness zone – people in zone 4 love to grow zone 5 plants; people in zone 5 love to grow zone 6 and so on.  Just because the new map may say you’re a zone warmer; your climate hasn’t changed, the map is just based on better and more recent data.

A plea for published “negative results”

Last week I was in Connecticut speaking to the Connecticut Tree Protective Assocation.  It was a great chance to meet arborists on the east coast, and especially heartening to meet yet another group of professionals who demand good science-based information to guide their practices.

After this meeting, I had a thoughtful email from one of the attendees regarding the lack of "negative results" publications in the scientific literature.  It’s a message that’s important for academics as well as the gardening public.  Here’s Henry’s email:

"Thank you for the comments and presentations you delivered on Thursday, January 19. I hope you had a pleasant and less difficult return journey from Connecticut.

"One point that you mentioned bears emphasis and enlargement although you got it right the first time. Specifically, you mentioned one anecdote that has additional implications, the researcher friend who was reluctant to publish findings that disappointed her because they did not bear out her original conclusions, i.e., the feeling of disappointment and the chagrin to have missed one’s own best guess. These are natural feelings and you are not the first in my experience to notice this very human inclination in scientific researchers. There is a rush to publish meaningful results, but the negative findings tend to pile up in the stack of unpublished material.

"The root of this matter, it seems, lies in the unwritten assumption that science is the means by which we discern and expose the truth. Certainly that’s what is hoped since it could lead to recognition and prestige.

"In fact, it is just as useful, if not more useful, to disclose that which is not true. The beneficiary is science itself and not the individual. Systematically done, this will eventually result in the elimination of errors of fact or judgment and prevent the repetition of similar investigations that for similar reasons might remain unpublished. Viewed in this manner, a failure is as valuable as a success and therefore just as deserving of publication as the most insightful of findings. Failures often precede success.

"Thanks again for your informative presentation. As a former horticultural extension agent, I understand just where you are coming from."

Henry A. F. Young, President
Young Environmental Sciences, Inc.

Black is the new…black?

Dark foliage and flowers have been popular for quite a while.  Heck, an entire book (Paul Bonine, Timber Press) features the darkest of the dark.

Of course, "black" is a bit subjective.  Dark purple, dark brown, dark green.  But dark is hot; plant breeders and marketers know it. Here’s a few things that have come out within the past couple of years…

Ball Horticulture’s new patented petunia ‘Black Velvet’ is all over the place, along with its cousins, Phantom and Pinstripe.

Bench card from Ball for use in garden centers.  Odd choice of editorial photo for the "little black dress."  Petunia’s cute enough, though.

Centaurea montana ‘Black Sprite’ is a new perennial from Sunny Border Nursery (marketed by Skagit Gardens). You may be familiar with the blue version (Knapweed, Mountain Bluets). I am, because it reseeds all over my stinkin’ garden.  Maybe this one is better behaved.

I snapped this at the OFA Floriculture trade show in July.  Love the black outline on the bud "scales."

A new ornamental eggplant certainly falls under the "black" category.  This super-cute guy was in the "new plants" display at OFA also, but some dork had snatched the tag from the display. Let me know if you recognize it…

Meeestery eggplant has nice flowers and foliage, too. Until the flea beetles come.

There are so many wonderful ornamental peppers out there – all easy to grow from seed.  Most are pretty hot (pop a ‘Black Pearl’ some time for a thrill). From the U.K. breeding company Vegetalis comes the F1 hybrid pepper ‘Chenzo’.

 Like ‘Black Pearl’, the fruit change from black to deep red as they ripen. It’s also hot as blue blazes, with a Scoville rating of 45,000 shu.