The Garden Professors™

Rotenone is an organic insecticide that has been voluntarily withdrawn by its manufacturer because it’s quite toxic, it’s dangerous to the environment, and there is some evidence that it causes Parkinson’s disease.  And there are safer choices.  For my post today I was thinking of posting about all of the places I could still buy rotenone, but after doing a web search I couldn’t find many – and most of the places I found to purchase it don’t really have it (I don’t think) – they’re just old pages that weren’t taken down.

But in my string of results I kept getting this one weird hit – something called Goodwinol ointment for dogs.  So I looked into it, and sure enough, there’s an ointment you can buy for your dog that contains    1.25 % Rotenone.  It’s supposed to be for mange, but no prescription is necessary, so anyone could buy it.  To me this is a little concerning.  Rotenone is some nasty stuff, 1.25% is a relatively large dose, and I’m not sure that most people using it would be careful to use gloves.  So I’m wondering, should this stuff really be out there?   

Despite Linda’s assertion to the contrary, I was not cow-tipping nor was I sampling micro-brews last week when I missed my regular post.  As usual, the beginning of spring is a busy time on the research side of my appointment.  This past week we began setting up for a major new project.  The goal of our newest study is to look at physiological traits of street trees that may enable them to better withstand future climate change. 

If you think about it, trees that are planted today may experience future climates in their lifetimes that will be different than the climates under which they were selected.  So how do we ensure that trees that are planted today can withstand a potentially different environment in 50 or 75 years?  It’s a very complex question.  An easy response would be to plant species or seed sources that have evolved in warmer, southern locations.  The problem is climate change is predicted to occur gradually so southern trees moved northward today will be subject to increased frost and freeze damage in the interim.

Grad student Dana Ellison (L) and undergrad research aide Aniko Gaal (R) pot up shade tree liners for a new project.

Another approach, and the one we are investigating, is that trees that are best suited for the future may be those that have a high degree of phenotypic plasticity.  What is phenotypic plasticity?  Simply stated is the relative ability of a species or genotype to acclimate to changes in their environment.  In our case we are going to look at the photosynthetic response of a range of street tree cultivars in order to identify their optimum temperature for photosynthesis or Topt.  But we know from other studies that Topt can vary depending on the environment to which trees are acclimated.  So we will acclimate our trees to a range of temperatures in a greenhouse study and determine which species or cultivars are best able adjust their physiology to changing environmental conditions.  In addition to the greenhouse study we will out-plant trees from the same cultivars in a parallel field study with the Greening of Detroit.  Working with the Greening we will identify sites around Detroit with contrasting temperature regimes and plant trees at these locations.  We will follow up with a similar suite of measurements as our greenhouse trial.

Will one study tell us everything we need to know about selecting street trees for a changing climate?  Of course not.  But it provides some important base line information and insights on approaching the problem.  Trees in urban and community forests are already operating at the margins and subject to myriad of stresses.  The argument can be made that urban ecosystems are among those most at risk under climate change.  Trees are an important component of many climate change mitigation strategies but they must be able to survive and grow in order to contribute this function.

The study “Urban tree selection in a changing climate” is funded by Michigan State University Project GREEEN, with material and in-kind support from J. Frank Schmidt and Sons Nursery, Nursery Supplies, Inc., Renewed Earth, Inc., and the Greening of Detroit.

I like to say that my taste in music is eclectic, but it’s not really true.  I like music that is known as classic rock (60s – 80s rock once known as pop) and I like music known as "alternative" (really a meaningless term — but I don’t invent the labels).  The one band that I love who might be considered completely out of the mainstream is Rasputina — a cello based group who sing about many things, including history.  1816 in particular.  Listen, it’s a history (and meteorology) lesson in a song.

So, that said, In 1816 there were freezes in every month of the year across much of the Northern part of the US.  Leaves were frozen off trees almost as they formed — and yet, unless trees were small and/or weak, they lived to see 1817 (also a tough year), and beyond.  Sure, fruit production was way down, but trees are prepared for tough conditions — they store plenty of carbohydrates to protect themselves against that very thing occurring.  So, if anyone asks what’s going to happen to our trees if they flush out early (which they are doing) and then there are some late frosts, just point to 1816.  Or, better yet, let them listen to the song.  

A few weeks ago I posted on the disappointing inclusion of compost tea in the APLD’s Guide to Sustainable Soils.  Included in my discussion of the issue was the suggestion that people involved in writing the guide also benefited financially from compost tea applications.  This led to some very honest and constructive emails between me and the APLD’s national leadership, which resulted in educating both parties.

Here’s what I found from the APLD’s President Susan Olinger and Sustainability Chair Toni Bailey:  “As members of the Board of Directors of APLD, we can verify that there was no financial motive behind the inclusion of compost tea by the volunteers that wrote the soils guide.”  This is heartening and makes me feel less cynical about the motives behind including compost tea in the publication.

And here’s what I was able to impart to the leadership of APLD:  that while landscape designers may like to include compost tea as a soil amendment, the belief in its efficacy in improving soil tilth or biology is not supported by legitimate science.  It’s not a matter of sides, or opinions, but a matter of scientific evidence.

If the APLD doesn’t intend its guide to be a scientifically supported document, that’s certainly fine; landscape designers aren’t scientists, after all.  But since good soil science-based information is found throughout most of the guide, the inclusion of compost tea and mycorrhizal inoculants could easily be interpreted by others as science-based as well.