The Garden Professors™

It’s been a busy spring around the Cregg lab.  In many ways, it feels more like mid-summer than mid-May.  One of the items my students and I have been with is installation of the Social Media Designed Tree Transplant Study (SoMeDedTreeS).  As loyal Garden Professor blog readers will recall, we conducted a Survey Monkey poll last fall to help develop a study plan to investigate tree transplanting practices of container-grown trees.  Based on the results of the survey we designed a study to look the effects of root-ball manipulation and post-transplant fertilization on 96 planetrees.  

Well, the time has arrived.  Last week we completed the first of two installations of the study – the second will be installed at the MSU Beaumont nursery soon.  Graduate research assistant Dana Ellison and summer research intern Aniko Gaal finished planting the first 48 trees last week at the MSU Hort Farm.  These two did yeoman’s (yeowoman’s?) work in handling the trees, applying the treatments and getting in the trees in the ground.  

Sometimes the best man for the job is a woman…

All of the trees are ‘Bloodgood’ planetrees that we have grown on in 25 gal. containers for past two years. The study was installed as a 3 x 2 factorial in a complete block design.  We have 3 root-ball manipulations: “shaving” the outer 1 in. of the rootball to remove circling roots; “teasing” apart the outer part of the rootball to pull appear circling roots; and “control” just pop off the container and drop ‘em in the hole.  The second part of the design is fertilization; with or without.  This results in 6 combinations (3 root-ball manipulations x 2 fert levels) times 8 reps = 48 trees total. 

Graduate Research Assistant Dana Ellison teases apart a root-ball

Summer Intern Aniko Gaal shaves a root-ball. Step one: remove the ‘pancake’ of roots  from the bottom.

Not to complicate life too much but I am considering a change to the protocol.  We will continue with the original rootball manipulation and fertilization trial at the second installation at Beaumont nursery.  In each test we would have 48 trees and 8 reps, which is better than a lot of landscape tree studies.   But given our recent discussion about mulching, I propose substituting with a mulch vs. without mulch treatment instead of the fert vs no fert at the Hort Farm installation.  We will water the trees once or twice a week to help get them established and then cut off the irrigation after about a month (simulating a city forestry department getting a budget cut and having to lay-off its temporary crews).  We will monitor soil moisture and tree water status in the subsequent months.   

Trees after planting

Before I make the change in the study, however, I’d like to get some feedback from our readers lest anyone feel there’s been a bait and switch.

OK, here’s a question for you.  How much would you pay for an online course taught by professors (perhaps garden professors?) about plants and gardening including things like fertilizers, pest control, etc.?

Hour long lectures once a week (through Skype or something similar) with an additional 1/2 hour built in for questions?  12 weeks of lectures.  No college credit.

I haven’t talked to the other garden professors about it — this is purely a hypothetical question for now.  I’m just wondering if there is interest in this kind of thing, and if so, how much. 

Thanks for your responses!

I’ve had an on-going discussion – OK, argument – with a fellow faculty member who does research on social dimensions of forestry, including urban forestry.  She contends that we basically know everything we need to know about growing trees in cities and that the real underlying problems in urban and community forestry these days are social issues.  This, of course, means that funding for urban forestry research, what little there is, should be directed at social sciences.  Needless to say, as a tree physiologist, I can point to lots of examples of trees in cities in pitiful conditions and under stress.  To which, my colleague would hasten to ask, “Is it because the urban forester (if the city can afford one) doesn’t know any better or because they don’t have the resources to do anything about it?”  Which is a valid point.  Most of the urban and community foresters I know are dedicated, well-educated, highly professional, and woefully under-staffed.  The Greening of Detroit, a community-based urban forestry non-profit, got its start several years ago because the city could not afford a tree planting program.  The city forestry department dedicated its meager resources to tree trimming; going into triage mode on a 125-year back-log of tree maintenance.  Why would a city plant trees when it can’t even care for the ones it has?

What got me thinking about this was a New York Times article on a rash of tree grate thefts in the city. http://cityroom.blogs.nytimes.com/2012/05/10/if-its-made-of-metal-thieves-increasingly-have-an-eye-for-it/  With the rising price of metal such as iron and copper, thieves are making off with just about anything made of metal including tree grates and man-hole covers.  We can probably start a whole other debate about tree grates and tree pits and whether they are effective, but, in any event, the city forestry department will now have to devote resources to replacing the stolen tree grates and figuring out ways to keep the replacements from disappearing as well.  

I’m not ready to concede that we know everything we need to know about growing trees, but the longer I’m at it, the more I see the need to integrate the biological and the social elements.  We can develop the best tree establishment and tree care protocols in the world but if there no money or no public support to implement them, it’s all for naught.

I’m not going to sugar coat it – I’ve been too cavalier in recommending iron phosphate for slugs and snails. 

A few days ago Erin Harris put a comment in my post about dandelions asking whether those iron phosphate baits you can buy for slugs might also be toxic to earthworms.  The answer is yes – they might.  And not only that, these iron phosphate baits can also be toxic to other animals such as dogs.

How bad might these products be for dogs and earthworms you ask?  I don’t think anyone knows exactly, but to my knowledge this is the most recent paper on the subject.  And here’s an abstract on dog poisonings.

Now, based on the data I’ve seen on poisoning incidents, iron phosphate is less likely to poison your dog than its closest competitor, metaldehyde (though the iron phosphate seems more likely to hurt earthworms than the metaldehyde).  I’m not going to stop recommending iron phosphate – Still, I can’t recommend it quite as freely as I have been in my talks — I need to add some real caveats. 

So then the question is, how did I not know about the potential problems of iron phosphate?  Simple.  I assumed that the compounds listed on the active ingredient list were really the only ingredients I needed to think about.  Silly me.  Just like Round-up, and almost any other pesticide you can name, there are other ingredients that help the active ingredients work — and that could cause issues.  For Round-up, the soaps mixed in there to help the product stick can hurt frogs or other amphibians.  For Iron phosphate, the extra ingredient that could do some damage is EDTA.

So, you’re asking, what is EDTA?  EDTA is a chemical which makes metals more soluble, called a chelate.  In iron phosphate products EDTA helps the iron to be taken up into the body of the snail or slug making it work much better than it might otherwise.  EDTA is also used in fertilizers so that elements (usually iron) are taken up more readily (because they’re soluble).  But because EDTA makes metals more soluble, it also helps them get to places they shouldn’t go – like into an earthworms body.

Now don’t go thinking EDTA is bad.  It’s not.  In fact, if you ever ingest lead or some other metal you’ll be thankful for EDTA because it is used to help clear potentially toxic metals from the body.  EDTA is even present in some of our foods for various reasons.  That said, as with any chemical (including water!), it is possible for EDTA to do things we don’t want it to do in the wrong circumstances.   And that’s why we need to be more careful with its use.

As I said before, I’m still OK with iron phosphate products, especially as they compare to metaldehyde products, but you can bet I’ll be spending more time stressing its drawbacks.  I’ll also be spending more time touting beer.

For slugs of course!

Now, a question for you.  These iron phosphate products are currently listed by the OMRI (Organic Materials Review Institute) and some labels list it as being safe to use around pets and wildlife.  If the products include EDTA, should that be the case?  (You can look up EDTA in Wikipedia if you want to see how it’s made.)  Are you comfortable with using EDTA in organic production?  Does it matter to you if it’s used as a fertilizer vs. as an ingredient in a pesticide?