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Posted by Sara Tanis and Bert Cregg

NOTE: Last week I gave an update on the 10-year anniversary of the discovery of the emerald ash borer in the U.S.  In response to the post, Sonia John raised a couple of points:

“Please share your knowledge about the status of efforts to: 1. introduce insect species or other biocontrols that predate the EAB, and 2. evaluation of the degree of resistance to EAB of Asian (and European) Fraxinus spp. as well as Asian/N.American hybrids)” 

Sonia is right on the mark because these two areas of investigation probably represent the best long-term solution to the EAB issue.  As I mentioned last week, EAB was a relatively obscure insect in its native range in Asia, rarely causing any significant damage.  This suggests that native (Asian) ashes are resistant, native biocontrols keep it in check, or both.

In order to reply to Sonia’s post I enlisted the aid of Sara Tanis.  Sara is a Ph.D. student in the Department of Forestry at MSU (and a former MS student of mine) and is studying variation in susceptibility to EAB among ash species for her dissertation.

 

Biocontrols 
Almost from the moment that EAB was first identified, USDA and US university scientists have been working with their Asian counterparts to identify diseases or other insects that keep EAB under control in Asia.  From this work, researchers have identified several parasitic wasps that affect EAB.  Some of the wasps lay their eggs on EAB eggs – when the wasp larvae hatch they feed on the EAB eggs.  Other wasps lay eggs on the EAB larvae and then the wasp larvae feed on the EAB larvae – yeah, pretty gross.  (for more information visit http://www.emeraldashborer.info/biocontrol.cfm).  A state of the art bio-control research facility has been established by USDA-APHIS in Brighton, Michigan to rear these parasitoids and to date they have been released in several locations throughout infested areas of the United States.   We know the wasps are highly effective in parasitizing EAB eggs and larvae in China.  The question is whether we can establish viable and self-sustaining populations in the US.  

  

In addition, a native parasitoid Atanycolus cappaerti, a Braconid wasp described in 2009, is also proving to be successful in curbing EAB densities.  At the MSU Tree Research Center, we have seen more than 70% parasitism on EAB in black ash and green ash trees.  Hopefully turn-about will be fair play and lack of co-evolution will back-fire on EAB and our all-American native wasp can do a number it.  All together now: USA! USA! USA!

 

Everybody’s All-American? Atanycolus cappaerti  Photo: David Cappaert

Variation in resistance among species.

One of the main points to hit home here is the fact that even though Asian ash are considered “resistant” in their native habitat, in North America where EAB population densities are extremely high, they do succumb to EAB attack despite their co-evolutionary history.  Here at MSU, Andrea Anulewicz has done extensive host preference work using a variety of ash species including those found west of the Rockies (F. anomala), south in the Carolinas (F. caroliniana), Europe (F. excelsior and F. ornus), and an evergreen species found in Central America (F. uhdei).   All of these ash species have proven to be viable hosts for both adults and larvae.  However, EAB do prefer some ash species over others.  At the top of the menu are green ash and black ash, less preferred is white ash, and least preferred is blue ash, our hope for the future.   In the field, of the five ash species that EAB has encountered to date, blue ash appears to be the most resistant or the least preferred ash species native to North America.  In order to quantify differences in EAB related mortality between blue ash and white ash, we inventoried all living and dead trees in two woodlots in Southeast Michigan in 2010
620
-2011.  We found approximately 68% (402 out of 590 trees) of the blue ash trees in these sites were alive, and most (60%) appeared healthy!  We calculated that these trees were subject to at least 178,000 beetles (calculated from dead ash phloem area) over the course of a 15+ year invasion.  That is a lot of beetles.  In contrast, only 29 of the 312 white ash trees survived, and these were likely too small to be infested during the peak of EAB invasion (around 2005).   Blue ash survival has also been reported in Ontario and Ohio.  Many of us assumed that there would be 99% ash tree mortality across North America.  Don’t get me wrong, many forests and urban areas DO have mortality this high because of the ash species found there.  However, we now have something positive to report.  Evidence suggests blue ash trees will persist in forests ravaged by EAB.  In addition, blue ash resistance might also enhance bio-control efforts.  The combination of a less susceptible host and a specialized parasitoid could maintain EAB populations at densities blue ash trees could sustain and possibly aid in slowing the spread of EAB across the US.  At this time, we don’t know the exact mechanism of blue ash resistance, but we are working on it.  Bert serves on my graduate advisory committee, so I’m sure he will keep you up to date as we learn more.  There are likely several factors that contribute, once isolated, we hope to incorporate these mechanisms into other ash species and introduce less susceptible ash tress back into the landscape. 

Variation in susceptibility to EAB between blue and white ash

USDA and Ohio State researchers are working with the Dawes arboretum to hybridize North American and Asian ashes.  This work is based on the model that the American Chestnut Foundation has used to breed blight-resistant chestnuts; starting with an Asian – American hybrid (1/2 Asian; ½ American) and then making repeated back-crosses with the American species to increase the desired horticultural characteristics while maintaining the resistance from the Asian parent.   Clearly this is a long-term proposition and so far the efforts have been slowed by poor crossibility among species and insect damage to seed.   Moreover, earlier hybrids that have been produced crossing Manchurian ash have not exhibited any resistant qualities.  Breeding work, of course, is always a numbers game.  As a point of comparison, the USDA National Arboretum’s program to select Dutch elm resistant American elms found only 11 survivors out of 21,000 seedlings screened for tolerance.

I get things wrong sometimes – I’ve had slip ups when speaking and said things I didn’t intend to say.  I’ve written things that I wish I had the chance to rewrite because I explained things poorly.  I’ve even gotten my facts mixed up from time to time.   Still, it bothers me when someone who should know better delivers information that is blatantly wrong.

Yesterday I was looking at YouTube videos regarding compost tea.  As anyone who has ever looked up compost tea on YouTube knows, if you look long enough you’ll eventually come to videos of Dr. Elaine Ingham.  She’s one of the biggest proponents of compost tea out there and is also Chief Scientist at the Rodale Institute.   Here’s a link to one of the videos that I ended up watching.  Interestingly, it doesn’t have much to do with compost tea.

http://www.youtube.com/watch?v=GEtl09VZiSU

To be fair, she makes some excellent points in the video about people needing to conserve the life in soil.  And I did like her basic definition of soil and dirt at the beginning.

Other points aren’t as well made.  As I was viewing this video I heard something that really ticked me off.

Go to 9:20 on the video and watch for a couple of minutes.  Listen to the insights about wartime munitions.

Then forget what you heard because it’s all just wrong.

Look, I know Dr. Ingham is a proponent of organic foods and techniques, but, if you’re going to talk about history, especially if it’s the history of a practice you’re opposed to, then you should really try to get it right.

She starts by talking about leftover munitions from World War Two and how we found that they could be put into farmers’ fields to kill weeds.

Wrong.

It’s true that one of our most used herbicides, 2,4 D, came from World War Two – but it wasn’t a munition (at least not in the classic sense of the word), and it wasn’t actually used in the war to any great extent.  It was released for use by farmers after the war was over.  And it sure wasn’t an explosive (otherwise there’d be lots of lawns in suburbia reduced to craters!)

Then she discusses using TNT as a fertilizer.  Was she joking?  If so that’s fine, but it didn’t seem like she was joking to me.

To be clear, while I’m sure somebody somewhere dumped TNT on their fields to see if it would work as a fertilizer, dumping munitions on fields to get plants to grow was in no way a common practice at any time.  In fact, a challenge for ecologists is getting rid of old munitions in contaminated sites (like old factories that made bullets and shells).

And then she says that synthetic nitrogen is Second World War technology, and that it’s the reason the Allies won.

Wrong.

Synthetic nitrogen is First World War technology and the Germans came up with it.  Haber and Bosch, the two guys who worked it out, both won Nobel Prizes for it.  (As a side note Haber was known as the father of chemical warfare for his WWI exploits with chlorine and other poisonous gasses).

Look, it’s not the end of the world if Dr. Ingham didn’t know this stuff, but my goodness, if you don’t know something mightn’t it be wise to avoid the topic?  If anyone is interested, the best books on synthetic nitrogen are Vacliv Smil’s Enriching the Earth and Thomas Hager’s The Alchemy of Air.

There were other problems on the video too.   For example, her bird guano comment didn’t really make sense since by World War Two it wasn’t economically realistic to use it any more –the guano, mined in Peru, had been largely used up – it’s not a quickly renewable source of fertilizer.  And the rain forest analogy she used is a terrible one because a rain forest is a relatively closed system containing organisms highly specialized for living in that environment while food production systems aren’t closed systems (and can’t be unless we reuse our own waste for fertilizer).  But I’ll leave those alone.  They were more irritating than infuriating.

Unfortunately Dr. Ingham has a little bit of a history with getting accurate information out. I won’t go into here, but you can use the links below to read about it in more detail.

Green-faced apology

Greens and Ingham apologise to Royal Commission

Did you hear about the GMO that almost destroyed all life?

I believe that the Rodale Institute is a quality institution, that its goals are honorable, and that organic techniques need to be given more consideration and implemented more frequently than they currently are in our country and the world.  That said, I question how seriously the good work that Rodale does will be taken with Dr. Ingham as its Chief Scientist if she continues to deliver information of the quality seen in this video.

This summer marks an anniversary of sorts.  Shortly after I joined the faculty at Michigan State University in the fall of 1999 MSU Extension began to get reports of dead and declining ash trees in and around Detroit.  Since ash trees had relatively few serious pest issues and none that routinely caused mortality, the mysterious ash decline was attributed to cumulative environmental stresses, ash yellows or various site factors.  In the summer of 2002, however, a little-known exotic beetle from Asia, emerald ash borer (Agrilis planipennis) was identified as the causal organism.  The beetle was so obscure that the first insects collected had to be sent to an entomologist in Eastern Europe for identification.  The summer of 2002 has become a point demarcation for those that work in landscape horticulture or urban forestry in the Midwest and East; now it’s before EAB and after EAB.  Prior to 2002,  EAB was completely unknown in the US, today it has been identified in 15 states and 2 Canadian provinces.

EAB range June 2012

In the intervening 10 years we have learned a lot about the beetle.  In fact, it seems likely that we have learned more about EAB in 10 years than just about any tree pest in history.  I did a quick Google Scholar search and there have been nearly 600 articles published with ‘emerald ash borer’ in the title since 2002. Below are some highlights of what we’ve learned.

In lower Michigan, EAB is able to complete its life cycle in one year.  Adults emerge in early summer, feed on ash tree foliage, mate, and lay eggs on ash tree bark.  When the eggs hatch the larvae burrow into the tree and feed on phloem under the bark leaving extensive galleries.  The larvae eventually pupate and overwinter before emerging as adults the next summer, leaving a characteristic D-shaped exit hole.

EAB life cycle – National Plant Gemplasm System

Host range.  When EAB was first discovered very little was known about the insect, even in its native range in China and Korea.  At the time, information from its native populations suggested that EAB could affect trees outside the genus Fraxinus.  Research in the US, however, has clearly demonstrated that EAB adults can only feed on Fraxinus foliage and EAB larvae can only develop by feeding on ash tree phloem.  So there is little likelihood that EAB will ‘make the jump’ to other tree species outside of Fraxinus.  That’s the good news.  The bad news is that all North American ashes are susceptible to EAB.  There are some differences in relative susceptibility; green ash trees are probably the most susceptible, while blue ash trees will hang in there the longest. Eventually, though, all North America ashes will succumb.

How not to stop an exotic invasion.  While much of what we’ve learned about EAB has been through systematic research, we have also learned by trial and error.  Immediately after EAB’s discovery regulators decided the best approach was try to eradicate the pest.  Historically eradication efforts have not been very successful but decision-makers at the time may have been buoyed by the recent successful eradication of Asian long-horned beetle in the Chicago area.  To make a long story short, EAB eradication failed.  In 2002 the EAB infestation was made up of a core population in and around Detroit and a series of isolated outlier populations.  The eradication strategy was analogous to fighting a forest fire – build a perimeter around the main hot spot and eliminate outlying ‘spot fires’ as soon as they appear.  With EAB the fire fighting analogy broke down for two reasons.  First, it was impossible to contain the main population since the insect was continually carried out of the core area, largely by campers moving firewood (It’s a Michigan thing).  Secondly, fire-fighters can rapidly respond to isolated spot fires because smoke identifies the location almost immediately. With EAB there is typically a 2-3 year lag period once the beetle moves into an area until trees begin to show symptoms.  By that time the population is well established and has likely already spread beyond any potential containment. 

Saving your ash. In 2002 there was no data on effectiveness of insecticides against EAB.  Therefore researchers and extensions specialists, did not provide recommendations for arborists to control it.  Several arborists ignored our advice and treated trees in the core infestation areas in Detroit with insecticides.  In some cases those trees are still alive.  So were the arborists right and were we wrong?  I think both groups did what they had to do.  As scientists and extension specialists we can’t make recommendations in the absence of data.  In many cases the arborists took a ‘sledgehammer’ approach, using multiple products and multiple applications. They saved some trees but they probably used more chemical than they needed to and probably hit some beneficial and other non-target insects along the way.  Today, with the benefit of nearly decade of research, we have effective controls for individual trees, primarily using trunk-injected systemic insecticides.

http://www.emeraldashborer.info/files/Multistate_EAB_Insecticide_Fact_Sheet.pdf

What’s next.  The range of EAB continues to expand.  While it is possible to protect individual trees, we need to remember those trees will require treatment in perpetuity to survive.   The development of hybrid ashes – similar to what has been done with elms – seems like to most likely scenario that will get ashes back into the landscape.  In the meantime, EAB joins chestnut trees and elms as another reminder of the need to diversify our landscape in order to reduce risks associated with exotic pests.

I performed a little demonstration the last few weeks which I thought you might be interested in seeing.   So here it is:

I took a little weedy spot of land out in the nursery and divided it into four sections.  Three weeks ago I applied Round-up to one of the sections and vinegar to another.  Then, a few days ago, I applied vinegar (again) to the third section and Round-up (again) to the fourth.  Then yesterday I took pictures of all four sections.  I conducted this little experiment so that I could demonstrate to a group what happens over time after you apply these chemicals.  The results are below.

Above is the Round-up treatment a week or so after application.

And here’s the Round-up after three weeks.

The Vinegar after a few days.

And the vinegar after three weeks.

Vinegar is great for little weeds, but boy oh boy, once they grow up, vinegar just doesn’t do it.

There’s a new report out from University of Copenhagen on killing weeds between paving stones. What they recommend is burning or steaming the weeds lightly and repeatedly. Boiling water, steam, even flamers can be used to wilt the leaves over the course of several treatments (six was recommended). This process damages the leaves beyond repair, slowly starving the roots to death.

I’m not sure exactly how I feel about this study (which is getting a lot of attention on the internet). On one hand, it is a chemical-free way to kill weeds…but on the other hand, it’s pretty labor intensive and requires energy inputs for generating heat. Moreover, what does one do once those weeds are gone? Those bare patches of sterilized soil are just going to be recolonized by new weeds.

Several years ago I had a Master’s student look at different methods of killing English ivy. She also tried the steam treatment.  Ivy laughs at steam. Aggressive perennial weeds like English ivy or blackberry or Japanese knotweed are unlikely to be much affected by blanching, and certainly not by half a dozen treatments.

But most of us probably don’t have big, woody-rooted weeds amongst our paving stones.  In my own garden, it’s a mixture of species that fill these gaps and some of them – like mosses and some smaller ferns – I actually enjoy.  So I pull out the things I don’t like, leaving the desirable species to fill in the gaps.  It’s simple and requires no special equipment.

Am I missing something here, or is this really much ado about nothing?

Admitting you’re wrong is difficult.   For exhibit A see the recent discussion between me and Jeff over alternative nursery containers.  We all like to think we’re open-minded but  when push comes to shove we all end up like the Fonz on Happy Days when it comes time to say ‘I was wrrrrr… I was wrrrr….  I was not exactly right.”  http://www.youtube.com/watch?v=uwkU8-d1gIk   As scientists we’re supposed to be objective and base our judgments on verifiable data and careful and repeatable observations.  But, as humans, we all have biases and preconceived notions that are hard to get around.

So here’s a challenge for our Garden Professors readers (and my fellow  GP’s too).  Give an example of a case where you’ve changed your mind about a landscape or gardening practice or product.  And what did it take to change your way of thinking and make you say, “Ya know, maybe I was not exactly right.”

I’ll start.  I have long been dubious about is the use of plant growth retardants (PGR’s) on landscape plants.  PGR’s are chemicals that reduce plant growth, usually by inhibiting shoot elongation.  There are a variety of PGR’s on the market but most work by inhibiting plant growth hormones such as gibberilin or auxins.  PGR’s have long been used by bedding plant producers to make plants more compact and easier to handle and ship.  One PGR, paclobutrazol, has been heavily marketed in recent years to control growth in landscape trees and shrubs.  The effectiveness of paclobutrazol at controlling plant growth has been well established in the literature, though there are some exceptions.  My long-held skepticism toward the landscape application of PGR’s stems from a couple factors.  First, the marketing claims are pretty fantastic: Not only does it control growth but it improves drought tolerance, heat tolerance, insect resistance, and disease resistance (no word on how it does on getting spots out of rugs).  Second, just because something works on containers of annuals in a greenhouse doesn’t mean it will work on trees and shrubs in the field with variable soils, weather, etc.  Third, why bother?  If something is growing too fast; back off the fertilizer, head it back with the Felco’s, or take it out and put something more appropriate there.

What changed my mind.  I’ve seen a couple of effective applications of PGR’s on trees and shrubs that have made me re-evaluate my opinion.  One was at a program at the Indiana Arborists Association a couple years ago.  The study tracked pruning cycles following utility line clearance pruning.  They found that treating trees with paclobutrazol following pruning reduced re-sprout growth and extended the cycle time between pruning by 2 to 3 years – which is a big deal to utility arborists.  More recently, I’ve been observing shrubs here on campus that our landscape service group has been treating with paclobutrazol after pruning.  Typically many shrubs are rejuvenated after pruning and put on a big flush of growth.  The PGR application was effective in keeping this in check.  (Some examples with burning bush appear below). Even to my highly skeptical eye, the treated plants just looked a heck of lot better than the untreated.

Do I believe all the marketing claims made about PGR’s for landscape plants?  No. But for extending pruning cycles and keeping plants in check, I have to admit I was not exactly right. 

Burning bush with PGR app.

Burning bush without PGR app. (Note treated and untreated were growing in same bed)

By controlling growth after pruning PGR application can help keep these shrubs in line and lengthen the time between pruning cycles.

I can’t decide if I like the fact that various companies read what I write or not. On the one hand, it’s kind of nice to know they care, but on the other, I kind of like to think that I can talk to people without them hanging over my shoulder.

How do I know they’re there over my shoulder?

They send me stuff.  Sometimes it’s a nasty or "educational" e-mail after I’ve published something about their product that they don’t like, and sometimes it’s a gift bag (or an offer of a gift bag) if I mention that I like something.

I never respond, with one notable exception.  Once I wrote a little something on bees for a newspaper and a small honey operation went out of their way to drop off some honey for me at the front desk.  I thought that was really nice so I wrote them a quick thank-you. 

I wrote something nice about Milorganite recently and they sent me a ballcap, some pens, and samples — along with some literature.  That was nice, but I feel like it wouldn’t be appropriate for me to write back.  I do like Milorganite, but if I start to think of them as my "friends" I don’t know how impartial I’ll be able to be if I find something out that changes my opinion.  I will use the free sample though.

On the boo-hiss side I had the lawyer from company in town call a newspaper where I published a story recently to tell them I got my facts wrong and that they needed to publish a retraction.  The company was wrong though — so no retraction was published, but it was still odd to have a lawyer get involved like that.  Will I think twice about talking about that company’s product in the future?  Not consciously.  But subconsciously?  Who knows (shoot — subconsciously it might make me talk about them more — I don’t know).

My wife and I were in Washington DC a few weeks back for a wedding.  I’ve been to DC a handful of times and it is one of my all-time favorite places to visit.  I love history so the memorials, monuments and Smithsonian museums are all high on my list.  But DC has a lot to offer plant geeks as well.  In honor of Memorial Day and the unofficial start of summer vacation season, here are my top three DC Horticultural Highlights.

National Botanic Garden.  Located nearly adjacent to the US Capitol, the Botanic Garden is easy to miss if you’re not looking for it.  The garden is comparatively small but offers a nice respite from the hustle and bustle (and interminable school groups) of the rest of the National Mall.  It’s also a cooler oasis to beat the heat if you visit the Mall in the summer and offers some unique views of the Capitol.  The conservatory has great on-going and rotating exhibits.  A current one was on medicinal plants.

The National Arboretum.  The Arboretum is a little more of challenge to get to and probably best if you have a car.  Some highlights include the Gotelli collection of dwarf conifers, the grove of state trees, and The National Bonsai & Penjing Museum.  Be sure to check on hours of operation before you go.  The first time I visited the Arboretum I arrived at 4:30 thinking I would have a several hours of prime late afternoon and evening light for pictures, only to find out they closed at 5:00.

Arlington Cemetery. Arlington is a special place is so many ways.  If you’re an American, these are images steeped in our collective consciences; the tomb of the Unknowns, the Kennedy gravesites, the Challenger memorial, and tens of thousands of headstones marking those that gave the last full measure of devotion.  The grounds are wonderfully tended and, like the Botanic Garden, provide a break from the din on the nearby National Mall.  The Cemetery grounds include dozens of memorial trees and several state Champion trees. Motorized trams are available but if you can walk a couple miles it’s a fascinating and moving place for a stroll.  Arlington is easily accessible by DC Metro or walk across the Memorial Bridge at the Lincoln Memorial end of the Mall.

Today I’m going to throw up a post that’s a little link-heavy, but I encourage you to follow these links because they show how prevalent the technology is that I discuss.  And a trip to the garden center will quickly show how infrequently this technology is used.

It’s frustrating.

Why the heck do we still buy plants grown in containers using 1950s technology?  I was reading Bert’s post this week about how to treat container grown trees before planting and also considering a somewhat similar experiment which I conducted about a year ago (stats are in and support my points in that article), and I couldn’t help asking, why do we put ourselves through it? 

The technology is out there for us to produce great root systems by using new types of pots that have become available over the last few years. Look up High Caliper Growing System, Rootmakers (which also includes RootTrappers — we’ve been using these for years), Smart Pots, Superoots, — and there are other systems out there too – all of these systems greatly reduce circling roots and are relatively easy to use.

Do we ask for record players or black and white TVs when we go to the electronics store?  No!  We want MP3 players and big flat screens.  So why are we content with plants grown in containers that come straight from 1954 in our garden centers? 

If we would just start to demand that garden centers and nurseries provide container grown plants with better root systems we’d get them – because they are out there.  But we need to be proactive or we’ll be stuck in the past forever.

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.