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As I noted a few posts back, this summer marks the 10^th anniversary of the discovery of emerald ash borer (EAB) in southeast Michigan.  While a lot of progress has been made on many fronts in the battle against EAB, the outlook for ash trees in North America still looks bleak for the foreseeable future.  Ash trees, both green and white ash, were popular choices as street and landscape trees throughout the Midwest and elsewhere.  In Michigan ashes comprised up to 30% of the overall tree cover in some communities.  Like chestnut blight and Dutch elm disease, EAB provides a cautionary tale of the destructive potential of invasive pests.  As global trade continues to increase (and the potential for exotic pest movement along with it), the most practical defense in the near term is to spread the risk and increase species diversity.  In spring 2003 Bob Schutzki and I installed an ash alternative species demonstration at the MSU Tollgate Extension Center in Novi, MI, near the epicenter of the EAB infestation.  As we near the completion of the 10^th growing season of the planting we can take stock of some of the better selections.

Dana (R) and Aniko assess the lindens

Hophornbeam Ostrya virginiana


Hardy rubber tree Eucomia ulmoides


Northern pine oak Quercus ellipsoidalis (R) can maintain good leaf color even when soil pH turns Q. palustris (L) chlorotic.

American Sentry linden Tilia americana ‘McKSentry’

Baumannii horsechestnut Aesculus hippocastanum ‘Baumannii’

State street maple Acer miyabei ‘Morton’

Thanks to our partners!

Over the weekend our blog was inaccessible.  The server room in Pullman (where this blog is housed) overheated and everything was shut down.  I apologize to those of you who tried to comment and/or post.  Things are back to normal, at least for the time being.

To those of you who don’t like Blue Oyster Cult, I’m sorry, I just couldn’t stop myself.

A couple of weeks ago I mentioned that I spend some time flame weeding.  It’s a technique for getting rid of weeds by frying them using a 500,000 BTU (I’m not kidding – that’s how powerful this thing is rated) torch hooked up to a propane tank.  It’s not something I do a lot, just something that I get the urge to do periodically — when I need to feel macho.

Here’s the blow by blow – it’s kind of a good news, bad news story.

 

a Good news – Igniting the propane torch was quick and straightforward process.  The torch lit on the first try!

 

Bad news – Here’s my hairless finger after igniting the torch.  Even though the process of igniting the torch was quick and easy, I still burned all of the hair off of the fingers on my right hand. The black dots are all that’s left of my fantastic finger fuzz.

 

Good news – Damn but I feel powerful using this thing!  It’s like holding a jet engine in your hands!  Yes, it does make me feel macho.

 

More good news – only a couple of days later the plot looks almost spotless!

 

Bad news – Two weeks later the perennial weeds are already on their way back.  The ground insulates the roots too well.

If you live anywhere east of Montana you know that two-thirds of the country has been roasting under record heat for the past few weeks.  While the weather has been a bane to farmers and many others, it has provided us with an ideal set of conditions to begin to look at the responses in the SoMeDedTREES project. 

To recap, we installed two experiments with 25-gallon container-grown ‘Bloodgood’ planetrees.  In both experiments we applied one of three treatments to the root systems at planting: 1) “Shaved” the outer  portion of the root system to remove  circling roots, 2) “Teased” apart the outer portion of the rootball to remove circling roots and 3) “Control” where we did nothing to the root system, or “Pop and drop” to use Linda’s terminology.  One set of 48 trees was planted at the MSU Beaumont Nursery where half the trees were fertilized (400 g of Osmocote 15-9-12) and half were not.   The second set of trees was installed at the MSU Hort Farm.  At this site I made an executive decision to change the Fertilizer treatment to a Mulch comparison based on our discussions related to a recent study that suggested mulching does not actually reduce evaporation or improve soil moisture. We applied 3” of ground red pine bark in a ring approximately 40” in diameter around each tree in the “Mulch” treatment and left the other half of the trees with bare ground.

Overview of SoMeDedTREEs site at MSU Hort farm

If I had a hammer…  Summer Intern Aniko Gaal demonstrates proper form for installing TDR rods in clay soil (also works for relieving frustrations with your choice of summer employment).

Obviously this is a long-term study and we’re a long ways from any definitive results – especially with regard to the impact of the root treatments on eventual root structure – but the point of this exercise is to allow GP blog readers to come along for the ride and get a glimpse of what goes into our research.  For the mulch study one of our primary objectives is to track changes in soil moisture and tree stress associated with mulching.   In order to monitor soil moisture we are using a technique called Time Domain Reflectometry or TDR for short.  A TDR system is basically a glorified coaxial cable tester.  The system sends out an electrical pulse to a set of metal rods that are buried in the soil and then measures the return signal.  The greater the moisture in the soil, the longer it takes for the signal to return.  The instrument converts this information into volumetric soil moisture (% volume water/volume soil).  For this study we installed rods at two depths 15 cm (6”) and 45 (18”). Rods were installed 12” from the trunk of the tree at the edge of the root ball (inside) and 24” from the trunk of the tree (outside).

Volumetric soil moisture at 15 cm and 45 cm depth of planetrees with and without mulch at MSU Hort farm, Summer 2012.

We planted the trees in mid-May and watered them from a portable water tank once a week until mid-June.   Since then we’ve left the trees on their own.   So far the trees actually seem to be fairing pretty well given the heat.  We have one tree that is beginning to drop a few leaves but most look pretty good.  Our soil moisture readings to date are consistent with a couple of related studies that we’ve done that show mulching increases soil moisture.  Soil moisture was greater at the 45 cm depth than at 15 cm and the difference between mulch and no mulch was greater at the shallow depth.  Still very early, obviously, but we will continue to update – sort of like FOX Radio news: “We report – you decide.”

Many blue spruce trees in our area are suffering from a progressive decline.  This is more than the usual combination cytospora canker & rhizospaera needlecast that tend to make most mature blue spruce look crappy.   The current syndrome has been linked to phomopsis blight and affected trees show increasing branch die-back and in some cases trees go from a having a few dead branches to completely dead in a 3-4 years.  Because of this alarming and pervasive issue, I’ve been asked to put together a list of alternative selections for blue spruce as part of my extension duties.

Whenever I put together one of these lists I always include my all-time favorite conifer; a graceful, elegant tree that is native to the Pacific Northwest but grows well in Michigan and fulfills a range functions in the landscape.  Of course that tree is… well, that’s the problem.  I’m not sure what to call it anymore.  In Mr. Chance’s 6^th period Botany class at Olympia High School 30-some years ago I learned it as Alaska yellow cedar, Chamaecyparis nootkatensis.  Had to get the Latin spelling right to get full credit.  When I moved to Michigan in 1999 I heard people talk about Alaska cypress or Nootka cypress.  Took me a minute but I figured it out.  At least I could take comfort in the scientific name.  After all, as Mr. Chance taught us, we use scientific names to eliminate confusion; using Latin since it is ‘dead’ language and not subject to change.

About the same time I came to MSU a new conifer was discovered in Vietnam.  The new tree, Vietnamese golden cypress, was originally described as Xanthocyparis vietnamensis.  Moreover, this new species was closely related to nootkatensis, so both were added to the new genus.  Subsequently it was argued that the genus Callitropsis was originally used for Xanthocyparis nootkatensis before it became Chamaecyparis.  So, based on precedent Callitropsis was the proper genus for nootkatensis and vietnamesis.  Got it?  Well, as Lee Corso would say, Not so fast my friend…   Here’s the rest of story from the font of all knowledge, Wikipedia:

‘In 2010, Mao et al. performed a more detailed molecular analysis and placed Nootka Cypress back to Cupressus. However, this is disputed, as the tree would compose a monophyletic subgenus. "The argument that it warrants treatment as a monotypic genus is not without merit, in which case the correct name is Callitropsis nootkatensis."’

Then the Wikipedia poster shows their true colors.

‘Although acceptance of the revised classification of this tree is widespread among botanists, inertia in the horticultural and forestry industries (both typically very slow to adopt the results of botanical research), mean the name Chamaecyparis nootkatensis is likely to continue being listed in many situations.’

So let me get this straight.   Taxonomists have put the tree in four different genera within ten years and in one sentence current molecular analysis puts the tree in Cupressus (which the International Botanic Congress approved last year) but that’s disputed by other botanists – and WE’RE the idiots because we won’t jump on board?!

Tuesday morning I started the day by going outside, lighting a propane torch, and doing a little bit of flame – weeding for a demonstration.  Then I went inside, answered a few e-mails, and worked on a paper.  Around 4:00 I decided to go get a haircut because Wednesday I was due to speak before a portion of the Minnesota congress, along with a Professor in the department of Plant Pathology, to seek funding for a project that we have which identifies Dutch elm disease resistant elms in Minnesota.

In short, up until about 4:00 on Tuesday, I was feeling pretty darn professorial not to mention highly important.

Then, just before I headed out the door, an e-mail came across my computer screen, letting our department know that Bud Markhart had passed away.

For those of you who didn’t know Bud, he was a professor in the Department of Horticultural Science here at the University of Minnesota.  He was a plant physiologist who also did a lot of lecturing and work with organics.  He taught, among other things, a hands-on organic production course.

His passing wasn’t a surprise.  He was only 60, but he’d been fighting cancer for a few years and all of us in the department were aware that he probably didn’t have much time left.  Still, it hurts to lose someone like him.

As I’ve gone through my academic career I’ve had the opportunity to meet a lot of academics.  To make an unfair generalization, we tend to be self-righteous, self-important, and highly critical of others.  Bud was none of these things, and because of that he was loved and respected by many people both inside and outside of academia, but especially by students who were deeply appreciative of a professor who treated them as equals and didn’t talk down to them.  He earned the highest teaching award presented by the University of Minnesota, the Morse Alumni Teaching Award, a couple of years ago.  But the fact that he taught a class this past spring despite his illness reveals more about his commitment to students than any award could.

Personally, well, this is the guy who invited my wife and I to his house for Thanksgiving the first year that I lived in Minnesota.  In fact, he’s the guy who invited my Dad and me over my first day in Minnesota.

I think that a lot of people who talk about the recently departed refer to themselves as being closer to the departed than they actually were, and I don’t want to do that.  Bud and I were colleagues and, though I considered Bud a friend, we weren’t particularly close.  Still, I always knew that Bud’s door was open if I ever wanted to talk about anything.  He cared about people and he let it show.  His presence in our department, and in the small world that is horticulture, will be sorely missed.

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.