Category: Uncategorized

A Garden Professor is most severely vexed

I’ve been thinking a lot about Jeff’s recent post on “What happens to the horticulturist.” It’s true – universities rely more and more on faculty-generated grants for funding, so new hires tend to be in “hot” areas of research.  Fewer horticultural generalists are hired in teaching/research positions, and the same is true for Extension – the educational outreach arm of land-grant universities.

Many of you might not even know what Extension really is.  In my opinion, that’s because Extension as a whole has done a pretty poor job of evolving with the times.  When small farms were the mainstay of life for many people, farmers relied on practical, science-based information provided by university Extension services.  We’ve become an increasingly urbanized society, but Extension just hasn’t kept up.  The bulk of the research and information coming from plant and soil science departments is still geared towards production agriculture.  It’s of little immediate use for the majority of us living in urban areas.

So we have an imbalance:  there are increasing numbers of people living in urban areas who want good information on home gardens and landscaping, and decreasing university resources to fill those gaps.  Nature hates a vacuum, and this information gap is quickly filled with all kinds of stuff: some good, some bad, some dangerous, some illegal.  The very worst offenders, in my opinion, are the fear mongererss with most definite agendas but no solid evidence to support their claims.  For instance: I’m always skeptical when I hear about an article in an “obscure journal” being the only source of new information. If there was something new out there on an important topic, the researchers would not be publishing in an “obscure” journal. It would be in a highly visible and highly regarded scientific journal.  In any case, the information would be easy to find and discuss, not hidden away in a secret location.

I don’t have a good way to end this post, because I don’t have an easy answer to the problems that both Jeff and I see in horticulture departments and in Extension.  Do you?

Spin Cycle

The issue of potential damage to conifers by the turf herbicide Imprelis continues to get a lot of air play in this neck of the woods.  One of the interesting things about watching an emerging story such as this is watching some of the sideshows that go on around it and how people spin the issue to match their needs and agenda.

 

Example 1:

Heritage Lawn Care Company put out flyers in neighborhoods in southeast Michigan with affected trees to promote their service.  The flyer incldued the heading “ALERT:DYING PINE AND SPURCE [sic] TREES”  The flyer claimed that issues related to Imprelis damage to trees are “99.9% applicator and mixing errors”.  Surprisingly, there was no mention of where they got the data for this assertion.  But fortunately Heritage stands ready to save the day by using “only organic based fertilizers giving the same or better results”.   Again, no mention of how organic fertilizer controls tough weeds like ground ivy and wild violet.  Thankfully, “If you prepaid (your lawn care provider) for 2011, and want to switch companies, Hertitage is willing to extend you credit until your current company refunds your money.”  Call it a hunch, but I don’t think the folks at Heritage will be receiving an invitation to the local landscaper’s group picnic this year…

 

Example 2:

Mother Earth News trumpeted the news on Imprelis with the headline “Imprelis: Another Deadly Herbicide, This Time From DuPont” http://www.motherearthnews.com/grow-it/imprelis-killer-compost-zb0z11zrog.aspx  First of all, isn’t ‘Deadly Herbicide’ redundant?  Every ‘icide’ is designed to kill something so I think they’re supposed to be deadly, at least on their target.  While the unintended damage to spruces and pines is certainly unsettling, especially for a newly released product, this group of herbicides has low toxicity to mammals and in many regards is comparatively safe.  I don’t consider myself a nozzlehead but I’m sure most GP readers recognize I have little aversion to judicious use of chemicals around Daisy Hill farm.  So I was a little taken aback to find my “Fasten your seatbelt folks, this could be a bumpy ride” (GP Blog 6/27/11) quoted in Mother Earth news.  My reference was to applicators having to deal with customer complaints and potential litigation – but that’s the nature of putting things into the blogosphere…

 

Example 3:

On July 14 I received an e-mail advertisement from Growth Products, Inc. breathlessly announcing “An Essential Cure For Trees Damaged By Imprelis Or Sahara Herbicides.”  Pretty impressive stuff: We’ve only known about the issue for three weeks and these guys have already found the cure.  I had to read on.  The cure consists of an “Essential Cocktail” of three Growth Products liquids including Essential Plus (a rich concentration of organic ingredients including humic acid), Micrel Total (“Eight chelated minors to help the tree through stress”) and Companion (a biological fungicide).  Alas, once again eye of newt and wing of bat were apparently out of stock.  But, “The magic mix can be used as a soil drench and/or a soil injection.”  The e-mail also included a link to an article I wrote for our extension news that included a photo of some maple trees that had largely recovered from herbicide injury by Sahara in 2009.  I also documented the case here on the GP blog I wasn’t aware, but apparently a landscaper treated the trees with some of these concoctions.  No word in the e-mail from Growth Products on how the untreated control trees did.

 

In defense of weeds?

Blog reader Shawn sent this link to me yesterday. It’s a pretty short take on a complex topic, but even so I was troubled by the perception that all nuisance weed species are our own fault.

Sure, it’s true that humans have moved plants or plant parts around with them for centuries. Sometimes it’s been deliberate, and sometimes it’s been accidental. But other animals also move plants around, especially seeds. When we draw this kind of distinction between what we do and what other animals do, philosophically we are removing ourselves from the natural world. True, we have technology and all kinds of other human inventions, but as a species we are still part of the biosphere.


Ivy’s little dispersal units – spread by birds

Philosophical issues aside, there’s another part of this blithe acceptance of weedy species that concerns me. Though plants take advantage of animals as a means of dispersal, the rate at which nonnative, weedy species are spreading and colonizing new environments is unprecedented (this is where technology comes in). Ecosystems can adapt to new species and other environmental challenges – but when the rate is accelerated, the adaptive process is impaired. Thus, some native species go extinct when the rate of change is too great.


Ivy left to its own devices in a natural area

These are basic ecological concepts – and we ignore them at our own peril.

Does native matter?

We’ve had lots of lively discussion on my post regarding the Mark Davis et al. comment in Nature on natives and exotics. I have been traveling and otherwise occupied and have not had a chance to comment so I feel a little like the kid that kicked the anthill and then ran away. Fortunately, Holly was gracious enough to forego her post today (I promise to return the favor, Holly!) so I can chime back in.

Obviously there are lots of layers to the debate but one of the main items in the discussion is whether there is an inherent ecological advantage in planting natives over exotics.  At this point the focus always seems to shift to herbivory and the question of whether native insects will eat non-native plants.  There are certainly examples each way; some insects are generalists while others are highly specific.  More importantly, however, plants fill many other roles in the environment beyond serving as food for insects.   Moreover, species composition is just one aspect of diversity.  The ecological function of landscape is also determined by how we manage other factors such as structural diversity and age class distributions.  In his book “Bringing Nature Home” Doug Tallamy shows a picture of a bland, sprawling suburban landscape ( p. 24) and notes “this highly simplified community is made up of a few species of alien ornamental plants that provide neither food nor shelter for wildlife.”  OK, I’ll buy that.  But would the situation change if the blue grass was changed to a native grass kept mowed to 2” and the two widely spaced shade trees were changed to natives?  Doubtful.   The structural complexity; that is, the number and arrangement of grasses, annuals, shrubs, and trees, is likely a bigger driver of ecosystem function than whether the plants are native or exotic.

In his thoughtful comments on the blog post Vincent Vizachero sums up, “I stand by my view that the general heuristic of favoring native plants over alien plants is better than the alternative of not caring about origin at all.”   I can buy that as well, but with the caveat that other factors are equal.  The rub, of course, is that other factors are rarely equal.  And I suppose this is where the pragmatic approach discussed by Davis et al.  resonates with me.  In my position I do a lot of programming on trees for urban and community forests.  I go through a list of criteria to consider for tree selection.  Here are some of the key factors I usually discuss:

Adaptation There is no argument that there are well-documented environmental, economic and social benefits to trees in urban and suburban areas.   But in order to fulfill these roles trees must be able to survive where they are planted.  This means being adapted to abiotic and biotic environmental conditions which are often adverse.  In this region of the country there are some native trees that fit the ‘tough trees for tough places’ bill, such as swamp white oak, bur oak, and honey locust.  Many other natives, especially understory species, are much more difficult to site.

This street planting in Lansing alternated green ash and Norway maple.  

Available space This seems like a no-brainer, but it’s amazing how often this gets overlooked and we end up with too much tree and too little space.  Again, we have some great small native trees; Carpinus, redbud, striped maple.  But these can be limited in their site adaptability.

Ash stumps

Diversity  In Michigan some communities have lost 30% of their tree cover to the emerald ash borer.  Have we learned our lesson about improving species diversity?  Not really.  But we need to keep trying.  Exotic pests are here and here to stay.  Does anyone believe that global trade will decrease in the near future?  Does anyone believe that there will be quantum leap in our ability to detect and intercept hitch-hiking pests?  In order to continue to accrue the benefits of urban and community forests we need to continue to diversify our portfolio; this includes a mix of natives and exotics.  I doubt there will ever be sufficient data to prove one way other, but it seems reasonable to me that an urban and community forest balanced among 20-25 native and exotic species will be better able to withstand the slings and arrows of weather and pests better than one made up of 8-10 natives.

Excerpt from Davis et al. letter to Nature on natives vs aliens

In yesterday’s post I linked to a letter in Nature by Mark Davis and a number of other ecologists on the role and native and alien plants.  Unfortunately the journal requires a subscription.   Copyright laws prevent me from re-printing the entire article, however, below is an excerpt from the conclusion, which I think captures most of their message.

“Most human and natural communities now consist both of long-term residents and of new arrivals, and ecosystems are emerging that never existed before. It is impractical to try to restore ecosystems to some ‘rightful’ historical state. For example, of the 30 planned plant eradication efforts undertaken in the Galapagos Islands since 1996, only 4 have been successful. We must embrace the fact of ‘novel ecosystems’ and incorporate many alien species into management plans, rather than try to achieve the often impossible goal of eradicating them or drastically reducing their abundance. Indeed, many of the species that people think of as native are actually alien. For instance, in the United States, the ring-necked pheasant, the state bird of South Dakota, is not native to the great plains of North America but was introduced from Asia as a game bird in the latter half of the nineteenth century.

“Specifically, policy and management decisions must take into account the positive effects of many invaders. During the 1990s, the US Department of Agriculture (USDA) declared several species of introduced honeysuckles to be alien (harmful), and banned their sale in more than 25 states. Ironically, from the 1960s to the 1980s, the USDA had introduced many of these same species in land reclamation projects, and to improve bird habitats. Recent data suggest that the agency’s initial instincts may have been appropriate. In Pennsylvania, more non-native honeysuckles mean more native bird species. Also the seed dispersal of native berry-producing plants is higher in places where non-native honeysuckles are most abundant (Gleditsch, J. M. & Carlo, T. J. Diversity Distrib. 17, 244-253 (2010).

“Clearly, natural-resource agencies and organizations should base their management plans on sound empirical evidence and not on unfounded claims of harm caused by non-natives. Another valuable step would be for scientists and professionals in conservation to convey to the public that many alien species are useful.

“We are not suggesting that conservationists abandon their efforts to mitigate serious problems caused by some introduced species, or that governments should stop trying to prevent potentially harmful species from entering their countries. But we urge conservationists and land managers to organize priorities around whether species are producing benefits or harm to biodiversity, human health, ecological services and economies. Nearly two centuries on from the introduction of the concept of nativeness, it is time for conservationists to focus much more on the functions of species, and much less on where they originated.”

Ecologists weigh in on native-exotic debate

Charlie Rohwer, a frequent guest contributor to the Garden Professors, brought to my attention a recent letter in Nature by Mark Davis and 18 other ecologist entitled, “Don’t judge species on their origins.” Davis is a leading authority on invasive species and author the book Invasion Biology. In their article, Davis and his co-authors make many of the same points that I’ve made here on the blog (Are natives the answer? Dec. 14, 2009; Restoration ecologists you need us – part 2. Aug. 9, 2010) regarding the native/exotic debate. The main point is that we need to develop a more pragmatic approach to managing landscape systems and this includes natives and exotic species; it’s not an either/or question anymore, not that it ever really was.

A couple of excerpts from their letter:

“It is time for scientists, land managers and policy-makers to ditch this preoccupation with the native–alien dichotomy and embrace more dynamic and pragmatic approaches to the conservation and management of species — approaches better suited to our fast-changing planet.”

“Clearly, natural-resource agencies and organizations should base their management plans on sound empirical evidence and not on unfounded claims of harm caused by non-natives. Another valuable step would be for scientists and professionals in conservation to convey to the public that many alien species are useful.”

The pragmatic approach that Davis and his co-authors (and I) advocate recognizes a several realities:

Exotics can fill many of the same ecological roles and niches as natives, Doug Talamy’s book notwithstanding.

Any inherent “ecological superiority” of natives over exotics has long since been negated by anthropogenic land-use change, alien pests, and climate change.

Attempts to eradicate alien species are largely warm-fuzzy exercises with little likelihood of success without liberal use of industrial-strength herbicides.

WOW again (Why oh Why?)

I’m going along with the “dead tree” theme of the week, but doing a little prognosticating at the same time.  Bert and Holly showed you tree demise on site; I’m going to show you tree demise in the making.  We can call this “dead plant walking.”

I’ve done a few WOW postings in the past, often with a focus at what you might find at a nursery or big box store.  Here’s a recent find at an unnamed BBS, in the “topiary” section:

Unless you intend to have a giant stake as part of your topiary statement, this tree (actually a juniper) will morph into a prostrate form before your very eyes. Fortunately, it probably won’t live long once transplanted since it’s so overdue for potting up that the pot has split:

You can just imagine the nest of woody roots fusing into a functionless mass, can’t you?

Run, don’t walk, away from nursery plants like this.  You’ll be glad you did.

Read and follow label directions…

Every extension specialist or educator that mentions any kind of pesticide in a talk or article always includes the disclaimer ‘Read and follow all label directions.” However that caveat ranks somewhere between “Your seat cushion may be used as a flotation device” and “Do not remove tag under penalty of law” as the most ignored phrase in the English language. While we can probably rationalize ignoring the last two (If a jetliner ditches in the middle of the Atlantic is a seat cushion really going to save you? And when was the last time you saw someone led away in handcuffs for pulling the tag off a mattress?); failing to pay attention to pesticide labels can have some real and immediate consequences.

 

I got called recently to inspect some tree and shrub damage at an industrial park in suburban Detroit.  (Because the case potentially involves some legal issues, I won’t mention names of any parties).  The industrial park included several hundred acres, much of it turf and landscape beds of trees and shrubs.  The park had its own groundskeeper but contracted out its spray applications.  A couple summer’s ago the staff groundskeeper complained several times to the contractor that they weren’t doing a sufficient job of keeping up with the weeds in the landscape beds.  The typical vegetation management tools of choice on this site were spot applications of Round-up (glyphosate) and hand-weeding.  For reasons that are not completely clear, this time the contract applicator reached for a jug of Sahara.    Even if you don’t know what Sahara is; what image does the name conjure up?  Parched. Barren. Lifeless.  Sahara is a combination of two herbicides (Diuron and Imazapyr) designed for complete vegetation control in non-cropland areas such as parking lots and rights of way.  And, unlike Round-up, Sahara provides foliar and root activity.  This is a product you use when you want complete burn-down and you don’t want anything growing there for a long time.

 


A hedge maple 2 years after herbicide application

Unfortunately, that was not the desired result in this location.  Within a week of the application, dozens of trees and shrubs all over the industrial park were either dead or wishing they were dead.  The smoking gun was not too hard to find.  The applicators had duly noted the herbicide application in their logbook and presence of active ingredient was confirmed in soil samples.  Although the parties are still working a settlement, the bids for replacing the affected trees and shrubs are well into six figures.

 


The unkindest cut of all.  These green ash were regularly treated with imidacloprid to protect against emerald ash borer.  An herbicide ap took them out instead.


Two years after application there are still bare zones where Sahara ran off from mulch rings and landscape beds.

Of course, all of this death and destruction (and legal wrangling) could have been avoided simply by…  Reading and following the label directions.  The Sahara label notes in several places that contact with roots can damage trees and other plants, including this explicit statement under a heading in all bold letters, PRECAUTIONS FOR AVOIDING INJURY TO NONTARGET PLANTS:  “Injury or loss or desirable trees may result if Sahara is applied on or near desirable trees or on areas where their roots extend.”  Sounds pretty clear to me folks – don’t use this stuff near plants unless you want them to die.

 

So, next time you or someone working for you has any question about what a pesticide does:  Read and follow label directions….

Update on root-rotted Cornus kousa

A little more than a year ago I posted a Friday quiz based on a failing Cornus kousa.The answer explained that our landscape has, in part, a perched water table that effectively rotted most of the roots of this poor tree over several years.  Last spring we moved it to a different section of our landscape where we know the drainage is better, and I’ve been monitoring its recovery since that time.


Cornus kousa leaves in 2007


Cornus kousa leaves in 2011

We were gratified to see that the leaves this year are significantly larger than those of previous years.  This tells us that root function has resumed, providing enough turgor pressure to expand the leaves to normal size.  It was especially helpful that we had one of the rainiest springs on record.

Take home lesson:  if a tree or shrub is failing in its current location, it’s worth digging up to see what’s going on.  Bad soil conditions?  Move it to a better location.  Bad roots?  Time to hone your root pruning skills.  But wait until fall to do this.  Transplanting this time of year is the most difficult for plants because of the increased water demands of warmer temperatures and expanding leaves.