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.

Right Plant, Wrong Place?

It’s (apparently) Dead Tree week here on the GP!

[To my GP colleagues…we should make “Right Plant, Wrong Place” one of our categories, sort of like  “Knock it Off.” Or maybe just “Dead Plants in Action.”] 

Exhibit A:

Some unhappy little Magnolias. Drip irrigation was running, which leads me to believe salt spray is the culprit.

I was pedaling my sweet Electra beach cruiser down the sidewalk on Cape San Blas, Florida (or Cape San Blarrrgh, if you caught my post last week) and happened upon this tragedy.  In the background is natural coastal sand pine scrub including saw palmetto and myrtle oak. Growing on nothing but sand and a bit of decaying organic matter, 300 yards from the ocean, these are tough plants. Pretty darn salt tolerant.  Cabbage palms, also very salt tolerant, marched along the sidewalk. Southern magnolias had been planted in between, and they weren’t faring as well.

Just like “deer resistant,” “salt tolerant” is a rather vaguely-defined grouping of plants. You can find list after list on the interwebs and in the back of nursery catalogs and reference books.  The source of the information is rarely confirmed, and if so, it’s the same Extension publication that has been cut and pasted to death. Degrees of salt tolerance are further described as “high,” “moderate” and sometimes “low” without any quantitative parameters (a range of soil electrical conductivity perhaps?).  There are tremendous scientific resources (including funding) devoted to breeding for salt tolerance of food crops like rice, barley, and soybeans. Ornamental plants are pretty unimportant in the grand scheme of things (like the global food supply) thus the mere smattering of practically unfunded research out there, leaving us with only anecdotal evidence. Though some lists have M. grandiflora listed a “moderately” salt tolerant, I vote to move it to “low.”

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….

A jewel of an orchid

Orchid fanciers Derek and Joseph correctly identified Friday’s mystery plant as a jewel orchid, specifically Macodes petola:

Friday’s sparkly leaf photo shows why “jewel orchid” is the common name used for several genera of orchids with showstopping foliage.

And Ray noted that Goodyera spp. (rattlesnake plantain) is a native US jewel orchid with beautiful variegated foliage. Next time you’re hiking in the woods, keep your eye out for this common yet striking plant.

Vinegar: A Garden Miracle!

I’ve been working with homemade garden remedies in one context or another for about 10 years now.  As someone who has spent days searching for odd cures to garden problems I consider myself qualified to say that, of all of the remedies I’ve seen, vinegar seems to be the product with the most (supposed) uses.  You can kill weeds with it, as well as plant diseases and insects.  You can also use it as a fertilizer or even to acidify your soil.  It’s amazing!  But which of these uses are real and which are just someone flapping their jaws?

Vinegar as an herbicide:  White vinegar which is about 5% acetic acid and does a nice job of burning the tops of plants, but not their roots – so a larger weed will live right through a spray even though it will look bad right after the spray.  You can buy 20% acetic acid.  It works faster, but it has essentially the same problem killing larger weeds that that 5% acetic acid does.  Besides efficacy issues there are safety issues also.  I’ve used 20% acetic acid and I think that this stuff is too dangerous for the average person.  A little in the eyes could cause permanent injury.  Just a little whiff of it is enough to make the nose start running (in other words it’s not good for mucous membranes).

Vinegar as a disease control:  What a great idea!  Spray something that kills plants onto your prized petunias to control disease!  OK, when you use vinegar as a plant disease control you do use a lower concentration which shouldn’t hurt the plant.  But vinegar has never proven to be particularly effective at controlling plant diseases.

Vinegar as a fertilizer: Nope, doesn’t work.  Acetic acid only contains carbon hydrogen and oxygen – stuff the plant can get from the air.  The other things that may be in vinegar could be good for a plant – but it seems an expensive method of applying an unknown amount of nutrition.

Vinegar as a soil acidifier:  This is one that I’ve seen a lot – and so I tried it.  In a nutshell, it just doesn’t work that well.  It takes a lot of vinegar and the pH change is brief at best.  Use something like sulfur instead.

So to summarize, despite a lot of recommendations, the only thing that vinegar has really proven to be good at is killing weeds – and then only if the weeds are young.

Grass, sedge, or weapon?

What is it?

Why, that’s a “Mace Sedge” – thus a medieval weapon AND a sedge. Actually…not very menacing.  But very cute. Carex grayi is a wonderful clumping sedge, native to Eastern North America.   Mine is situated at the edge of a home-made bog, and is at least 2.5′ tall with an upright habit.

More common in the trade are the cascading Asian sedges such as Carex dlichostachy ‘Kaga Nishiki’, C. oshimensis ‘Evergold’, and C. morrowii ‘Variagta’, all fabulous plants for the part-shade garden.  My hair has been likened to New Zealand native C. buchananii, the coppery leatherleaf sedge (I took this as a compliment).

The genus is chock full of garden-worthy species, of which the North American natives are finally getting some attention. Folks like grass guru Rick Darke and meadow man John Greenlee have been promoting the heck out of native sedges for both the east and west coasts, respectively. I can’t even remember where I put my mitts on this one, but have been enjoying the heck out of it for the past two years.

Does colored glass help root cuttings?

I get a lot of questions about a lot of different products and practices.  New topics send me to the scientific data bases and that’s where I went for today’s posting.  One of my garden writing colleagues asked me about colored glass rooters – glass containers in different colors that can be filled with water and a plant cutting.  The conventional internet wisdom, according to my colleague, is that green and blue glass rooters are the best.

The first mention I could find of such a practice is from an 1801 publication called The Cottage Gardener.  In it, we’re informed that for rooting cuttings “such coloured glass is useless; it has no influence over the production of roots.” Nevertheless, 200 years later web postings like “I have found that cuttings placed in colored blue or green glass root faster than clear glass” are taken as solid evidence that blue or green glass containers are best for rooting cuttings.

There is science behind different colors of light and rooting, but it’s a little more complicated.  Chlorophyll absorbs red and blue light best, so plants whose leaves are exposed to red and blue light grow well and tend to produce a healthy flush of roots.  On the other hand, plants whose roots are exposed to blue light have decreased root growth compared to those under white light conditions.  In this case, the photoreceptor called cryptochrome might be responsible for inhibition, as it is a blue light absorber.  Similarly, plant roots exposed to green light do not grow as well as those exposed to white light.

In my opinion, this is another example of aesthetics trumping science.  Of course colored glass rooters are more attractive that plain old glass jars.  And that’s a perfectly valid reason to use them as part of one’s home decor.  But it’s not science, nor is it necessarily the best way to encourage rooting.

What seems to be most important in rooting cuttings in water is to use indirect lighting (north-facing windows in the northern hemisphere, for example) so that the water doesn’t get too hot.  And keep in mind that not all species root well from cuttings.

Getting to the root of the problem

After getting off to a cool and soggy start, summer has come with a vengeance to Michigan, with heat indices expected to push 100 degrees by Wednesday.  Along with warmer temperatures, summer also means our research season is getting into full swing as well.  One of our biggest efforts these days involves our project to look at pre-plant storage and handling on shade tree liners.


As many GP blog readers are aware, emerald ash borer (EAB) has dominated the conversation regarding shade trees in the Midwest for the past 6-8 years.  Ashes made up 20 to 30% of the shade tree cover in many urban and community forests, so their loss has been devastating.  A major thrust of our extension programming during this time is to promote a wide range of ash alternative to increase species diversity.  One of the challenges we find in making this pitch is that many of the species we recommend (oaks, hackberry, baldcypress) are trees that nurseries often find difficult to grow from standard bare-root liners.


My graduate student, Dana Ellison, is in the second year of a project to look at some of the practices that growers use on the difficult to transplant species and some of the underlying causes of poor transplanting.  Dana is looking at a variety of attributes including plant water relations and carbohydrate status, but the order of business these days is roots.  Specifically we’re evaluating root growth potential of oak, baldcypress, and hackberry.  We’ve also included white ash, which transplant easily, as a positive control.

Graduate research assistants Dana Ellison (right) and Brent Crain (left) and undergraduate assistant Arriana Wilcox (center) pot up shade trees for root growth potential testing.

Root growth potential (RGP) is a common parameter in evaluating quality of reforestation seedlings but is measured less often on larger liner material.  The logic is pretty straightforward; a plant’s ability to initiate root growth after plating and re-establish root-soil contact is one of the biggest determinants of its ability to survive and grow.  A variety of systems have been used to evaluate RGP for seedlings – most involve growing seedlings for a set time (3 weeks is standard) in an aeroponic system and then counting or measuring new root growth.

Growing the trees in pea gravel makes it easy to get a look at new roots.

For Dana’s shade tree liners (5’-6’ whips) we’ve adapted a system based on the Missouri gravel bed system (which I first got to see in person at Jeff’s research nursery in Minnesota – thanks Jeff!).  Dana and her helpers pot the trees up in pea gravel in 25-gallon containers.  The trees are grown on for three weeks in a greenhouse while the roots are kept moist with spray stakes operated by a mist system timer.  After three weeks, we dump out the gravel, wash the root systems, and carefully count the number of new, white root tips.

Dana washing roots.

So what have we learned?  Well, the work is still on-going but some trends have emerged.  Baldcypress may experience some transplant issues but they don’t appear to be related to producing roots.  We had several baldcypress trees that produced 400 or more new roots during the RGP test – and, yes, we counted them all!  Red oak and northern pin oak, on the other hand, are very slow to put out new roots.  For hackberry trees, our other measurements suggest their transplanting issues may be related to their inability to re-hydrate after lifting, storage and transport.  These insights should help us provide some guidelines to growers to help them produce a wide pallet of trees for the landscape market and increase species diversity in the wake of EAB.

Counting roots.  Almost as much fun as it sounds…

The defending champion baldcypress: 614 new roots.

Mystery pits revealed

I’d turned Friday’s picture on end to try to fool you…but to no avail.  Deirdre and Gail both guessed woodpeckers, and yes, this is sapsucker damage:

Though some woodpeckers look for insects under the bark, sapsuckers drill neat lines of wells that fill with sap.  The birds can then move down the line of wells, lapping up sugar water.  (Kind of the avian version of lining up tequilla shots on the bar.)  Healthy trees are generally not at risk of dying from drilling injury, though if the tree is completely girdled that would be a problem.  Trees stressed by other factors could be also be killed by this final straw.

(Deb and @s both thought the photo might be a cactus skeleton, and it certainly looks like one!  Hadn’t thought of that myself.)