Should I boycott cypress mulch?

It’s hard to think of mulch as a controversial topic but, as with most things these days, we find people on both sides of an issue.  And, as with most things these days, some of opinions are based on substance, others are not.  In the southern U.S. some environmental groups are advocating a boycott of cypress mulch.

Cypress mulch is derived from baldcypress and pond cypress, which grow in ecologically sensitive wetlands in the Southeast.  Cypress wood is highly valued for is natural decay resistance.  Florida and Louisiana are the leading states for cypress harvesting for timber and other products.  In Louisiana it is unclear if cypress is logged solely for mulch but cypress harvesting for mulch does occur in Florida.  According to Dr. Jim Chambers, professor of Forestry at Louisiana State University and Chair of a governor’s science panel on forested wetlands in Louisiana, cypress mulch production is a sensitive issue.  “Many of our cypress-tupelo forests are in a severe state of decline. As you can imagine, these forests are very important to south Louisiana for many reasons. Areas permanently flooded, areas that are flooded for substantial parts of the growing season, and areas subjected to salt water input cannot regenerate. The amount of forested areas with these conditions continues to increase as subsidence increases, coastal wetlands are eroded by storms and human impacts on hydrology continue to degrade many sites.”

The inability to regenerate new stands of cypress is an important concern and calls into question the sustainability of cypress harvesting on these sites.  Chambers is working with environmental groups and others to develop a process to certify that mulch is produced from sustainable forest harvest operations

Another issue related to cypress mulch is a claim that is circulating in parts of Michigan (and perhaps elsewhere) that cypress mulch is linked to cancer.  I conducted a search of the National Library of Medicine and National Institutes of Health literature database ( on ‘cypress’ and ‘cancer’.  The only hits I found were related to studies looking at falsecypress (Chamacyparis) extracts for anti-cancer properties, similar to taxol.  The claims of cypress mulch and cancer may be an amalgam of the environmental concerns over cypress harvesting discussed above and concerns over use of mulch derived from CCA (chromated copper arsenate) treated wood, which is used for decking and other uses similar to cypress.  Research has shown that leachate from mulch containing CCA treated wood can have elevated levels of arsenic and metals above established health standards.

We all know Linda’s fondness for wood chips as mulch.  My personal favorite is ground red pine bark for its durability and natural appearance.  The key is to look for renewable mulch products that are locally sourced.

Epicormic mystery solved!

Good morning (at least it is in my time zone)!   And welcome to those of you who found us through Blotanical or another blog site.  We love seeing the increased participation on our blog.

Since I am a teacher at heart, I was glad to see so much thoughtful discussion over the weekend.  Many of you suggested that pruning for vehicular traffic was the trigger for this growth, and it’s true that removing large limbs or heading back branches will result in vigorous epicormic growth.  But I cheated on the photo and cropped it above the point of interest.  Here’s the entire photo of this tree:

You can doubtlessly see that dark line encircling the trunk just above the two branches with the shoots.  Here it is close up:

Venturing around to the back of the tree, we can see the source of this line – neglected staking wire that has now been enveloped by the trunk.

What this wire has done is to girdle the phloem elements, which as you’ll remember from basic plant science, are directly below the bark and the cork cambium.  Without functional phloem, nutrients from the crown can’t reach the roots.  Since the two lower branches were spared this girdling, they can still transport sugar to the roots, so the tree hasn’t died.  But now it’s directing resources (water and nutrients) into the lower branches, where the new epicormic shoots are forming a new, functional (albeit ugly) crown.  In time, the original crown will probably fail; there’s already evidence that the trunk is dying:

What could be done with this tree?  If the wire were removed or at least cut so that the trunk could pop it apart, there is the possibility that the crown could have been saved.  But since the upper trunk already looks severely compromised, it’s probably too late.

As a sad update to this set of photos, the owners had a tree “service” (I use the term loosely) to remove all the epicormic shoots from the lower limbs!  I will let you know when and if the whole thing fails.

Oh, and gold stars to all who participated in the quiz!

Quiz time!

One of the things we Garden Professors can do is give tests!  And the nice thing is you don’t get penalized for being wrong.  So this will be my inaugural Plant Puzzler.

Below is a photo of a tree with epicormic shoots on its two lower branches.  Epicormic shoots are vigorous, upright branches that have more of a juvenile than mature appearance.  They often appear when a plant has been stressed, perhaps by overpruning, or maybe the roots were damaged by construction:

So here is your test question.  Why are these epicormic shoots primarily (if not exclusively) on the two lower branches, and not elsewhere in the crown?  (You can’t see the top of the tree, but I promise there are no epicormic shoots up there.)  And what evidence would confirm your diagnosis?  While there is only one correct answer for this particular tree, let’s see how many possibilities you can come up with.

Answers and more pictures next week!


The Flap Over Burlap

This month’s issue of the Oregon Association of Nursery’s Digger magazine includes the second part of a two-part article on urban foresters’ perspectives on nursery stock.  It was interesting to note that some urban foresters felt they were in a quandary because their specs require removal of burlap from B&B trees, yet many nurseries will void their warranty if burlap is removed from the root ball.

Removing burlap from B&B trees is a practice that is widely recommended, yet there is little, if any, data to support it.  The logic, of course, is that burlap will prevent root egress into the surrounding soil after planting.  But is this really the case?  We conducted a study a couple of years ago using 3” caliper B&B green and white ash trees as part of a trial on the movement of a systemic insecticide (imidacloprid) for treatment for emerald Ash Borer.  Since we were using radioactive carbon-14 as a tracer, safety regulation required us to keep the trees contained.  The trees were dug with a 36” tree spade and placed in burlap-lined wire baskets by a local nursery (Discount Trees. Inc.) using their standard procedures. For the study we placed the root balls in large orchard boxes backfilled with top soil.  We removed all ropes and the top of the burlap.  The trees were used for a study that lasted two growing seasons.  At the end of the second season we conducted whole tree harvests on a sub-sample of the trees.  My vision for the root system harvest was that we would simply chain up the baskets and pop the trees out of the boxes; the burlap would help contain the roots, right?  Wrong.  Separating the root balls from the boxes became a major ordeal that involved a whole lotta shakin’ with the front-end loader.  Once the root balls were finally extracted it was obvious that the burlap provided little resistance to root egress into the surrounding soil.

burlap roots
My former grad student, Grant Jones. “He said it would come out easier than that…”

Mike Kuhns at Utah State University conducted a trial several years ago (J. Arbor. 23:1-7) in which he observed a similar phenomenon.  Mike compared root egress of B&B maples with burlap removed versus a single or double layer of burlap by calculating a RTRATIO which was based on the amount of the total root system weight that was found outside the original root ball.  There was no difference in the RTRATIO between trees with single burlap and trees without burlap at any date during the 2-year study. Double burlap decreased RTRATIO initially but there was no difference by the end of the study.    Annela et al. (Arb. & Urb. For. 34:200-203) compared various growth parameters of baldcypress, plane tree, and freemani maples transplanted bare-root or B&B with only the top of the burlap removed.  After two years the only statistically significant difference was an increase in shoot growth for the B&B maples.

So what does it all mean?  My personal opinion is that when it comes to establishing trees in the landscape we spend way too much time worrying about trivial matters like this.  (Digging a planting hole 3X the width of the root ball and amending backfill are others but we’ll save those for another post).   Matching species to site, quality planting stock, and proper after transplant care – especially mulching and irrigation – are way more important but still neglected.  If we plant quality plants in the right place and take care of them properly the first two years after planting we would eliminate 80%+ of the transplant issues I see.  Burlap or no is a tempest in teapot.

Chad and Jeff’s Excellent Nursery Adventure

About 3 months after I started my job in Minnesota I hired a technician to help me run the nursery and to manage research plots.  His name is Chad and he stands about 6 foot 4, has shoulders that threaten to pop the sides of the skid steer loader whenever he enters it, and he knows his stuff because he needs to (and even if he didn’t know his stuff you’d be scared to tell him that because he looks dangerous with his frightening Fu-Manchu moustache).  Currently Chad is responsible for day to day operations in the nursery as well as writing publications.  In other words he’s indispensible.  When you read a post from me, particularly when it’s regarding nursery or landscape research, you’re usually reading a combination of both of our thoughts.  

Over the years Chad and I have seen a lot of nursery stock; some of it good, and some of it bad.  Between us we’ve seen poor pruning, unhealthy root systems, pot-bound plants, trees planted in soil that was much too alkaline or acidic for them, trees planted in the wrong zone, trees sold that weren’t close to the size that they were supposed to be, trees that were girdled by critters, root systems completely eaten by voles and even a tree shot with a handgun.  I once saw a whole field of Japanese maples topped (basically topping is when you cut horizontally through a trees canopy to give it a flattop – talk about competing leaders and narrow crotch angles!).  Seeing that field almost made me cry – A planting worth $20,000 – $30,000 wholesale almost instantly became worth the price of kindling.  But we agree that none of that can hold a candle to Sara’s Nursery (Named after the owner’s daughter).

I received a call a few years ago from a nursery in western Wisconsin (which, for those of you who aren’t familiar with this part of the world, is much closer to the Twin Cities than to Madison, WI where the University of Wisconsin is).  The caller was very concerned that the plants in the nursery which she had been hired to run were failing.  Basically, their leaves were dropping and she couldn’t figure out why.  This was even happening to plants that we usually consider “indestructible” like potentilla.  I had never heard of such a thing, but it sounded like a soil problem and so I asked her to have some soil tests done and to send me the results.  She agreed, but she was distraught and asked me to come and take a look at her operation.  I balked at first, but after a few minutes of begging I gave in.  I asked Chad if he’d like to join me on a trip to the nursery the next day; he agreed and we were off.

The nursery that we found was a retail operation on a road which was once a major thoroughfare, but had been reduced to a minor highway when the interstate, which ran parallel, had been expanded.  Still, it seemed like a pretty good location for a retail nursery in terms of customer traffic.   After we parked the car Chad hopped out and began inspecting balled and burlapped evergreens while I joined the manager to look at their container stock.  It was a mess.  It was the end of summer when we visited, but the leaf drop made it look as though we were in the late fall.

I popped a potentilla out of a container and could find no roots reaching the containers edge.  Taking a closer look I quickly discovered one major problem.  These were bare root plants planted into containers filled with soil.  Soil is almost never a good thing to put into a container because it’s usually too heavy and prevents air from working its way down to the plant’s roots.  The gentleman who owned the nursery (not the manager – in most cases she just seemed to do what the owner wanted to do) was a farmer who had decided that it made sense to save money by using this soil which grew his field crops so well.   This nursery was buying bare-root plants, popping them into containers filled with field soil, and then selling them at quite a mark-up (by the way, this is considered an unethical practice).

This field soil was obviously a problem, but, while plants usually suffer because of the use of soil in containers, I didn’t think it was likely to cause the carnage that I was seeing.  I asked about their fertilizer and watering practices.  Both of those seemed reasonable and unlikely to cause a major problem.

Meanwhile, Chad came back to report on the evergreens.  Almost all of the evergreens (which showed signs of repeated shearing – good for Christmas trees — not good for the long term health of landscape trees) were missing needles close to the base of the tree and appeared to be suffering somewhat.  I thought it might be a water issue, particularly if city water were being used, and asked where it came from.  The manager told me that all of their water came from a well on site.  In this part of the world we frequently have issues with well water being too alkaline, but it usually doesn’t cause the type of damage that I was seeing here.  I filed water away as a possible, but unlikely cause.

I was pretty stumped, as was Chad.  Obviously we saw problems, but these just didn’t seem sufficient to cause what we were seeing.  The manager offered to show us the potting operation, we followed.  The first thing that struck me about the potting shed was that it seemed old, and yet the timbers themselves hardly showed any rot which is kind of unusual.  We asked when the shed had been built and the manager indicated that she had reason to believe that the shed had been built in the 1940s or 50s.

We entered the shed and noticed a large pile of what we assumed to be soil.  Nothing special.  Then our eyes began to adjust to the dim light and we realized that this was no ordinary pile of soil.  It was mostly white.  We were confused.  The first thought that went through my head was “what is this, cocaine?”  Then I thought, no, it must be perlite.  I looked at Chad.  His eyes were big and round.  I went over to the pile, poked my finger into it, and then touched it to my tongue.

“What the EXPLICATIVE DELETED is this place?” I asked Chad (OK, I may not have used those exact words, but it was something close).  The manager must have overheard.

“Well, it’s a potting shed now, but it was built to store salt for the highway” she responded. “That’s just a pile of leftover salt.  We stack our soil against it when it comes in.”

We tested both the soil from the pots and their irrigation water.  Both were ridiculously high in salt (and, not coincidentally, sodium levels).  In fact, salt levels were high enough in the irrigation water that it would literally burn foliage off of the plants.

Shortly after visiting this nursery Chad became a Buddhist and my beard turned more gray than brown.  I can’t swear that it was this nursery that caused these changes, but I can tell you that I haven’t been the same since.

EverGreen or EverYellow?

In last week’s post I mentioned that many tree problems can be difficult to diagnose and require a thorough inspection and site analysis to get to the root of the problem.  In contrast, a recent issue that has generated a lot of calls is easy to explain and is not a cause for major concern.  Many homeowners and others are alarmed that needles on their white pines are turning bright yellow.

“Is my pine dying?”

The key in assessing this situation is looking at which needles are turning color.  Except for southern pines, most conifers produce only one, single flush of new needles each spring.  Because of this, we can work our way down a shoot and tell when each group of needles was formed.  The outermost needles were formed in the current year, needles in the next internode were formed the year before, needles formed in the next internode were formed the year before that, and so on.  Most evergreen conifers keep their needles for 3-6 years and then the needles senesce and fall off.  The longest-lived needles, perhaps not surprisingly belong to bristlecone pines, which are also the longest living trees on earth.  Bristlecone pines, the oldest of which is over 4,500  years old, have needles that persist for 13 to 17 years.  But I digress, back to the white pine.  White pine needles last 2 or 3 years.  Each fall, many of the previous year’s needles turn yellow and senesce.  Since the needles often turn bright yellow and almost half the needles on the tree are affected it can certainly grab attention.  As long as only older needles are turning, the process is natural and there’s no need for concern.  On the other hand, if this year’s needles are dropping that’s another issue and warrant further investigation.

White pines don’t keep their needles very long.  As long as this year’s needles aren’t senescing, the tree should be OK.

Pining to learn more about conifers? The Gymnosperm database  is an awesome and authoritative site that has information on just about every conifer known to science.

Blog bizarre

Jeff’s post yesterday gave me the perfect opportunity to showcase the star of my bizarre book collection..  It’s called “Evolution of Botany:  More Fact Than Theory” written and published by Benjamin Zarr (author of several other books, including “Evolution:  No One Can Break Down My Theory!”)  Jeff, he’s written more books than you and I put together.

This book was “willed” to me by a dear colleague at Buffalo State College after he retired.  When I first received it, I tried to read a chapter, but found it impossible to finish.  Here’s an example of one of the numerous illustrations on a chapter about plant heredity:

The discussion around this illustration is too long for this blog.  Plus, it hurts my brain.  You might notice some interesting botanical terms, like “red paste” and “yellow dough” for instance.  Here’s part of the text on these details:  “I say red “dough” and red pastes always reproduce the color red because pollen always inherit a specific “melting” point.  When the heat of the sun warms the starchy contents of a seed or the pastes of a seed coat red has the lowest melting point therefore it shows up before any other color.  Just like in a specturm of light red appears first and purple last, all other colors come in between.  When red has been eliminated it fades into pink, then into the color with the next higher melting point until white appears as the hardiest color of all.”


Not content to write just about plants (which evolved after animals, but that’s a whole different chapter), he ventures into the evolution of animals:

Words fail me.  (But they don’t fail a reviewer for the Quarterly Review of Biology, which you can read here.)

Though this book is an extreme example, it fits in with Jeff’s post yesterday about critical thinking.  (If you’re interested in the dissection of yet another book – The Sound of Music and Plants – click here for an online column of mine from 2003.)


Posted in honor of Garden Rant’s Halloween-related garden photo contest.

Pick me, Amy, pick me!!!

Now For The Scary Part

This little dude is the Florida Semaphore Cactus, native only to hardwood hammocks in the middle and lower Keys. According to the Center for Plant Conservation, Opuntia corallicola may very well be the most endangered plant in the United States.”  Only one wild population remains (eight individuals), plus a few sites of re-introduction. Loss of habit and an exotic cactus moth have contributed to the demise of this most personable of cacti.

Arbitrary travel tip: I snapped this photo during a recent visit to the fabulous Key West Tropical Forest & Botanical Garden. Please pay them a visit if you’re ever in the vicinity – they are doing so many great things, with so little $$$, as is the case for many small public gardens. And then head straight to Kelly’s on Whitehead Street for outstanding $3 margaritas…served in a pint glass!

Alternatively:  "Aieeeee!

As Bad As It Gets?

Last week I took a look at old, out of print books that are worth finding and reading.  This week I think I’ll take a slightly different track and instead turn my attention to a book that is currently in print, but which shouldn’t be.  In fact, 1001 All-Natural Secrets to a Pest-Free Property by Myles H. Bader can be found in many bookstores, was actually one of the best selling garden books of 2006, and is still selling today.  There are other books that I have problems with (Jerry Baker comes to mind) but when considering the worst of the worst this book is all by itself.

I was first introduced to Dr. Bader (he reportedly has a doctorate in Preventive Care from Loma Linda University) one night when I couldn’t sleep.  He was on one of those “paid programming” shows talking about homemade cures for insects around the house.  Normally these half-hour long advertisements cure my insomnia, but not this time.  As someone who loves to learn about and test homemade remedies I was mesmerized by his recommendations and quickly ordered the book.  Sure, on the show he seemed to “dumb things down” a little, but here was a bonafied professor who might have some really cool stuff for me to look at!  I couldn’t wait.

After I received the book I discovered that Dr. Bader used the English language poorly.  This didn’t turn me off to the book though.  I’m pretty forgiving of bad English.  I know that mine isn’t the best and there are sections in all of my books which still haunt me.  Still, the sheer number of errors in Bader’s book was staggering.  For example, here’s a paragraph from page 3:  “His interests have always been in the field of food and cooking and many of his books are related to helping the chef or cook with cooking and kitchen secrets that may gave been forgotten over the years.  This has lead him to include household hints and other related subjects in his books.”   (yes, the words gave and lead are used in the book exactly as they appear above).  And this is just the first page with a significant amount of writing!

Still, I didn’t buy this book for good editing; I bought it for cool, “all-natural” cures.  And so I turned the pages hoping to find something useful.  On page 23 I discovered that the insecticide “Sevin” is organic and is composed of pyrethrums and diatomaceous earth (This is completely wrong, the active ingredient in Sevin is carbaryl, a synthetic insecticide).  I also learned, on the same page, that mixing horse manure with hot water, letting the mixture cool, and then spraying it onto fire ants will kill them (What!?!!?).  There are no instructions about how much of the manure or hot water to use.  Other interesting remedies that you should probably avoid include spraying hairspray onto flies to kill them and using a mixture of 1/3 cow manure, 1/3 sand, and 1/3 clay to coat the trunk and branches of a tree infested by aphids (I’m not sure how this would work since most aphids attack the leaves of trees…). At the end of the book there is a glossary where I learned that Rotenone is a low toxicity poison (never mind that this organic poison was recently voluntarily withdrawn by its makers for use as an insecticide at least in part because of safety/health concerns).  Indeed, almost every organic pesticide was treated lightly, apparently simply because they’re “natural” (which, as some of you may know, is a pet peeve of mine).

The interesting thing about this book is that there were a few useful tips, but with so much hooey it was often tough to tease those tips out.  If you’re one of those people who thinks that a book can be so bad that it’s good then you might enjoy paging through this book, but, other than that, I think this book is best used as a doorstop.

And now I have a challenge for all of you.  Does anyone know of a worse book?  (and, if so, where can I buy a copy?)

Whoo hoo!

I promise I’ll post something more substantial today…but I had to pass this email message along that I received this morning.  Way to go colleagues and commenters!

Hi Linda,

Your new weblog, the Garden Professors, is an impressive piece of work! I plugged it today in the consumer horticulture CoP blog [].


Bill Hoffman
National Program Leader (Ag Homeland Security)