Sheep-eating flowers?!

I was planning to follow up on Jeff’s phosphorus post with a bit more “phun with phosphorous.” However, I was completely derailed by Ray Eckhart’s message and link left for me on our GP facebook page with this headline:

RHS ‘sheep-eating’ plant about to bloom in Surrey

“The Royal Horticultural Society (RHS) at Wisley said the Puya
chilensis, a native of Chile, would bloom in the next few days and last
about a week.

In the Andes it uses its sharp spines to snare and trap sheep and other animals, which slowly starve to death.”

“The animals then decay at the base of the plant, acting as a fertiliser.”

[Dear BBC News: “Snare” and “Eat” are not really interchangeable]

How…have I not heard of this before.

I’ve posted previously on my Puya fixation. I asked readers to bet on how long it would take for me to kill my wee Puya bertoniana, mail-ordered from Annie’s Annuals. I am happy to report that it made through the winter (greenhouse) and is now sunning itself on our deck.

Now this really ups the ante – it captures sheep! Maybe P. bertoniana isn’t as robust as P. chilensis though. Perhaps…a vole or rabbit?

Phosphorus and Big Macs

Minnesota, and I were cruising through old pictures and files and getting all sentimental about the cool stuff we used to do. A lot of it was never published just because after we were done with one thing we were just too damn excited to move on to the next. Anyway, one of the neatest experiments that we never wrote up was a phosphorus experiment. Here’s what it looked like to the casual observer.

Now let me explain the neat part to you a little. Inside those boxes, underneath three of the six plants in each container, are vials set up like this – three vials per plant (the black tubes provide air to the vials).

Each plant had one root placed into each of the three vials – one vial contained 1 ppm phosphorus, one vial contained 10 ppm phosphorus, and one vial contained 30 ppm phosphorus. The tub itself was also filled with one of these three solutions (1, 10, or 30 ppm phosphorus) as seen below.

At the end of the experiment we weighed the roots filling each vial, as well as weighing all of the roots from each plant. Here’s what we found for the individual vials.

As you can see, more phosphorus in a vial meant that the plant would devote more energy to growing roots there – but also notice that the 10 ppm solution has the greatest mass of roots overall. Here’s what we saw when we looked at the total size of all of the roots from plants for the different solutions.

As you can see, the roots from the plants in the 10 ppm solution are the largest (shoots showed the same trend). So here’s the way I see it (this is the Big Mac part). I love Big Macs. If I see a McDonald’s I want to go in there – I gravitate towards McDonald’s to get Big Macs. But too many Big Macs aren’t good for me. They might even stunt my growth! It’s the same for phosphorus. Roots do grow towards phosphorus (this isn’t technically correct, but it works for my analogy so I’m sticking with it!), but that doesn’t mean that a tremendous amount of phosphorus is actually good for them. In fact, it might even stunt their growth! This could be for a variety of reasons, but most likely because the phosphorus would interfere with the uptake of other elements.

Label GMO foods? Sure, why not?

Lots of coverage in the mainstream media these days over various initiatives to label GMO foods. I think GMO foods should be labeled; but not for the reasons you might think.

My personal opinion on GMO foods is that their benefits outweigh the potential downsides. I think GMO foods should be labeled to make the public aware of how much of our food supply depends on GMO’s and the cost of not using GMO’s. Obviously this will raise some social justice issues since wealthy people will have more opportunity to opt out of buying non-GMO products than the poor but it’s the same problem we have with organic already and it doesn’t seem to cause much of a stir. My hope is that once GMO products are labeled we could get to the point where the main discussion on GMO’s focuses on the rational and scientific questions, not the irrational and emotional. This weekend our Sunday paper included a quote from a local anti-GMO activist who tried to link the rise in obesity to increased use of GMO’s. How about we’ve become too sedentary and we’re eating too much, period? Or this from the “Health Ranger” Mike Adams: “Roundup herbicide devastates soils, rendering them contaminated and unable to produce healthy crops using traditional (or organic) farming methods. Once a farm plot is destroyed with Roundup, that farmer is forever enslaved to a chemical-based farming protocol.” Hmmm… last time I checked farms could be certified organic after three years without synthetic chemicals.

Which is not to say I don’t have concerns about GMO’s; there are issues with any technology. The largest questions I see, and the ones that are most difficult to answer, relate to unintended consequences. One of the biggest selling points of Round-up ready technology, for example, is that it enables farmers to manage weeds with glyphosate, a relatively safe product in the world of industrial-strength herbicides, in order to reduce tillage and maintain crop productivity. But as farmers use more and more glyphosate, they are also selecting for Round-up resistant weeds. How long until glyphosate is no longer effective? Difficult to predict, but glyphosate resistance has already evolved in many weeds.

On the other side of the equation, the world’s population is projected to exceed 9 billion by 2050, with a disproportionate increase in the least developed countries. As the need for food increases, land and water resources will become more limited and catastrophic droughts are likely to increase. While it is easy to demonize industrial agriculture, it’s difficult to envision feeding ourselves and the world without the technology it has developed.

Moss-tacular!

Mosses are soft, green, and tough as nails, as shown in a recent article in the Proceedings of the National Academy of Science (prestigious, high impact journal with a rather unfortunate acronym).

Dr. Catherine La Farge and associates, from the University of Alberta, visited a remote glacier on Ellesmere Island, Nunavut while studying the wild, wide world of arctic bryophyte systematics. Bryophytes are ancient, non-vascular, non-flowering plants – mosses and liverworts, mostly.

Long story short, they harvested bits of moss that had been trapped in ice for about 400 years and were now exposed. Several species were collected, taken back to the lab, ground up, placed on growing media in a growth chamber, and they soon had mosses galore.

This is fascinating on several levels, as pointed out by the authors. One is the power of totipotency – the ability of a cell to “de-differentiate into a meristematic state that can then reprogram the cell for development of the organism” a la stem cells. Another is the mosses’ ability to “shut down” when dry and “revive when conditions are favorable” (like not frozen in ice for 400 years?!)

The article also graphs the disturbingly accelerating rate of retreat of the Teardrop Glacier, where the mosses were collected. Aargh. The window of favorable conditions may not be open long for these little wonders.

Lights!

Today I want to share something that I’ve been working on recently with Fine Gardening that is really cool! So you know all of those lights you can buy to get your plants started over the winter? Did you ever wonder which of those lights really work? I’m going to leave the final answer for my article, but let me tell you, there’s a world of differences between the lights. The best seem to be some LED lights that aren’t available yet, but are made by a company called Heliospectra. Mostly they make high end lights for commercial producers and researchers, but they will be entering the home market soon. Man, these lights are SWEET!

Interestingly, the other LED lights fail miserably because their light is so columnated (in other words the light doesn’t spread out), as you can kind of see in this picture (there’s another pic on facebook that shows it a bit better):

Most of you are probably using fluorescent lights, and, in terms of bang for your buck, I’d say those are pretty good. We tested a bunch of different fluorescent, as well as incandescent lights. Be on the lookout for the article in about a year!

The Canary in the Coal Mine

Three weekends ago marked a milestone of sorts as mean daily CO2 levels at the National Oceanic and Atmospheric Administration observatory at Mauna Loa, Hawaii topped 400 ppm for the first time ever. Rising levels of CO2 and other greenhouse gases could result in significant increases in temperature in the Upper Midwest over the next century. When we think about trees in cities the scenario is even worse since not only will urban trees have to deal with overall temperature increases but they must also contend with urban heat island effects, which can add another 8 deg. C or more of heat load. Because of this ‘one-two punch’ of global climate change and urban heat island effect, I often refer to urban trees as the proverbial ‘canary in the coal mine’ with respect to climate change since they will likely be impacted sooner and more dramatically than trees in woodlands.

In general, organisms have three options to deal with a change in their environment: They can migrate, they can adapt, or they can acclimate. Since trees are sessile organisms, they can’t pick up and move so migration is out. Current predictions are that climate will change faster than trees can evolve so natural selection and adaptation will be limited. Which leaves us with acclimation, or the ability of a tree to adjust its physiology and morphology to its environment. A common example of an acclimation response is the development of sun and shade leaves on the same tree. Another example of an acclimation response is an increase in the optimum temperature for photosynthesis in response to exposure to increasing temperatures. In theory, trees that have a greater capacity to adjust their physiology to increasing temperature will be better suited for future, presumably warmer climates.

We are currently testing this idea in a two-part study. In part one we are growing trees from several shade tree cultivars in greenhouses under three temperature regimes; ambient temperature, ambient + 5 deg. C, and ambient +10 deg. C. In part two of the project we planted trees of the same cultivars in two sites in Detroit in cooperation with the Greening of Detroit. The Greening of Detroit is community based non-profit organization that assists neighborhood groups, churches and schools in their efforts to improve the ecosystem in Detroit through tree planting projects, environmental education, urban agriculture, open space reclamation, vacant land management, and workforce development programs.

Many hands make light work. Greening of Detroit volunteers plant trees along a street median.

With the help of Greening staff and about 90 Greening volunteers, we recently planted 160 shade trees in downtown Detroit. One site of the study is in a park, representing a relatively mild micro-climate; while the other site is along a street median surrounding by asphalt with a much higher reflected heat load. Both sites with be instrumented with environmental sensors and we will compare growth over time as well as physiological responses such as the response of photosynthesis to temperature. The long-term goal is to identify traits that will be most important to guide future selections of trees of urban and community forestry under changing climatic conditions.

Research Technician Dana Ellison (left) and Research Aide Aiman Shahpurwala finish planting a park tree.

A pick ax as a planting tool? Dana shows how it’s done in Detroit.

Should back-fill be amended? My usual answer is ‘no’, but then again it depends what your back-fill looks like…

Sizing things up. Aiman and Dana collect initial data on trees after planting.

Container planting: intuition vs. reality

I’m just starting to think about getting my containers planted for the summer and happened to get an email on the topic from a blog reader. John was frustrated with a local columnist’s advice on using gravel in the bottom of the containers for drainage. When challenged, the columnist refuted John’s accurate comments with “logical thinking.” (You can find the posting and comments here.)

Here’s part of the post: “I like to cover the hole with a layer of gravel to improve drainage. Plants need to have their roots exposed to air in the soil to survive and thrive. If the container has no holes for drainage, it will fill with water and drown the plants very quickly. It is better to keep your plants on the drier side than to keep them constantly moist or wet. The big danger in using pots is drowning plants.” Later, he goes on to explain “The potting soil plugs up the drain hole and the water is trapped behind the plug. The layer of gravel creates an area for the water to drain through to escape. The creation of drainage commonly involves a layer of gravel.” This reasoning is part of what he calls “Logical thinking 101.”

As my husband pointed out, this isn’t logical thinking: it’s intuitive. It’s what we think is going to happen in the absence of any evidence. And in this case, it’s wildly inaccurate.

Jeff and I have both discussed the phenomenon of perched water tables in containers as well as the landscape in previous posts and on our Facebook page. The fact is, when water moving through a soil reaches a horizontal or vertical interface between different soil types, it stops moving. Here’s a photo from a very old research paper on the topic:

A layer of silt loam sits above a layer of sand, and water from an Erlenmeyer flask drips in. Intuition says that when the water reaches the sand, it will move more quickly through the sand because the pore spaces are larger than those in the silt loam. But intuition is wrong, as this series of photographs clearly demonstrate. Water is finally forced into the sand layer by gravitational pressure, after, of course, saturating the silt loam.

Intuition has its uses (I am quite proud of my own intuitive powers), but it doesn’t trump reality.

**This is an older post, so I’ve added this link to a peer-reviewed publication on the topic by Dr. Jim Downer and myself.**

Buying locally-grown plants

Of course we want to buy locally-grown plants! There are a gazillion sound reasons to do so. In a paper that may be from near here, or not, I perused the gardening column over Sunday coffee, written by (a human) (name withheld to protect the very, very nice and usually accurate author). But in this particular article, the writer ventured deep into huh? territory.

And that territory is my area of expertise: nursery and greenhouse production and marketing. My favorite talk to give to gardening groups is “From Grower to Garden Center.” As the Garden Professor Least Likely To Get Riled Up, it pains me a bit to even bring this up when someone’s willing to crank out a column week after week. Heck, I haven’t been able to write anything lately, accurate or otherwise. The bulk of the article was correct and positive, plus promoted a great local grower (of which we have very, very few), BUT there were a few statements made that I thought might make good points for clarification (teaching moments) and maybe generate some discussion.

“Just like locally grown food, a locally grown plant is going to be much easier on the environment. Transportation and fuel costs are lower, and carbon footprint emissions are decreased. Plus, without a need for the special packaging to ensure a safe journey across the country, less packaging ends up in a landfill.”

I’ve unloaded plenty of trucks – the only things that use any “special packaging” are poinsettias and sometimes florist mums – sleeves and or boxes. “Cross-country” is rarely the case, even for big box stores – they work with regional growers (albeit large ones) for annuals and perennials. However, the writer’s point is well taken in that even here in the “far east,” some independent garden centers and big box stores get shrubs and trees from the west coast (Monrovia must give them a heck of deal). One of our two local garden centers carries Japanese maples from Monrovia; this retailer is located less than 10 minutes from a nursery that specializes in Japanese Maples. Go figure.

“Beyond the environmental impact, when you buy a locally grown plant you usually are buying a healthier plant. It will already be accustomed to our native soils and growing conditions.”

“Usually” is a good qualifier here. Regarding health, I’ve seen amazing quality from far, far away, and real crap from a couple local growers. Local does not automatically equate to pest and pathogen free, well-rooted, non-stretched, or any other criteria for quality. The second sentence, however, has haunted me for a week. Nursery and greenhouse plants are grown in soilless media – peat or peat alternatives; pine bark; fir bark; etc. How can that particular plant be accustomed to “our native soil”? To put a finer point on it, what, exactly, IS our “native soil”? Our own 19 acres has yellow clay, red clay, forest duff, sandy loam, loamy sand (I made that one up), and everything in-between.

Regarding growing conditions, your spring-purchased plant has most likely been in a controlled environment of some degree, whether a greenhouse or coldframe. If I went shopping at any retail greenhouse or garden center (which I probably will do this weekend), I would probably purchase some plants right out of the greenhouse. Of which they are accustomed.

“And, with less travel time, the plant is less likely to be stressed by excessive handling and is less likely to be over watered or over fertilized.”

On the truck, off the truck. Place on retail bench. This is how a plant would be handled whether it was grown by a local wholesale nursery 10 miles away or 1000. How excessive is that? And why would travel time cause over-watering or over-fertilizing? If anything, the inverse is true.

“New gardeners can be assured that they are buying a variety that grows well in our climate, as local growers supply what grows here. The plant will be put out for sale when it’s actually time to plant, not when a buyer across the country wants to sell it to you.”

Grows well? What grows here? I’m not even sure where to begin with that bit of information. Isn’t that part up to the gardener, new or otherwise?

And wherever you may live, I guarantee there were plenty of tender annuals, tomato transplants, and other jump-the-gun goodies available for sale from your local grower or garden center 45 days before your last frost date. What IS true – a good grower/retailer or garden center staffer won’t let you leave without a gentle (or not-so-gentle) reminder to keep ’em in until after last frost. To which I always nod, agree, and then commence with trying to produce the earliest tomato in the tri-county area. Because I’m an expert.
*snort*

Rubbing salt into wounds

Last week I posted about some horticultural disasters I witnessed in the Czech Republic. This week the chamber of horrors is little closer to home; virtually in my back yard to be specific. Our property backs up to US 127, the main North-South through route in our area. It’s a limited access highway with a posted speed of 70 mph, which means an average speed of 82.7 mph. It also means the road is regularly salted whenever it snows during the winter. As a result, some plants along the highway really take a beating, sometimes with some interesting results.

On Friday I received an email from Susan Gruber, our Undergraduate Advisor, who also commutes on US 127. “Hey Bert, Have you seen the pear trees on the east side of NB 127 just south of the Round Lake Road (and Price Rd) exits? Street side fried, shows up great with flowers on the other side. Also same trees planted at the same time doing great by the ramps, farther from the road, slower traffic, some up on the berms etc. Make great GP fodder, but I didn’t have a decent camera or the guts to pull over and do phone photos in rush hour.”

Unaffected pears upslope and away from salt exposure

Indeed I had seen the trees. As Susan noted, the sides of the trees facing the highway were fried, the opposite sides were in full bloom. I got a few photos over the weekend but the effect was a little less striking than earlier in the week when the trees had blooms but hadn’t begun the leaf out.

Pear trees in the line of fire

The planting illustrates a classic example of wrong tree-wrong place. Interestingly there are several crabapples that were installed as part of the same planting project that seem to be doing well. Selecting trees for exposure to deicing salt is a dicey proposition since, like this example, most of our information is anecdotal. Where the effects of deicing salt on plants have been systematically examined, the studies may focus on only soil exposure or only aerial deposition; whereas trees in the real world get it with both barrels.

Eastern white pine after one winter at a rest area along I-96 east of Lansing. An ideal proving ground for salt tolerant plants.

Ironically a colleague of mine in our department and I put together a proposal several years ago for our state Department of Transportation (MDOT) to identify salt tolerant plants for roadside plantings. Our plan was to install a series of replicated plantings of perennials (trees, shrubs, herbaceous perennials) at highway rest areas throughout the state. We would then correlate plant performance with degree salt exposure and identify plants that could survive, grow and maintain their aesthetic value under the highest salt loads. Initial discussions were positive until the proposal worked its way up the chain of command. Finally it was determined – I am not making this up – that MDOT could not participate in a project on indentifying plants that were tolerant of deicing salts because that means they would have to admit that salt was causing a problem. OK; just don’t tell the trees on US 127…

In our studies we rate plants on a scale of 1 (alive) to 5 (dead). These are class 4 (wish they were dead…)

Five little lavenders…four years later

If you’ve been following us for a while, you might remember a post from August 2009 when I got cranky about a pot of lavenders with horrendous root systems. I intervened with my Felcos and planted out the patients, hoping for the best.
Lavender #2 before root pruning

In July of 2010, I gave an update on their progress. At that point, one of the lavenders had died but the other four were perking along. And now it’s time to show them in their floral glory:

Root washing is still controversial, as is corrective root pruning. However, all five of these plants would have died had I not corrected the spiraling root systems. Published and ongoing research at several places around the country continues to support the practice of bare-rooting and correcting root flaws of woody plants.

Is this a practice that the landscape industry will adopt? Probably not on a large scale: it is time intensive and requires careful work. But home gardeners can do this themselves and have done so successfully.

If you’re interested in more information on how to do this, you can download this fact sheet. Until production nurseries change their practices to avoid these fatal root flaws, it will be up to home gardeners and a handful of landscapers to repair the damage.