Among other things, part of my job involves reviewing educational materials for use in WSU’s Extension programs related to urban horticulture. One of the books is “Gaia’s Garden: a guide to home-scale permaculture” (T. Hemenway). It occurred to me that my review might also be of interest to our GP readers.
I’ve created a fairly extensive review and I will break it into separate posts over the next few weeks. So let’s start the discussion off with a topic we already know is inflammatory: invasive species. To be clear, we are not talking about the many introduced species, plants and animals alike, who appear to be well-behaved in our country. Here’s my take on “The Natives versus Exotics Debate” (pp. 12-17):
The author, with no formal training in biology past his bachelor’s degree, states that “calling a species ‘invasive’ is not good science.” This will come as news to researchers in the field of invasion biology. He blithely disregards the real environmental and economic damage caused by invasive species and erroneously believes that invasive species selectively appear only as a result of human-caused environmental disturbance. Apparently natural disturbances (from fire, volcanic eruption, flooding, etc.) don’t open themselves up for invasion (again, a notion that is incorrect and refuted by a number of obvious examples, such as the 1988 zebra mussel invasion of Lake St. Clair and the subsequent colonization of many freshwater habitats). The author seems not to understand that there may be unfilled niches in certain ecosystems that can be exploited by invasives, endangering native species whose niches may overlap; there are obvious lessons from Hawaii, Australia, and other parts of the world. In any case, the author’s naive tolerance of invasive species is a poor example to follow and certainly not based on current, mainstream science.
So, fans of permaculture, what do you think? If permaculture is a legitimate science-based practice, how do we reconcile the very real issue of invasive species? If you disagree with me, keep in mind one of the hallmarks of pseudoscience: attacking the motives or character of anyone who questions the claims. The arguments should contain content, not insults.
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With the advent of Spring comes a myriad of calls on distressed plants from homeowners, nurseries and landscapers. One of our better tree service companies (I’ll call the owner/operator ‘Mark’ to protect his clients’ identities) in southeastern Michigan called with a series of problems this spring so I decided to take drive over and get a first hand look. We looked at several problems on plants ranging from trees to ground covers but there soon emerged an consistent thread: overwatering. Plant problems related to overwatering and poor soil drainage are among the most common landscape issues I see year in and year out. The stops I made with Mark last week were typical. Mark works in several very affluent suburbs around Detroit (I know readers around the country don’t associate Detroit and affluence, given our recent press, but there is still some serious money in the area). Some of Mark’s clients spend up to $20,000 per year just to maintain the trees and shrubs on their property – that’s not including lawn maintenance. Needless to say, these folks want everything perfect. In their effort to have their landscape look more perfect than the neighbors, the homeowners and their gardeners often go overboard – especially with irrigation. One of the things that caught my attention during our site inspection was recurring issues with Norway spruce. For the most part, we regard Norways as a cast iron plant and one of the last trees with which we’d expect to have problems. Yet we saw several instances were established specimens were suffering needle die-back and declining.
In each case the trees were irrigated in situations where they would likely grow well without supplemental watering. But the trees were surrounded by ground covers or annual beds with heavy soils that were heavily irrigated. Problems usually increased on down-slope positions.
The solution? Back off the irrigation. Everyone knows trees need water, but roots their roots also need oxygen. At one site we visited, the homeowner already had his gardener running the irrigation system – in April! This is truly killing with kindness. Most established landscape trees, shrubs and perennials in this part of the world need little, if any, irrigation. Newly planted trees and shrubs need an occasional (weekly to bi-weekly) drink in the first year and some follow-up the second year. After that they can manage most years on our rainfall. In the end, a lot comes down to design. Establish thirsty annual beds where they can be irrigated without drowning hardier trees and shrubs.
As with last week, this past week and weekend were largely occupied by my role as a faculty advisor for the MSU Horticulture club. This weekend was our annual Spring Show and Plant Sale. Each year our undergraduates commandeer the Horticulture department’s conservatory, bring in a boatload of plants, pavers, turf and mulch and design and install a landscape. It’s actually quite a process to watch. http://www.youtube.com/watch?v=4NTPzB6YVSk
In addition to the Spring Show the Hort Club puts on a plant sale, which is the group’s principle fund-raiser for the year. My duty station for this year’s plant sale was working outside in the tree sales yard. For the record, retail is not my thing but, hey, it’s for a good cause. The star of our tree sale this year was a container-grown 14’ dawn redwood (Metasequoia glyptostraboides).
For those not familiar with this tree, dawn redwood is an incredible tree. It’s a deciduous conifer, similar in many respects to bald cypress (Taxodium distichum) but with a finer, more refined character. Metasequoia is considered by some to be a ‘Living fossil’, similar to Gingko biloba. The genus Metasequoia was originally described in 1941 from Chinese fossils from the Mesozoic era. Although local people in China knew the tree and used it as an ornamental, living trees were not formally described by botanists until 1948.
Dawn redwood is well adapted to wetter sites
Seed collected by Arnold Arboretum in the late 1940’s were distributed to universities and arboreta and this attractive, fast-growing tree found its way into the nursery trade. Ironically, millions of Metasequioa have been planted as ornamental trees but the species is considered critically endangered due to loss of its native habitat in China. Dawn redwood is extremely fast growing and some trees planted in the U.S. from the original collections in the 1940’s are reportedly 3’ in diameter.
Dawn redwoods on MSU campus
So, how did I fare in nursery sales for a day? Put it this way, I better hang on to my day job; retail is still not quite my thing – though I did move the dawn redwood and got to spend a good bit of my weekend talking about this awesome tree.
It was fun to read all of your comments last week about your opinions on lawn care. To follow up on it I’m going to talk a little bit about why I’m not fond of companies which apply herbicides multiple times throughout the year. But first I think I’ll mention why I apply herbicides at all — aesthetics. That’s it — the whole reason. Could I go the no-lawn route? Yes, but I like having a yard to run in. Not a huge yard, but a little yard to play tag with the kids.
What I long for though is the yard from the house that I grew up in. Our house in southeastern PA (About an hour west of Philly and an hour east of Lancaster) was set back about 800 feet from the road and was on old agricultural land. The area around the house was planted in grass in the mid 70s and then it was left alone. Fertilized once the first year I think, but that’s it. Dandelions invaded quickly as did clover. Over the years the clover began to dominate the grass, but not to the point that the grass disappeared, and the lawn actually appeared relatively homogeneous. Dandelions never left, but their numbers declined. The clover grew low and the grass never shot up like it does in a heavily fertilized lawn and so mowings only happened once every two weeks or so (well, OK, sometimes more often depending on the weather and where on the lawn you were — the spot over the septic tank needed mowing every 48 hours or so). The grass did go dormant most summers, but 800 feet from the road there wasn’t anyone to complain, and besides, the clover kept the lawn from appearing completely scorched. The lawn looked good for well over 30 years (until my parents remodeled the house and the yard was torn up).
The typical suburbanite might not have liked this lawn, but to me this lawn looked great, and, besides, it was low maintenance. The reason I’m bothering to tell you about this lawn though is because it illustrates so well what lawn care companies make impossible. They say (and by “they” I mean professors like myself) that pesticides beget pesticides and fertilizers beget fertilizers, and nowhere is that as true as in a well manicured lawn. The herbicide of choice is 2,4 D (though there are many others that are used) which lawn care companies apply multiple times over the the course of a year. This pesticide does a great job of killing dandelions, but it also kills clover. It rarely hurts grass unless it’s grossly over-applied. The problem with killing clover is that this clover is the stuff that fed the grass in the house where I grew up. Clover takes nitrogen out of the air and makes it available to grass every time the lawn is mowed (the clipped off pieces of clover degrade and the nitrogen in them feeds whatever plants are around). Without the clover you need to add fertilizers. So, because the lawn care company is keeping the lawn free of weeds they also need to fertilize because they’re killing all of the natural fertilizer. Here’s the thing, the weed that most people in the suburbs like least, dandelions, is actually very sensitive to low potassium. The lower the potassium in the soil the worse it does. In fact, dandelions can easily be out-competed by grass and clover if potassium is low — just as happened in the yard of the house where I grew up. But do lawn care companies pay attention to this (by using high nitrogen, low potassium fertilizers?) What do you think?
My guess is that many of you thought that I’d cite all kinds of scary side effects of the pesticides used on lawns. Nope. In general I think that, if used properly, they’re pretty safe for humans (with a few notable exceptions). I’ve spent a lot of time reviewing epidemiological and toxicology studies and I can think of many worse things. I am somewhat fearful of what 2,4 D may do to dogs in particular — they can’t excrete this poison like we can. Don’t think for a minute that I’m calling these poisons perfectly safe — I just think there are plenty of other better established reasons to avoid lawn care company pesticide schedules.
What do you get when you combine 900 wildly enthusiastic undergraduate students from 70 colleges and universities with 29 horticultural competitive events in a landscaping Olympics? The marvelous mayhem of the PLANET (Professional Landcare Network) Student Career Days. Last week, three of my colleagues; Brad Rowe, Tom Fernandez, Marcus Duck, and I traveled to Atlanta with 15 Michigan State University Horticulture students to compete at the 34th annual PLANET student Career Days hosted by Chattahoochee Technical College. The Student Career Days incorporates an array of activities including tours, workshops, speaker presentations and a career fair. But the unquestioned highlight of the event is the student competition. Students compete in 29 landscape horticulture events ranging from arboriculture to computer aided landscape design. Some events require physical skills such as paver construction and landscape installation; while other such as plant identification and sale presentation test the student’s plant knowledge or interpersonal communication skills. The logistics for the host school and event sponsors is truly staggering. For example, in the Landscape Installation event, 50 three-person teams are given a 12’ x 20’ plot of ground, identical landscape plans, and identical sets of plant materials (a 15 gallon tree, shrubs, annuals, sod) and given 2 hours to complete the installation. Likewise, in paver construction and wood construction, 50 two-person teams are given identical supplies, tools and a design and must complete the project in less than two hours. Awards are presented to the top three students in each event and the top ten teams overall. Beyond the awards, however, the program offers tremendous opportunities for student to network with industry leaders, meet and compete with students across the country, and challenge themselves and build confidence. We Garden Professors are sometimes given to being a bit curmudgeonly but spending a few days at this event will definitely restore ones faith and enthusiasm in the next generation.
For the record; Chattahoochee Technical College was this year’s SCD Champion followed by perennial powers BYU-Provo and BYU-Idaho. Michigan State was 10th.
Mitch Zost tackles tree climbing in the Arboriculture event
The Lanscape Installation event is the final and culminating event of the Student Career days. Think of the 4 x 400 relay with shrubs and annuals…
Zeke Kadish negotiates the treacherous Truck and Trailer course.
MSU Horticulture faculty members Brad Rowe, Tom Fernandez, and Marcus Duck capture the action for posterity.
Joel Franken found out that accidents can happen during irrigation assembly.
Yesterday evening I took my older daughter to dance class while my wife stayed home. While she was entertaining our younger daughter, the TruGreen guy came to the door to tell us that we had weeds in the yard (Damn, I had no idea!). He went on to tell my wife that we really needed to use his company to get rid of them. I was so disappointed that I missed him because I wanted to know all about what he had planned for our yard. Many of our neighbors use TruGreen and I have to say that I’m not particularly impressed. It’s not that they’re not professional — they certainly are. It’s not that they don’t do things by the book — they certainly do. It’s just that the book that we use is getting a bit outdated. When I read TruGreens online FAQ it looked like they actually plan six applications of chemicals per year. I’m assuming (I don’t know this for sure), that at least four of those include herbicides to one extent or another. It looks like people who have no tolerance for weeds should love TruGreen. But really, how many weeds should people allow in their yards? Is it one per square foot? Two? Five dozen? And what are weeds? Is clover a weed? At what point do we say enough is enough and that we’d rather just cope with a few weeds than hose down our whole yard with herbicides.
After reading my own words I feel like some kind of radical. In my job I tend to see two types of people, those who can’t stand pesticides and those who can’t stand weeds. One group is happy to spray five times a year if it means that their lawn will be weed free, and one won’t touch an herbicide. I’m not sure that either group is correct. I tend to handle weeds in my yard the same way I handle haircuts – I hate having my hair cut so I don’t go to the barber that often, but I do go to the barber eventually because my hair looks pretty ridiculous if it grows too long. I feel the same way about weeds (specifically dandelions) which infest the grass in my yard. I prefer not to add herbicides, but there’s a big weed bank in the area and so I end up needing to apply once every two years or so because otherwise it looks pretty bad. Rather than making either the making the weed-free lawn or the no-chemical group happy though I think that it just pisses them both off. They see my unwillingness to commit to one way or the other as a cop-out rather than reasonable moderation. What do you think?
Spring is off to a warm and fast start here in Michigan. March was unseasonably warm and the past week or so has seen temperature 20 degrees above average or more. Needless to say this is pushing all of our landscape trees and shrubs. Forsythia and saucer magnolia are in full bloom, at least two weeks ahead of schedule. The warm weather also has us scrambling to get some research projects in the ground as well. Today I was working with members of my lab to install a trial to look at the relationship between fertilization in the nursery and subsequent of shade trees in the landscape. For the past two years we’ve grown Acer miyabei (‘State street’ maple) and ‘Harvest gold’ Linden trees in 25 gallon containers as part of a trial on controlled release fertilizer. Interestingly, in the nursery we saw a significant increase in chlorophyll index and foliar nitrogen with fertilization (no surprise) but no difference in caliper or height growth (somewhat of a surprise). This indicates that in the nursery, fertilization induced ‘luxury consumption’ or an uptake of nutrients beyond what the trees need to meet their growth requirement. This observation provided the opportunity for our current, follow-up study. In the forest nurseries there is a growing interest in the practice of ‘nutrient loading’ seedling trees before they are lifted. Forest nursery managers deliberately induce luxury consumption by fertilizing late in the season. At this time seedlings have set a hard bud and won’t grow but can take up additional nutrients. Numerous studies, particularly by Dr, Vic Timmer and his associates at the University of Toronto have shown that nutrient loaded seedlings will outgrow standard seedlings when out-planted on reforestation sites; even though the seedlings are the same size when transplanted. How does this apply to large-caliper shade trees? We don’t know. There are certainly some underlying commonalities that are intriguing. Nutrient loaded forest seedlings have an advantage when planted on tough sites where follow-up culture is minimal – basically the seedling has to get by initially with its own energy reserves and resources. Shade trees planted as street trees often face the same hardship; once planted they may receive little or no after-care beyond an initial watering. Could nutrient loading provide a better internal nutrient reserve and jump start the re-establishment process for street trees like it does for the smaller forest cousins? We should gain some insights this summer and next.
There are people who are fascinated by plants and people who are fascinated by the science of growing plants. While I love plants I must confess that I consider myself to reside more firmly in the latter group that the former. I do love to see the beautiful flowers on an apple tree in the spring, but I’m more fascinated by the nitrogen, phosphorus, potassium and other elements that the tree obtains from the soil. I like to contemplate the complex ecosystem that surrounds the tree, including the tree’s pests and the possible things that we can do to protect the tree from pests. I love to learn about insecticides, herbicides and fungicides, and I especially love to learn about alternatives like beneficial insects that may be used to control pests. Histories that cover fertilizers and pesticides are pleasure reading.
One of the most important things to ever happen to the world as we know it was the discovery of a process to take nitrogen from the air so that we could use it as a fertilizer. During the 1800s we discovered that applying nitrogen to our soils made plants grow really fast. Though this nitrogen could be supplied with manure we quickly learned that Peruvian Guano and Chilean nitrates had more concentrated nitrogen and so less needed to be added to fields to get bigger responses. Incidentally we could also use the nitrogen from these sources for bullets and bombs. Nitrogen is a cornerstone of most conventional explosives. Unfortunately these sources of nitrogen did have a drawback, they are not renewable resources. You may say — Hey, Guano’s renewable! — But you’d be stretching the truth. You see, guano is aged manure where the nitrogen has had a chance to become concentrated.
Anyway, by the time the 20th century rolled around we had used up much of the nitrogen available from South America and so we (and by we I mean the world in general) were hurting for nitrogen — particularly Germany. Germany had a feeling there was going to be a war and she needed a way to get nitrogen other than sailing all the way to Peru or Chile. So she put money into research. Pretty soon two researcher, Haber and Bosch, came up with a method to take nitrogen directly out of the air and make it into ammonia. Once present in ammonia it could then be used to make any number of other nitrogen based compounds, from fertilizers to bombs.
Coincidentally, Haber is also known as the father of chemical weapons. He led the German poison gas program and had a hand in developing such things as mustard gas. He was considered to be a patriot, but, born a Jew, the rise of Hitler wasn’t good for him and he was forced to leave in the early 1930s.
The story of Haber and Bosch is absolutely fascinating, not only because of the colorful characters, but because their discovery is, arguably, the most important factor in the increase of the worlds population over the last century. The best book that I know of on this topic is Enriching the Earth by Vacliv Smil. It’s a great book, but it does get a little technical. But my dad (he’s a chemist) showed me another book yesterday that is much more entertaining and readable than Smil’s book while retaining most of the pertinent science. It’s called The Alchemy of Air by Thomas Hager and, if your interested in fertilizers and the people who first developed them, then this is a must read.
This time of year is very exciting for the students in my plant propagation class because now is when they all get to try grafting. In particular, they get to place buds from an apple tree onto a rootstock. There is nothing like placing a bud from one tree onto another to make a person feel as though they’re a horticulturist (NOT HorticulturALIST — that’s not a real word). Especially if that bud successfully grows on the plant where it was placed and produces a happy new tree — What a warm fuzzy feeling!
There are all kinds of things that a rootstock can offer to the bud placed on it. The rootstock can make the tree a dwarf, it can be resistant to certain diseases which the bud isn’t, it can even add some degree of cold hardiness. In return, the bud produces a cultivar that the grower wants such as ‘Honeycrisp’ apple. Additionally, the bud also offers an older tree. This probably doesn’t make sense at first, so think about it for a second or two. The bud that was grafted onto the rootstock came from a mature tree and so it may be more mature than the rootstock (which may have come from a seed — if the rootstock came from something besides a seed — like cuttings — then the rootstock may also be quite mature). Because the bud from which the top of the tree will grow is more mature than the base the tree will usually come into bearing sooner than if it were grown from seed.
Tree age is a funny thing. Though you wouldn’t expect it, the base of a tree is actually the youngest part of the tree physiologically while the older portion of the tree is at the top from which most new growth comes. The reason for this is that the bottom of the tree was laid down first as the tree first emerged from the soil and so the bud from which that growth came hadn’t had the chance to age much yet. After a few years of growing up the terminal bud developed more and more “age” and so the top of the tree is more mature. Confusing? It confuses me too — and I’m oversimplifying things quite a bit here. Making it even worse, no two tree species seem to age in exactly the same way.