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Categories » Trees
We’re in the bitter end of fall here, at least in terms of foliage. To me, this is when trees really start to shine. Maybe it’s all the bare trees nearby, or the perpetually cloudy skies, but the remaining foliage seems to take on an extra glow, or maybe urgency. Foliage colors that wouldn’t have turned a head 2 weeks ago now looks spectacular in the dying season, like the russet brown of the Star Magnolia behind Voter Hall. Sunlight breaking through the clouds acts like a highlighter pen. The wet cold makes any color seem all the more special. Here’s a little slideshow of trees and some shrubs that turned my head late last week.
Every year, people working in Facilities start bringing me these tennis ball sized fruit. Last year, I decided to have some fun, and started freaking people out, acting incredulous they were actually touching them, and insisting they go wash their hands immediately, or terrible things would happen. This year I’m pretending they fell off the moon, and just happened to roll down to the front of the auto shop.
The truth is almost as strange. Middlebury College is in posecession of Vermont’s largest Osage Orange tree, Maclura pomifera. The circumference of the trunk is only 40″, nowhere near the record tree in Virginia of 321″. Ours is under the shade of a large sugar maple, and sits at the top of Stewart Hill, where its tennis ball sized fruit promptly roll downhill, over the speed dip, and end up near all the equipment.
Originally native only to southern Oklahoma and northern Texas, the Osage Orange was introduced far out of it’s range by using it as fencing, as it’s thorns and brushy nature made great hedges to keep out cattle. It met the demand of a hedge in the wild west , “horse high, bull strong, and pig tight.” I’ve chased a loose pig before. Pig tight is saying quite a bit.
Alas, it was not hedge clippers, but barbed wire that won the west, replacing Osage Orange in the 1880’s. The edible (?) fruit is cherished by squirrels, but more commonly used as holiday decorations. Some have described the fruit as “brain-like”. If my brain were only that large…Chemical compounds in the fruit repel insects, although the whole fruit itself does not. The fruit is anachronistic. Usually large fruit is a method of seed dispersal, but squirrels are notoriously finicky on that front. Some theorists state that an extinct Ground Sloth used to aid in the spread of the plant. Indeed, the fossil record shows a much larger range to the genus than what we see now.
The wood itself is remarkably able to resist rot and decay-and has been used as railroad ties and pavement blocks, as well as a superior wood for bows (archery, not violins). A bright yellow dye can be extracted from the bark.
Horticulturists like some parts of the Osage Orange. It’s yellow gold fall color can frequently rate spectacular, and it also boasts a pretty orange brown older bark. Michael Dirr, expert on all landscape plants, says the fruit is “effective in September, and lethal in October if one is sitting under the tree” and states that one should “select male trees; the large fruits are a nuisance and a problem around public areas as people will invariably use them for ammunition”. Male trees are being selected, and cultivars developed for use as a street tree. The species is remarkably tough, able to grow nearly anywhere. One last thought-Osage Orange is dioecious. Male and female flowers appear on separate plants, and of course you need both to pollinate. So, while our clearly female tree still sets fruit, they are sterile. Large, but sterile nonetheless.
So ours sits, unremarkable most of the year, until the fruit starts rolling. I don’t know how it ended up planted there, or even where it was grown. I’ve never even seen one for sale.
Personally, I was hoping we were done with this. I’m as tired of writing of it as you are of reading.
Since the school year started, our landscape department has seen an additional 4 incidents of tree vandalism. One, a newly planted tree was broken in what appeared to be a climbing attempt (no, we’re sure it wasn’t a squirrel of exceptional size). An arborvitae was snapped in half in front of a dorm, and a random branch broken off a a large sugar maple in front of Johnson.
The final straw, though, and the reason for the quick post on a lunch hour, was the near total destruction of a little red oak by the Davis Family Library. Nearly every single branch on this street tree was broken or bent downward, leaving only the very top branches. This wasn’t just a random “lets grab a branch and break as we walk by”, this was intentionally standing in front of a tree, breaking as many branches as you can reach. Cruel, senseless, disheartening, and more than a little bewildering. What can we do as a community?
Just the other day a crew chief and I were interrupted by a student walking to class, and he’d mentioned how he had joined us tree planting on Arbor Day. He pointed to the tree he did, and said he can’t wait to bring his kids to see it in 30 years. So we keep planting, and keep pruning broken branches.
I’ve been reading quite a bit this fall in various newspapers, web sites, etc. about the science of leaf change, and I thought, well, heck, there goes another blog post. I don’t see the sense to retread ground others are covering.
By now, you’ve probably read that leaf color changes by the shortening of day-length light triggers the tree to begin shutting down the leaves, and that chlorophyll breaks down, and sugar is absorbing into the tree. In a nutshell, the veins connecting the leaf to the tree are closed (abscission layer), and once this is complete the leaf falls.
Weather does play a part in leaf color, and in the color you see in the hills as you visit your children on parent’s weekend here (Hi parents! Your kids are doing fine. They want more money.) Many articles have talked about warm weather delaying fall, cool nights are good, drought bad. It’s easy to understand, though, if you think of it in terms of plant health.
A happy, healthy tree in a good growing season will more than likely have pretty spectacular colors. The factors responsible for bad fall color aren’t good for the tree health either. Drought is bad for fall color, and also bad for the trees. Southern Vermont this year had a pretty bad late summer drought, and when I was on route 4 a week or so ago near Woodstock the leaves were terrible, turning brown and falling off, rather than turning nice colors. Here at Middlebury it’s been a dry September, and then the recent rain storms came at just the right time, and the leaves held on long enough to turn well. Warm fall days and cool nights? Good for sugar production, and the breaking down of chlorophyll in the active leaf. A late spring or a severe summer drought can delay fall color-the tree holding on to it’s leaves as long as possible, storing as much energy as it can before winter.
Another leaf color fact plant geeks have probably noticed is called the Leaf Wave Model. An article at the University of Georgia discusses this: Peak color is an opinion. Different trees turn at different times, and in differing colors. Yellows dominate early, then oranges as both later trees turn, as well as some yellow leaves becoming more orange. Finally reds dominate the landscape, with accompanying orange. Browns come last, generally in oaks. The leaves in Vermont are spectacular because of the forest cover types found here, yellow Ash, orange and red maples, along with splashes of green from Pine and Spruce. By paying careful attention to the mountains in the fall you can watch this leaf color wave happen.
Some other reading I’ve been doing this fall was about the color red, something I’ve never thought about. An interesting question for botanists has been “Why red?”. As chlorophyll disappears from the leaf, the other colors emerge, such as yellows and oranges provided by Carotenoids. Red, though, is expressed through Anthocyanin, but is not found in a leaf, and must be produced. The question, therefore, becomes why would a plant be producing a compound, expending energy, at a time in it’s life cycle when it is trying to store and conserve? There are two schools of thought, and probably both are correct, some for some plants, some for others.
One theory is that anthocyanin is produced in trees in nitrogen poor soils. In some varieties of trees, as the green chlorophyll breaks down, the leaves are vulnerable to bright sunlight, and this sunlight breaks down the produced sugars, thereby not being absorbed back into the tree as energy storage. The red pigmentation acts like a barrier from the sunlight, allowing the tree to absorb more of the sugars it has produced. Nitrogen poor soils means the tree would have produced less sugars, being weaker growing, so more red pigmentation would conserve more of the valuable food.
The other theory is one of coevolution, that red leaves are a signal to insects as a repellent, a red warning signal to the insects attempting to use the tree as an overwintering site. A study has shown this in aphids and apple trees, that wild apple leaves turn red in the fall, and suffer less aphid predation.
Of all the work we do here in the landscape department, some of the best is the tree planting.
Think of our landscape at Middlebury as a living organism, changing and evolving. Trees have a lifespan, like us, only measured not in decades but hopefully in centuries, for the best and strongest. Site vagaries not withstanding, most species live for a similar amount of time. A mad rush of planting one year will mean that down the road a large hole may develop in the landscape, as the same aged trees all need replacing at the same time. Take, for instance, some work being done at Utah State University.
The main quad at Utah State is lined with 80 year old Norway maples, which in Utah live about 60-80 years. Plans are underway to replant the green, and to remove the Norways before they fail. This has met with some resistance, probably based more on disappointment, as the look of a beloved quad radically changes in the space of a couple short years.
We started our tree planting this year on Arbor Day, thanks to Hilary Platt and Chelsea Ward-Waller, two of my students from Winter Term, and the driving force behind getting Middlebury to become a Tree Campus. Many students helped plant trees around Bi-Hall, and near Coffrin. The focus for this area was to help define some of the space around Bi-Hall Park, as well as planting in between Coffrin and Bi-Hall to help with storm water abatement. We used Sweet Gum there, Nyssa sylvatica, and a variety of other native trees nearby, such as Hop Hornbeam, Scarlet Oak, Red Oak, and Ohio Buckeye.
The second focus of tree planting this year happened later, after the rush of commencement and reunion. I enjoy this so much so I almost don’t want to tell of it.
Part of a happy and sustainable campus landscape involves diversity. Having as many different species of trees as possible ensures that should the next insect (Asian Longhorn Beetle, Emerald Ash Borer) or disease come to campus, large sections of our tree population won’t get wiped out, like the aging Norway maples at Utah State.
So I prowl nurseries and garden centers, looking for healthy plants that will do well on our campus. With such a varied landscape, it isn’t difficult to find a spot to tuck in some type of tree somewhere. We focused this year on areas of the campus lacking in tree color, and used ornamental flowering varieties of trees to liven up otherwise very static green locations. An example of this is a small section of lawn right to the north of Painter Hall.
While not a large area, comparatively, it was large enough for three small flowering trees, set in a triangle. One was a Butterflies Magnolia, small yellow flowers in early spring. Later in June will come flowers from the Yellowwood nearby, followed by a small tree in bloom now, a Heptacodium, Seven Sons Flower. More on that species in a later post-it’s spectacular.
Other areas planted include North of Warner Science, where many over-mature Sugar maples are slowly showing the effects of time, as well as along the east side of Hepburn Road, and North of Gifford.
Other fun varieties planted were a “Discovery” hybird Elm, Red Obelisk Beech, “Katsura” Japanese Maple, Kousa Dogwood, and Yellow Birch (the kind they make Birch Beer from). 4 Different varieties of Magnolia were planted, one red, one pink, and two yellow. In all, 32 trees have been planted so far, and a couple more are still on the way. The Tree Karma count? Not exactly sure, with all the storm damage, but I’m thinking it’s still holding at 3.5 to 1 or so.
The study of plant diseases made me terribly depressed in school, but also made me laugh on occasion. I imagined two plant pathologists walking around, looking at sick leaves. Of course, each of them wouldn’t admit to the other that they didn’t know or recognize some strange disease, so they’re making up names as they go along. Strange fungal spores on a cherry tree? Well, it looks like Black Knot, and the disease is named.
A fall arrival on campus (and occasionally in my inbox as a question) is always the blatetenly named Giant Tar Spot. (“Hey, what’s this?” “You don’t know that? Any idiot knows thats, um, Giant Tar Spot. Yeah, that’s it. Giant Tar Spot”) You guessed it, huge jet black spots on the leaves of primarily Norway Maple. This, too, is a fungus, Rhytisma acerinum for you latinally inclined. It infected the leaves way back in early summer, but they don’t really show up until now. When it’s too late to treat.
Not that you need to. Late diseases and insects like this look terrible but, let’s face it, the leaves are only around for a couple of more weeks anyway. It’s not a bad year for it this year on campus, we’ve had it much worse. If you’re looking to get rid of it on your tree at home, rake and dispose of the trees at your neighbors…
I may be risking excommunication.
The landscape department, probably like many others across campus, has its share of secrets, little things nobody else knows about. My inside mole at the Grille keeps me updated when the linzertorte cookies are around. The view from the Bi-Hall roof after a snowstorm is spectacular. And, there’s a pretty spectacular plum tree on campus.
Plums are in the Rose family, the genus Prunus, which it shares with Cherries, Peaches, Apricots, and Almonds. The full latin name of the plum is Prunus domestica, The latin genus stolen from the greek word προῦνον (prounon), and the specicies domestica from the botanists term for “such a long and muddled history of hybridization we can’t possibly straighten it out”. It is no exaggeration to state that plums have been cultivated for thousands of years-Pliny the Elder writes of Apricots, stating them to be a type of plum, and a 6000 year old apricot pit was found in an archeological dig in Yerevan, the capital of Armenia. The earliest Prunus appear in the fossil record in the middle Eocene, about 45 million years ago.
Our plum is one of the first trees to bloom on campus, at about 80 degree days. In a good year, about 50% of the blossoms are pollinated, and bear fruit. Dry condidtions in the late spring will cause the fruit to drop while still small, and overly wet conditions are prime for Brown Mold, as unattractive as it sounds. Most plums are covered in a white waxy coating-this is a epicuticular wax that protects the fruit from UV light and also repels water.
There are many cultivars of plum. I’m betting, though, that our plum is a popular (and hardy, fortunately) variety known as Stanley. It’s a beautiful blue-purple color, with a golden meaty center, surrounded by a small pit. It was bred in the New York State Agricultural Experiment Station, part of Cornell University, located in Geneva. The station is the mecca of hardy fruit hybridization, and brought us the Empire and Cortland apple. Stanley is literally the plum all others are now compared against. Richard Wellington developed the Stanley plum in 1926-when he started at the station, there was estimated to be 1 million plum trees in the state of New York.
Plums have a greater variety than other tree fruits, coming in many colors, sizes, sugar contents, and textures. They are an excellent source of anti-oxidants, more so than tomatoes, bannanas, apples and oranges. Marketeers are busy trying to sell us “dried plums”, hoping we forget grandmother’s name for them, the evil and dreaded prune. A sugar plum, aside from dancing in your head, is by law a plum with greater than 20% sugar content, at least according to the California Tree Fruit Agreement.
I enjoyed selling plum trees in my retail days. I was forever talking customers out of apples, as they aren’t really a tree as much as a pet, requiring greater care than anybody realizes. (Leave the apples to the experts-there is sanity in bulk) Plums, however, are carefree, without the serious pests and diseases of other tree fruits, and are self fertile, meaning one tree is all you need. Stanley should be hardy in most of the Champlain Valley, with perhaps the occasional late frost nipping the buds.
Oh yeah. I forgot to tell you where the tree is.
Our wild and crazy summer weather here at Middlebury continues, this time with a tree being struck by lightning. (Side note to the faithful readers out there. I feel for you-has this blog been getting depressing lately? With vandalism, more vandalism, storms, more storms, even still more storms, and disease, it seems like the Middlebury Landscape is getting tragic. Hold the faith! We’ve been planting as well. Posts coming soon on this year’s tree plantings, as well as a new look for Pearson Hall.)
The tree hit is a Ginkgo ( read here if you’ve forgotten about them) located in front of one of Middlebury’s “outside” houses, near Public Safety at 121 South Main Street. I don’t know the night it got hit, but it was brought to my attention by one of the diligent members of our crew. Looking at the tree originally, I first thought the tree had just cracked down near the base, possibly in some strong wind. The tree shows what arborists call co-dominant trunks, where two trunks of equal size meet and grow together. This is frequently a recipe for disaster, as a bad union often results, where included bark makes a weak joint, and the two trunks typically fall apart away from each other.
I called an Arborist friend to consult on the damage-this is one of our favorite trees in Facilities, many of us would mourn the loss. His skill, knowledge, and experience led him to look up the tree, rather than me just jumping to the first obvious conclusion, and that was how he discovered the damage around the cable up top, as well as noticing the toothpick sized wood pieces scattered around the yard, small pieces of trunk blown away from the tree from the force of the lightning. Being tree geeks, we climbed up to investigate.
Trees are frequent targets of lightning. Standing alone, frequently taller than many buildings around them, many trees get hit each year. Lightning is fascinating all on it’s own, with their impressive 100 million volts and temperatures greater than 50,000 degrees fahrenheit. 16 million lightning storms are estimated worldwide in a year, and measuring instruments record over 100 million strikes in the U.S. each year, killing on average 90 people. They even get their own phobia, Astraphobia, fear of lightning.
The conditions needed for lightning are still debatable, but should those conditions exist, negative ions accumulate at the base of the storm clouds, while positive ions pile up on the ground. “Stepped Ladders” descend from the clouds, while “streamers” arise from the earth, typically strongest from the tallest structures, such as buildings or trees. Should they build strong and fast enough, they meet to form a lightning bolt, and this electrical discharge super heats the air around it to 36,000 degrees fahrenheit, compressing the air creating supersonic shock wave we hear as thunder.
When lightning strikes a tree, the sap in the tree boils, turning to steam and blasting the bark away from the trunk. The electrical charge flows through the tree, exiting out the root system, which could be severely damaged in the process, sometimes with no visible sign above. In most cases, though, a strip of bark is torn from the tree, often in a long strip, but sometimes, like this ginkgo, only above and below. Trees with only one crack tend to close the wound and suffer, yet live, while trees with wounds on both sides of the trunk are frequently killed outright. Obviously, even a wounded tree can die from secondary reasons, such as insects and diseases, less able to fight them off.
Trees vary in their susceptibility to lightning strikes, possibly for biological reasons, or possibly simply because of their height. Elms, Oaks, Black Locust and Ash tend to be very susceptible, while Beech, Horsechestnut, and Birch tend to not be very susceptible. It may be the starch content of the tree making it more susceptible, while resinous trees are poorer conductors.
So there is hope for our Ginkgo. The wound at the bottom was traced, where loose bark is peeled away carefully from the trunk to the point where it attaches again. The thinking with bark tracing is that loose bark can trap moisture and disease, so by removing it the wound can dry better. Maybe it’s just something to do to make arborists feel not quite so helpless…
The cabling up in the crown of the tree is a little more problematic. Originally put in place to help stabilize the two co-dominant stems, the system now obviously cannot be trusted, as the wood surrounding the bolts holding the cable is now dead. We decided to replace the cable with two others, one above the old cable (a better location from an engineering perspective), but also one looser below, in case one of the stems fails completely at the original cable site, and breaks. The tree will then still be braced by the lower cable.
So now, we wait. The rest of this year, and into next spring, will be the crucial time, and when we shall see just how bad the strike was. Should it still appear somewhat healthy next spring, we will aerate the soil around the tree, add compost, fertilize, and mulch. Hard to imagine now, but, if we get a little drought this summer, we’ll even go down to water.
The storms certainly keep coming, and, worryingly, the trees keep succumbing. Today at 3:30 a very brief but intense cell blasted through campus. We’d lost power for a little bit, I don’t know why. The weather station recorded about 1/4″ of rain in 15 minutes, with a peak wind gust of 35 mph, from the north. This was enough to take the life of a poor Hackberry tree.
This poor tree had been scarred at the base years ago, maybe by a random mouse, maybe by something mechanical. At any rate, the worst place to wound a tree is right at the base. A tree has a very hard time compartmentalizing the wound at the base, and structural integrity of both trunk and root system is compromised. Look at the picture below-the wound was on the north side of the tree. The roots rotted away on that side, and the strong north wind gust toppled the tree right over.
I took these pictures on my way home at 4, but I would imagine the rest of the campus trees are fine. A perfect wind knocked this one down. I’ve already got a replacement in mind.
EDIT: Middblog just posted some YouTube video of the rain here-it’s impressive.
I’m not much of a Twitterer, although I’ve been called a twit many times.I don’t want to get tweets on my cell-my phone vibrates so violently at the slightest ring or text message that while weeding I end up shrieking like my 10 year old thinking I just weeded a bee’s nest. But I do check some from time to time, MiddBlog being one of my favorites, and they cross-tweeted (is that the right phrase?) a posting from Audrey Tolbert, who with Cody Gohl are blogging their Middlebury summer. (They are going to learn the Vermont secret-we put up with winter for the summer. Not too hot, not too sticky, and, so far this year, not too buggy.)
Anyway, she posted a picture asking“If a tree falls in Midd and there’s no one on campus to hear it, does it make a sound?”. Yes, Virginia, it certainly does.
This is a Silver Maple tree behind the Chellis House. The storm I reported on last week, well, this was one of the trees that fell over. The picture does not do the size justice, as the trunk of the tree was at least 4′ in diameter. Look carefully, you’ll see about 1-2″ of live wood around the trunk, and the rest was hollow.
One of the surprising things about this tree falling was its aim-it fell in absolutely the perfect direction, missing the woodline separating Hillcrest Road from Adirondack Road, missing Chellis House, the Queer Studies house, and the garage next to Chellis. We couldn’t have asked for anything more.
I wasn’t going to write about this poor tree. I am actually embarrassed by this. While I knew the tree had structural problems, I had no idea the extent of the damage inside the trunk. Look at the close up picture-those are weeds growing between the main stems at the top of the trunk. Large trees like this will often collect leaves there, and eventually grow things. It is the trunk decay that is surprising, and I feel like I should have known about this problem. Two arborists I respect both looked at this tree, though, and said that I had no way of knowing how bad it was, that they see this all the time, one going so far as to say “this is what Silver maples do.” So they made me feel a little better, and now I’m not blushing in embarrassment posting these pictures.
This tree is now cleaned up and gone. We’ve caught up on most of our storm damage, thanks to some very hard work by our landscape department and some excellent outside contractors. The elm I wrote about below Mead Chapel is OK, although more bare now. Once the hanging branches were pruned out there was more left of the tree than I had first thought, so that’s good. Many of the elms had some broken branches here and there, and a handful of other trees on campus had a branch or two break. Overall, not as bad as it could have been.