This year we're teaming up again with Saint Paul Parks & Recreation to add a few more flowering cherry trees at the Mannheimer Memorial in historic Como Park.

Last year, we had the great honor of taking care of the Spring Wonder flowering cherries (Prunus sargentii 'Hokkaido Normandal') prior to the planting that celebrated the 100th Anniversary of the original donation to the United States from Japan in 1912.   

I finally got our stereoscope linked up with our digital camera and thought to share some VERY close up photos from our flowering cherry collection.  Photos like this really help me appreciate the wonder of spring and how great and beautiful things are possible from such simple beginnings!

Kwanzan (Prunus serrulata 'Kwanzan')

Yoshino (Prunus x yedoensis)

Pink Flair (Prunus sargentii 'JFS-KW58')
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Check out this neat time-lapse video of our elm grafting process! Created by our very own J.W. Fillmore...and featuring American elm roostocks from our friends at Three Rivers Parks District Nursery.

Last fall I had the opportunity to join Mr. Don Willeke in observing the removal of a large 'Iowa State' American elm at his neighbor's house in the Dean Park area of Minneapolis. This large tree was planted in 1978, shortly after Don grafted it onto a wild American elm seedling.  Unfortunately, the tree had developed major defects over the years (it had already been cabled and braced) and required removal for safety purposes. 

Don is a local elm aficionado and has been "speaking for the trees" since the 1970s. He has been my host on many visits to the forest of elm trees (amongst other species) in and around his Dean Park home.

'Iowa State' was discovered and screened by Prof. Sandy McNabb at Iowa State University from the late 1960s to early 1970s where it proved to be quite resistant to Dutch elm disease (DED) when inoculated with the fungus. While not widely released (at least to my knowledge) this tree remains an important reminder of those lucky escapes - native American elms with high tolerance to DED. Unfortunately, the structure of this tree is less than ideal as it has a tendency to form weak branch unions due to inclusions and very acute angles of attachment.

In my ongoing efforts to make-lemonade-outta-lemons I worked with Don and Jay Linn from Log and Limbs Company (who was performing the removal) to collect some prime cuttings material for cloning of this now rare tree.  

By the end of the removal process Don and I were able to collect some vigorous vegetative shoots from the very top of the tree, which I brought back to the University for propagation and inclusion into our elm program.

Now, weeks later, I transplanted some of the first rooted cuttings of 'Iowa State' and can now add this tree to the growing collection of elms at the University of Minnesota.

Plants are also slated for distribution to the USDA National Arboretum in Maryland for inclusion into their continuing work on the American elm.

This December Jonathon and I (Greg) trekked out around Minneapolis collecting cuttings for asexual propagation for the Heritage project and came across this champion black willow (Salix nigra). Willow is considered to be a short lived tree that is prone to decay and failure because it grows too quickly for its own good. That is a good thing if you need a large tree fast but not if you want a tree that will last longer than you. This champion willow is located right across from the main parking lot of Lake Nokomis by field #5 if you care to see it up close. The circumference of the trunk is 379 inches and it stands 70ft. tall with an average canopy spread of 73.5ft! What a monster!

Jonathon Standing IN the monster!

Even with decay regularly pruned out this tree is still huge!

For the tree of the week, I chose the Minneapolis Heritage Horse Chestnut (Aesculus hippocastanum). This is the largest Horse Chestnut in the city, and it is right in front of Folwell hall on East Bank Campus! I would walk right by this tree every day, and until recently never took the time to notice it. It used to have another similar Horse Chestnut across the sidewalk, but that has been replaced with a new tree.

Horse Chestnuts are native to Greece and Albania, but are now widely cultivated in parks and urban areas. They grow very slowly, but can reach 50' to 75' on average, with some up to 100'. They grow taller than they are wide, and have a dome shaped or oval final form. The name comes from their large, hard seeds, that were once believed to cure horse chest ailments, but have since been proven to be poisonous. The seeds, which can be messy, and dangerous if ingested, along with their tendency to grow to massive size are the main concern when planting a horse chestnut.

Despite this, they enjoy enormous popularity.They are hardy trees, in zone 3, making them great candidates for Minneapolis. They also do well in most soil types, preferring moist roomy soil. The trees have showy white, yellow, and red flowers and rich foliage.

Other than this heritage sample, the Horse Chestnut has enjoyed popularity as a common choice for German beer gardens. It was a common choice because of its wide deep shade, that kept patrons cool. Also, the "Anne Frank Tree", which Anne Frank mentions in her diary multiple times, was a Horse Chestnut. It was locate in the middle of Amsterdam. This tree sadly blew over in 2010, weighting in at 27 metric tons.

Many of my friends assume that I am out of the job now that the snow has fallen, and the 

days are short and cold. Although we don't get outside as much anymore, there is still a lot of work for team tree over the winter months. Recently, we drove out to St. Paul to take data on the High Bridge dog park. There is an earlier article that talks about the dog park in more detail, but it is basically a remidation site where we planted groups of 1 1/2" caliper trees on the site of a former rail yard for a coal plant. The site is a difficult place for trees, with poor soil conditions, and of course, lots of dogs, who may or may not be nice to the trees we planted. We have been taking data for awhile on how well they are growing to see what varieties do well in the adverse conditions.

During our check up on the trees, we were going to collect data on caliper and take photos of 

the trees. 

Sadly, many of the trees have lost all their cambium at some points, which will most likely kill the trees. Chad said that when he originally checked the site out, the trees in the surrounding area showed signs of damage from critters, and there was probably a lot of them living in the area.

The remaining trees that survive the winter will make it to the 2" caliper mark, where the bark usually will become hard and inedible. Also, there was generally less damage on Catalpa, Birch, and Alder than other varieties. 

Team Tree met up with some Saint Paul Forestry after our initial visit and wrapped the stems, so some of the trees will make it to spring!

We say goodbye to another member of Team Tree. Greg was the most senior member of team

 tree, and was a very valuable addition. He was the only one who could give Chad a run for his money on Skiddy, has extensive horticultural knowledge, and lots of nursery experience. Greg graduated with a degree in horticulture and is working at a landcare company in the southwest metro area.

Greg, you will be missed. The best of luck in your future endevors

There is a lot of work we have to do around the nursery to get ready for winter. The trees we 

grow expect, and rely on winter to come, but they are also used to being under the ground, away from the harsh temperatures of the surface during winter. They are also vunerable to animals who will nibble away their cambium, which, if it gets bad enough, will kill the trees. If a tree is small enough, animals will leave you with only a frayed stump. 

When planning to keep trees alive over winter, you need to keep these concerns in mind: to keep them protected from animals, and also to keep them in enough mass that the roots don't freeze and kill the plant. In planning for this, you need to take into account the amount of snow you will get. If you put a 6 inch wrap on a tree and there is 2 feet of snow, the wrap is going to be a foot and a half under, leaving the tree exposed. For our nursery stock, we placed as many as we could in the pot-in-pot section, and for the rest, we packed them in with mulch and then wrapped the stems.

When we are growing trees to send out to our research partners, or for study in our research nursery, we are looking to set a permanent canopy at around 12 feet. With the conditions most trees are growing in, they would be shrubby and around 7 feet tall. To get them higher, and keep them straight, we have a lot of methods, like pruning, staking, and tree therapy.

Tree therapy isn't really an official term. It is simply the bending of trees to get them to develop caliper and grow in the direction we would like them to. When you bend a young tree, you can almost feel the fibers inside of it breaking. When a tree bends and moves, it responds by growing stronger, similar to human muscles after exercise. This also occurs naturally, from the blowing of the wind. This response is called "thigmotropism," which I talked about earlier in relation to staking.

Tree therapy can be a tricky thing. If you bend too lightly, you aren't going to do much. If you bend too hard, the tree snaps. Either of these results doesn't help much. It takes quite a bit of practice to get it down correctly, and every once and awhile you will have a snapped limb.

In the nursery, we are proud of all the trees. They all give it all they can, every day, rain or shine, sleet or snow. Sometimes trees die, sometimes trees don't make the cut, and sometimes trees are never even given a chance. That is just the nature of the work.

At the begining of the season, we notice a willow had germinated in the gravel pile that is going to top off our drainage ditch. We never got around to filling it up this year, and the willow steadily punched its way through the season, growing in terrible soil with zero attention from Team Tree.

Today, this brave willow is aorund nine feet tall. That is tree-spirational. That deserves the "Rocky" soundtrack. Gravel Willow, you are the Contender of the Season. Congratulations. We will probably put this tree in the rain garden, to help bioremidiate the soil, which is more gravel and chopped up elm trees. It has a rocky road ahead of it, but I believe in this tree.

Chad next to the gravel willow "Rocky" marking it's original height this season