Nursery Nightmares
"A Look at the Dark Side of Nursery Prodution"
Radical Root Systems
Quality root systems are a result of good managment in the field and proper after-care in cold storage. This Fraxinus pennsylvanica root system is structured well and includes a good amount of fibrous roots. Notice the location of the graft union in relation to the first main-order roots - well above the soil line and never buried!
The trees shown above were probably grown in a container for too long. There are no true girdling roots present yet, but some of the circling roots may become girdlers later on. These root systems won't properly support the top of the tree either, strong winds or other mechanical forces may cause a tree with a root system like this to windthrow. Most experts suggest upgrading and correcting encircling root patterns for container-grown trees every growing season.
These are shots from a root system of a 6" caliper Sophora japonica. This tree was in the process of being harvested and the soil ball literally fell apart when placed in the basket. A closer look showed extensive girdling roots and about 6 to 7" of soil above the first main-order root. This tree also showed symptoms of decline in the crown prior to digging. Growers can prevent situations like this by a quick inspection of planting depth in their field stock every season, especially after cultivation between rows.
Some Scary Stem Situations
Hackberry, Celtis occidentalis, is a real bear in the nursery setting. They are notorious for having narrow and weak branch attachments, and require a lot of pruning and training to get a quality landscape specimen. This is from a 5" caliper hackberry that received no pruning or training after being planted out as a liner - looks like it's a little late for this one!
These shots are from the same tree as above showing the decay due to the splits at branch inclusions. Hackberry has poor resistance to decay so inspections for branch bark inclusions should be frequent to avoid problems like this.
This is another poor hackberry with all sorts of problems: crossing and rubbing branches, narrow branch attachment, and bark inclusions. All of these problems can be corrected if they are caught soon enough. Trees with decurrent growth habits should be inspected frequently for central leader co-dominance and narrow branch attachments; many times you only get one chance to correct a problem
Acer X freemanii, or Freeman maple, is another tree that often shows poor branch attachment. This was a young tree, around in 6 inches diameter, that was recently planted to replace a windthrown tree. Unfortunately, this was split in two from an inclusion only two years later, just about when the homeowner was beginning to enjoy it. Many of the fast growing trees need frequent inpections both in the nursery setting and after planting out in the landscape to avoid needless losses such as this.
Many of the new Ulmus hybrids that are Dutch Elm reisistant require close attention for narrow branch attachment. This failure occurred about 10' off the ground on a tree that was of prime size for transplanting. Get a ladder and check out these trees every year - otherwise you'll find out the hard way later on.
This corktree, Phellodendron amurense, is another fast grower, but take a look at this branch attachment - excellent! (The cracks you see occurred after cutting.) This shows that there is hope for these fast growing species, it just takes a little time and proper maintenance.
Take a good look at the nice branch bark ridge (BBR) on this Tilia cordata (littleleaf linden.) Lindens and basswoods can be trouble for branch inclusions but they will behave if trained and pruned properly. Most Tilia should be pruned as much as possible as a young tree to establish initial branch height and structure. It's a lot better than having to remove large, low-hanging branches later in life.
Here are more Tilia cordata branch samples. The one on the left shows proper branch attachment while the middle and the one on the right show obvious signs of included bark. You can already see signs of decay on the sample on the right. This tree could probably still be salvaged for a park-grade transplant if a proper pruning cut was made. Many people are tempted to either make a flush cut or leave an overly large stub on bigger included branches. It's important to do neither. By removing as much of the inclusion as possible without stripping cambium or enlarging the wound, chances of successfully "reforming" the trees are still quite good.
These branches formed the first branches of the crown on a nice-looking river birch (Betula nigra.) After taking a closer look, though, we found a major inclusion and the beginnings of decay.
This is how it looked from the top. This one was a little hard to see in the nursery as the exfoliating bark tends to hide the branch attachments. Just imagine as this tree grows the increasing amount of weight that this already stressed union will have to bear. Central leaders are critical in maintaining a healthy and structurally sound crown in river birch.
Bad Bugs
Here are some insect galls on young Quercus bicolor and Q. macrocarpa trees. In many cases there is little permanent damage, but all insect pests should be monitored, however, as they can sometimes cause injury and hurt sales due to poor aesthetics. Often times the galls are more obvious on young trees because their young, tender branches are more visible. Most galls on oaks are caused by wasps that lay eggs in the oak stem. When the eggs hatch the larvae produce growth-altering chemicals the create a gall around the developing larvae.
Tag Terrors
Here's a common problem: this metal tag and wire was included by this tree over the course of just one season! While most growers don't use tags like this for production, even the plastic "slip-and-lock" tags can girdle the tree in a single growing season. It's often better to locate the tag on a "temporary" side branch, that way if it does cause trouble the branch isn't critical to the tree's future.
Devilish Decay
These are shots from a columnar Norway maple with some severe wounding on the central leader. Following the branch up about 4 feet we were able to still find signs of decay in the branch (the smaller branch in the top photo.) This kind of damage is consistent with winter injury and rodent damage. Some of this damage can be prevented with temporary stem wrapping and other techniques to thwart rabbits, mice, voles, and woodchucks.
Here's another maple that had a branch stub left on too long. Decay and soft rot ensued but was compartmentalized forming a distinct boundary layer from the rest of the stem. Although this tree will probably be OK, it's another good reason to always make proper pruning cuts.
This is a branch from a bur oak (Quercus macrocarpa) that was growing a little too close to the freeway. The salt kills the apical meristems on the branches causing latent buds to break further up the stem, giving it a "witches-broom" appearance. Always check the wind direction when planting or growing near busy roads. There are also many options for more "salt-resistant" species.
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