Saturday, 23 April 2011

Bad Practice Or...

How To Kill A Tree And Maim A Shrub…A Little Plant Physiology

Not really, after all, I love all plants and would never want to see any die. But there are several ways you can kill them unintentionally.  So, a quick lesson in woody plant physiology…

Without getting overly technical, there are five parts to a tree or woody shrub that we should be aware of.  They are illustrated in the diagram below:

1)      Bark: The bark is what protects the inner workings of a woody plant, similar to our skin.

2)      Phloem: This is the part that moves “food” that the leaves produce to the rest of the plant.

3)      Cambium: A thin layer of tissue which is responsible for cell reproduction. This is what causes a plant stem or trunk to grow in girth.

4)      Xylem:  Moves water and minerals from the root system to other parts of the plant.

5)      Heartwood: This is what your floors are made of. It’s the structure of the tree. The solid center.

The tree, shrub, branches, twigs …all of these have the same internal structure running up and down them. It’s how they move nutrients to where they are needed. It’s how the plant grows.  If you damage parts of the plant it interferes with it’s thriving and growing.

So how do you kill a tree and maim a shrub?

1)      Leave the tags on from the nursery. I have never understood why people leave the tags on their plants. It damages the branch they are attached to as they eventually get ripped off by wind, sleet and little kids. I don’t go walking around with the price tag on my clothes hanging out for months on end. Do you? No, of course not. A torn branch invites infection and disease. If you think you will never remember what you planted where, invest in some proper plant markers. Do not use popsicle sticks in the garden. They fade; they rot and are eventually eaten by dogs (my dog in particular). Cut off the tags and save them in a special gardening file with your receipt from when you purchased them (many nurseries offer warranties on their plants). If the plant markers go missing you’ll have a picture on the tag to compare to what is blooming in your garden.

There's the tag, right next to the ADT sign.

2)      Stake the tree/shrub. I am firmly against the practice of staking trees. It is simply not necessary and causes trouble in the long run. Trees/Shrubs need to develop a root base. The way they do this is by swaying in the wind and growing roots to stabilize them. If you stake them they don’t get a chance to develop a strong root system.  Furthermore, unless you are trying to create an espalier (training, typically a fruit tree, to grow on a flat plane) tying the tree to stakes can cause damage to the tree’s vascular system.  Some of the  materials I have seen used for tying plants to stakes are strips of burlap, twine, wire, zip ties and…I kid you not, shoelaces. It’s like tying a tourniquet around a limb which cuts off the blood supply. Eventually, if the tie is sharp enough, it will cut through the tree bark and start killing off the supply of nutrients to branches. If the tie is loose, it can rub against the bark of young saplings and allow in disease and infection. Either way, not a good idea.
This little tree is not going anywhere!
This j-cloth tie is doing absolutely nothing.

3)      Over Mulch.  Mulch snuggled up against the base of any plant, shrub or tree invites rot. There is a reason people use it to keep out weeds; it suffocates them. It will do the same to your plants if you drown them in mulch. A couple of inches of mulch, leaving room at the base of your plants, will suffice to keep out weeds and moisture in.

The one place homeowners routinely over mulch are their trees. If you live in a new subdivision, the city eventually comes and plants boulevard trees. Invariably, they do this in the heat of mid-summer, when it’s especially hard to keep thirsty plants satisfied.  To keep in moisture, a huge volcano-like moat of mulched bark is piled around the base of the newly planted tree.  It’s nearly always too much mulch, but at least the trunk of the tree isn’t buried under it. And the “moat” helps to keep the abundance of water a new tree needs in place, in theory. As seasons go by, the mulch degrades, as it’s supposed to do. At this point people often add a ton of new mulch and prop it up against the tree trunk‘s base. Not only does it look unsightly but it’s not healthy for the tree. It stresses the tree by keeping in excess moisture which invites root rot, insects and disease. Resist the urge to over mulch.
Mulch volcano

4)      Leave the burlap on.  Some trees, especially large ones do not come potted but wrapped in burlap with or without a wire cage around them. In the past it was common to only pull back the wire and the burlap and plunk the tree in the ground. The idea was that the burlap would eventually degrade and the roots make their way past the wire cage. Personally, I think, you are taking your chances doing this, especially in Southern Ontario or a new subdivision where virtually all the soil is clay and/or compacted. The roots are going to have a hard enough time as it is, why make it more difficult? When you buy Tulip bulbs you don’t dig a hole, throw in the package, store wrapping and all, and wish them good luck. You take the time to tuck them in individually and properly. Why not take a moment to do the same with your trees and shrubs? Sometimes, though, it’s not possible to remove the burlap wrapping. The tree may be too big and heavy to maneuver the burlap off. Whatever the reason, it may just not be possible. In that case, at least free the burlap from the base of the tree to give it room to breathe and grow before you fill in the hole.
You can see the yellow and black ties from the burlap still wrapped tightly against the tree trunk. Poor thing doesn't stand a chance. I am so tempted to free it, but don't want to be caught with a knife in someone else's yard. Too much explaining!

Do not do any of the above and your trees will thank you by growing happy, large and healthy!

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