[dropcap]W[/dropcap]hen I was up in Colorado this summer I was introduced to a poster by the late Bonnie Appleton (a horticultural educator) entitled ‘How to Kill a Tree.’
This tongue in cheek title was followed by an illustration showing all of the mistakes that people make when planting and caring for trees.
While many of her guidelines are universal, it got me thinking that there are also some specific care and planting techniques that are important to follow here in central Texas in addition to general tree rules.
It is important to realize that a stressed tree does not always let you know in time to save it. By the time it shows outward stress (especially for mature, established trees) it may be too late to reverse the internal damage.
Trees can, in some cases, take several years to show visible symptoms of damage (i.e. drought or compaction stress) so it is important to treat them with respect from the start and continue to care for them even into old age.
With oak wilt so rampant in our part of Texas, many of the actions on this list can hasten the demise of these majestic trees. Please pay special attention to numbers 1-4.
1. Use of weedcloth. First of all, I have grown to hate the stuff in general, but that’s a ‘rant’ for another day! As for underneath trees, it may appear that it will help to keep weeds down and moisture in, but in reality it can help to harbor disease underneath the weedcloth and keep the tree from breathing properly.
Also, while the tree is young, the Bermuda grass will weave its way through the weed cloth making its removal both unpleasant and impossible. As the tree grows larger, its natural shade will help to eliminate many weeds without outside assistance.
2. Cross contamination through garden tools. When we move from plant to plant and tree to tree disease can cling to our garden pruners and saws and spread to the next plant we touch. It is important to sterilize your tools between uses, especially if you are moving on to red or live oaks or have been working with diseased plants to begin with.
3. Spraying herbicide around roots (especially feeder roots). It is easy to inadvertently hit the smaller roots on the outside canopy of a tree when applying weed killer. While a single hit may not cause much damage, that stress can build up over time and potentially damage the long-term growth of the tree, especially when they are young.
4. Improper pruning (techniques and timing). It is critical that you prune your trees at the correct angle to prevent weak joints. Make the cut smooth and make sure you haven’t ripped that last bit off leaving a substantial wound that can allow disease and insects in.
Prune in late winter for best results with hardening off new growth (after most hard frosts have passed) and healing over of the wounds. Wait until after bloom for many spring blooming trees. If you have oak trees, the timing of your pruning is especially critical: the beetle that helps spread oak wilt is at its least active between October and February, so this is the optimum time.
5. Suffocating the roots with too much mulch or dirt, compaction, concreting over, etc. Tree roots are quite sensitive to environmental stresses, especially the outer edge of the canopy, which are known as feeder roots.
Covering them up with too much dirt or mulch, let alone concrete or other solid structures can cause the tree to decline and eventually perish. Compaction of the soil from traffic (or other similar activities) can have similar results as the soil itself suffocates the root system.
6. Forgetting to water. New trees will need supplemental moisture for the first several years. But even larger, mature trees need special attention sometimes too. Forgetting is easy to do when you have established trees that have been there for countless decades.
We don’t think of them as part of the active landscape, but more as a background for where we do our landscaping. But they are some of the most critical to remember to water, especially during drought to keep their stress at a minimum and ensure a quick bounce back when Mother Nature starts to water them again herself.
7. Girdling with a weed-eater, old stake wire, etc. This is a big issue because it can quickly kill a tree and it is easy to do if you are not paying attention. I know I am even guilty of weed-eating just a little too close to the trunk of that new tree trying to neaten up my yard. It is also easy to forget that those tree stakes and wires should be removed after the first 6 months to a year (or a little longer if in a windy area).
The problem lies in the phloem and cambium layers that move moisture up and down the length of the tree. If these layers (which lie just beneath the bark) are cut all the way around, it stops all growth of the tree immediately leading to its imminent demise.
8. Damaging the roots with mowers, trenches and heavy traffic. The blades of the mower, cutting in irrigation and other trenches, or cracking under heavy machinery can cause the trees to lose the ability to take up moisture from the damaged roots. Those cuts and holes can also become a portal for diseases to enter into the tree from below.
All in all trees are easy to take care of when we just follow a few easy steps, from proper planting (see Planting a New Tree article in November) to maintaining and playing/working carefully around our existing trees. When followed they can give lasting shade and a general sense of beauty and serenity for generations to come.
Happy gardening everyone!
If you have a question for Chris or Amanda, send it via email to [email protected]. Or mail a postcard to It’s About Thyme: 11726 Manchaca Road, Austin, TX 78748 www.itsaboutthyme.com
