Abiotic disorders and what to do about them

Abiotic refers to “non-living” as opposed to biotic (living). An abiotic disorder is a plant malfunction caused by non-living, environmental or human-made agents. Yes, humans are living but generally the implements they wield which harm trees are not: e.g., lawn mowers, weed eaters, vehicles, herbicides. Another criterion that defines abiotic is they are not infectious. Animal damage is listed under abiotic as the damage they cause is not pathogenic or infectious. (I know, life gets confusing.)

When clients call about a problem with their trees or other plants, they often do not consider abiotic possibilities, rather assuming the problem stems from insects or disease.  The reality is the vast majority of time, the problem is abiotic in nature or stemmed from an abiotic injury.

Environmental extremes are beyond our control: e.g., lightning, heavy snow and wind. Damage caused by these agents should be assessed for prognosis of safety and survival and a management plan devised. Is the damage significant? Can it be rectified? Will the tree survive? Does it pose a safety issue due to proximity to infrastructure or human proximity?

Activities which cause abiotic injuries we can influence involve common practices in managing our landscapes.

Lawn mowers and weed eaters can be deadly weapons to trees. My blog, Can My Weed Eater Really Kill a Tree, goes in to this implement in detail. Lawn mower damage from constantly striking the tree trunk close to the ground is also a common agent of creating an infection court allowing diseases to gang a toehold but can result in progressive decline even without a disease. It is easy to discount incidental contact with a tree, thinking “it can’t be that bad”. But it can and it is.

Another lawn care practice potentially damaging to trees that many don’t consider is the application of herbicides in controlling broadleaf weeds.

Many fertilizer products are listed as “weed and feed”, meaning they contain an herbicide in them as well as a fertilizer. This is supposed to address those pesky dandelions and other weeds in lawns. However, trees, shrubs and many perennials and annuals are broadleaf species as well. And in the case of trees and shrubs, their root systems may be occupying the same soil space as the lawn. What is applied to one affects the other. This is why we recommend creating tree islands or mulched areas around trees. (See my blog, The Benefits of a Tree Island)

Tying strings, garden hoses, installing swings or laundry lines by wrapping chains or line around limbs are another practice that may cause serious injury to a tree.

This includes staking for stability after planting and the tags that come with the tree from the nursery. Limbs grow, but strings, lines, ropes and chains don’t. The tree grows around them often resulting in constricting the vascular system of the branch, stem or trunk.

And then we have irrigation practices. It is easy to get into a rhythm of watering without really checking to see if the plants are being appropriately watered. Consequently, it is all too common to see over- or under-watered plants. One size does not fit all. And, yes I am going to say it again, trees grow. As they get bigger, their water requirements increase. Not only that, but if you have a sprinkler system that was set up when they were first planted, the system needs to be moved away from the trunk.

The roots are far away from the trunk and that is where the water needs to be applied. That growing trunk and buttress roots can also pinch off the water lines entirely.

Trees should be protected from animal damage before it happens. Waiting until you see the damage is too late. Some trees will stay vulnerable to animal damage their entire life and you need to make the decision whether you want to deal with that kind of commitment or pick a tougher species.

Planting herbaceous barriers to discourage browsing from larger animals may work but can backfire as they provide protection for rodents from natural predators.

There are many products to discourage browsing by deer. I have had good luck with liquid products as well as hanging bits of Irish Spring soap from target trees. You may need to experiment to see what will be effective in your area. However, if you are in a particularly heavy use area, fencing might be your only reliable recourse. You can be as creative and decorative as you wish, or keep it simple but effective, combining form and function.  Works very well.