What Common Reasons Cause Trees To Die Before Old Age?

Posted on by Andrew Turff

			What Common Reasons Cause Trees To Die Before Old Age?

Like all living organisms, trees eventually die, there are five main reasons why trees die, death from its environment, death from harmful insects and diseases, death from a catastrophic event, death from age-related collapse (starvation) and of course, death from harvest .

Why trees may succumb and die in your garden include:-

Trunk Damage

During transportation or planting, in older trees, damage may be due to strimmers and lawnmowers. If you live in a more rural location then the trunk damage may be caused by deers or rabbits.


If a trees roots become waterlogged for a long period then this is in effect the same as drowning, the roots of trees like any plant need oxygen as well as water to survive. If the roots are deprived of oxygen for extended periods of time then the root tissue will start to decompose.

Too Dry

If a tree is subject to prolonged periods of dry weather or drought then it will suffer some stress, it is important for the well being of the tree that it has adequate water, the same as any living organism.

The effects of drought on trees and shrubs can be characterised as short term or long term. Short-term damage, caused by one dry spell, includes wilting, leaf scorch, and some defoliation. Long-term damage from drought happens over a period of years and includes stunted growth, branch die-back, and possible death of the plant. Many woody plants can take up to three years after a drought to display negative long-term effects.

A common long-term effect of drought is stem dieback, which is a result of the loss of fine feeder roots. Another problem caused by long-term drought is pest infestation. Many pests, like wood borers and bark beetles, cannot survive in a healthy tree. As a tree or shrub becomes weakened from drought, these pests invade rapidly.

Choosing the right plants for your location and caring for them properly are the best ways to lessen a drought’s long-term effect. Incorporating plenty of organic matter into your soil, weeding regularly, watering infrequently but deeply and applying mulch around your plants are the best ways to help them survive a drought.

Planted too deep

You need to plant trees so the root balls sit firmly on the bottom of the hole with the top of the root ball even with the surrounding soil. Dig or hole the same depth as the root ball and then dig the width of the hole at least twice the width of the root ball. Place the tree in the hole, fill the hole with the original soil, and water thoroughly to settle the tree. Do use a mulch to help with moisture retention. One word of caution, however, do not touch the trunk of the tree with mulch. It is important that any plant is planted as soon as possible and that the roots are not left to dry out, if you purchase bare root stock then make sure the roots are kept moist up to the point of planting.

Undeveloped roots that have failed to grow out into the surrounding soil 

When a new pot grown tree is planted it is important to tease out the roots from the clump that will have formed in the pot, if not you may find that the roots never get a chance to spread and develop into a good structure. This should not be an issue if the plant is a bare root specimen.

Root  Disturbance or Damage

Trees and shrubs that have been moved do not always re-establish successfully and some woody plants such as broom and magnolia resent root disturbance at any stage of their growth cycle. If a plant's roots are damaged through building work, digging footings etc. then this can also have an adverse effect on the plant.

Suffering from a disease

Trees can die from disease, which can be either soil or airborne. 

There are certain diseases that are particular to a given species such as ‘Dutch Elm Disease’ or ‘Ash Dieback’ or other diseases which attack any species of tree.

Some airborne diseases are only prelevant at certain times of the year, causing open wounds to a tree by pruning gives an opening for the spores to enter, this is why it is important to prune the tree at the correct time of the year.

Too much herbicide

When used properly, chemicals can benefit trees and their growth. But improperly used, herbicides can interact with the roots and damage the tree's health. Make sure the instructions for application are carefully followed and seek professional help whenever you are not sure.

Soil Compaction 

This is a slow tree damage process, often with few or no other signs of the cause. In compacted soil, pore space has been reduced and roots do not get enough oxygen. Often the tree slowly declines and dies. Soil compaction can be avoided by aerating the soil, by mulching and by preventing soil disruption around trees on construction sites where heavy machinery can cause soil compaction.

Unsuited to the site

Any plant grown in the wrong situation will not thrive as well as one grown in the perfect situation. So for that reason, it is always best to seek the advice of a qualified arborist before selecting a tree for a certain situation. It is all too easy to plant a tree too close to property or other plants, it can be difficult to estimate the final size even when supplied by the seller. Likewise, certain trees like to grow in damper or drier conditions, some will prefer full sun or maybe dappled shade. It is also important to check the ph level of your soil and the requirements of the particular plant you have selected.

Weak or Unhealthy Plant

If you have purchased or been given a plant that is unhealthy before planting it, it will be more likely to die than a healthy specimen, especially if it is subject to another stress such as drought.


Dead patches on conifers are a relatively common sight, these are usually caused by overzealous pruning but can be caused by disease.

Conifers will not grow back when pruned back to old wood; with a few exceptions, so before pruning conifers you have to ask yourself is it really necessary. There are cases for pruning conifers such as removing dead, diseased or crossing branches but other than that it’s best just to trim back new growth to keep the shape or form.