If you’re concerned about the condition of your trees due to recent severe weather, you may be wondering if there’s a way to find out how safe they are.
While it is difficult to predict or prevent tree falls during extreme weather, there are clues that can help identify trees that are under stress and steps you can take to prevent these trees from falling under normal circumstances.
Recognizing a tree under stress
The two experts we spoke to agree that taking a close look at the tree is the best place to start to identify problems.
The tree crown is the “part that bears leaves, flowers, fruit and seeds,” explains arborist and secretary of the Tasmanian Tree Care Association Rebecca James.
Rebecca James gives tips on how to recognize a tree under stress. (ABC News: Georgia Hogge)
“The crown provides insight into the functioning of a root system and because it is furthest from the root zone, it suffers first,” adds Jason Court of the City of Hobart’s tree care program.
One of the clearest signs of poor health of a tree is Edge dieback in the crown.
If the tree is diseased, it will not produce as many leaves as it should and premature leaf fall may occur.
The leaves may also be smaller than the previous year.
“Other indicators could point to a nutrient deficiency,” says Ms James.
“So, Trees that normally have a bright, rich green color may have a duller colormaybe even towards yellow.”
Yellowing leaves or dying leaf edges can be an indication that the tree is under stress. (ABC Hobart: Lucie Cutting)
Further down on the trunk, wetness and spots is an obvious sign of a problem.
Another clue, according to Mrs James, is Bird activity.
An infestation of pests is a tempting meal, especially for birds like the ever-cheeky Sulphur-crested Cockatoo, which nibbles at the points where branches join the main trunk to dig for insects.
Like a canary in a coal mine, nibbling birds “can be an indication that there is trouble,” Ms James says.
“If the tree responds to these defects by forming new tissue, it is not necessarily a problem, but it at least indicates that wood is being lost.”
Birds nibbling on a tree can indicate problems. (Source: Loretta Lohberger)
At ground level, cracks emanating from the trunk, spongy or springy soil indicate instability, as does torso movement on a windy day.
Most of the roots that give a tree stability are found in the top 12 to 24 inches of soil. Severing these roots compromises the tree’s ability to anchor itself in the soil.
It can also mean that a tree is not getting as much water or nutrients.
Excavation work near a tree such as laying underground cables or lowering fence posts, can sever roots and cause problems.
A clear sign of root damage is edge dieback.
If the ground is hard, this can also affect access to water.
“Look at the soil to see if it has any problems absorbing water,” Court says.
“If the plant does not absorb water, the leaves may become discolored, for example if the roots are damaged,” he says.
DIY care for healthy trees
While there are free and inexpensive measures available to maintain a tree’s health, unfortunately they do not guarantee catastrophic failure or protection from extreme weather events.
Mrs James’ most important recommendation is Do not park cars under a tree and do not plant grass directly under a tree..
Vehicles and heavy equipment reduce the air space in the soil and cause compaction, which means less movement of important nutrients. Grass competes for these nutrients.
Another simple step is Applying an organic mulch.
“Wood chips, bark or even pea straw in and around the trunk of the tree can be extremely useful,” says Ms James.
“It seems like such a simple activity, but it actually serves three or four different functions.”
Mulch around the trunk of a tree has several benefits. (AdobeStock)
Mulch acts like an insulating blanket and reduces water evaporation.
It suppresses weeds and serves as food for soil invertebrates, which in turn recycle the nutrients and make them more available to the trees.
For broken or hanging branches that can be handled with an extendable pruning saw, Rebecca says, “Definitely try it,” but Make sure you sterilize your cutting tools to avoid cross-contamination.
To sterilize garden tools, a mixture of three quarters methylated spirits and one quarter water can be used.
If possible, avoid excavation work near the treeThe Australian Standard for the Protection of Trees on Building Sites requires a protection zone of excavation of 12 times the trunk diameter, measured 1.4 metres above ground, to ensure tree health.
When working within this zone, careful techniques such as hydro-excavation can be helpful.
When you should call the professionals
If you need to get the ladder out To examine the health of a tree, Ms. James recommends calling in a qualified arborist.
Similar, a tree that rises and falls in the ground or in cracked ground is a strong indication that an arborist needs to be called “fairly” quickly.
If a tree cannot be saved and must be removed, you should check with your local council before removing it to see if the tree is protected under a government planning law or significant tree register and whether you need a permit.
If you are on council land, “contact us and let us know if you have any concerns about a tree,” says Mr Court.
The cost of tree removal can range from several hundred dollars for a small tree to several thousand dollars for a more complicated, large project.
Jason Court is part of the City of Hobart’s tree care team. (Source: Jason Court)
Both experts agree: prevention is better than cure.
“It takes a long time for a tree to reach the final stages of falling, so if you have any concerns, contact a qualified local arborist who will be able to advise you on what might be wrong with the tree,” says Mr Court.
“But just take care of the trees. Prevention through water and mulch is key.”
