Healthy tree recovered from borer insects

This is an image of the recovered tree – located in a business park… hence the bin!

What are borer insects?

Borer insects are usually the larvae of particular moths and beetles. The adults lay their eggs either on or in the bark of a tree and the larvae hatch and start consuming the tree.
Tell tail signs of borer insects are: leaves on whole branches dying off; holes in the bark; bark lifting off or falling off; and sawdust on the ground and/or on the trunk itself.


What can we do about borer insects?

There are many products on the market that promote the death of borers. These chemicals are unnecessary and are overkill. They do nothing to treat the problem – they only treat a symptom.

We can think of borer insects as a secondary issue.  The key cause of a borer insect infestation is a sick tree. A healthy tree has healthy sap and this sap can surround and drown borer larvae. It’s a natural defence mechanism.
Therefore, if we can increase the health of a tree, we should be able to stimulate sap production and this natural defence mechanism. But does that actually work?


Case study of effectively treating borer insects

One of my commercial clients has a tree that had leaves on whole branches browning and dying off. My client suggested we might chop the tree down but I was reluctant.
That particular site is in the middle of an industrial area.

There are two significant gardens at the front and back of the site. The site itself is mostly concrete and houses approximately 34 businesses. It’s a business park of approximately 2-3 acres.

Because of the front and rear gardens, this site houses a number of native birds. One of which are the Superb fairy-wren – blue wrens. I love these little guys and I have noticed they tend to use the tree as protection.  There are other small birds that also use this tree.

Therefore, I recognise this tree as key habitat for those birds.  The tree is located in the middle of the site. It’s the only native tree in that vicinity and its surrounded by concrete. I’ve noticed that the wrens land there when flying from between the front and rear garden areas. I explained that to my client and they agreed that I could try to treat the tree rather than chopping it down.



Dying off branches of a tree from borer insects

Fairly poor image of the tree in a sick and distressed state. We can see brown leaves and branches dying off.

The tree is surrounded by Lomandra longifolia – an Australian native clumping grass. When I cleared some of the Lomandra, I noticed that some of them were growing right next to the trunk.  It also became obvious that the tree had fallen over at some stage. The trunk was actually horizontal.

There were a significant number of exposed roots. The horizontal trunk had small holes in it. There was a marked absence of bark – much of which was lying on the mulch underneath. I also noticed a fine woody substance like sawdust.
I concluded that we were probably looking at borer insects!

Exposed roots from sick tree suffering from borer insects

We can see the trunk is horizontal and there is some bark missing. We can also see some saw dust on the trunk and the exposed roots.


Saw dust from borer insects

Another fairly poor image – sorry about that – showing a close up of the saw dust from the borer insects.

Remedy for Borer Insects

My aim was to increase the health of the plant so that it could deal with the borer insects itself.  I cut off the dead branches.  This relived the tree from the weight of the dead wood, thereby reducing stress.  I also cut back and pulled out some of the Lomandra that was in the immediate vicinity of the trunk – where it met the soil.

To the exposed roots I added a compost mix and ensured they were completely surrounded by soil.  I poked and prodded the compost into the exposed roots.  Note that some composts are hydrophobic, so we may need to add an organic liquid soil wetter.

To the root zone and the surrounding top soil I also added some rock minerals and two types of soil conditioner: one fish based and the other seaweed based.  I added a hoop pine mulch and watered the root zone well.

That’s all I did and it didn’t cost my client much at all.


Recovery after borer insects

Unfortunately, I didn’t map the recovery rate.  But the tree has certainly recovered.  It’s been about 18 months now but I recall seeing a marked improvement within 6 months.

Therefore, in my opinion, the key to helping a tree infested with borer insects is to help the tree to increase it’s health.  This stimulates it’s natural defence mechanisms.  This is the case with most plant health problems.  Read my blog on sap sucking insects for more information.

Focusing on plant health is also a healthy and non-toxic process.  It’s the key to creating organic gardens and healthy, organic ecosystems and can be applied successfully in commercial gardens…

Healthy tree recovered from borer insects

The recovered tree showing healthy leaf growth and coverage… despite being packed in by bins and boxes and industrial stuff!


Same tree different angle recovered from borer insects

This is the same tree from another angle. Again, it shows healthy leaf growth and coverage.

Isn’t that interesting?


Robyn McGennan · September 12, 2018 at 4:07 pm

Thankyou garden tara for this alternative procedure to what I’d been reading on other sites . I have twin blireana x prunus trees approx.16yo and 2 mt.apart .The grandkids and I have had lovely sheltered picnics for most of those years between the trees in our coastal , regional town . They have been my favorite tree since growing up with them in nature strips planted by Melbourne councils .
Sadly there is borer in one of our trees with all the classic signs . I pruned it hard in Autumn, preparing for removal and interestingly it displayed blossoms and now copper leaves . I’d like to save it , however it is badly infested and the trunk has a split down the centre . I’m concerned for the surviving twin that the moth might travel to it after the removal of it’s habitat .
What do you suggest ? Thankyou , Rob.

    Amber Hall · September 13, 2018 at 8:35 am

    Hi Robyn, what lovely trees blirenana x prunus are.

    Regarding the borers, if you increase the health of the tree following the procedure in my blog the borer issue should be reduced or eliminated. That remedy utilises the tree’s own defence mechanisms but the trees need the nutrient resources to do so. It sounds like one tree is in distress and the other may follow suit. Therefore we need to tend to the soil.

    I’d be placing a healthy amount of compost and composted manure around their bases. Spread it up to 1 metre from the trunk because roots extend beyond the trunk. I’d be adding some rock minerals to that compost and also a rescue remedy in the form of a liquid seaweed and fulvic acid mix and water it in well. You can also use this liquid remedy as a foliar feed to quickly get nutrients into the plant. Cover the compost with a mulch such as dried leaves or sugar cane mulch. I wouldn’t use a bark based mulch at this stage. Read my blog on hydrophobic soil to determine the state of the soil before composting and also regarding the water infiltration of new compost:

    Regarding the split down the centre. There are remedies for split trunks and it does depend on a number of things such as: the degree of the split; how old the split is; its exact location; and the tree’s growth habit etc. Pruning it recently would have reduced the weight and should have reduced the chance of more splitting. So it’s great you did that. To further reduce the split you can attempt to bring the two parts together. You’d do this by drilling through the split parts and bolting them together. Care needs to be taken using the drill bit so that it doesn’t get stuck in the trunk. You may want to call on an arborist or caring tree doctor to do this. The weight on the split branch/s should be reduced until you feel the tree has recovered.

    I hope this helps 🙂

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