Will Cercis Avondale trees survive borer attack?

[gmc713]

Hi, just wanting some advice. I have two Cercis Avondale, 8 yr old.  Both trees had suckers on them for the past few years. (I didn’t realise this was a sign of stress) They leafed out as normal last year They came into bud this year but in the first week of October they still hadn’t flowered or leafed out. My neighbour was walking by as I was looking at the trees and he said 3 out of 5 of his hadn’t flowered yet and not to worry as they have got buds and it had been a cold start to spring. I kept checking on the trees, one bloomed a few flowers, but the flowers never reached their full bloom and were dry. The branches were still bending and when I scratched the branches, they were still green.  Two weeks ago (early November) I noticed frass and borer holes. I have been giving the trees Seasol weekly and treating the borers with Pyrethrum (injecting in the holes) and Neem Eco Oil  I have got out about 20 borers out of the two trees.  Tree #2 had sent out suckers in early October which I have cut off, it doesn’t seem to be in as bad a state as tree #1. Tree # 2 looks to be getting ready to flower. Both trees have small branches that snap, but some of the branches that snap still have a green appearance and some are still bending.  It is now the third week of November. Should I keep persevering in hopes of a recovery, or should I cut my losses and call in the arborist to remove them? Is there a likelihood they will recover? Also there are some tiny black bugs about 1mm wide and 5mm long that are fast crawling that sometimes come out of the borer holes when I treat them. Does anyone know what they could be? I thought maybe a predator of the borer. There is weed mat under the stones in the garden. I don't know if this is an issue or not.

 BorerTree # 1 borer holesTree # 1 borer damageTree # 1 Current StateTree # 2 Flower buds getting ready to bloom?Tree # 2 suckers

[JacobZ]

Hi @gmc713,

A warm welcome to the Bunnings Workshop community, it is wonderful to have you with us.

I'm sorry to hear of your borer issue, but it sounds like there is still hope, especially with tree #2 as it is still showing signs of blooming and new growth.

Everything you have done to this point has been beneficial and I think you should persevere, however calling in an arborist who specialises in saving at-risk trees might be the best course of action. 

I don't think it is time to cut your losses and remove the trees, but an arborist will be able to advise you on the best course of action moving forward.

Unfortunately, I haven't been able to identify the beetle with any certainty, but it looks like it could be a bark beetle.

Allow me to tag @Noelle, @robchin and @mich1972 for their thoughts.

Let me know what you think.

Jacob

[robchin]

Hi @gmc713 

Where abouts are your trees? Borers do vary around Australia. Not sure if they're the source of all of your problems but could be. The trick is to find the eggs before they hatch and treat those - no good just treating the emerging beatles. You have to break the cycle. 

Knowing exactly which beatle  you have will help you confirm the life-cycle. 

This article from our good friends at Yates is quite informative: How to Get Rid of Tree Borers in Your Garden | Pests | Yates Australia

Good luck. 

[gmc713]

Hi @robchin, 

I live in North East Victoria (Albury/Wodonga).

[mich1972]

Good morning @gmc713 I can’t say what insect it is sorry. I do agree with @JacobZ about contacting an Arborist, also you may want to contact your local Agricultural Department as they may be able to help you.