AusBonsai

This spring some leaves on a couple of my banksias have turned brown. It looks like the shoots are dying.

Does anyone have any ideas?

Hi Neil a few years back I lost a couple of banskia marginatias with the foilage turning brown then the whole branch dying and loss of tree with a boring pest laying its grubs right in the collars of where the branch meets the trunk the hole being a bit bigger than pin hole..hard to see before it was too late the cunning buggers basically ring barking from the inside, maybe worth a look.

Anthony

Yeah that doesn’t look good. I swear this species is the bane of my banksia collection. I love them, but fair dinkum they are temperamental. I’ve found them to be somewhat tolerant to pest sprays, but other than that they are the most prone to pests and root issues of them all.

I wish you well Neil. I’ve lost 2 in the last year.

Since adding river sand to the mix, ive managed to get on top of the drainage issues.

Damn. I hope you can find what's causing it mate

Can you rule out P toxicity?

Thanks for the ideas everyone.
I did not think of borers in this case Anthony but I have just checked - no signs. These shoots are quite small - see photos below.
This is a Tassy form of B. marginata. Another small B. integ (I think) has the same signs.

Never rule out anything Mike but also look past the 'accepted' for other possibilities. Although I do sometimes use standard fert on some of my banksias I can't remember whether these ones have had any thrive or just powerfeed.

Since those previous photos the affected shoots have continued to die back. Death is limited to last year's shoots. Now, new shoots are growing strongly The other banksia has even stronger new shoots growing in some places I can even see new shoots starting to grow from the base of some dead areas.

Any further ideas?

Neil,

I do have a type of botrytis that affects all my Banksia. It starts out with a look similar to the red circled areas I highlighted from your pic. Just curious, but after a period of cloud or long periods of rain, do you notice it gets slowly worse?
It only really seems to affect the banksia in my collection. It comes from the Euc leaves and branches that drop from trees around me. I now have it in check thankfully.

But it looks similar to those highlighted areas for what is slowly starts out at.

The fact that whatever it is has spread to the integrifolia and caused die-back there is a little concerning. I do get the botrytis on my integrifolia too, but it isn't as impacting as it is on the serrata / aemula and marginata, I presume because of the stronger and faster growth the integrifolia exhibits.

Thanks for adding that as a possibility Rory. This usually happens in spring here, as the weather starts to get warmer and drier. I have no overhanging eucs or other trees but fungal infection could still happen.

I note that you appear to have made the assumption that this has spread from one plant to the other...........

shibui wrote:This is a Tassy form of B. marginata. Another small B. integ (I think) has the same signs.

Sorry Neil. Yes I didn't read that properly, I must have skim read that comment assuming you said it definitely had spread from one to the other. My bad.

I had a hunch about the cause of this dieback and this afternoon there are signs that my guess could be correct.

Take a look and see what you think.

Well.. the suspense is killing me.. but I’m off to bed..

What... whaaaaaat? Shade? Tiny pot?


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Lack of water.
Potbound?

Would it be the heat transferred from the corrugated iron ?

Fiona

I think you could be on to something shibui....