AusBonsai

Hello everyone,

I hope you are all well.

A couple weeks ago I picked up a new Casuarina Equisetifolia. It's a beautiful tree and it has a lot of potential.
When I purchased the tree I checked with the nursery if I was ok to repot it, which it was. I did then repot it from a nursery growing pot into a fairly large bonsai pot. I ended up cutting back approximately half the root base to fit it into the new pot, so I cut back approximately the same from the branches/leaves.
I was also told Casuarina like to have the soil fairly moist.

The tree is now having an issue. The leaves are becoming white on the tips...the tree looks like it is dying.

For all of my trees I use the following combination for soil, approximately: Pumice 40%, Zeolite 20%, Perlite 10%, Soil 10%, Bark 5%, River Sand 5%, charcoal 5%, mixed with a bit of blood & bone fertiliser. My other trees seem to do ok with this combination of soil.

I am not sure what is causing the Casuarina to die. Could it be that it doesn't like the soil type, I haven't pruned it back enough with having cut 50% of the roots, am I over-watering it, are the leaves being burnt (it sits in open sunlight and receives 100% sun from 8am-2pm), or something else I am not thinking of?

I am not sure what to do. Would I:
1. Leave it as it and it will hopefully recover from being repotted?
2. Should I repot it again into a different type of soil? Maybe back into a growing pot to see if it recovers?
3. Prune it back some more?
4. Water it less?
5. Change the amount of sunlight it is getting?
6. Anything else to revive it?

Any help would be greatly appreciated as I really don't want this tree to die. I can upload some pictures tomorrow night if they will help.

Cheers,
Cam

Hi Cameron and welcome to Ausbonsai.
I've dug (yamadori) several casuarinas locally. Don't know the variety and I do have a couple of different looking ones. All but one of mine have lost their original leaves before resuming growth. They sit around and sulk a bit after root pruning before pushing new buds. After that hiccup all of mine are now doing well with a lot of new growth on the trunks which I had chopped down to half of the original size. Looks like your potting mix is well draining, so just let them be but keep the water up to them.
One I had dug last autumn looked like it had died, so after 4 months I pulled it out of the pot to discard it and found it had grown some new roots , but it didn't survive after that.
Hope yours make it. Cheers, Frank.

I'm no expert Cam, but I do have quite a few C. equisetifolia I have been growing for a few years from seed. In my experience (Brisbane also), they do like to be kept moist after repotting. I initially give them partial shade even after a corresponding foliage reduction, but I tend to move them into full sun quicker than my other plants as they do like the sunlight.
Your mix sounds fine, and don't give up on the tree even if you get significant die back, as they can resurrect themselves from dry looking sticks (ask me how I know )
I wouldn't repot it or prune it back any more (it will dump the foliage it can't support). I would ease up on the watering if/when the foliage dies back significantly (match the watering to the tree's needs). Consider moving it to a position of filtered/ morning sunlight until you see new growth.
Hopefully, more experienced bonsai people can chip in here too.

You need to understand that those 'leaves' are actually stems, even though they are green. The leaves of casuarina are minute. Tiny. So small you need a magnifying glass to see them. Leaves are around the nodes on those green stems. look for the small ridges every cm or so along the stems to identify the nodes.
What I'm leading up to is that you have pruned through the stems and pruned stems always die back to the nearest node where there are leaves. I would say that the white tips are just the ends of the stems where you have cut between the nodes. They should only die back to the closest node then drop off.
If more than just the tips are dying you may have a problem. In future if you want to avoid white/brown tips on pruned casuarina you can pull with fingers and they usually break right at the node.

I wouldn’t do anything more with the tree now. Leave it alone... for months.

Shibui is spot on that the ends will die back if you’ve cut off the stem segments to the previous nodes.

Redsonic is also spot on that the tree often dies back after a repot and root removal to a point where its now adequately supplying the remaining structure and the rest dies off. However I wouldnt put a casuarina in less sun than it got, especially after a repot etc. Unless the casuarina was previously growing in heavy shade, it’s going to love full sun.
Redsonic touched on the most important point about after-care for casuarina. If the medium is reasonably good and you haven’t over-Potted the tree, then the uptake of water is going to be very very low. Only water the soil when it needs it.
Going into summer the sun will slowly dry out the soil between waterings. But don’t be surprised if you can leave it for a long number of days before watering it again. If it has dried out at some point this also might be a problem. But again, either issue means it will now significantly slow down water uptake.

Did you work the entire root ball, or leave the main rootball alone?

I have repotted many casuarina with 50% root removals and what you are describing sounds like die back to a comfortable proportion. It can even take up to 6 months for casuarina to recover.

I would leave it alone and only water it when it needs it.

Hey everyone.

A very big thank you to those of you that responded. The information you have provided is excellent and greatly appreciated. Thank you.

I'll follow the advice provided and monitor the tree closely.... It's sounds like I have no major concern in regards to the tree surviving, with time and care it will be ok.

Thanks once again,
Cam