Banksia root rot solutions

[MattM]

I have 3 Integrifolios with root rot. The weather has been crazy in Western Sydney in the last 2 months from 48 degrees to wet humid days and they have been overwatered. I sprayed them with Yates Anti Rot and haven't watered them and left them under the car port where they get half day sunshine.
Should I replace the soil as well?
What other advice can people offer?

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[SquatJar]

Diluted peroxide drench or dunk?

[MattM]

Sorry SquatJar, can you give me a little more information.
Is that hydrogen peroxide that you can buy from woolies?
What dilution strength?
Do I sit the container in a bucket of it?
Can the solution get sprayed on the leaves?

Thanks
Matt


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[SquatJar]

yep, normal hydrogen peroxide from the supermarket or pharmacy. Most products you buy will be 3%. Roots love it, it will react with organic matter (fungus, bacteria, algae) and bubble releasing oxygen, all that's left after the reaction is finished is water.

There's plenty of dilutions recommended, just google. You can spray it on the leaves at quite a weak dilution. I normally use roughly a tablespoon in a 500ml spray bottle for foliage spray. Although I don't use it like that much as it will only kill whatever it touches on the leaves and then is gone very quickly. For root drench I dilute it 1:2 or 1:3. Again, only rough I don't measure it out. If you want to use it as a complete dunk (likely to be more effective than a drench) I would dilute it further but again, a quick google should give you links of what dilutions people have used without it causing damage to the roots.

goodluck, I too have had issues with root rot with banksia

[Rory]

Yes, I’ve mentioned this before too.

There are quite a few Banksia prone to it.
Over-watering, bad drainage, long periods of rain and cloud all combine and you can develop root rot.

Unfortunately if the foliage looks really bad, it is often too late and the rot has spread far up into the trunk.

I would repot immediately and remove all the spongy rotten root, and cut back into the healthy roots, assuming it has some left though.
Remove ALL the old potting mix. And I mean all, bare-root them all now. Start with fresh potting mix and add 50% washed river sand to the new potting mix.
This will allow the mix to drain fast.

You can buy washed river sand from landscaping supplies or soil suppliers or sometimes gardening centres will recommend where to get it. Also you can add rocks to the mix, like about 5mm - 10mm course, to really air the mix.

Do not leave the roots until you next repot. These trees will soon die if you do.

Integrifolia is one of the only Banksia I have had survive from having bad root rot.

Don’t remove foliage. Let it sort itself out. Just deal with the roots now.

Get it out of the Bonsai pot, and buy orchid pots to immediately improve the drainage flow.

Do not over pot them either, you want small orchid pots that are just the right fit for the remaining roots.

[MattM]

OK so as a comparison I have repotted in an orchid pot my "oldest" and special integrifolio in new soil. It's a nursery plant I've been learning off for 8 years.
The other 2 integrifolios, one an air layer and another nursery stock, I have sat in a peroxide mixture as recommended.
I'll let you know the results

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