How to treat Murraya yellow leaves?

We had a hedge of murrayas in place for about 10 years. In one section there was 2 - 3 plants that were never quite as strong as the rest.

Mid 2024 these 3 finally died. I put in replacements - they to have died off.

Now one both sides of the gap the leaves are yellowing - see photo of the worst one.

Our soil is pretty wet - so wonder if it is that. In the past we have had borers, but I thought I had sorted them...

I am wondering why this section has died off recently (after approx 10 years) and replacements struggle.

I am in Brisbane and our garden is pretty low so if it is drainage, I wonder what I can practically do.

Grateful for thoughts.

Thanks

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Comments

MitchellMc

Welcome to the Bunnings Workshop community @Timo14. It's wonderful to have you join us, and many thanks for your question about murraya care.

How wet is the soil in that section? After watering or rain, how long does it take for the soil to dry out? Most plants, including murrayas, don’t tolerate having consistently soggy roots, and prolonged wet conditions can lead to root rot.

One common reason for plants declining after reaching a certain height is that they were planted on top of a solid clay base. Often, they do well initially because their roots remain within the topsoil layer, but as they grow, their roots penetrate deeper, hitting the clay. If the clay holds water, the roots can end up sitting in a pool for days or even weeks after heavy rain, which suffocates them and causes a rapid decline.

This could explain why your established murrayas eventually died off and why the replacements struggled. Young plants are even more sensitive to poor drainage, and if they were planted in already soggy soil, their roots might have rotted before they had a chance to establish.

If drainage is the issue, there are a few things you could try. Raising the planting area by mounding up soil or using a raised garden bed can help keep the roots from sitting in water. Alternatively, improving soil drainage by incorporating organic matter or gypsum (if it’s clay) might help over time.

Have you noticed pooling water in that area after heavy rain?

Please let me know if you have any questions.

Mitchell

Timo14

https://www.workshop.bunnings.com.au/discussion/comment/50303#Comment_50303

Thanks Mitchell

Regarding your questions:

How wet is the soil in that section? After watering or rain, how long does it take for the soil to dry out?

The other week when I had a dig down, I actually got to "free water" ie there was a pool of water in the hole. This weekend on digging down I got to pretty wet clay, but no free water. After decent rain (which we have had a bit of in BNE recently) it can take the adjacent lawn area over a week to dry so that it is no longer "squelchy" to walk on.

For improving the drainage - what can I do given the current plants there with their root system? It is hard to dig down (to get organic matter etc in) with the roots in place.

I was thinking the other day whether I could dig / drill a drainage well / column. However given how it is clay below approx 10 cm, I am not sure if any decent area would drain into it.

Also can the current plants (the ones with leaves already yellow) be saved?

EricL

https://www.workshop.bunnings.com.au/discussion/comment/87263#Comment_87263

Hello @Timo14

That is a bit of a predicament as your Murraya is already very well established. Some possible solutions are to break up the clay if you can get to it, use a garden fork or crowbar to break up the clay at the bottom of the hole. You don’t need to dig deeper just loosen it to allow some drainage. Avoid making a "bowl" where water can collect. Another way is to try and improve the drainage, mix gypsum into the clay at the bottom and sides of the hole if you can get access to the bottom. Gypsum helps break down clay structure over time, improving drainage without affecting soil pH.

One other method is to raise the planting level of the existing tree. Raise the level of tree by creating a mound. Fill the hole with a mix of good-quality soil, compost, and some coarse sand or fine gravel (about 30% sand) to help water drain through. Position the root ball so it sits slightly higher than the original ground level, then taper the soil down. But because your Murraya is already very big, I'm not sure if this will still work for your tree.

One other option is to perhaps relocate the tree to another spot where there is good soil drainage. You would need to investigate the new area thoroughly to make sure that it does not have the same issue with the bottom having a clay base.

Let me call on our experienced members @Noelle and @mich1972 for their recommendations.

If you need further assistance, please let us know.

Eric

Noelle

https://www.workshop.bunnings.com.au/discussion/comment/87263#Comment_87263

Hi @Timo14

Gypsum doesn't need to be pout into the bottom of the planting hole to improve clay soils. It can be spread on the top of the soil, and rainfall and watering will wash it though the soil/clay over a period of time. However, amending a clay soil with gypsum is a longterm project - it can take a few tears years for a significant difference in texture to become noticeable.

I think Eric's suggestion of raising the murrayas and establishing planting mounds is probably your best option.

mich1972

Good afternoon @Timo14 Everyone has given great advice and I absolutely agree with them. Definitely raise up / mound your soil to help with free drainage.

Timo14

https://www.workshop.bunnings.com.au/discussion/comment/50443#Comment_50443

Thanks everyone for your responses.

Not sure how practical the raising up is - my murrayas are in a row of approx 30 m long, forming the hedge between me and the neighbours - one side of the murrayas is fence, the other side is my lawn. Hell of a job to dig them all up and raise them.

As a half measure I might try to crowbar etc around the roots to aid drainage, and try some (a lot??) gypsum.

mich1972

https://www.workshop.bunnings.com.au/discussion/comment/87331#Comment_87331

Good morning @Timo14 Ok well that’s a shame you can’t lift and replant but that’s understandable. Gypsum spread over the top of the soil is ok and it is a clay breaker. Just go by the instructions on the bag.

Timo14

https://www.workshop.bunnings.com.au/discussion/comment/87331#Comment_87331

Just done some quick googling: is liquid gypsum worth trying to “inject “ around roots using a length of pipe pushed into soil around roots?

mich1972

https://www.workshop.bunnings.com.au/discussion/comment/109163#Comment_109163

@Timo14 @I think that may damage the root system and cause more damage. With liquid Gypsum, it has to be applied with a watering can as per the instructions and after application, make sure to water straight away if it is sitting on the foliage. You have to do a couple of applications depending how heavy your clay is.

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