How to treat Murraya dropping leaves?

[cjcjay]

  

 

Hi we’ve had these murraya hedges for >10 years. They have always been thriving but in the past 2 weeks we have noticed rapid leaf drop. It is patchy but appears to be spreading. Hedges on the opposite side of our driveway are fine. What can we do? We haven’t mulched for some time, and recently had robinas cut down (6 months ago) but there is leaf drop even where we did not do this. 

[JacobZ]

Hi @cjcjay,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Rapid leaf drop is almost always a stress-related response to some kind of change. Our first step should be identifying what has changed, as this is likely the cause of the issue.

Have a look at How to diagnose a sick plant for some guidance from one of our resident horticultural gurus @Noelle.

Check the leaves closely for pests like scale, mealybug, or leaf miner damage, as well as signs of sticky residue, sooty mould, or yellowing before they fall. Inspect stems and branches for dieback, discolouration, or cankers, and scratch the bark to see if it’s green and healthy underneath.

Examine the soil around the base to determine if it’s consistently soggy or very dry and consider whether nearby tree removal may have disturbed roots.

Finally, note whether the problem is spreading plant to plant or appearing randomly, as this can help distinguish between pests, disease, or environmental stress.

Identifying the issue will give us a better idea of how to fight back, but at this stage, focusing on the general health of the plant would be the best course of action. I'd suggest clearing up the base of the trees, so the trunks have good airflow, then applying a slow-release native fertiliser such as this Scotts Osmocote Native Controlled Release Fertiliser to ensure your Murrayas are getting the nutrients they need to fight back.

When we can identify the issue, I can assist further.

Allow me to tag @mich1972 and @robchin to see if they have any thoughts.

Jacob

[cjcjay]

Thanks @JacobZ ! The problem appears to be spreading rapidly. I cannot see sooty mould, or signs of fungus. However I do see brown patches on leaves and on the other side of our driveway another hedge is now affected but there are white patches. I have tested the pH and it’s 8.5. Is adding sulfur going to do the trick or do I have something else going on like a pest or disease?

  

 

[EricL]

Hello @cjcjay 

Thank you for sharing that extra information about your Murraya.

From the photos and description, it looks like your Murraya hedge is under stress from a combination of environmental and possible pest or disease issues.

First, the high pH of 8.5 is a strong signal. Murraya prefers slightly acidic to neutral soils (around pH 6–7). At pH 8.5, essential nutrients such as iron, manganese, and phosphorus become “locked up,” which can cause leaf yellowing, brown patches, poor new growth, and in severe cases leaf drop. Adding elemental sulfur is one way to gradually lower soil pH, but it works slowly over months. A reliable option is Manutec 1.5 kg Sulphur Fine Granules or Yates 3 kg Sulfur Soil Improver Granules from Bunnings, both of which can be spread around the base and watered in. 

For quicker results, Yates 500 ml Soil Acidifier Liquid Sulfur can be mixed in with water and applied as a drench. In the meantime, using acidifying fertilisers and organic matter such as composted pine bark or peat can help buffer the soil. Applying chelated iron or liquid trace elements will also quickly correct deficiencies while the soil is being adjusted.

Second, the leaf symptoms. The brown patches and uneven yellowing suggest more than just pH stress. On closer inspection of your second hedge with “white patches,” that may point to scale insects. Citrus leaf miner is another common pest in Murraya that distorts and discolours new leaves. Scale insects often bring on secondary sooty mould, but you said you have not seen any, which means it could be an early stage. 

It is worth checking the undersides of leaves and along stems for small, flat or domed insects. If present, Bunnings has several suitable control options including Yates 750 ml Ready To Use Scale Gun Insect Pest Killer for immediate knock-down, Yates 500 ml Pest Oil Concentrate for larger hedges, or Seasol 1 L EarthCare White Oil Insect Spray and Multicrop 1 L EcoPest Oil Insect Spray for a gentler white oil approach. These oils smother pests like scale, leaf miner, and mites, and are best applied in the cool of the morning or late afternoon.

Third, the rapid defoliation suggests that the plants are already weakened. Stress from the alkaline soil, possibly made worse by dry conditions, is opening the hedge up to secondary problems like scale, leaf miner, or fungal leaf spot. Some of the brown blotches on leaves could indeed be fungal, even if you are not seeing mould on the surface yet. Consistent deep watering and the addition of mulch will also reduce stress and improve soil health.

To tackle this, I recommend three parallel steps. First, begin soil correction gradually with elemental sulfur products such as Manutec Sulfur Fine Granules or Yates Soil Acidifier Liquid Sulfur and mulch with organic matter. Second, apply a balanced liquid feed with trace elements to give the plants a quick nutrient boost and offset the effects of high pH. Third, carefully inspect for pests such as scale or leaf miner and treat with one of the horticultural oil sprays mentioned above. Avoid overfertilizing with lime-based or high-alkalinity fertilisers, as that will worsen the problem. Ensure consistent deep watering rather than frequent light watering, as drought stress can accelerate leaf drop.

Please remember to wear personal protection such as gloves, goggles and a mask when spraying chemicals.

If you need further assistance, please let us know.

Eric

[cjcjay]

Thanks so much @EricL , we’ll do that. What balanced feed would you recommend and which pine bark mulch? Many thanks.

[EricL]

Hello @cjcjay 

I propose looking at using the Yates 500ml Health Tonic Trace Element Chelates and Richgro 70L Pine Bark Mulch. Please remember to keep the mulch away from the main stem of the plants.

If you need further assistance, please let us know.

Eric