How to treat lawn grubs around macadamia nut trees?

CharlieBear62

3 days ago one of my 3 year old macadamia nut saplings keeled over and died.

It's been recommended that I treat around the now 4 saplings with a lawn grub treatment.

Has anyone had to treat their garden soil with a lawn grub treatment and for around saplings do we simply water in the granules without having to remove the soil and compost first.

Until I can get to town and but a lawn grub treatment is there any homemade treatment I can make to help protect the other 4 healthy saplings.

The second photo is of how all 5 saplings had beautiful new growth in September.

(RIP) 28th December 2025Beautiful new growth 24th September 2025

MitchellMc

It sounds like the sudden loss of your sapling could definitely be related to pests like lawn grubs @CharlieBear62, but it’s worth looking at the bigger picture. Lawn grubs are usually fairly widespread rather than isolated to one plant, so nearby saplings could also be at risk if grubs are present. A quick way to check for them at home is to mix a squirt of dishwashing detergent into a litre of water and pour it in one spot at the base of the plant just outside the pot. If there are grubs or beetles in the soil, they’ll come to the surface fairly quickly. This won’t get rid of them, but it will tell you whether they’re present.

Once you’ve confirmed grubs, the most effective approach is a proper lawn grub and beetle treatment. These are designed to target them directly and are safer for your trees than homemade remedies long-term.

That said, it’s not guaranteed that grubs were the sole cause of your sapling’s collapse. Other factors, like soil type and watering, can contribute. For example, if the saplings are planted in clay-based soil, the roots might eventually reach a poorly draining layer where water collects, which can suffocate the roots over time. Environmental stress, sudden changes in water, or even a plant just failing naturally, are also possible.

So while checking for and treating grubs is a good precaution, it’s also wise to review soil conditions, drainage, and watering practices to protect your remaining saplings.

Please let me know if you have any questions.

Mitchell