Pocket Botanist
Check these first
- Check the soil moisture 3 inches deep with your finger.
- Inspect the base of the trunk for dark, sunken spots.
- Examine the drainage of the surrounding soil after a heavy rain.
Likely causes
Phytophthora root rot
Most likelyHow to tell: The foliage wilts and turns yellow while the soil remains soggy. You might notice a dark, weeping lesion on the lower trunk.
What to do: Improve soil drainage by adding organic matter or installing drainage tiles. Apply a phosphorus acid fungicide as a soil drench if the infection is caught early.
Waterlogged soil
PossibleHow to tell: The soil feels heavy and smells sour or swampy. The tree shows general decline and lack of new growth.
What to do: Stop watering until the top 3 inches of soil are dry. Ensure your planting site is on a slight slope to allow excess water to run off.
When to worry
If the trunk lesions are spreading or the entire canopy is wilting, the tree may be beyond saving. Some minor leaf yellowing is normal during seasonal shifts.
Stopping it coming back
Plant your macadamia in well draining, sandy loam soil and avoid overwatering during the cooler months.
Not sure which one it is? Photograph your macadamia nut.
This page lists the usual causes. Pocket Botanist looks at your actual leaf and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
Questions people ask
- Can I save a tree with root rot?
- If the damage is limited to a few roots, you can save it by improving drainage and using fungicides. If the trunk is girdled by rot, the tree will likely die.
- How often should I water?
- Water every 7 to 14 days depending on your local heat. Always check the soil moisture before adding more water.
More problems with Macadamia nut
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This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.