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Can anyone identify whether this is sun damage, overwatering or a disease? It is throughout the whole tree.
Hello @KazTCB
Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your eucalyptus tree.
The brown patches on your eucalyptus leaves are most likely caused by a fungal disease, commonly known as leaf spot, rather than sun damage or overwatering. The appearance of tan to brown irregular spots, some with a grey or papery centre, is characteristic of fungal infections like Mycosphaerella species, which are particularly common in eucalyptus trees exposed to humidity or poor airflow.
Since the damage is visible throughout the entire tree and not limited to newer or older leaves, it strongly points to a fungal issue rather than watering problems, which usually result in yellowing or soft leaf edges, or sunburn, which tends to affect only outer, exposed leaves.
To treat this, start by pruning off the most severely affected leaves and disposing of them—do not compost them, as this may spread the spores. Then, apply a fungicide such as Yates Mancozeb Plus Garden Fungicide and Miticide, available at Bunnings. Be sure to spray the leaves thoroughly, including the undersides, and repeat the treatment every 7 to 10 days if the weather remains warm and damp.
To help prevent further spread, avoid overhead watering and instead water at the base of the tree in the early morning. Improving air circulation around the tree by thinning out dense foliage or nearby plants will also help reduce humidity and fungal activity.
For ongoing support, consider feeding the tree with a gentle, balanced fertiliser such as Seasol + PowerFeed All Purpose, which will help boost its natural defences. Keep an eye out for any insect pests as well, since they can weaken the tree and make it more susceptible to disease. If the issue continues despite treatment, taking a few affected leaves to your local Bunnings or nursery for further advice is a good next step.
If you need further assistance, please let us know.
Eric
Hello @Aleisha124
Welcome to the Bunnings Workshop community. It's sensational to have you join us.
Thank you for sharing your knowledge and experience in regards to the Eucalyptus tree. Let me tag @KazTCB to make them aware of your recommendations.
Were keen to hear more about all your projects and plans around the house and garden. Please feel free to reach out whenever you need assistance or would like to share a project with the community.
Eric
Just also wanted to extend a very warm welcome to the Bunnings Workshop community @Aleisha124. It sounds like you have a lot of knowledge and experience to share with other members. Feel free to join in the discussion anytime you have something to contribute. I trust you'll get plenty of ideas, inspiration and advice in return from our clever and creative community.
Jason
