Hi @adamjc,
A warm welcome to the Bunnings Workshop community and thank you for your post.
You might like to start by having a read through How to diagnose a sick plant and How To Grow And Care For A Eucalyptus Tree.
Has the problem only arisen recently? If so, was their growth up to this point good?
Have you noticed any insects?
When you planted the trees, did you dig out a hole and add any soil to the hole? What is the soil like? Is it sandy, or heavy clay?
Have you been following any kind of care plan? Stuff along the lines of watering and fertilising. If so, what have you been doing?
Have you been getting huge downpours of water like a lot of the east coast of Australia has been experiencing lately?
Usually, problems like this are a stress reaction. It could be a number of things with over or underwatering, insect attack, poor soil conditions or lack of nutrients being common causes.
If you can answer the above questions, this will help us narrow down the problem and offer a solution.
Jacob
