Tree does not seem to be doing well. I am concerned about watering – over/under? I am in Escondido CA. Planted the young tree Nov last year. Ten got into high 30’s couple of days but rarely. Soil drains well. Currently watering 1 gallon every 3 days.
You are outside the recommended growing zone for the Rainbow Eucalyptus.
The temperatures and growing conditions may not be meeting the needs of this tree.
This is the likely reason for the poor condition of your tree.
I would also urge caution in growing this tree in a home landscape environment.
Here is a link with more information.