Q.Rainbow Eucalyptus issue?
I have two of these trees next to each other. They are about 25′ and been in the ground 8 months. They look to be doing very well, but one of the trees is getting small brown spots on the leaves and shedding leaves more than the other. All of the leaves on this tree are a paler green than the other. What would cause this?
Leaf spots are caused by both bacteria and fungus.
Brown, black spots or circular and ragged edges may be seen.
Insects and rain can be causes.
You can use fungicides to help control the disease from spreading.
There are more serious diseases that have to be considered.
Some may be treated others may result in loss of the tree.
You may want to consider having a professional Arborist inspect the tree.
Contacting your local County Extension office to ask for references to your area is a good idea.
Here are some links for you.