My Lemon Scented Gum Tree Has Turned Browny / Purple

Question

It is a mature tree approx 25m high.

Answer 1

Discoloration can be attributed to light stress (they prefer full sun), fungal diseases, or insect invasion. They are susceptible to pests such as borers, psyllids, and beetles. The bronze bug can cause changes to leaf color. A local nursery professional may be familiar with these trees. These articles should help:

https://ipm.ucanr.edu/legacy_assets/PDF/PUBS/greenbulletin.2017.may.pdf

https://www.public.asu.edu/~camartin/plants/Plant%20html%20files/corymbiacitriodora.html

https://plants.ces.ncsu.edu/plants/eucalyptus/

https://ucanr.edu/sites/UCCE_LA_County/files/96659.pdf

https://www.gardeningknowhow.com/ornamental/fungus-lichen/types-of-tree-fungus.htm