Black Ooze from Eucalyptus Might Be New Problem

Q. I have an ornamental Eucalyptus tree in my back yard that is 20' tall and facing west.  It has been steadily losing leaves and branches the past two years.  There is a black sap that has been oozing sap through the bark. It crystalizes into a hard substances.  Can you provide a diagnosis and treatment?

Not the readers, but this is a eucalyptus and many have a similar form.

A. Your description of this problem about your Eucalyptus bothers me. The loss of leaves, the branches dying back coupled with black sap that oozes through the bark is a very good sign of Eucalyptus borer.
What does Eucalyptus borer look like?

To my knowledge, this insect is not been reported in southern Nevada. It has caused a lot of destruction in Eucalyptus in California.

I would consult this information from California: Information on Eucalyptus borer

I am paraphrasing now from California information:
"Holes in the bark and stains or oozing liquid on limbs or trunks are common symptoms of longhorned borer damage. When this borer is a problem, leaves can discolor and wilt, and limbs can die back."

"Longhorned borers usually attack stressed or damaged plants, leaving vigorous, appropriately watered trees alone. In California, however, many eucalyptus trees are seasonally water stressed during hot summer months, rendering a significant proportion of them susceptible to beetle attack. Tree species with some resistance to these wood borers can produce copious amounts of resin in response to an attack."

"Extensive larval feeding beneath the bark can spread around the entire circumference of a tree, girdling, or completely removing a strip of bark from, the trunk. Trees at this stage of infestation have a thin canopy with wilted or dry leaves, and the bark is cracked and packed with larval excrement. Infested trees usually die within of a few weeks of girdling, although resprouting can occur from the tree base."
What does this borers damage look like?

If you believe this could possibly be the problem I would hope that you would contact the Nevada Department of Agriculture and start asking some questions.They might ask you to send up samples Carson City for identification by the entomologist. This borer usually attacks trees that are not getting enough water or are not being watered often enough or both.

Nevada Department of Agriculture in Las Vegas: 702-486-4690