Q. I need your help again. I have two Swan Hill olives trees in the back yard. One has lost
a lot of leaves and looks sparse and the other looks good. I have also taken a couple pictures of
of the problem tree. Do you think the sparse looking tree could have verticillium that you mentioned in your newsletter?
A. The tree looks pretty young and I would not expect it this soon in its life if it appeared at all. This disease is not common here.
It is hard to really know if the disease is present or not just by looking at a tree. Olive has few problems.
It is by deduction. Verticillium wilt causes limb dieback in trees. My olive tree has limb dieback. Therefore my olive tree has Verticillium wilt. That’s how it is diagnosed now without sending a sample to a pathologist.
Typical Verticillium wilt symptoms do not occur in olive like they do in other trees. Upon close inspection of an infected limb, olive looks normal instead of having the vascular streaking common to that disease.
Two things you can do; watch it and see if it gets worse or send a sample to the state pathologist with the Nevada Department of Agriculture. This would be in Carson City. His contact information is on their website or call their local office at 702-486-4690.
I would not cut any limbs or remove them until you have some better idea of what is going on from a source that does not profit from tree removal. In the meantime, water it frequently and deeply. Fertilize it now for good growth.