That is Necrotic Ring fungus. The fungus is root borne.

Yes, 3 eagles is correct. That is NRS. The area is small, so fungicide may make sense. As I mentioned before, Nitrogen applications can exacerbate the disease, so no unnecessary fert apps.

quote:

Originally posted by parabellum:
Oh, thank God. I thought it might be a physical condition.

It actually can be medical. Pressure sores, decubitis ulcers, caused by ischemia, loss of blood flow, are not only caused by linear surfaces with irregularities. They can also be caused by arm bands that are too tight or even by pushing up your shirt sleeves. Anything that shuts down blood flow.