Figure 2. A tree with the full canopy in decline tells you that the problem originates from the trunk or roots. Cutting in with a knife or hatchet is a great next step in diagnosis. For prune brownline (left) a thin dead zone of tissue can be found between rootstock and scion. For phytophthora a canker often with associated gumming originates from below ground, although lab diagnosis may still be needed for confirmation. Photos by Jaime Ott.