Resistance
Observation and Theory
Conclusion from Histopathology
American chestnut is recognizing and responding to the blight fungus equally as fast as Chinese chestnut.  This implies that chestnut has a different mechanism of resistance to blight than occurs in biotrophic and hemibiotrophic pathosystems, where all resistance appears to be based on recognition of the pathogen and where avirulence involves suppression of ÒantigenÓ display.  Chestnut blight resistance may or may not be more stable than resistance to biotrophs, but it is hard to imagine it being less stable.

Histopathology on older cankers was also helpful to me in understanding what is occurring inside cankers with various morphologies, facilitating interpretation.