A project summary on understanding brown etch of pumpkins is available here.
Brown etch almost always starts where the fruit is in contact with the ground, a stem, or another pumpkin. A reddish brown stain spreads across the skin, developing as a series of concentric rings or irregular, blotchy patches. Only the skin colour changes; etched areas remain rm. With time, the etched tissue dries out, developing a whitish appearance reminiscent of petri ed wood. Fungal spores can sometimes appear in the centre of these dead areas.
Symptoms of brown etch are always super cial. The underlying esh is una ected and there is no impact on eating quality. Despite this, even a small amount of etch can lead to rejection by retailers.