Is the gummosis on the trunk? If so, it's unlikely to be Monilinia blight. It's possible it's a canker pathogen, such as Cytospora canker: https://extension.psu.edu/stone-fruit-disease-cytospora-canker If you remove the tree and destroy or dispose of it, the pathogen will not persist in the soil. If you'd like to confirm, feel free to submit a sample to the UD Plant Diagnostic Clinic, which is free. See submission instructions here: http://www.udel.edu/extension/plantclinic