I have a peach tree in my yard in St. Paul. It is doing well, except that the fruits are all blemished (see attached photo). What is causing this? Also, do you have any suggestions on how I can stop squirrels from climbing the tree and attacking my fruit?
Ramsey County Minnesota
What you are seeing looks like Brown Rot. Sanitation is extremely important to get rid of this disease as it carries over on material from one season to the next. The link I am giving you has suggestions. As far as the squirrels, the only think I can think of is to enclose the tree in netting secured firmly at the bottom so the critters cannot reach the fruit. https://hgic.clemson.edu/factsheet/peach-diseases/#:~:text=Peach%20Diseases%201%20Brown%20Rot.%20Brown%20rot%20is,Peach%20Tree%20Short%20Life.%20...%20More%20items...%20
I'm pretty sure that this is not brown rot. The blemishes on the fruit are just on the skin. When I had the same problem last year, if I peeled the fruit, the inside was just fine.
Then maybe it is powdery or downy mildew. It still will be important to practice good sanitation to prevent the fungus from overwintering on your tree and fallen fruit. Perhaps you could use a fungicide labeled for use on fruit trees early next spring as leaves as just starting to expand. Read the label as to timing. Good luck.