What are the grayish spots on the surface of my peaches?

September 13, 2024 Ask the Expert, Fruit Trees and Small Fruits, Managing Insect, Diseases, and Animal Pests

Question:

I have had a peach tree for six or seven years. This year we seem to have a bumper crop of peaches growing on our tree. However, the majority of them have some grayish spots on the surface which seems to be only on one side of the peach. I have attached three pictures. The first is a picture of our tree. The second is a picture of two peaches showing the grayish spots on one side. The third is a picture of the opposite side of the peaches that show they are essentially clear of these spots. Can you identify the issue and if so what is it and is there any way to prevent it either now or in the future. Also can the fruit be eaten by just removing these affected areas?

Answer:

Jonathan Foster, Home Horticulture Outreach Professional

This doesn’t appear to be brown rot (a common and more serious condition), unless it’s very early on. I can’t be 100% certain just from a visual diagnosis, but I would guess this is either peach scab or bacterial spot. There are management recommendations for both conditions in that link–peach scab is very common and has some intervention options, while bacterial spot is tougher to control and is often simply tolerated. Both conditions are improved/mitigated/possibly prevented by good cultural practices for growing and pruning peaches, as the best practices approach promotes general tree health and minimizes the still, moist, warm air among the canopy that promotes the spread of infections. The warm, wet summer we’re having is great for these kinds of infections, unfortunately. :-/

If the above advice doesn’t improve things, or if it’s not matching what you’re seeing, you can submit photos and/or a physical sample to the UMaine Plant Disease Diagnostic Lab for testing. There is small fee for their service, but you’ll have confirmation of any pathogens present.

Good luck and happy gardening.