Nectarine Fruit Tree Disease

This is one of the 3-in-1 fruit tree (Peach+Nectarine+Plum), I think the nectarine is infected by bacterial spot. On the same tree, only the nectarine and peach have disease problem, the plum fruits seem to be disease resistant. I guess there is no such thing as perfect gardening!
Recipe for less toxic “dormant oil" to suffocate overwintering pests, such as aphids and mites.
INGREDIENTS
1 cup vegetable oil
2 tablespoon liquid soap
1 gallon water

Insect Control: Horticultural Oils

Bacterial Spot Info

Bacterial spot of peach factsheet

Peach Bacterial Spot

Peach and Nectarine Disease resistance Varieties

How to Prevent Diseases and Insects that Attack Peaches/Nectarine?
Notes - Chemical sprays for bacterial spot are not practical for the home grower. The best way to control bacterial spot is to select resistant peach varieties. Peeling fruit removes most traces of the disease.
- Spray program with dormant sprays and carry on through the growing season
- Collecting diseased fruit as soon as it appears and removing infected twigs and mummies from the trees will reduce the carry-over of brown rot to the next season.
- If fruit ripening occurs during a period of warm, wet weather, a very rigid spray program is required to control brown rot.
- It is important to begin spraying just before the fruit ripens. Delaying a spray program until rotten fruit is evident will result in very poor control regardless of the effort.
- Controll Peach Scab with chemical sprays applied at the "shuck split" stage and every 14 days for the next four to six weeks
- Never plant a peach tree in an old vegetable garden site. Root-knot nematodes can build up on many vegetables. The safest planting sites are portions of the yard where bermuda or other lawns have been established for years.
- Oak Root Rot disease is caused by a soil borne fungus that attacks and kills peach roots. The fungus will survive for many years in the soil on roots of hardwood trees long since removed. There is no control.
- Do not prune trees in October, November, December and January, wait until mid-February to prune the trees. Pruning in late winter reduces the chance of winter injury and infection by the bacterial canker organism.