The jelly substance could be natural sap from the tree, or, it could be bacterial canker, the jelly substance is called gummosis. It is caused by bacterial infection which is prevalent in cooler wet weather, so early spring when buds are emerging. 
Peaches are very popular fruit trees. They require adequate summer watering, deep and well-drained soils, high nitrogen fertility, fruit thinning, and pest control sprays to prevent peach leaf curl and brown rot.
Peach trees are short-lived trees (15-20 yr). Peaches (like nectarines) are self-fruitful (self-compatible), which means that they do not require a pollinizer tree.
Spray fixed copper to control peach leaf curl December 1 and February 1. Prune out 50% of last year’s wood to thin the crop, insure good shoot growth and fruiting potential for future years. Thin fruits to about 6" apart when marble-sized. Thinning reduces fruit numbers, but increases size, prevents limb breakage. In the summer, fertilize young trees monthly. Use 0.5 lb. urea or 25 lb. manure/tree/appl. Mature trees need 50% more. Water fertilizer in. If drip irrigated, do not exceed 1 oz. urea/emitter/mo. Drip irrigate daily or sprinkler irrigate about every 3 weeks. Maintain a weed free area around the base of the trees within 3' of the trunk with an organic mulch 3–4" deep. At leaf fall, remove and destroy or compost leaves to prevent the spread of peach scab. Remove mummies from tree.

Here are some publications you can read:

https://gardenerspath.com/plants/fruit-trees/how-grow-peach-trees/

https://aggie-horticulture.tamu.edu/fruit-nut/files/2015/04/peaches_2015.pdf

Hope this helps!