My nectarine tree has grown rapidly, it has been a great fruiter, however the fruit is always brown & rotten inside around the seed. Please help!
Without seeing or knowing more, Brown Rot most certainly could be the culprit. The first and best remedy is cleaning up the ground every fall. I would also try to remove any 'mummies' left hanging on your tree.
This article discusses spraying and timing of spraying with fungicide. I have to disagree with this article about the use of a fungicide/pesticide. Insects are not your problem yet and pesticide is never used as a preventative. Fungicide is always used for a preventative. It is like a little raincoat. Spore + water drop = infection of the entire plant.
Never use 'Tangle Foot' or any sealant on pruning cuts. Otherwise the information is basic. Maybe I'll just go find a better article? I also do not like, "...naturally rather than using toxic chemicals...". Everything is chemistry. Chemicals can be considered toxic to some plants, yet safe for others. Bad for humans, bad for insects, safe for plants. Chemistry is chemistry.
Another article on Brown Rot... Brown Rot prevention