I was wxited this spring when my nectarine tree was full of fruit. I sprayed with organtic fungicide about a month ago . Now all the fruit is shrivelling down to brown lumps. Shucks,what went wrong?
Check the label of the product you used; make sure it was suitable for fruit trees.
Check your tree for signs of pests or disease.
This does sound like Brown Rot Fungus.
These links will help with more information.