Large photo of a Val dwarf peach tree suffering from a bad attack of curly leaf.
Val dwarf peach tree with a bad attack of curly leaf.  The attack was so severe that all of the peach buds fell off.  I had not sprayed the tree with a fungicide.

Photo of nectarine showing no signs of curly leaf.
In contrast this nectarine tree grown from a seedling, planted just metres away from the above peach tree and photographed on the same day is showing no sign of curly leaf.

It is best to grow peach and nectarine varieties that are resistant to curly leaf, otherwise you will be forced to spray each year to keep the curly leaf in check.