The best dormant spray for pit fruits that I have encountered is oil emulsion
(dormant oil spray) Lime and sulphur combination dormant sprays is good for
certain conditions. Copper sprays are normally used only for control of fungus
like brown rot in fruits and are applied after fruit set. In any event, unless
you have a huge orchard and are comfortable mixing chemicals, buy a prepared
mix which sets the amount water to be used in dilution.

Drops of sap, especially on the trunk, may indicate borers which requires a
fairly strong pesticide applied when they become active ie about full bloom to
petal drop.