I believe curc is repelled by the fuzz on peaches. Nectarines are usually hit a lot harder. Up here Jap plums are much more likely to avoid damage than the Euros. Tarnished plant bug does a number on peaches at a lot of sites and leave most other fruit undamaged. TPG hangs out in the broadleaf plants in the turf and jump on the trees after mowing I'm told. All in all peaches do better here without spray than most fruit if they don't get killed by borers.
Some varieties of apples suffer less damage from PC. At one site I manage there are a lot of old strain yellow deilicous (prone to russetting and they ripen later than some of the new strains). Without spray there is a good crop most years. The Macs, Red D.s, Baldwin, newer strain yellow D.and RI Greening apples seldom yeald fruit at this site without spray.
Zone 6 southeastern NY
[NAFEX] plum curc peaches etc.,
Alan Haigh, 06/20/2008