This year I'm trying a completely environmentally-friendly approach to treating peach-leaf curl, by using a new product called "Serenade." Flushed with success using the bacteria-based treatment Bacillus Thunbergensis (or BT / Dipel) to kill-off cabbage white caterpillars before they can devastate a brassica crop; I've forgone the usual copper-based fungicide application in favour of using Serenade, which contains another commonly-soil-based-bacteria called Bacillus Subtilis.
In mid-late February all peaches and nectarines were sprayed at least twice with Serenade at twice the
stated concentration (based on research from Canada this double concentration gave peach leaf curl control similar to standard fungicidal controls).
the leaves are just starting to emerge on the
nectarines (left), which are always a little ahead of the peaches. The young leaves are usually flushed with red, so it's hard to see how many have been infected by peach leaf curl.
Last year one dwarf nectarine was very badly infected and all of the fruit remained green and stunted, until I felt sorry for it and took them off at the end of the season. Avalon Pride was completely unaffected. New peaches this year are Saturn and Redwing (which is purported to be partially resistant).
you know how the new regime is faring by variety.