junkyardcat wrote:

I have several plum and peach trees. We moved here last year, and were
excited about having fruit trees, but alas, when the fruit came out, it all
got this ugly mildew and shriveled up to nothing! This year, I want to spray
the trees so they don't any pests or diseases, but I have no idea when is
the correct time to spray. Does anyone know when is the appropriate time?

I spray my peach tree and grape vines with a mix of dormant oil
and copper sufate right after pruning, which is in early January.
(I also use this on my roses, which I prune at the same time.)
Then, only on my peach tree, I use the same spray again when the
flower buds show red, just before opening. After the peach is
through blooming and the petals have fallen, I spray both the
peach tree and my roses for bark borers (a serious problem here).

These are the only preventative sprayings I do. Any other
spraying is in response to an existing infestation, which means
that -- in some years -- I do no other spraying.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 19 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a)
Gardening pages at http://www.rossde.com/garden/