EV said:

The prune plum is a whole other story. ...
Last year it bore heavily, but dropped about a third of it's fruit
before it ripened. I lost half of what was left to various bugs in
various stages. And some of the fruit had what looked like crystallized
loops and nubs and dribbles of sap on them. What is that?

This year the tree fruited even more heavily, but has dropped about 2/3
of its fruit, either green and shrivelled, purple and shrivelled, or
purple and hard. The crystallized stuff is on many of them too, and I
can see bumps and punctures on much of the fruit. If I get a dozen
edible plums, I'll be lucky. So much for the plum jam and the galettes.

Where are you located? In eastern North America this is most likely
plum curculios, a type of weevil.

http://ohioline.osu.edu/hyg-fact/2000/2043.html

I'm not big on pesticides and such, but will definitely be using dormant
oil this fall and next spring. Any comments, insights or suggestions on
the plum problems would be appreciated.

Of the pesticides recommended for plum curculios, phosmet (Imidan) is
considered less harmful to non-target insects.

Cleanup is important. Pick up all fallen fruit and send it off with the trash.


--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)