Thin the fruit until the branches can support the fruit without props. Remove more fruit from the tips than close to the trunk.

Yes, you will probably remove 2/3 to 3/4 of the crop, but the goal in a young tree's management is to create a healthy tree structure. The fruit is a bonus for the first several years.

http://homeguides.sfgate.com/thin-plums-44277.html
http://umaine.edu/fruit/growing-fruit-trees-in-maine/fruit-thinning/

Not only will thinning help your tree it will allow fruit that's sweet enough to actually enjoy eating. At this point you may be too late to help the fruit but at least you can help the tree. I remove 50-90% from my trees depending on how heavily a variety sets.

This post was edited by fruitnut on Tue, May 20, 14 at 13:42