Why do my plums turn blue then fall off prematurely

Yes you should prune them off. I would wait till the summer heat cools down in the fall.

Friar black plum has dark skin, small seed, and is very sweet. Flesh of the plum is amber.

Varieties of Sweet Black Plums

Friar Plum Dave Wilson Nursery

http://www.gardenguides.com/83554-diseases-plum-trees-cures.html

either too much water or not enough

46-(10x4) +4= everyone gets 5 plums.

Lack of pollination or brown rot could be the cause.They are generally not self-fruitful meaning they need a different plum and often a specific variety for pollination and fruit development. If the plums were not full size and lacked a seed (stone) this was the problem.If not try a general fungicide.

Thanks for visiting FixYa!

There are at least four Plum Phones (maybe more).

The first is the Samsung Comeback (SGH-T559)
http://www.phonedog.com/products/samsung-comeback-sgh-t559-pearl-white-plum/manual/

The second is the HTC My Touch 4G Plum.
http://member.america.htc.com/download/Web_materials/Manual/T-Mobile_My_Touch_4G/myTouch_4G_UM.pdf

The third is the Nextel i880 Plum
http://shop2.sprint.com/assets/pdfs/en/support/guides/phones/i880/ug.pdf

The fourth is the LG CU515 Plum
http://www.phonedog.com/products/lg-cu515-plum/manual/

For fall plums and rich browns. Do a smokey charcoal eye. I too have blue gray eyes but very dark hair.

I don't think this is a GE model #, but any who, if you hear a humming <water valve sol> the product valve is not getting water to it, first, don' laugh, make sure both plumming valves are on..
If they are off and no one knows how they got turned off, it falls under the old "****-happens" deal !