Sudden plum death?

I've had several plum trees, in two different places on the property, die suddenly.  Trees were previously healthy and starting to bear.  Other types of trees seem to be fine.  Any ideas?

I would be tempted to cut the trunk/branches open and see what it shows...leaves inspected for bugs or fungus, I would go all CSI on it.

Also, dig up the roots, could voles or some such have nibbled the roots and now the heat of summer is upon us, they were simply too damaged to draw enough water?

Lorinne Anderson wrote:I would be tempted to cut the trunk/branches open and see what it shows...leaves inspected for bugs or fungus, I would go all CSI on it.

Also, dig up the roots, could voles or some such have nibbled the roots and now the heat of summer is upon us, they were simply too damaged to draw enough water?

Trunks seem fine.  Trees didn't leaf out after winter.  Voles could be the culprit, but I would have expected a slower death...