Does this look anything like what you are seeing? (see link below)

Here is a link that might be useful: crown gall fact sheet

hmmm, raspberries are susceptible to a number of pests and diseases - it sounds like yours has been affected by phytopthera fragariae. This horrid disease has been a problem in the US for some time but has now appeared in the UK (around the late 80s). Although there are chemical controls, there is not certain cure. A strategy of integrated pest management, including soil amendemnts with calcium (there seems to be a connection involving nutrient uptake and increased calcium levels in soil, although raspberries prefer a neutral to slightly acidic soil), planting on ridges to improve drainage (hilling), working to a shorter rotation, allowing the soil to remain fallow for several years after removal of infected canes (I have a five year rotation, replacing canes and planting in a new area) and using chemicals such as mancozeb (although I am not up to date on this and I am sure that other chemicals have been introduced as this has devastated crops in raspberry growing areas such as Scotland).
Phytopthera can remain in the soil for several years so new polanting should happen in a different location and basic hygiene should be followed (avoiding walking on affected soil and spreading the disease to other parts of your plot, scrupulous cleaning of tools and boots).

RpR do you live in a state with a local agricultural bureau? Some states have very helpful organizations. That would also be a great resource to ask.

Wirosarian:
No they look more like a tree root that is rotting in the ground only the roots are white not yellow.

In the area where the Raspberries are and have been for about eight years, rhubarb used to be there but all but one plant died and new ones died, usually in the first year.

Now that may not be related but that is also odd and the original plants were decades old as is the lone survivor which is getting bigger.

Hoovb:

Yes we have U of M dept. that handles that but having spoken to them over the years, I have been under-whelmed by their responses.
Not saying they are bad, but they have not impressed me.

Can you get a digi-pix of what you are seeing?

Jeri

There is also a raspberry crown borer that can affect roses, tunneling in the base of the plant and the roots. It is a small insect and not very noticeable. After the plant is killed, the remains would rot and might give the impression of being killed by a fungus. But do investigate campanula's suggestion of phytopthera.

Your description sounds like a fungi mycelium, the plant body of the fungus. Armillaria travels through the soil, from root mass to root mass, 'eating' everything in its path. Perhaps you have something along those lines? That would explain the "white, tree root like" growth and the movement of plant death from one end of the area to the other. Kim

Here is a link that might be useful: Armillaria

Jeri:
No not only because the ground is frozen under several inches of snow but I removed all the infected plants.

I removed about two feet of good ones, just in case and dug a trench.