On Sat, 17 Jan 2009 08:25:50 +0000, Adam wrote:

Hi All

I've recently taken over a garden, and discovered a few raspberries
growing among the undergrowth. The canes have been neglected, are
surrounded by rampant weeds, and produced a very meagre crop last year.

The conventional wisdom is that raspberries and the like pick up viruses
over the years and become less productive. Conventional wisdom is that
every four or five years they should be uprooted, burnt and fresh
certified stock planted in a different place. But, hey! it's your garden.
Well rotted manure each spring as a top-dressing is usual, I believe.