Hello Chris
There are two types of raspberries - Summer fruiting which fruit on
last years canes and autumn raspberries that fruit on this years
canes.
Anne suggests cutting the lot down - which has some merit in that you
clear the groound, remove any infected material and can clearly see
what is there - but you might not get a crop of berries if they are
the summer fruiting kind.
An alternative, if you can't stand the thought of being without fruit
is to prune out all wood that shows signs of having fruited, you
should see the flower stalks still in the canes. Those will fruit
next year - even if they are autumn fruited ones. Leaving non
fruiting primocanes (autumn fruiting raspberry canes) will yeild a
summer crop.
So how will you know what kind you have. Well if you leave the non
fruiting canes and they fruit in the summer - it could be either,
however if the new canes that grow this year fruit, then you have
autumn raspberries.
Raspberries have a life of 12-15 years before becoming tired. 10 new
canes can cost around the £10-12 mark out of the catalogues. So the
choice is yours....
Good luck

Clifford
Bawtry, Doncaster, South Yorkshire.