On 6 Jul 04 at 9:35, zonneveld wrote: > ...most clones of vegetatively propagated plants have to be > replaced by new ones due to loss of vigour. But isn't that loss of vigor usually due to the slow buildup of the viral titer? I am aware of a number of old clonal cultivars that were very weak and very tricky to keep going but which recovered vigor when put through tissue culture to eradicate viruses. -- Rodger Whitlock Victoria, British Columbia, Canada "To co-work is human, to cow-ork, bovine."