This is the repost from Conifers forum since I got no responces there. Maybe I'll have a better luck here?

For the last two years cone production on my Picea abies Acrocona had been greatly reduced from 100's in 2004 to just handfull in 2006.

I remember seeing/reading somewhere suggestion of root pruning to stress the plant in order to induce heavy(ier) cone production, but absolutely have no memory about when, how, etc.

Could you please enlight me on a subject?