I have had one for some years - growing in a wild flower meadow, in rough grass, on heavy clay soil. It has clumped up a bit, but in that situation I have not noticed any seedlings.
You put greasebands around the trunks in autumn to stop certain wingless moths climbing into the trees to lay their eggs. In spring these eggs turn into caterpillars which eat the leaves. On occasion they have stripped the leaves of my cherry tree almost completely - but grease bands do prevent this happening. You can buy them from most garden centres in the autumn.
THere's more information here http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=518