Promotion of lawn growth with fertilisers, increase the volume of the plant material production to be laid down as thatch.  Fertilised lawns are always at risk of producing thatch accumulation rates, which are ahead of thatch decomposition rates. 

Some lawn grasses have high thatching potentials, eg. Browntop, Fine Fescue, Poa, Couch & Kikuyu. Therefore, we provide dethatching to reduce the lawn stress toleration.

This is what a lawn looks like after a dethatch: