In article , Andrew Newton
writes
We've moved house recently and I'm now attacking the lawn. I've got quite a
bit of trefoil which is now in flower. As I don't want to use chemicals can
I remove this by raking the patches before I mow (as I've successfully done
previously with clover) each time. Also any idea what cause this to grow so
I can take some preventitive measures.

Trefoil is a legume, legumes are able to 'fix' nitrogen and therefore
compete well in low-nutrient soils. Therefore, try to increase the
nitrogen levels in the soil so that the grass will compete better.
--
Kay
"Do not insult the crocodile until you have crossed the river"