Brutting is a really simple technique to make your hazel or cobnut trees produce more nuts. It is done in August.
All you do is snap (but don't break off) the ends of all the new shoots that were made this year. Count up to six or seven leaves on the new shoot from where it comes out of the older wood and snap the shoot there. This will stop the tree trying to make a new shoot and force the bit below the snap to make more flowers, which will turn into more nuts next year. That's it!