Although truffles first form in December, the first visible signs generally show in late February or Autumn. These surface signs occur on the portion of the truffles that have either formed too close to the surface, or become so large a substantial amount of soil has been pushed toward the surface.
With access opened to the truffle via the cracks in the soil, these truffles are more susceptible to insect damage (Eg. slater & millipede in second pic above). Regular searches for such signs, inspection and removal of rotten/damaged truffles, and covering the good ones is an important task at this time of year. Rabbit’s that manage to get past the fencing are also attracted to the disturbed soil, and expose the truffles, sometimes learning to eat them too..
Along with other tasks, Autumn is now a full time job. For every days work in harvest season, there’s around 5 days in supporting work such as this.