A one-year-old child has become ill after eating wild mushrooms in a Kapiti Park, prompting a warning from Wellington Regional Public Health.

All wild mushrooms should be treated as potentially poisonous because it was very difficult to tell which were safe to eat, Medical Officer of Health Jill McKenzie told The Dominion Post.

She said parents should remove mushrooms from backyards and gardens and watch children closely at parks because the cooler weather provided ideal conditions for fungi to grow.