I know that they grow in the tree near Lake poli during the proper season and that Erik sell all the specific season fruits in their respective season and I'm pretty sure that they aren't dropped by any monster. But are there any boxes or chest that contain any of them?
Probably you already know this, but for any one else who may read this topic looking for this information:
Cherries: Spring Oranges: Summer Chestnuts: Fall Apples: Winter
You can find the fruits growing on the Cornucopia Trees on the Mountain Road and in the Orchard of Plenty at Lake Poli. Use your hammer to knock it from the trees, and use a charged-up attack/better hammer for more and higher level fruit. Erik will always sell whatever fruit is currently in season, and Rita will always sell whatever fruit was from last season at the bar.
Besides that, it may be possible to get them rarely from chests, but I don't know if all of them can be obtained this way. I do know for a fact I got an orange once from a treasure chest on Whale Island, though. If I remember correctly, it was from one of the three chests outside the entrance to the Tower of Glory. I'll see if I can get another one from there, or any other kinds of fruit. --- "There is nothing sad about being of a fragile race." -Diana, Legend of Mana
Oh, it turns out you can win all the seasonal fruit if you take first place at the quiz game. How many you get depends on the final tallies XD That was a hilariously fun festival; definitely my favorite of any HM/RF I've played. --- "There is nothing sad about being of a fragile race." -Diana, Legend of Mana