It is planned that with end of the event all pumpkin fields are deleted.
That will destroy my collection of 3 years. (http://prntscr.com/8v35ro)
To avoid that I have come up with the following solutions:

1)
The amount of pumpkins is set to 0. The graphics for a depleted pumpkin field is changed from that of a depleted field to that of a pumpkin field.

2)
With end of event all existing pumpkin fields are given the status of decorative item.

3)
They could become a different item with different graphics, for example the smoke could cease and the pumpkin cemeteries could be called rotten pumpkin field.

I do not believe any of this becoming true. I just wanted to show that there would have been ways to avoid destroying the cemeteries without giving the players with old cemeteries an advantage at next halloween event if only there had been given some thought to it.