Disuse as prima facie evidence of abandonment. In all cases arising under ORS 97.870 to 97.900, the fact that the owner, holder or interested party, of the unused and unimproved portion of the cemetery has not, for a term of 20 years or more, used the plot and has failed to keep it clear of weeds or brush is prima facie evidence that the owner, holder or interested party has abandoned it

ORS 97.910 — under Chapter 97.