<Is the original graft union below the soil line? If the graft union becomes covered with soil, the scion cultivar will root, possibly send up suckers, and the dwarfing habit induced by the rootstock will be lost.>
No the graft is above ground level. The sucker is from the rootstock. Good
question though.
Chris Mauchline SE PA, zone 6 40° 5' N 75° 51'W ~650 ft elevation