 Ascorbic acid is vitamin C, which is essential for repairing tissues and absorbing iron.Various "Prunus" species are winter hosts of the Damson-hop aphid, "Phorodon humuli", which is destructive to hops "Humulus lupulus" just at the time of their maturity, so plum trees should not be grown in the vicinity of hop fields.Corking is the drying or withering of fruit tissue.