Conelet abortion in longleaf pine (Pinuspalustris L.) ranged from 85 to 100% in 4 of 5 years in a clonal seed orchard in southeastern North Carolina. Investigation of the cause of the malady was inconclusive, but freeze damage, seed bugs, and inadequate pollen supply were excluded as principal causes. Where combinations of balanced fertilizers and ammonium nitrate had been used in the orchard, abortion was variable by clone, with some clones showing more abortion under higher fertilizer regimes.