At ECHO NARIC we have had the best success cleft grafting young Black Sapote rootstock with young terminal Black Sapote budwood.
Because Black Sapote in particular seems to keep the growth habit of it’s position on the scion tree we are careful to select budwood only from branches with upright growth habits or or grafted trees will always need management to keep them growing straight.
Ideal budwood is using terminal buds. Look for buds that is swollen at the bottom, but have not started to push a leaf. We think they look like little talons or hooks. It is important that the leaves around the bud are hardened off and dark green.
