Trunk chopping and leader selection: building taper in segments

A trunk with real taper is not grown, it is assembled — one segment at a time, each one thinner than the last, with a change of direction at every junction. Trunk chopping is the method, and leader selection is the decision that determines whether the next three years produce taper or a kink.

Why chop to a third and not to a half

Taper is a ratio: the trunk should be roughly twice as thick at the base as it is at the first branch, and each segment above that should reduce again. If you chop at half the final height, you have only one more segment to work with and the finished trunk will be a cone rather than a taper. Chopping at about a third gives at least two more chop-and-regrow cycles, each adding a segment, and each cycle adds interest because the direction of the trunk changes at the junction. On a tree destined for 45 cm, that means the first chop is at 15 cm.

Choosing the leader: three criteria, in order

First, direction: the shoot must already point where the trunk should go, because a leader that has to be bent into position will leave a straight section and then a curve, which reads as a fault. Second, vigour: the thickest of the candidate shoots will grow fastest and close the wound soonest. Third, height on the trunk: the lowest suitable shoot gives the best taper ratio above the chop. When these three conflict — and they often do — direction wins, because a wrong direction is permanent and slow growth is temporary.

The wound, and where it should end up

The chop wound will take three to six years to close on a vigorous deciduous tree, and it will always be visible as a change in bark texture. That is why the chop is planned so the wound faces away from the front. Where a chop has to be on the visible side, the wound is made as small as possible by cutting close to the chosen shoot, and the resulting scar is used to suggest age rather than hidden. Cut paste is applied to the rim of the wound, where the callus will form, and not over the whole face.

The unchecked season, and why it matters

The single most common mistake after a chop is to start wiring and pruning the new leader in its first season. That season is the one in which the leader has to (a) grow tall enough to add girth to the section below it and (b) begin closing the wound. Cutting it back or wiring it in year one slows both. The rule here is one full season completely unchecked, then the first selection of side shoots in the following winter, and only then the next chop when the new section has reached the target thickness.