Topworking

Topworking is a grafting technique used in horticulture to change or improve the characteristics of a fruit tree or ornamental plant. It involves grafting a scion, or a cutting from a desired variety, onto the upper branches of an established rootstock. This is typically done when the rootstock is already mature and has developed a robust root system. The primary purpose of topworking is to introduce a new fruit variety onto an existing tree, such as changing apple varieties on an old tree, or to improve pollination by adding a compatible pollinator variety. It can also be used to introduce disease-resistant rootstock characteristics to a less resistant scion.

The process involves carefully selecting and preparing both the scion and the rootstock. The scion is usually taken from a healthy, mature branch of the desired variety. The branches of the rootstock where the graft will be made are typically cut back to encourage new growth. Common grafting methods used in topworking include whip and tongue grafting, cleft grafting, and bark grafting. The success of the graft depends on the cambium layers of the scion and rootstock being aligned, allowing them to fuse and form a vascular connection. This union enables the scion to receive water and nutrients from the rootstock, eventually leading to the growth of the new variety.

Topworking is a valuable tool for orchard management and plant propagation, offering a way to rejuvenate old trees, diversify fruit production, and introduce desirable traits without the need to replant entire trees. It can take several years for a topworked tree to produce significant fruit, as the scion needs time to establish and mature.