Familiarity with the propagation technique of layering is a valuable horticultural skill.

Propagation by layering has a rich history in Europe, particularly in the production of hazels and magnolias, systems that can still be seen in England and Holland, and of fruit tree rootstocks in the states of Oregon, Washington, and the province of British Columbia. In the past, layering was the preferred method of propagating woody plants that needed to be propagated vegetatively (cloned) and on their own root systems, but that were difcult to root from stem cuttings. For certain plant species or cultivars, grafting was not convenient or not desirable (e.g., if there were a high incidence of rootstock suckering). Many of the shrubs that are now rooted under mist and grown in containers were layered in the past. Most growers now consider layer propagation too labor intensive. Yet, the majority of apple and pear rootstocks are still produced by the tens of thousands in extensive stool bedding elds. The mounding and harvesting processes

Concept Box 24.1

that are considered too laborious for many crops, in this instance, are now highly mechanized.