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The Honolulu Advertiser
Posted on: Friday, February 8, 2008

Duplicate fruit trees with air-layering

By Jari Sugano and Steve Fukuda

Fruit trees propagated from seed often take years to become fully productive. It is further disappointing to propagate plants by seeds only to discover the fruits are nothing like the parents you remember. air-layering is one way to propagate difficult-to-root plants in a shorter period of time.

Air-layering is a vegetative process which allows roots to develop on the stem of a tree while it is still attached to the parent. Since it is a vegetative process, the newly air-layered plant has the same characteristics (taste, color, seasonality, size) as its parent plant.

Another advantage of air-layering plants is that they have ability to bear fruit a few years after planting.

Popular fruit trees such as lychee, longan, mountain apple and citrus, as well as many ornamental crops, can be air-layered.

Select branches that are approximately 1/3 to 1 inch in diameter. Using a sharp knife, make a circular cut around the selected branch. Make a second cut approximately one inch away from the first cut. Remove the ring of bark. Scrape the cambium layer (just under the bark) off from the exposed woody area with a knife. It is important that all of the cambium (slimy material) is scraped off to force roots to be initiated.

Moisten and squeeze a handful of sphagnum moss to serve as the rooting medium. It is important to retain the proper amount of moisture. Do not squeeze too much moisture out of the moss as it needs some for root development. On the other hand, too much water creates waterlogged conditions; there is no oxygen for root development. Cover the exposed woody section with the moss, wrap moss with a piece of plastic, and tie tightly at both ends so proper moisture level is retained. Cover the plastic wrap with aluminum foil to eliminate light.

Rooting hormone may be applied to the girdled area to encourage rooting. Three to four months later, roots should be visible through plastic wrap. Cut below the root ball and place in a bucket of water.

Careful handling of roots is necessary when moving newly layered plants into planting containers. Plants should be severely pruned back and put in a shaded area, high in humidity, to "harden" off.

As new growth appears, plants can be slowly introduced to more sunlight.

Air-layering is not difficult to do, but it does take practice.