To reproduce the characteristics of a preferred strain, air-layering has been successfully practiced on a small scale. All offshoots except the lowest one are girdled and layered after the parent plant has produced the first crop of fruit. Later, when the parent has grown too tall for convenient harvesting the top is cut off and new buds in the crown are pricked off until offshoots from the trunk appear and develop over a period of 4 to 6 weeks. These are layered and removed and the trunk cut off above the originally retained lowest sprout which is then allowed to grow as the main stem. Thereafter the layering of offshoots may be continued until the plant is exhausted.