Ambjent Malta and Heritage Malta are implementing a conservation plan to protect an olive grove in Bidnija that includes trees that are more than 600 years old and are of antiquarian value. The olives are protected under the provisions of the Trees and Woodlands Protection Regulations (2011), as per Government Notice number 473/11, and the site is a scheduled Tree Protection Area, Area of Ecological Importance and Site of Scientific Importance.
The conservation plan includes occasional pruning of dead branches, restorative pruning, the testing for pests including Xylella fastidiosa, genetic testing and polyphenol content in collaboration with the University of Malta, fire prevention measures and the restoration of dilapidated rubble walls.
One of the main conservation actions is the propagation of these trees through air layering methodology. Air layering is a method of growing rooted saplings directly on the branches of a parent plant. This is carried out as follows:
• The first step of the air layering process involves taking a grafting knife and stripping the bark from a small section of a branch, with the approximate thickness of a pencil. In order to prevent infection of the cut stem, all tools utilised are properly sterilised prior to use and likewise potting medium must be fresh and sterilised.
• Once cut, rooting hormone are applied to the section stripped of bark. The cut stem is then dressed with a thin plastic bag, leaving holes at each end for the remainder of the parent branch.
• The plastic bag is then filled with wet compost, and secured to the branch using agricultural grade tape. A hole is poked at the top and bottom of the bag to allow water seepage. Additionally, the compost is periodically moistened by light watering with a conventional watering can.
• This process is carried out starting mid-March, when plants start generating new growth, having been dormant during the winter months. After several months, typically early summer, the status of root development is checked by cutting open the bag and identification of any new and healthy saplings. If no new growth is identified, the cut section is covered with a fresh bag filled with wet compost and re-checked after a couple of weeks.