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The Swiss pine is a member of the white pine group, Pinus subgenus Strobus, and like all members of that group, the leaves ('needles') are in fascicles (bundles) of five, with a deciduous sheath. The mature size is typically between 25 metres (82 ft) and 35 metres (115 ft) in height, and the trunk diameter can be up to 1.5 metres (4.9 ft).
This fungal disease affects the needles of conifers, but is mainly found on pine. Over 60 species have been reported to be prone to infection and Corsican Pine (Pinus nigra ssp. laricio) is the most susceptible species in Great Britain. [3] It was first recorded in Britain on Corsican pine in 1954 in a nursery in Dorset.
The chilling requirement of a fruit is the minimum period of cold weather after which a fruit-bearing tree will blossom productively. It is often expressed in chill hours, which can be calculated in different ways, all of which essentially involve adding up the total amount of time in a winter spent at certain temperatures. [1] [2]
Cold hardening is a process in which a plant undergoes physiological changes to avoid, or mitigate cellular injuries caused by sub-zero temperatures. [1] Non-acclimatized individuals can survive −5 °C, while an acclimatized individual in the same species can survive −30 °C.
The most important tree for use in resin extraction is the black pine (Pinus nigra), which has the greatest resin content of all of the European coniferous trees, and it was even used as early as by the Romans for this very purpose. [2] These trees are generally best tapped for their resin between the ages of 90 and 120 years old.
In temperate regions of the northern hemisphere where cold temperatures are expected seasonally and are usually for long periods of time, the main strategy is freeze avoidance. In temperate regions of the southern hemisphere, where seasonal cold temperatures are not as extreme or long lasting, freeze tolerance is more common. [ 2 ]
Thermotropism or thermotropic movement is the movement of an organism or a part of an organism in response to heat or changes from the environment's temperature. A common example is the curling of Rhododendron leaves in response to cold temperatures.
The temperature of the preservative in the hot bath should be between 60 to 110 °C (140 to 230 °F) and 30 to 40 °C (86 to 104 °F) in the cold bath (depending on preservative and tree species). The average penetration depths achieved with this process ranges from 30 to 50 mm (1.2 to 2.0 in).