Eucalyptus Foliage Production

Abstract

The main objective of this project was to determine, for the main species of Eucalyptus grown in the south west of Ireland (Kerry), the best means of pruning to optimise marketable juvenile foliage production and quality over the crops life cycle. The majority of the trials were carried out in Co. Kerry where a higher concentration of production is located. The favourable climate and light acid soils in this region promote satisfactory growth and enables harvesting to take place from autumn to March which is the premium period. Results of extensive trials over a four year trial period showed that new plantations should not be pruned until the end of the second growing season to allow the trees to become well established and help build up photosynthetic food reserves and prevent tree losses. However in some situations where very vigorous growth was achieved during the first growing season a very light pruning at 1.3 m high helped stabilise trees. After the second year's growth, pruning back to a height of 1.2 m consistently produced the highest marketable production of quality juvenile foliage of Eucalyptus species pulverulenta, perriniana, parvifolia, and 'Glaucescens' over the trial period. Pruning back to this level helped develop a single or multiple main stem framework (2-3 stems) for future production purposes, providing a nice manageable tree facilitating not only harvesting but other technical operations such as pruning and spraying. It was found that more severe pruning, especially back to 15-25 cm from the ground, reduced output and in some cases quality but was responsible for significant tree losses varying from 8-12% in the second growing year to over 30% losses with four year plantations, with further losses of 5-10% expected as well because of very weak plants. The main recommendations of this study are that no pruning be carried out for the first two growing seasons and thereafter a relatively light pruning of all main framework leaders back to 1.2 m high after the winter period. As the plantations grew older, stronger side branches could be shortened and later still could be removed to facilitate management of the crop. The light pruning treatments to 1.2 m high in contrast to the most severe pruning regimes produced no significant tree losses in the main production areas in Co. Kerry and would appear to be the most sustainable system of pruning management over the crops life cycle.