291 Influence of Canopy Density on Efficiency of Trunk Shaker on Olive Mechanical Harvesting A. Tombesi, M. Boco, M. Pilli and D. Farinelli Department of Arboriculture and Plant Protection, University of Perugia, Italy atombesi@unipg.it Keywords: tree vibration, pruning intensity and interval, leaf area index. Abstract On 10-year-old trees of Frantoio, planted at 5x5m and trained to vase, a light, moderate and heavy pruning was applied at intervals of 1, 2 and 3 years. In 1998, in conditions of high crop load and at the third year of trial, trees with the complete range of treatments were available. The tree production on annual pruning was 6.9, 11.5, and 20.83 kg for heavy, moderate and light pruning; for intervals of 2 and 3 years the yields were higher than 20 kg for light and moderate pruning, while for heavy pruning it was about 17 kg. On these conditions the trunk shaker showed a significant increase in percentage of fruit removal from light to heavy annual pruning, passing from 82.76% to 93.66%. On trees pruned at intervals of 2 and 3 years the average fruit removal was 84%, with the tendency to have better results when heavy pruning was used. Therefore the trunk shakers were effective for mechanical harvesting of medium sized trees, during an optimal harvesting period for oil quantity and quality. The moderate and heavy annual pruning helped mechanical fruit harvesting because of a larger fruit size, a less dense canopy, a regular distribution without bundling and overlapping of fruity shoots. However in trees with longer intervals of pruning good results were also obtained. INTRODUCTION Reducing production costs is a major objective in all olive-producing countries in order to be more competitive on the world market. Some cost cuts are possible by reducing harvesting and pruning expenses, which exert the greatest weight on overall costs. For harvesting, trunk vibrators have the greatest working capacity, and their use should be encouraged (Tombesi, 1989b). For pruning, simple practices have been adapted at different intervals in an attempt to find economic solutions without altering production (Tombesi 1989a). Therefore, the efficiency of the shaker was evaluated in relation to different methods of pruning in order to better understand how the two cultivation techniques interfere and how they can be applied. MATERIALS AND METHODS Ten-year-old trees of the cultivar Frantoio planted at 5x5 m and trained according to the vase system were used. Starting in 1996, they were subjected to a factorial design of pruning in which comparisons were made between pruning done annually, every two years and every three years at different intensities (light, medium and heavy) to find the combinations which gave the best productive and economic results. In 1998, the trials were comprised of three sectors: an annual pruned, a biennial (pruned in 1997) and a triennial (pruned in 1996) sector. In the spring, after pruning in the annual sector, the pruned wood was weighed. Using 3 trees per combination, the leaf area index (LAI) was then determined by counting the leaves that came into contact with a vertical metal pole, which was moved in a 25x25 cm grid until the entire crown was covered. At harvesting, the crown volume and the size and height of the trunk were measured. The fruit detachment force was measured on 100 drupes per tree on 6 trees with a Carpo dynamometer. For the harvest, a trunk shaker with multidirectional and orbital vibrations with variable frequency was used that was mounted on an 80 HP caterpillar tractor. The olives were collected on nets placed under the tree and those removed by the shaker or remained on the tree were then weighed. An olive sample was taken to determine the unit Proc. 4 th IS on Olive Growing Eds. C. Vitagliano & G.P. Martelli Acta Hort. 586, ISHS 2002