MECHANICAL HARVESTING OF STANDARD HEDGEROW AND OF INTENSIVE PRUNE ORCHARDS

Attemps to mechanically harvest the prune cv. "Stanley", in both medium (625 trees/ha) and relatively high density plantings (1000 trees/ha), have been carried out using the ICA-University of Bologna harvester.

The trees (8 and 6 years old) on Myrobalan, were trained as standard hedgerows (palmette) in the m.d. planting (distance 4 x 4 m); and as irregular palmettes, free spindle and double trellis-Ypsilon in the h.d.planting (distance 5 x 2 m).

The yield per tree was 86.7 kg in the medium density planting and 35.8, 40.0 and 45.7 kg per tree respectively for the 3 different training systems of high density planting.

Data were recorded on the working times of the harvester, on the output of its trunk-shaker and equipment (3 men) and on the quality of the harvested fruits. Mechanical harvesting was faster in the standard hedgerow orchard with an average of 28 trees/hr, reduced to 25 trees/hr in the palmette h.d.p.

For the free spindle and double trellis the operating capacities were reduced to 15 and 12 trees/hr respectively, because of the low branches which handicap mechanical harvesting. The percentages of fruits caught by the frames were 91.7 and 90.2 % for the palmette trees, intermediate for the free spindle trees (85.8 %) and less for the double trellis trees (75.4 %). The remaining fruits were lost mainly on to the ground because of the flattened shape of the palmette trees, or remained on the trees because of the strenght of the wire structure of the double trellis.

A high percentage of undamaged fruits (92.3 %) was obtained from the free spindle shape, which should be more suitable for mechanical harvesting. With the palmette this percentage ranged from 83 to 88 %, only slightly less than for hand harvesting and practically equal to that for the mechanical harvesting of the double trellis trained trees.

On the whole, our data indicates that mechanical harvesting of h.d.p. and standard prune orchards is feasible. The two units prototype of the harvester, which were built to operate for both standard hedgerow and sigle vase shaped trees, worked more rapidly in the former. Even though fruit damage was slightly greater for the hedgerow systems, it was always within acceptable limits for the processing industry (dried fruit) and even within the limits acceptable for the fresh fruit market if prior selection of the fruit was done.