Total strawberry production in both Canada and the United States has been steadily declining for the past decade. This trend can, to a large extent, be attributed to the increasing cost and difficulty of getting this crop manually harvested. This research, therefore, is directed toward development of a mechanical harvesting system for strawberries. During initial development of any new concept, a system analysis should be undertaken to ensure that excessively complicated problems will not arise unexpectedly and to ensure that redundant research is not undertaken. Such an analysis indicated that the development of a once-over harvesting system is more feasible than the development of a selective harvesting system. The analysis also indicated that system development will require input from engineers, fruit growers, fruit processors and horticulturalists. An attempt is made to allocate appropriate areas of investigation and research to each of these groups. Group interactions are also investigated. To successfully develop the proposed system, one essential step is development of a mechanical picking machine. A design, based on the physical and mechanical properties of the strawberry fruit and plant, was used to build a picking -machine model. This model was field tested and evaluated. Limited field tests indicated that some field preparation for mechanical harvesting is essential and that a vacuum fruit pick up device should be considered to assist machine feeding. Tests indicated, however, that the proposed concept can be used to remove berries from the plant with very little fruit damage. / Land and Food Systems, Faculty of / Graduate

At its peak, Oregon produced 21 percent of the nation's total commercial strawberry production. However, since 1971, Oregon's share of strawberry production has been declining steadily. In fact, for the last three years strawberry production in Oregon constitutes only 8 percent of the nation's total production, which is the lowest since the end of the Korean War (Figure 1). Among other factors, the increase in harvest cost without an offsetting increase in the farm prices of strawberries, is the main cause for the continuing decline of strawberry production in Oregon. Decrease in the supply of strawberry pickers is the main cause for the upward trend of the strawberry harvest cost in Oregon. Particularly, since 1973, due to enactment of the child labor law, the shortage in the supply of strawberry pickers in Oregon has intensified, causing further escalation in harvest cost. Thus, in order to alleviate the problems associated with harvest cost, since 1967, Oregon has been actively seeking to mechanize its strawberry harvest. The principal objective of this thesis has been to evaluate the economic feasibility of mechanical strawberry harvest in Oregon. As demonstrated in Chapter V, depending on the assumptions about the quality and the average yield of the strawberry varieties that would eventually be harvested mechanically, and the efficiency of the harvester; the expected savings per acre to the strawberry growers from the use of mechanical harvester was shown to range from a net saving of $523.50 to a net loss of $186.76 (Table 9). Even though negative savings are shown to appear when extremely unfavorable conditions are assumed, in the majority of cases discussed in Chapter V, the implementation of mechanical strawberry harvesting in Oregon is found to be associated with significant positive returns to the growers. In addition, in Chapter VI, under certain conditions which are expected to prevail if mechanization of strawberry harvest become a reality in Oregon, the annual gross and net 'social rate of returns' were estimated to be 330 percent and 95.7 percent respectively. The difference between the gross and net social rate of return is the wage loss of the displaced workers. Based on the above social return figures and the estimated savings to the growers, it appears that mechanical strawberry harvesting is an economically viable alternative that could eventually solve the problem of the growing shortage of strawberry pickers in Oregon. / Graduation date: 1978