The frequency and amplitude of the shaking movements
are some of the most important factors involved in the
detachment of these fruits. In theory, natural frequencies
cause the highest fruit displacements and therefore the
highest detachment percentages are expected, but in practice
Adrian and Fridley (1958) and Diener, Levin, and
Whittengerger (1968) found that shaking at the natural frequency
of most fruit was not very effective, with greater effi-
ciency being achieved using higher frequencies. Similarly,
Lenker and Hedden (1968) noted that citrus detachment increases
with frequency