W.F. Millier, R.A. Pellerin, A.N. Lakso
Damage to fresh market apples during detachment by conventional inertial shaking can reduce marketable grades by up to 25 per-cent. It was hypothesized that a more precise control of the shaking action would reduce the detachment damage. Spring-activated trunk and limb impacting shakers were developed to provide the controlled shaking.

The trunk shaker produced two impacts, each separately adjustable for impact energy, in time controlled sequence. When the trunk reached maximum displacement from the first impact the second impact was applied to move the trunk in the opposite direction. The time between the two impacts was small, around 0.025 seconds, and varied with impact energy. The trunk shaker harvested fruit from open center McIntosh/MM.104 and MM.111, open centered Mutsu/MM.111 and "Y" trellised Red Delicious/MM.111 trees. The double impact trunk shaking increased for each successive shake. Impact energy could be varied from 150 to 1250 joules. The energy level used was determined by trunk size.

The spring activated under limb shaker harvested fruit from the "Y" trellised Red Delicious trees. The limb shaker was a continuously operating unit and impacted the limb three to four times to remove the fruit. The velocity of the impactor was approximately 285 cm/sec. Fruit was sampled from a quilted, plastic bead filled collecting pad placed under the tree. The results in terms of market grades and damage per apple are summarized below.

Grades of Fruit Harvested by Various Shaking Methods

  Extra         Skin Stem End
Variety Fancy Fancy Utility Culls Bruises* Breaks* Punctures*
  % % % % # # #

    Double Impact Trunk Shaking    
McIntosh 74.8 5.5 2.7 17.0 0.48 0.21 0.09
Mutsu 75.1 8.5 5.4 12.9 0.68 0.15 0.08
Red Delicious 77.2 5.3 4.4 13.1 0.45 0.15 0.06
    Under Limb Impact Shaking    
Red Delicious 92.7 0.5 0 6.8 0.18 0.10 0.04
    Inertial Trunk Shaking    
McIntosh** 59.4 15.9 4.4 20.2      
Mutsu 48.1 15.0 16.9 20.1 1.51 0.15 0.03
Red Delilious** 65.9 12.6 2.5 10.0      

*Number per apple

**Test Conducted in 1977

Millier, W.F., Pellerin, R.A. and Lakso, A.N. (1981). APPLE DETACHMENT BY IMPACT SHAKING. Acta Hortic. 114, 244-244
DOI: 10.17660/ActaHortic.1981.114.34

Acta Horticulturae