Cherry harvesting equipment costs between $5,000 and $7,000. AERD esti- 

 mates that if a grower has at least 2,250 trees (about 25 acres) and harvests about 

 100 pounds of cherries from each tree, he could pay for the equipment in about II/2 

 years. If the equipment were depreciated for 3 years (it would last much longer 

 under normal use), a grower who had only 15 acres of cherry trees could normally 

 afford harvesting equipment. 



AERD also found that cherries could be mechanically harvested with no more 

 bruising than normally occurs when cherries are picked by hand. Undergoing 

 mechanical shaking, falling through the tree, striking the collecting unit and rolling 

 over it to the conveyor bruised the cherries very little. Decelerator strips, how- 

 ever, are necessary over conveyors and desirable over catching surfaces. 



In three of six orchards mechanically harvested, about 2 percent of the cherries 

 retained their stems. In the other three, however, 7 percent retained their stems. 

 (Stem retention is undesirable in cherries destined for processing.) Causes for this 

 variation are not definitely known. In some tests, however, attachment was found 

 to vary with the maturity of fruit and the nature of shaking — the number of at- 

 tached stems decreased as cherries became riper ; mechanical shaking yielded fewer 

 with stems than manual shaking. AERD is investigating the possibility that a 

 relationship exists between stem attachment and the amount of nitrogen in the soil 

 or tree. A small percentage of stemmed cherries does not seriously hamper proc- 

 essing. 



Sweet Cherries 



A considerable portion of the sweet cherry crop is harvested for brining be- 

 fore the cherries are mature enough to go to the fresh fruit market or to the canner. 

 Mechanically separating such immature fruit from the tree requires rather violent 

 shaking and causes considerable bruising. None of 20 or more chemicals that AERD 

 tested to loosen the cherries before attempts at mechanical harvesting proved to be 

 satisfactory. 



Further AERD investigation, however, reveals that sweet cherries allowed to 

 reach full maturity increase in size and weight by about 31 percent and that such 

 mature cherries can be mechanically harvested. Whether they can be successfully 

 brined remains to be determined. 



AERD research also showed that sweet cherries can be handled in bulk boxes 

 at depths of 16 inches without loss in quality and with savings in time, labor, and 

 money. 



Plums 



Equipment used to harvest sour cherries mechanically can be used to harvest 

 Stanley Prune plums. Many growers in Michigan and elsewhere are profitably ex- 

 ploiting this fact since the two crops mature at different times. 



Compared to handpicking, mechanically harvesting Stanley Prune plums saves 

 the grower about 23 cents per bushel. About 80 trees yielding 5.1 bushels per tree 

 would justify spending $90 for the use of mechanical harvesting equipment. 



When AERD experimentally harvested 39 Stanley Prune plum trees, 3.1 per- 

 cent of the plums were severely bruised and an additional 4.2 percent were slightly 

 bruised. Leaves and twigs that shook off with the plums accounted for 2.7 percent 



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