before ethephon is used to retard growth of 

 mature, bearing trees: 1) ethephon is a poten- 

 tial thinner, so significant thinning may result if 

 appropriate conditions exist; 2) extension 

 growth may not be reduced dramatically, but 

 lateral shoot development may be reduced, pro- 

 ducing more of a spur-type growth habit and 

 reducing the time required to dormant prune 

 trees; 3) ripening may be advanced and drop 

 may be increased, so plans must be made to 

 harvest ethephon-treated trees earUer than 

 normal; and 4) fruit size may be reduced. The 

 potential reduction in size is of major concern 

 and may negate any positive effects of ethephon 

 treatment on bearing trees. 



A strategy that was used with Alar® was to 



direct the spray into the top, vigorous portions of 

 the canopy. Using this technique, carryover 

 effects and reduction in fruit size were mini- 

 mized. This approach may not work with ethe- 

 phon, since it would cause finiit in the top of the 

 tree to ripen earlier than the rest, making har- 

 vest troublesome and possibly resulting in dam- 

 age to lower fruit from upper frmt dropping 

 through the canopy. 



For vigorous,nonfruiting trees, ethephon 

 may be more beneficial than for bearing trees. 

 In young trees, its major positive response is to 

 initiate flower bud formation. The season fol- 

 lowing the ethephon treatment should see en- 

 hanced finiit production and, therefore, less veg- 

 etative growth. 



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Fruit Notes, Fall, 1993 



13 



