from growing into lateral 

 shoots. In this experiment, we 

 measured terminal length, 

 terminal diameter, and the 

 time required for dormant 

 pruning. Not surprisingly, 

 ethephon did not significantly 

 alter terminal growth, but it 

 did reduce the time required 

 for dormant pruning of Deli- 

 cious by approximatlely 25%, 

 which likely was related to a 

 reduction in the number of lat- 

 eral shoots produced from 

 spurs. 



When used on excessively 

 vigorous, young trees that are 

 essentially nonbearing, ethep- 

 hon may be very effective at 

 reducing all excessive vegeta- 

 tive growth, but indirectly, 

 since it can stimulate flower 

 bud formation. In this way, 

 the tree can be shifted from a 

 vegetative habit to a bearing 

 habit the year after ethephon 

 application. In our experi- 

 ment, we were using mature, 

 bearing trees, so this was not a 

 factor. 



Very importantly, the ef- 

 fects of spring-applied ethep- 

 hon were apparent in the fall. 

 Figures 1 and 2 show the fruit 

 drop that occurred from ethep- 

 hon-treated and untreated 

 trees. Overall, for ethephon- 

 treated trees, drop was nearly 

 double that of untreated trees. 

 Fruit from ethephon-treated 

 trees also ripened sooner (Fig- 

 ure 3), and for Mcintosh, they 

 were significantly smaller 

 than fruit from untreated 

 trees (Figure 4). 



In conclusion, several 

 points should be understood 



9/15 9/20 9/25 9/30 



Date of 1 ppm ethylene 



10/5 



Figure 3. Effects of spring-applied ethephon on the time 

 of ripening of fruit from Gardiner Delicious/MM.106 

 trees and Rogers Red Mclntosh/MM.106 trees. 



Average count per 42-lb box 



140 



130 



120 



110 



100 



90 



80 





&tt«ph*m 



y >jk 



^ioi^^i^^S^^^ 



Cont|t)l 



Ethephon 



Delicious 



Mcintosh 



Figure 4. Effects of spring-applied ethephon on size, 

 presented as average counts per 42-lb. box, of fruit from 

 Gardiner Delicious/MM. 106 trees and Rogers Red Mcln- 

 tosh/MM.106 trees. 



12 



Fruit Notes, Fall, 1993 



